unit 1 Water cycle

The water cycle, also known as the hydrologic cycle, describes the continuous movement of water on, above and below the surface of the Earth. Since the water cycle is truly a "cycle," there is no beginning or end. Water can change states among liquid, vapor, and ice at various places in the water cycle. Although the balance of water on Earth remains fairly constant over time, individual water molecules can come and go.Contents

Description

The sun, which drives the water cycle, heats water in the oceans. Water evaporates as vapor into the air. Ice and snow can sublimate directly into water vapor. Evapotranspiration is water transpired from plants and evaporated from the soil. Rising air currents take the vapor up into the atmosphere where cooler temperatures cause it to condense into clouds. Air currents move clouds around the globe, cloud particles collide, grow, and fall out of the sky as precipitation. Some precipitation falls as snow and can accumulate as ice caps and glaciers, which can store frozen water for thousands of years. Snowpacks can thaw and melt, and the melted water flows over land as snowmelt. Most precipitation falls back into the oceans or onto land, where the precipitation flows over the ground as surface runoff. A portion of runoff enters rivers in valleys in the landscape, with streamflow moving water towards the oceans. Runoff and groundwater are stored as freshwater in lakes. Not all runoff flows into rivers. Much of it soaks into the ground as infiltration. Some water infiltrates deep into the ground and replenishes aquifers, which store huge amounts of freshwater for long periods of time. Some infiltration stays close to the land surface and can seep back into surface-water bodies (and the ocean) as groundwater discharge. Some groundwater finds openings in the land surface and comes out as freshwater springs. Over time, the water returns to the ocean, where our water cycle started.

Different Processes

Different Processes

PrecipitationCondensed water vapor that falls to the Earth's surface. Most precipitation occurs as rain, but also includes snow, hail, fog drip, graupel, and sleet.[1] Approximately 505,000 km 3 (121,000 cu   mi ) of water fall as precipitation each year, 398,000 km3 (95,000 cu mi) of it over the oceans.[2]

Canopy interceptionThe precipitation that is intercepted by plant foliage and eventually evaporates back to the atmosphere rather than falling to the ground.

SnowmeltThe runoff produced by melting snow.

RunoffThe variety of ways by which water moves across the land. This includes both surface runoff and channel runoff. As it flows, the water may infiltrate into the ground, evaporate into the air, become stored in lakes or reservoirs, or be extracted for agricultural or other human uses.

Infiltration

The flow of water from the ground surface into the ground. Once infiltrated, the water becomes soil moisture or groundwater.[3]

Subsurface FlowThe flow of water underground, in the vadose zone and aquifers. Subsurface water may return to the surface (eg. as a spring or by being pumped) or eventually seep into the oceans. Water returns to the land surface at lower elevation than where it infiltrated, under the force of gravity or gravity induced pressures. Groundwater tends to move slowly, and is replenished slowly, so it can remain in aquifers for thousands of years.

EvaporationThe transformation of water from liquid to gas phases as it moves from the ground or bodies of water into the overlying atmosphere.[4] The source of energy for evaporation is primarily solar radiation. Evaporation often implicitly includes transpiration from plants, though together they are specifically referred to as evapotranspiration. Total annual evapotranspiration amounts to approximately 505,000 km3 (121,000 cu mi) of water, 434,000 km3 (104,000 cu mi) of which evaporates from the oceans.[2]

SublimationThe state change directly from solid water (snow or ice) to water vapor.[5]

AdvectionThe movement of water — in solid, liquid, or vapor states — through the atmosphere. Without advection, water that evaporated over the oceans could not precipitate over land.[6]

CondensationThe transformation of water vapor to liquid water droplets in the air, producing clouds and fog.[7]

TranspirationThe release of water vapor from plants into the air. Water vapor is a gas that cannot be seen.

Residence times

Human activities that alter the water cycle include:

agriculture

industry

alteration of the chemical composition of the atmosphere

construction of dams

deforestation and afforestation

removal of groundwater from wells

water abstraction from rivers

Average reservoir residence times[8]

Reservoir Average residence timeOceans 3,200 yearsGlaciers 20 to 100 yearsSeasonal snow cover 2 to 6 monthsSoil moisture 1 to 2 monthsGroundwater: shallow 100 to 200 yearsGroundwater: deep 10,000 yearsLakes (see lake retention time) 50 to 100 yearsRivers 2 to 6 monthsAtmosphere 9 days

urbanization

[edit] Effects on climate

The water cycle is powered from solar energy. 86% of the global evaporation occurs from the oceans, reducing their temperature by evaporative cooling. Without the cooling effect of evaporation the greenhouse effect would lead to a much higher surface temperature of 67 °C (153 °F), and a warmer planet.[12]

Effects on biogeochemical cycling

While the water cycle is itself a biogeochemical cycle,[13] flow of water over and beneath the Earth is a key component of the cycling of other biogeochemicals. Runoff is responsible for almost all of the transport of eroded sediment and phosphorus [14] from land to waterbodies. The salinity of the oceans is derived from erosion and transport of dissolved salts from the land. Cultural eutrophication of lakes is primarily due to phosphorus, applied in excess to agricultural fields in fertilizers, and then transported overland and down rivers. Both runoff and groundwater flow play significant roles in transporting nitrogen from the land to waterbodies.[15] The dead zone at the outlet of the Mississippi River is a consequence of nitrates from fertilizer being carried off agricultural fields and funnelled down the river system to the Gulf of Mexico. Runoff also plays a part in the carbon cycle, again through the transport of eroded rock and soil

Urban ecosystems are the cities, towns, and urban strips constructed by

humans.

This is the growth in the urban population and the supporting built infrastructure has impacted on both urban environments and also on areas which surround urban areas. These include semi or 'peri-urban' environments that fringe cities as well as agricultural and natural landscapes.

Scientists are now developing ways to measure and understand the effects of urbananisation on human and environmental health.

By considering urban areas as part of a broader ecological system, scientists can investigate how urban landscapes function and how they affect other landscapes with which they interact. In this context, urban environments are affected by their surrounding environment but also impact on that environment. Knowing this may provide clues as to which alternative development options will lead to the best overall environmental outcome.

CSE's urban ecosystem research is focused on:

* Understanding how cities work as ecological system * Developing sustainable approaches to development of city fringe areas that reduce negative impact on surrounding environments * Developing approaches to urban design that provide for health and opportunity for citizens.

IV. ENVIRONMENTAL IMPLICATIONSA. Ecological Planning / Sustainable Design

It seems appropriate to conclude by looking at the environmental implications of site planning. There is a burgeoning awareness of the critical need to change the American attitude toward land. Until recently we seemed to treat land as a disposable commodity, to be used and then discarded, moving on to a new site. This attitude is manifested by the “urban sprawl” that is prevalent in increasing patterns around our major cities. This phenomenon which has been widely reported on in recent years has resulted in, as Vincent Scully describes it, “that vast area in which most Americans now live, sprawled between the metropolitan center, which is emptying out, and the open countryside, which is rapidly being devoured” (qtd. in Katz 221).

Essentially, as America became more mobile as a result of the automobile, people began to move out of the city to the suburbs. This not only was the cause of urban decline, but it has placed an increasing demand on the conversion of rural agricultural lands to housing and other more intensive development. As our highway system expanded, people were able to commute greater and greater distances from their homes to their jobs in the city. This in turn soon led to the demand for more convenient retail, service, and recreational facilities closer to home. Eventually these decentralized clusters of commercial and office buildings outgrew the old cities that they surrounded. This phenomenon has resulted in what Joel Garreau has coined as “Edge Cities.” We now find that people are moving outward even farther from these nodes, creating yet another layer of sprawl. Peter Calthorpe discusses this situation, pointing out the irony that today, “the suburb-to-suburb commute represents 40% of total commute trips while suburb-to-city comprises 20%” (Katz xii).

In terms of public attitudes, we now seem to be realizing the folly of this spiraling uncontrolled growth. Once land is developed it is gone. As Mark Twain once said, “God’s not making any new land these days” (qtd. in Castillon 359). There are several anti-sprawl or “smart growth” movements currently gaining headway. In a recent Time Magazine article, there was a discussion of the political mobilization of smart growth on the local, state, and national levels. Vice President Gore is even being touted as the anti-sprawl candidate of 2000 (Lacayo 45).

People are beginning to see that sprawl is not simply a result of population growth, but equally the end product of a series of compounding factors. For example, local land use controls actually encourage new development on the fringes by making it easier and less expensive to build beyond existing development. Since local governments must generate funds to provide required infrastructure they are often in competition with one another for tax revenues. This creates an environment in which they are inclined to give preferential treatment to higher tax-producing land uses such as retail centers rather than residential uses. Large lot, low-density residential zones also discourage new development within the urban areas where land values are higher. The outlying lands – agricultural lands, woodlands, open space – are often the least resistant to development, physically and legally. Lastly, federal funds, through highway expansion programs, actually facilitate the movement outward from the city, making it easier for people to commute greater and greater distances.

The solution to this growing problem lies in an overall comprehensive approach such as we discussed earlier. Some communities have developed growth management programs that literally establish a ring around the city. New, compact, mixed land use development is channeled into designated “Growth Areas” within the ring. Outside of these “Growth Boundaries” growth is severely restricted, keeping sprawl out of open lands, preserving them for agriculture, woodlands, and recreation.

Such a program must be supported by stronger regulations. Local ordinances must be adapted to provide for higher density mixed land use growth within the urban boundaries. Policies also need to be established that encourage urban in-fill. There are several approaches to revitalization that provide financial incentives to homeowners and businesses to locate within the city through historic restoration or

adaptive re-use of existing buildings or sites. At the same time local and state planning regulations and policies can support growth management strategies by delineating environmental and conservation priorities. A commitment to conserve open space and critical habitats, supported by programs providing tax incentives, facilitates the decision of land owners to protect ecologically sensitive lands and encourages the developer to consider other options. From a regional perspective, alternatives to new highways, ranging from improvement of local roads to the development of mass transit systems, can significantly deter the impetus of sprawl.

While from an individual standpoint the current growth pattern may seem economically beneficial, the cumulative costs are not. Growth management techniques such as Urban Growth Boundaries work by treating “the city, its suburbs and their natural environment . . . as a whole – socially, economically, and ecologically . . .” (Katz xi). This is all part of a more proactive approach to planning for land development to simultaneously contribute to our quality of life while maintaining a sense of ecological integrity.

The concepts of ecological design and sustainable design, which support this newer approach, are used interchangeably. “Sustainability allows us to provide for present needs, while promoting long-term ecological and physiological health and productivity” (Motloch 267). Ecology is the study of the relationship of all living things to their biological and physical environments. Sustainable design is then “the intentional planning and design of human ecosystems through the application of ecological understanding, to make conscious informed decisions concerning conflicts between human and ecosystem needs” (Motloch 272).

Steiner proposes an ecological planning model that attempts to use “biophysical and sociocultural information to suggest opportunities and constraints for decision making about the use of the landscape” (Steiner 9-10). This model involves eleven interconnected steps, including:

1. Identification of issue or issues. 2. Establishment of a goal to address the issue(s). 3-4. Inventories and analyses of biophysical and sociocultural systems from the larger down to the specific level. 5. Detailed studies to link inventory and analysis to problem(s) and goal(s). 6. Development of concepts and options. 7. Preparation of a landscape plan. 8. Presentation to and response from affected public. 9. Development of detailed designs for individual sites. 10. Implementation of detailed designs. 11. Administration of plan.

(See Figure 20)

B. Environmentally Sensitive Design

1). Planning Level – On the regional level there are some approaches that can be implemented to provide for economic development while protecting the landscape character and minimizing the negative

environmental impacts of growth. The University of Massachusetts Center for Rural Massachusetts identified the Connecticut River corridor as a critical area vulnerable to mounting development pressures. The planners identified a number of significant issues ranging from soil erosion and stream sedimentation, to loss of natural resources, threats to agricultural lands, and incompatible historic and cultural impacts. After analyzing these issues, the University of Massachusetts group devised an approach for sensitive growth and development utilizing a series of legal controls and planning and design recommendations. One of these, Open Space Development Design (OSDD), utilizes optional or mandatory regulations to establish overlay zones. For example, a “Rural Preservation District” might be established that prohibits subdivision development from consuming more than 50% of any parcel. If the base density is 1 unit /10 acres, then the maximum lot size is five acres, with the remaining five acres permanently restricted from development. Using a sliding scale approach, as the area actually allocated for development decreases, the number of lots can increase (e.g., 60% open space would allow twelve 3.3 acre lots instead of ten; 70% open space twenty 1.5 acre lots instead of ten, etc.) (Arendt 226-230).

Transfer of Development Rights (TDR) is another flexible method in which areas suitable for development are designated as “receiving zones”, with increased use densities. At the same time, open farmlands and woodlands (or other protected areas) are designated as “sending zones”, in which the property owner may sell the development rights to build in the receiving zones. In return, the sending zones are retained in their undeveloped state, without unduly penalizing the property owner.

Another legal mechanism is the use of conservation easements. Conservation easements refer to the transfer of partial interest in property, either in the form of a gift or for a price, to a nonprofit or governmental entity. The conditions of the easement restrict the use of the land, the character of development or management conditions (i.e., to protect historic or scenic values, to retain the natural conditions, etc.) As a charitable contribution, the reduced price or donation of land provides a tax incentive for property owners to restrict development of environmentally sensitive lands.

These sorts of techniques provide the legal basis for the planners to address the issues created by increased development pressures. The University of Massachusetts group, among others, has proposed techniques for careful expansion while maintaining the rural countryside and cultural and historic regional patterns. Referred to as “Connecticut Valley Design Guidelines”, these include such creative development alternatives as:

a. Clustering residential development along the edge of the existing woodland to minimize the visual impact of growth on the open rural pastureland. b. Restricting lot sizes, development densities, architectural character, to respect the historic and cultural character of existing communities. c. Designating visually and environmentally sensitive areas as agricultural districts to restrict new growth from encroaching upon them. d. Restricting development adjacent to environmentally sensitive areas (river’s edge, wetlands, ridgelines, etc.) by zoning and or building restrictions to protect the resource and retain its scenic amenity. (Arendt 100-102)

The benefit of such techniques is to protect the rural landscape from uncontrolled or poorly controlled patterns of development over open fields or wooded hillsides. The growing acceptance of such approaches is due to the fact that they encourage sensitive development without restricting the overall growth potential of an area or penalizing the landowner from realizing a profit.

2). Site Design Level – There are many specific design recommendations that can be made at the scale of individual site design. These may relate to specific environmental issues such as energy and/or natural resource conservation or to cultural and aesthetic concerns. In essence, they are specific design guidelines that may be used to achieve the general goals established by the comprehensive planning and facilitated by the land use controls discussed earlier. They may include such general responses as:

a. Considering solar orientation when siting facilities to maximize the potential benefits of active and/or passive solar energy. One example of this would be to lay out a housing development with streets

running generally east-west to facilitate a north-south orientation of the houses.

b. Selecting and placing vegetation:

1) Utilizing deciduous trees adjacent to facilities to provide for cooling shade in the summer, while allowing for the benefit of solar warming in the winter. 2) Buffering prevailing winter winds with evergreen plant massing. 3) Channeling cool summer breezes into suitable exterior spaces of a development with masses of vegetation.

c. Considering facility placement to minimize energy costs of grading and to minimize erosion potential from disturbed slopes.

d. Minimizing use of impervious surfacing to reduce surface runoff thereby recharging the water table on site and minimizing potential soil erosion. (c and d relate equally to the cultural and aesthetic as well. By concentrating development and nestling it into the edges of the woodland, we can minimize the visual intrusion into the rural character of an area subject to expanding development pressures.)

e. Preserving as much of the existing vegetation as possible as a site development is designed. Using native or naturalized plant materials will provide suitable habitats for native wild life and facilitate the preservation of migration patterns.

f. Utilizing native building materials, e.g., field stone, native timber, etc. as well as local styles will also help to preserve the visual character of a place.

These kinds of recommendations will also facilitate the overall issue of land use compatibility, minimizing conflicts between adjacent developments and disruption of the regional landscape visual character. They will be illustrated by the site designer through project drawings, diagrams, and details as she or he move through the design process explained above

Climate change is a change in the statistical distribution of weather over periods of

time that range from decades to millions of years. It can be a change in the average weather or a change in the distribution of weather events around an average (for example, greater or fewer extreme weather events). Climate change may be limited to a specific region, or may occur across the whole Earth.

In recent usage, especially in the context of environmental policy, climate change usually refers to changes in modern climate (see global warming). For information on temperature measurements over various periods, and the data sources available, see temperature record. For attribution of climate change over the past century, see attribution of recent climate change.

CausesFactors that can shape climate are often called climate forcings. These include such processes as variations in solar radiation, deviations in the Earth's orbit, mountain-building and continental drift, and changes in greenhouse gas concentrations. There are a variety of climate change feedbacks that can either amplify or diminish the initial forcing. Some parts of the climate system, such as the oceans and ice caps, respond slowly in reaction to climate forcing because of their large mass. Therefore, the climate system can take centuries or longer to fully respond to new external forcings

built environment refers to the man-made surroundings that provide the

setting for human activity, ranging in scale from personal shelter to neighborhoods to the large-scale civic surroundings.

The term is also now widely used to describe the interdisciplinary field of study which addresses the design, management and use of these man-made surroundings and their relationship to the human activities which take place within them. The field is generally not regarded as an academic discipline in its own right, but as a "field of application" (or "interdiscipline") which draws upon the individual disciplines of economics, law, management, design and technology in sustainable sense.

In architecture and environmental psychology, the phrase is a useful acknowledgement that a small fraction of buildings constructed annually, even in the industrialized world, are designed by architects, and that users of the built environment encounter issues that cross the traditional professional boundaries between urban planners, traffic engineers, zoning authorities, architects, interior designers, industrial designers, etc. Historically, much of the built environment has taken the form of vernacular architecture, and this is still the case in large parts of the world. In the industrialized world, many buildings are produced by large scale development remote from its eventual users.

In landscape architecture, the built environment is identified as man-made landscapes as opposed to the natural environment. For example, Central Park in New York City may have the look, feel and quality of natural surroundings, but is completely man-made and "built".

In urban planning, the phrase connotes the idea that a large percentage of the human environment is manmade, and these artificial surroundings are so extensive and cohesive that they function as organisms in the consumption of resources, disposal of wastes, and facilitation of productive enterprise within its bounds. Recently there has also been considerable dialogue and research into the impact of the built environment's impact on population health

Ozone depletion describes two distinct, but related observations: a slow, steady

decline of about 4% per decade in the total volume of ozone in Earth's stratosphere (ozone layer) since the late 1970s, and a much larger, but seasonal, decrease in stratospheric ozone over Earth's polar regions during the same period. The latter phenomenon is commonly referred to as the ozone hole. In addition to this well-known stratospheric ozone depletion, there are also tropospheric ozone depletion events, which occur near the surface in polar regions during spring.

The detailed mechanism by which the polar ozone holes form is different from that for the mid-latitude thinning, but the most important process in both trends is catalytic destruction of ozone by atomic chlorine and bromine.[1] The main source of these halogen atoms in the stratosphere is photodissociation of chlorofluorocarbon (CFC) compounds, commonly called freons, and of bromofluorocarbon compounds known as halons. These compounds are transported into the stratosphere after being emitted at the surface.[2] Both ozone depletion mechanisms strengthened as emissions of CFCs and halons increased.

CFCs and other contributory substances are commonly referred to as ozone-depleting substances (ODS). Since the ozone layer prevents most harmful UVB wavelengths (270–315 nm) of ultraviolet light (UV light) from passing through the Earth's atmosphere, observed and projected decreases in ozone have generated worldwide concern leading to adoption of the Montreal Protocol that bans the production of CFCs and halons as well as related ozone depleting chemicals such as carbon tetrachloride and trichloroethane. It is suspected that a variety of biological consequences such as increases in skin cancer, cataracts,[3] damage to plants, and reduction of plankton populations in the ocean's photic zone may result from the increased UV exposure due to ozone depletion.

unit 2solar radiationAlmost all of the energy that drives the various systems (climate systems, ecosystems, hydrologic systems, etc.) found on the Earth originates from the sun (Figure 1). Solar energy is

created at the core of the sun when hydrogen atoms are fused into helium by nuclear fusion (Figure 2). The core occupies an area from the sun’s center to about a quarter of the star’s radius. At the core, gravity pulls all of the mass of the sun inward and creates intense pressure. This pressure is high enough to force the fusion of atomic masses.

Figure 2: Major parts of the sun. Solar energy is produced at the core of the sun by nuclear fusion. This energy is then radiated to the convection zone, where mixing transfers the energy to the photosphere. The photosphere is the surface that emits solar radiation to space. On the photosphere, localized cool areas called sunspots occur. Erupting from the photosphere, are solar flares composed of gas, electrons, and radiation. The corona is the upper portion of the sun’s atmosphere. (Source of original image: SOHO)

For each second of the solar nuclear fusion process, 700 million tons of hydrogen is converted into the heavier atom helium. Since its formation 4.5 billion years ago, the sun has used up about half of the hydrogen found in its core. The solar nuclear process also creates immense heat that causes atoms to discharge photons. Temperatures at the core are about 15 million degrees Kelvin (15 million degrees C or 27 million degrees F). Each photon that is created travels about one micrometer before being absorbed by an adjacent gas molecule. This absorption then causes the heating of the neighboring atom and it re-emits another photon that again travels a short distance before being absorbed by another atom. This process then repeats itself many times over before the photon can finally be emitted to outer space at the sun’s surface. The last 20% of the journey to the surface the energy is transported more by convection than by radiation. It takes a photon approximately 100,000 years or about 1025 absorptions and re-emissions to make the journey from the core to the sun’s surface. The trip from the sun’s surface to the Earth takes about 8 minutes.

The radiative surface of the sun, or photosphere, has an average temperature of about 5,800 Kelvins. Most of the electromagnetic radiation emitted from the sun's surface lies in the visible band centered at 500 nm (1 nm = 10-9 meters), although the sun also emits significant energy in the ultraviolet and infrared bands, and small amounts of energy in the radio, microwave, X-ray and gamma ray bands. The total quantity of energy emitted from the sun's surface is approximately 63,000,000 Watts per square meter (W/m2 or Wm-2).

The energy emitted by the sun passes through space until it is intercepted by planets, other celestial objects, or interstellar gas and dust. The intensity of solar radiation striking these objects is determined by a physical law known as the Inverse Square Law (Figure 3). This law merely states that the intensity of the radiation emitted from the sun varies with the squared distance from the source. As a result of this law, if the intensity of radiation at a given distance is one unit, at twice the distance the intensity will become only one-quarter. At three times the distance, the intensity will become only one-ninth of its original intensity at a distance of one unit, and so on.

Living envirolmentChapter 5: THE LIVING ENVIRONMENT

People have long been curious about living things—how many different species there are, what they are like, where they live, how they relate to each other, and how they behave. Scientists seek to answer these questions and many more about the organisms that inhabit the earth. In particular, they try to develop the concepts, principles, and theories that enable people to understand the living environment better.

Living organisms are made of the same components as all other matter, involve the same kind of transformations of energy, and move using the same basic kinds of forces. Thus, all of the physical principles discussed in Chapter 4, The Physical Setting, apply to life as well as to stars, raindrops, and television sets. But living organisms also have characteristics that can be understood best through the application of other principles.

This chapter offers recommendations on basic knowledge about how living things function and how they interact with one another and their environment. The chapter focuses on six major subjects: the diversity of life, as reflected in the biological characteristics of the earth's organisms; the transfer of heritable characteristics from one generation to the next; the structure and functioning of cells, the basic building blocks of all organisms; the interdependence of all organisms and their environment; the flow of matter and energy through the grand-scale cycles of life; and how biological evolution explains the similarity and diversity of life.

SanitationSanitation is the hygienic means of promoting health through prevention of human contact with the hazards of wastes. Hazards can be either physical, microbiological, biological or chemical agents of disease. Wastes that can cause health problems are human and animal feces, solid wastes, domestic wastewater (sewage, sullage, greywater), industrial wastes, and agricultural wastes. Hygienic means of prevention can be by using engineering solutions (e.g. sewerage and wastewater treatment), simple technologies (e.g. latrines, septic tanks), or even by personal hygiene practices (e.g. simple handwashing with soap).

The term "sanitation" can be applied to a specific aspect, concept, location, or strategy, such as:

Basic sanitation - refers to the management of human feces at the household level. This terminology is the indicator used to describe the target of the Millennium Development Goal on sanitation.

On-site sanitation - the collection and treatment of waste is done where it is deposited. Examples are the use of pit latrines, septic tanks, and imhoff tanks.

Food sanitation - refers to the hygienic measures for ensuring food safety.

Environmental sanitation - the control of environmental factors that form links in disease transmission. Subsets of this category are solid waste management, water and wastewater treatment, industrial waste treatment and noise and pollution control.

Ecological sanitation - a concept and an approach of recycling to nature the nutrients from human and animal wastes.

Wastewater Sanitation

Wastewater collection

The standard sanitation technology in urban areas is the collection of wastewater in sewers, its treatment in wastewater treatment plants for reuse or disposal in rivers, lakes or the sea. Sewers are either combined with storm drains or separated from them as sanitary sewers. Combined sewers are usually found in the central, older parts or urban areas. Heavy rainfall and inadequate maintenance can lead to combined sewer overflows or sanitary sewer overflows, i.e. more or less diluted raw sewage being discharged into the environment. Industries often discharge wastewater into municipal sewers, which can complicate wastewater treatment unless industries pre-treat their discharges.[3]

The high investment cost of conventional wastewater collection systems are difficult to afford for many developing countries. Some countries have therefore promoted alternative wastewater collection systems such as condominial sewerage, which uses smaller diameter pipes at lower depth with different network layouts from conventional sewerage.

[edit] Reuse of wastewater

The reuse of untreated wastewater in irrigated agriculture is common in developing countries. The reuse of treated wastewater in landscaping (esp. on golf courses), irrigated agriculture and for industrial use is becoming increasingly widespread.

In many peri-urban and rural areas households are not connected to sewers. They discharge their wastewater into septic tanks or other types of on-site sanitation.

[edit] Ecological sanitationFor more details on this topic, see Ecological sanitation.

Ecological sanitation is sometimes presented as a radical alternative to conventional sanitation systems. Ecological sanitation is based on composting or vermicomposting toilets where an extra

separation of urine and feces at the source for sanitization and recycling has been done. It thus eliminates the creation of blackwater and eliminates fecal pathogens from any still present wastewater (urine). If ecological sanitation is practiced municipal wastewater consists only of greywater, which can be recycled for gardening. However, in most cases greywater continues to be discharged to sewers.

[edit] Sanitation and public health

The importance of waste isolation lies in an effort to prevent water and sanitation related diseases, which afflicts both developed countries as well as developing countries to differing degrees. It is estimated that up to 5 million people die each year from preventable water-borne disease[5], as a result of inadequate sanitation and hygiene practices. The affects of sanitation have also had a large impact on society. Published in Griffins Public Sanitation proven studies show that higher sanitation produces more attractiveness.

[edit] Global access to improved sanitation

The Joint Monitoring Program for water and sanitation of WHO and UNICEF has defined improved sanitation as

connection to a public sewer

connection to a septic system

pour -flush latrine

simple pit latrine

ventilated improved pit latrine [6]

According to that definition, 62% of the world's population has access to improved sanitation in 2008, up 8% since 1990. [1] Only slightly more than half of them or 31% of the world population lived in houses connected to a sewer. Overall, 2.5 billion people lack access to improved sanitation and thus must resort to open defecation or other unsanitary forms of defecation, such as public latrines or open pit latrines.[7] This includes 1.2 billion people who have access to no facilities at all.[8] This outcome presents substantial public health risks as the waste could contaminate drinking water and cause life threatening forms of diarrhea to infants. Improved sanitation, including hand washing and water purification, could save the lives of 1.5 million children who suffer from diarrheal diseases each year.[8]

In developed countries, where less than 20% of the world population lives, 99% of the population has access to improved sanitation and 81% were connected to sewers.

Solid waste disposal

Disposal of solid waste is most commonly conducted in landfills, but incineration, recycling, composting and conversion to biofuels are also avenues. In the case of landfills, advanced countries typically have rigid protocols for daily cover with topsoil, where underdeveloped

countries customarily rely upon less stringent protocols.[9] The importance of daily cover lies in the reduction of vector contact and spreading of pathogens. Daily cover also minimises odor emissions and reduces windblown litter. Likewise, developed countries typically have requirements for perimeter sealing of the landfill with clay-type soils to minimize migration of leachate that could contaminate groundwater (and hence jeopardize some drinking water supplies).

For incineration options, the release of air pollutants, including certain toxic components is an attendant adverse outcome. Recycling and biofuel conversion are the sustainable options that generally have superior life cycle costs, particularly when total ecological consequences are considered.[10] Composting value will ultimately be limited by the market demand for compost product.

Unit 3

Sustainable developmentScope and definitions

The concept has included notions of weak sustainability, strong sustainability and deep ecology. Sustainable development does not focus solely on environmental issues.

In 1987, the United Nations released the Brundtland Report, which defines sustainable development as 'development which meets the needs of the present without compromising the ability of future generations to meet their own needs.'[6]

The United Nations 2005 World Summit Outcome Document refers to the "interdependent and mutually reinforcing pillars" of sustainable development as economic development, social development, and environmental protection.[7]

Indigenous people have argued, through various international forums such as the United Nations Permanent Forum on Indigenous Issues and the Convention on Biological Diversity, that there are four pillars of sustainable development, the fourth being cultural. The Universal Declaration on Cultural Diversity (UNESCO, 2001) further elaborates the concept by stating that "...cultural diversity is as necessary for humankind as biodiversity is for nature”; it becomes “one of the roots of development understood not simply in terms of economic growth, but also as a means to achieve a more satisfactory intellectual, emotional, moral and spiritual existence". In this vision, cultural diversity is the fourth policy area of sustainable development.

Economic Sustainability: clearly identified information, integration, and participation as key building blocks to help countries achieve development that recognises these interdependent pillars. It emphasises that in sustainable development everyone is a user and provider of information. It stresses the need to change from old sector-centred ways of doing business to new approaches that involve cross-sectoral co-ordination and the integration of environmental and social concerns into all development processes. Furthermore, Agenda 21 emphasises that broad public participation in decision making is a fundamental prerequisite for achieving sustainable development.[8]

According to Hasna, sustainability is a process which tells of a development of all aspects of human life affecting sustenance. It means resolving the conflict between the various competing goals, and involves the simultaneous pursuit of economic prosperity, environmental quality and social equity famously known as three dimensions (triple bottom line) with is the resultant vector being technology, hence it is a continually evolving process; the ‘journey’ (the process of achieving sustainability) is of course vitally important, but only as a means of getting to the destination (the desired future state). However,the ‘destination’ of sustainability is not a fixed place in the normal sense that we understand destination. Instead, it is a set of wishful characteristics of a future system.[9]

Green development is generally differentiated from sustainable development in that Green development prioritizes what its proponents consider to be environmental sustainability over economic and cultural considerations. Proponents of Sustainable Development argue that it provides a context in which to improve overall sustainability where cutting edge Green development is unattainable. For example, a cutting edge treatment plant with extremely high maintenance costs may not be sustainable in regions of the world with fewer financial resources. An environmentally ideal plant that is shut down due to bankruptcy is obviously less sustainable than one that is maintainable by the community, even if it is somewhat less effective from an environmental standpoint.

Some research activities start from this definition to argue that the environment is a combination of nature and culture. The Network of Excellence "Sustainable Development in a Diverse World",[10] sponsored by the European Union, integrates multidisciplinary capacities and interprets cultural diversity as a key element of a new strategy for sustainable development.

Still other researchers view environmental and social challenges as opportunities for development action. This is particularly true in the concept of sustainable enterprise that frames these global needs as opportunities for private enterprise to provide innovative and entrepreneurial solutions. This view is now being taught at many business schools including the Center for Sustainable Global Enterprise at Cornell University and the Erb Institute for Global Sustainable Enterprise at the University of Michigan.

The United Nations Division for Sustainable Development lists the following areas as coming within the scope of sustainable development:[11]

Sustainable development is an eclectic concept, as a wide array of views fall under its umbrella. The concept has included notions of weak sustainability, strong sustainability and deep ecology. Different conceptions also reveal a strong tension between ecocentrism and anthropocentrism. Many definitions and images (Visualizing Sustainability) of sustainable development coexist. Broadly defined, the sustainable development mantra enjoins current generations to take a systems approach to growth and development and to manage natural, produced, and social capital for the welfare of their own and future generations.

During the last ten years, different organizations have tried to measure and monitor the proximity to what they consider sustainability by implementing what has been called sustainability metrics and indices [12] .

Sustainable development is said to set limits on the developing world. While current first world countries polluted significantly during their development, the same countries encourage third world countries to reduce pollution, which sometimes impedes growth. Some consider that the implementation of sustainable development would mean a reversion to pre-modern lifestyles.[13]

Others have criticized the overuse of the term:

"[The] word sustainable has been used in too many situations today, and ecological sustainability is one of those terms that confuse a lot of people. You hear about sustainable development, sustainable growth, sustainable economies, sustainable societies, sustainable agriculture. Everything is sustainable (Temple, 1992)."[13]

[edit] Environmental sustainability

Environmental sustainability is the process of making sure current processes of interaction with the environment are pursued with the idea of keeping the environment as pristine as naturally possible based on ideal-seeking behavior.

An "unsustainable situation" occurs when natural capital (the sum total of nature's resources) is used up faster than it can be replenished. Sustainability requires that human activity only uses nature's resources at a rate at which they can be replenished naturally. Inherently the concept of sustainable development is intertwined with the concept of carrying capacity. Theoretically, the long-term result of environmental degradation is the inability to sustain human life. Such degradation on a global scale could imply extinction for humanity.

Consumption of renewable resources State of environment SustainabilityMore than nature's ability to replenish Environmental degradation Not sustainableEqual to nature's ability to replenish Environmental equilibrium Steady state economyLess than nature's ability to replenish Environmental renewal Environmentally sustainable

.

[edit] Purpose

Various writers have commented on the population control agenda that seems to underlie the concept of sustainable development. Maria Sophia Aguirre writes:[20]

"Sustainable development is a policy approach that has gained quite a lot of popularity in recent years, especially in international circles. By attaching a specific interpretation to sustainability, population control policies have become the overriding approach to development, thus becoming the primary tool used to “promote” economic development in developing countries and to protect the environment."

Mary Jo Anderson suggests that the real purpose of sustainable development is to contain and limit economic development in developing countries, and in so doing control population growth.[21] It is suggested that this is the reason the main focus of most programs is still on low-income agriculture. Joan Veon, a businesswoman and international reporter, who covered 64 global meetings on sustainable development posits that:[22]

"Sustainable development has continued to evolve as that of protecting the world's resources while its true agenda is to control the world's resources. It should be noted that Agenda 21 sets up the global infrastructure needed to manage, count, and control all of the world's assets."

Brown field developmentBrownfields are abandoned or underused industrial and commercial facilities available for re-use. Expansion or redevelopment of such a facility may be complicated by real or perceived environmental contaminations.[1]

In the United States city planning jargon, brownfield land (or simply a brownfield) is land previously used for industrial purposes or certain commercial uses. The land may be contaminated by low concentrations of hazardous waste or pollution, and has the potential to be reused once it is cleaned up. Land that is more severely contaminated and has high concentrations of hazardous waste or pollution, such as a Superfund site, does not fall under the brownfield classification. Mothballed brownfields are properties which the owners are not willing to transfer or put to productive reuse.[2]

Locations

Generally, brownfield sites exist in a city's or town's industrial section, on locations with abandoned factories or commercial buildings, or other previously polluting operations. Small brownfields also may be found in many older residential neighborhoods. For example, many dry cleaning establishments or gas stations produced high levels of subsurface contaminants during prior operations, and the land they occupy might sit idle for decades as a brownfield.

Typical contaminants found on contaminated brownfield land include hydrocarbon spillages, solvents, pesticides, heavy metals such as lead (e.g., paints), tributyltins, and asbestos. Old maps may assist in identifying areas to be tested.

Innovative redevelopment strategies

A number of innovative financial and remediation techniques have been used in the U.S. in recent years to expedite the cleanup of brownfield sites. For example, some environmental firms have teamed up with insurance companies to underwrite the cleanup of distressed brownfield properties and provide a guaranteed cleanup cost for a specific brownfield property, to limit land developers' exposure to environmental remediation costs and pollution lawsuits. The environmental firm first performs an extensive investigation of the brownfield site to ensure that the guaranteed cleanup cost is reasonable and they will not wind up with any surprises.

After the dot-com bubble of 2000, many venture capital firms looking for new businesses in which to invest have done so in brownfields. Venture capital investments in brownfield-related businesses have included companies developing new cleanup technology, companies that do remediation, and development projects in brownfield lands.

Innovative remedial techniques used at distressed brownfields in recent years include bioremediation, a remedial strategy that uses naturally occurring microbes in soils and groundwater to expedite a cleanup, and in-situ oxidation, which is a remedial strategy that uses

oxygen or oxidant chemicals to enhance a cleanup. Often, these strategies are used in conjunction with each other or with other remedial strategies such as soil vapor extraction. In this process, vapor from the soil phase is extracted from soils and treated, which has the effect of removing contaminants from the soils and groundwater beneath a site. Some brownfields with heavy metal contamination have even been cleaned up through an innovative approach called phytoremediation that uses deep-rooted plants to soak up metals in soils into the plant structure as the plant grows. After they reach maturity, the plants – which now contain the heavy metal contaminants in their tissues – are removed and disposed of as hazardous waste.

Research is under way to see if some brownfields can be used to grow crops, specifically for the production of biofuels.[4] Michigan State University, in collaboration with DaimlerChrysler and NextEnergy, has small plots of soybean, corn, canola, and switchgrass growing in a former industrial dump site in Oakland County, Michigan. The intent is to see if the plants can serve two purposes simultaneously: assist with phytoremediation, and contribute to the economical production of biodiesel and/or ethanol fuel.

Regulation

In the United States, investigation and cleanup of brownfield sites is largely regulated by state environmental agencies in cooperation with the Environmental Protection Agency (EPA). Many of the most important provisions on liability relief are contained in state codes that can differ significantly from state to state.[5] The EPA, together with local and national government, can provide technical help and some funding for assessment and cleanup of designated sites. They can also provide tax incentives for cleanup that is not paid for outright; specifically, cleanup costs are fully tax-deductible in the year they are incurred.[6]

Barriers to redevelopment

Many contaminated brownfield sites sit unused for decades because the cost of cleaning them to safe standards is more than the land would be worth after redevelopment. However, redevelopment has become more common in the first decade of the 21st century, as developable land grows less available in highly populated areas. Also, the methods of studying contaminated land have become more sophisticated and established.

Many federal and state programs have been developed to help developers interested in cleaning up brownfield sites and restoring them to practical uses. Some states and localities have spent considerable money assessing the contamination on local brownfield sites, to quantify the cleanup costs in an effort to move the redevelopment process forward.

In the process of cleaning contaminated brownfield sites, surprises are sometimes encountered, such as previously unknown underground storage tanks, buried drums or buried railroad tank cars containing wastes. When unexpected circumstances arise, the cost for clean-up increases, and as a result, the cleanup work may be delayed or stopped entirely. To avoid unexpected contamination and increased costs, many developers insist that a site be thoroughly investigated (via a Phase II Site Investigation or Remedial Investigation) prior to commencing remedial cleanup activities.

[edit] Valuation

Acquisition, adaptive re-use, and disposal of a brownfield sites requires advanced and specialized appraisal analysis techniques. For example, the highest and best use of the brownfield site may be affected by the contamination, both pre- and post-remediation. Additionally, the value should take into account residual stigma and potential for third-party liability. Normal appraisal techniques frequently fail, and appraisers must rely on more advanced techniques, such as contingent valuation, case studies, or statistical analyses.[

Vegetation Vegetation is a general term for the plant life of a region; it refers to the ground cover provided by plants. It is a general term, without specific reference to particular taxa, life forms, structure, spatial extent, or any other specific botanical or geographic characteristics. It is broader than the term flora which refers exclusively to species composition. Perhaps the closest synonym is plant community, but vegetation can, and often does, refer to a wider range of spatial scales than that term does, including scales as large as the global. Primeval redwood forests, coastal mangrove stands, sphagnum bogs, desert soil crusts, roadside weed patches, wheat fields, cultivated gardens and lawns; all are encompassed by the term vegetation.

importance

Vegetation supports critical functions in the biosphere, at all possible spatial scales. First, vegetation regulates the flow of numerous biogeochemical cycles (see biogeochemistry), most critically those of water, carbon, and nitrogen; it is also of great importance in local and global energy balances. Such cycles are important not only for global patterns of vegetation but also for those of climate. Second, vegetation strongly affects soil characteristics, including soil volume, chemistry and texture, which feed back to affect various vegetational characteristics, including productivity and structure. Third, vegetation serves as wildlife habitat and the energy source for the vast array of animal species on the planet (and, ultimately, to those that feed on these).Perhaps most importantly, and often overlooked, global vegetation (including algal communities) has been the primary source of oxygen in the atmosphere, enabling the aerobic metabolism systems to evolve and persist.

Rainwater harvestingRainwater harvesting is the gathering, or accumulating and storing, of rainwater.[1] Rainwater harvesting has been used to provide drinking water, water for livestock, water for irrigation or to refill aquifers in a process called groundwater recharge. Rainwater collected from the roofs of houses, tents and local institutions, or from specially prepared areas of ground, can make an important contribution to drinking water. In some cases, rainwater may be the only available, or economical, water source. Rainwater systems are simple to construct from inexpensive local materials, and are potentially successful in most habitable locations. Roof rainwater is usually of good quality and does not require treatment before consumption. Household rainfall catchment systems are appropriate in areas with an average rainfall greater than 200mm per year, and no other accessible water sources (Skinner and Cotton, 1992).

There are a number of types of systems to harvest rainwater ranging from very simple to the complex industrial systems. Generally, rainwater is either harvested from the ground or from a roof. The rate at which water can be collected from either system is dependent on the plan area of the system, its efficiency, and the intensity of rainfall.

Ground catchment systems

Ground catchments systems channel water from a prepared catchment area into storage. Generally they are only considered in areas where rainwater is very scarce and other sources of water are not available. They are more suited to small communities than individual families. If properly designed, ground catchments can collect large quantities of rainwater.

Roof catchment systems

Roof catchment systems channel rainwater that falls onto a roof into storage via a system of gutters and pipes. The first flush of rainwater after a dry season should be allowed to run to waste as it will be contaminated with dust, bird droppings etc. Roof gutters should have sufficient incline to avoid standing water. They must be strong enough, and large enough to carry peak flows. Storage tanks should be covered to prevent mosquito breeding and to reduce evaporation losses, contamination and algal growth. Rainwater harvesting systems require regular maintenance and cleaning to keep the system hygienic and in good working order.

Subsurface dyke

A subsurface dyke is built in an aquifer to obstruct the natural flow of groundwater, thereby raising the groundwater level and increasing the amount of water stored in the aquifer.

The subsurface dyke at Krishi Vigyan Kendra, Kannur under Kerala Agricultural University with the support of ICAR, has become an effective method for ground water conservation by means of rain water harvesting technologies. The sub-surface dyke has demonstrated that it is a feasible method for conserving and exploiting the groundwater resources of the Kerala state of India. The dyke is now the largest rainwater harvesting system in that region.

Groundwater recharge

Rainwater may also be used for groundwater recharge, where the runoff on the ground is collected and allowed to be absorbed, adding to the groundwater. In the US, rooftop rainwater is collected and stored in sump.[2] In India this includes Bawdis and johads, or ponds which collect the run-off from small streams in wide area.[3][4]

In India, reservoirs called tankas were used to store water; typically they were shallow with mud walls. Ancient tankas still exist in some places.[4]

Advantages in urban areas

Rainwater harvesting in urban areas can have manifold reasons. Some of the reasons rainwater harvesting can be adopted in cities are to provide supplemental water for the city's requirements,

to increase soil moisture levels for urban greenery, to increase the ground water table through artificial recharge, to mitigate urban flooding and to improve the quality of groundwater. In urban areas of the developed world, at a household level, harvested rainwater can be used for flushing toilets and washing laundry. Indeed in hard water areas it is superior to mains water for this. It can also be used for showering or bathing. It may require treatment prior to use for drinking

In New Zealand, many houses away from the larger towns and cities routinely rely on rainwater collected from roofs as the only source of water for all household activities. This is almost inevitably the case for many holiday homes.

Recycling and reuse

Recycling involves the collection of used and discarded materials processing these materials and making them into new products. It reduces the amount of waste that is thrown into the community dustbins thereby making the environment cleaner and the air more fresh to breathe.

Surveys carried out by Government and non-government agencies in the country have all recognized

the importance of recycling wastes. However, the methodology for safe recycling of waste has not been standardized. Studies have revealed that 7 %-15% of the waste is recycled. If recycling is done in a proper manner, it will solve the problems of waste or garbage. At the community level, a large number of NGOs (Non Governmental Organizations) and private sector enterprises have taken an initiative in segregation and recycling of waste (EXNORA International in Chennai recycles a large part of the waste that is collected). It is being used for composting, making pellets to be used in gasifiers, etc. Plastics are sold to the factories that reuse them.

The steps involved in the process prior to recycling includea) Collection of waste from doorsteps, commercial places, etc.b) Collection of waste from community dumps.c) Collection/picking up of waste from final disposal sites.

Most of the garbage generated in the household can be recycled and reused. Organic kitchen waste such as leftover foodstuff, vegetable peels, and spoilt or dried fruits and vegetables can be recycled by putting them in the compost pits that have been dug in the garden. Old newspapers, magazines and bottles can be sold to the kabadiwala the man who buys these items from homes.

In your own homes you can contribute to waste reduction and the recycling and reuse of certain items. To cover you books you can use old calendars; old greeting cards can also be reused. Paper can also be made at home through a very simple process and you can paint on them.

 

 

The schematic diagram below depicts recycling of wastes

 

Source: CPCB Report on Management of Muncipal Solid Waste 

Waste recycling has some significant advantages. It leads to less utilization of raw materials.reduces environmental impacts arising from waste treatment and disposal.makes the surroundings cleaner and healthier.saves on landfill space.saves money.reduces the amount of energy required to manufacture new products.

In fact recycling can prevent the creation of waste at the source.

 

Some items that can be recycled or reused

Paper Old copiesOld booksPaper bagsNewspapersOld greeting cardsCardboard box

Plastic ContainersBottlesBagsSheets

Glass and ceramics

Bottles PlatesCupBowls

Miscellaneous Old cansUtensilsClothesFurniture

Alternative technologyAlternative technology is a term used by environmental advocates to refer to technologies which are more environmentally friendly than the functionally equivalent technologies dominant in current practice.

It is technology that, as an alternative to resource-intensive and wasteful industry, aims to utilize resources sparingly, with minimum damage to the environment, at affordable cost and with a possible degree of control over the processes. The term is sometimes confused with appropriate technology, but while there is significant overlap, the terms have different meanings, particularly related to the importance of low cost and ease of maintenance for developing country applications.

Alternative technologies themselves are part of environmentalist politics. Common political issues related to alternative technologies include whether they are practical for widespread use; whether they are cost-effective; whether widespread adoption would produce negative impacts on the economy, lifestyle or environment (production energy costs/pollutants); how to encourage rapid adoption; whether public subsidies for adoption are appropriate; which technologies government regulations should favor, if any, and how environmentally unsound technologies and practices should be regulated; what technological research should be done and how it should be funded; and which of a field of competing alternative technologies should be pursued.

Some "alternative technologies" have in the past or may in the future become widely adopted, after which they might no longer be considered "alternative." For example the use of wind turbines to produce electricity.

Alternative technologies

Alternative technologies include the following:

Anaerobic digestion

Composting

Fuel cells

Fuels for automobiles (besides gasoline and diesel)

o Alcohol (either ethanol or methanol)

o Biodiesel

o Vegetable oil

Greywater

Solar panels

o Silicon-based

o Photosynthetic "Gratzel cells" (Titanium dioxide)

Landfill gas extraction from landfills

Mechanical biological treatment

Recycling

Wind generators

Alternative natural materialsAlternative natural materials is a general term that describes natural materials like rock or adobe that are not as commonly in use as materials such as wood or iron. Alternative natural materials have many practical uses in areas such as sustainable architecture and engineering. The main purpose of using such materials is to minimize the negative effects that our built environment can have on the planet while increasing the efficiency and adaptability of the structures.

Materials

Rock

Rock is a great way to get away from traditional materials that are harmful to the environment. Rocks have two great characteristics: good thermal mass and thermal insulation. These characteristics make stone a great idea because the temperature in the house stays rather constant thus requiring less air conditioning and other cooling systems. Types of rocks that can be employed are reject stone (pieces of stone that are not able to be used for another task), limestone, and flagstone.

Straw

Straw bales can be used as a basis for walls instead of drywall. Straw provides excellent insulation and fire resistance in a traditional post-and-beam structure, where a wood frame supports the house.[3] These straw walls are about 75% more energy efficient than standard drywalls and because no oxygen can get through the walls, fire cannot spread and there is no chance of combustion.

Bamboo

In Asian countries, bamboo is being used for structures like bridges and homes. Bamboo is surprisingly strong and rather flexible and grows incredibly fast, making it a rather abundant material. Although it can be difficult to join corners together, bamboo is immensely strong and makes up for the hardships that can be encountered while building it.

Cordwood

Cordwood is a combination of small remnants of firewood and other lumber that usually go to waste. These small blocks of wood can easily be put together to make a structure that, like stone, has great insulation as well as thermal mass. Cordwood provides the rustic look of log cabins without the use of tons of lumber. You can build an entire building with just cordwood or use stones to fill in the walls.

Rammed Earth

Rammed Earth is a very abundant material that can be used in place of concrete and brick. Soil is packed tightly into wall molds where it is rammed together and hardened to form a durable wall packing made of nothing more than dirt, stones, and sticks.[3] Rammed Earth also provides great thermal mass, which means great energy savings. In addition, it is very weatherproof and durable enough that it was used in the Great Wall of China.

Earth-Sheltered

Earth-Sheltering is a very unique building technique in which buildings are completely constructed on at least one side by some form of Earth whether it be a grass roof, clay walls, or both. This unique system usually includes plenty of windows because of the difficulty involved with using too much electricity in such a house. This adds to the energy efficiency of the house by reducing lighting costs.

Papercrete

Papercrete is an interesting and very new material that is a good substitute for concrete. Papercrete is shredded paper, sand, and cement mixed together that forms a very durable brick-like material. Buildings utilizing papercrete are very well-insulated as well as being termite- and fire-resistant. Papercrete is very cheap as it usually only costs about $0.35 per square foot.

Adobe

Adobe is an age-old technique that is cheap, easy to obtain, and ideal for hot environments. A mixture of sand, clay, and water is poured into a mold and left in the sun to dry. When dried, it is exceptionally strong and heat-resistant. Adobe doesn’t let much heat through to the inside of the structure, thus providing excellent insulation during the summer to reduce energy costs. Although this clay mixture provides excellent insulation from heat, it is not very waterproof and can be dangerous in earth-quake prone areas due to its tendency to crack easily.

Sawdust

Sawdust is a good material to combine with clay or cement mixtures and use for walls. These walls turn out surprisingly sturdy and effectively recycle any trees that may need to be excavated from the building area. Depending what type of sawdust used (hardwood is best) the wood chips in the walls absorb moisture and help prevent cracking during freeze/thaw cycles.[1] Sawdust may be combined with water and frozen to produce a material commonly known as pykrete, which is strong, and less prone to melting than regular ice.

recyclling

Recycling involves processing used materials into new products to prevent waste of potentially useful materials, reduce the consumption of fresh raw materials, reduce energy usage, reduce air pollution (from incineration) and water pollution (from landfilling) by reducing the need for "conventional" waste disposal, and lower greenhouse gas emissions as compared to virgin production.[1][2] Recycling is a key component of modern waste management and is the third component of the "Reduce, Reuse, Recycle" waste hierarchy.

Recyclable materials include many kinds of glass, paper, metal, plastic, textiles, and electronics. Although similar in effect, the composting or other reuse of biodegradable waste – such as food or garden waste – is not typically considered recycling.[2] Materials to be recycled are either brought to a collection center or picked up from the curbside, then sorted, cleaned, and reprocessed into new materials bound for manufacturing.

In a strict sense, recycling of a material would produce a fresh supply of the same material, for example used office paper to more office paper, or used foamed polystyrene to more polystyrene. However, this is often difficult or too expensive (compared with producing the same product from raw materials or other sources), so "recycling" of many products or materials involves their reuse in producing different materials (e.g., cardboard) instead. Another form of recycling is the salvage of certain materials from complex products, either due to their intrinsic value (e.g., lead from car batteries, or gold from computer components), or due to their hazardous nature (e.g., removal and reuse of mercury from various items).

Critics dispute the net economic and environmental benefits of recycling over its costs, and suggest that proponents of recycling often make matters worse and suffer from confirmation bias. Specifically, critics argue that the costs and energy used in collection and transportation detract from (and outweigh) the costs and energy saved in the production process; also that the jobs produced by the recycling industry can be a poor trade for the jobs lost in logging, mining, and other industries associated with virgin production; and that materials such as paper pulp can only be recycled a few times before material degradation prevents further recycling. Proponents of recycling dispute each of these claims, and the validity of arguments from both sides has led to enduring controversy.

Aggregates and concrete

Concrete blocks

Main article: Concrete recycling

Concrete aggregate collected from demolition sites is put through a crushing machine, often along with asphalt, bricks, dirt, and rocks. Smaller pieces of concrete are used as gravel for new construction projects. Crushed recycled concrete can also be used as the dry aggregate for brand new concrete if it is free of contaminants. This reduces the need for other rocks to be dug up, which in turn saves trees and habitats

Ferrous metals

Steel crushed and baled for recyclingMain article: Steel recycling

Iron and steel are the world's most recycled materials, and among the easiest materials to reprocess, as they can be separated magnetically from the waste stream. Recycling is via a steelworks: scrap is either remelted in an electric arc furnace (90-100% scrap), or used as part of the charge in a Basic Oxygen Furnace (around 25% scrap).[51] Any grade of steel can be recycled to top quality new metal, with no 'downgrading' from prime to lower quality materials as steel is recycled repeatedly. 42% of crude steel produced is recycled material.[52]

Non-ferrous metals

Main article: Aluminium recycling

Aluminium is one of the most efficient and widely-recycled materials.[53][54] Aluminium is shredded and ground into small pieces or crushed into bales. These pieces or bales are melted in an aluminium smelter to produce molten aluminium. By this stage the recycled aluminium is indistinguishable from virgin aluminium and further processing is identical for both. This process does not produce any change in the metal, so aluminium can be recycled indefinitely.

Recycling aluminium saves 95% of the energy cost of processing new aluminium.[6] This is because the temperature necessary for melting recycled, nearly pure, aluminium is 600 °C, while to extract mined aluminium from its ore requires 900 °C. To reach this higher temperature, much more energy is needed, leading to the high environmental benefits of aluminium recycling. Americans throw away enough aluminium every year to rebuild their entire commercial air fleet. Also, the energy saved by recycling one aluminium can is enough to run a television for three hours.[

Timber

A stack of wooden pallets awaits reuse or recycling.Main article: Timber recycling

Recycling timber has become popular due to its image as an environmentally friendly product, with consumers commonly believing that by purchasing recycled wood the demand for green timber will fall and ultimately benefit the environment. Greenpeace also view recycled timber as an environmentally friendly product, citing it as the most preferable timber source on their website. The arrival of recycled timber as a construction product has been important in both raising industry and consumer awareness towards deforestation and promoting timber mills to adopt more environmentally friendly practices.

Wood recycling is a subject which has in recent years taken an ever greater role in our lives. The problem, however, is that although many local authorities like the idea of recycling, they do not fully support it. One of the countless examples, which has been in the news is the concept of actually recycling wood which is growing in the cities. Namely, recycling timber, trees and other source

Electro mechanical systemMicroelectromechanical systems (MEMS) (also written as micro-electro-mechanical, or MicroElectroMechanical) is the technology of the very small, and merges at the nano-scale into nanoelectromechanical systems (NEMS) and nanotechnology. MEMS are also referred to as micromachines (in Japan), or Micro Systems Technology - MST (in Europe). MEMS are separate and distinct from the hypothetical vision of molecular nanotechnology or molecular electronics. MEMS are made up of components between 1 to 100 micrometres in size (i.e. 0.001 to 0.1 mm) and MEMS devices generally range in size from 20 micrometres (20 millionths of a metre) to a millimetre. They usually consist of a central unit that processes data, the microprocessor and several components that interact with the outside such as microsensors[1]. At these size scales, the standard constructs of classical physics are not always useful. Due to MEMS' large surface area to volume ratio, surface effects such as electrostatics and wetting dominate volume effects such as inertia or thermal mass.

The potential of very small machines was appreciated long before the technology existed that could make them—see, for example, Richard Feynman's famous 1959 lecture There's Plenty of Room at the Bottom. MEMS became practical once they could be fabricated using modified semiconductor device fabrication technologies, normally used to make electronics. These include molding and plating, wet etching (KOH, TMAH) and dry etching (RIE and DRIE), electro discharge machining (EDM), and other technologies capable of manufacturing very small devices.

Building Fabric

The building fabric is a critical component of any building, since it both protects the building occupants and plays a major role in regulating the indoor environment. Consisting of the building's roof, floor slabs, walls, windows, and doors, the fabric controls the flow of energy between the interior and exterior of the building.

For a new project, opportunities relating to the building fabric begin during the predesign phase of the building. An optimal design of the building fabric may provide significant reductions in heating and cooling loads-which in turn can allow downsizing of mechanical equipment. When the right strategies are integrated through good design, the extra cost for a high-performance fabric may be paid for through savings achieved by installing smaller HVAC equipment.

The building fabric must balance requirements for ventilation and daylight while providing thermal and moisture protection appropriate to the climatic conditions of the site. Fabric design is a major factor in determining the amount of energy a building will use in its operation. Also,

the overall environmental life-cycle impacts and energy costs associated with the production and transportation of different envelope materials vary greatly.

In keeping with the whole building approach, the entire design team must integrate design of the fabric with other design elements including material selection; daylighting and other passive solar design strategies; heating, ventilating, and air-conditioning (HVAC) and electrical strategies; and project performance goals. One of the most important factors affecting fabric design is climate. Hot/dry, hot/humid, temperate, or cold climates will suggest different design strategies. Specific designs and materials can take advantage of or provide solutions for the given climate.

A second important factor in fabric design is what occurs inside the building. If the activity and equipment inside the building generate a significant amount of heat, the thermal loads may be primarily internal (from people and equipment) rather than external (from the sun). This affects the rate at which a building gains or loses heat. Building Configuration also has significant impacts upon the efficiency and requirements of the building fabric. Careful study is required to arrive at a building footprint and orientation that work with the building fabric to maximize energy benefit

Curtain wallA curtain wall is a building façade that does not carry any dead load from the building other than its own dead load, and one that transfers the horizontal loads (wind loads) that are incident upon it. These loads are transferred to the main building structure through connections at floors or columns of the building. A curtain wall is designed to resist air and water infiltration, wind

forces acting on the building, seismic forces (usually only those imposed by the inertia of the curtain wall), and its own dead load forces.

Curtain walls are typically designed with extruded aluminium members, although the first curtain walls were made of steel. The aluminium frame is typically infilled with glass, which provides an architecturally pleasing building, as well as benefits such as daylighting. However, parameters related to solar gain control such as thermal comfort and visual comfort are more difficult to control when using highly-glazed curtain walls. Other common infills include: stone veneer, metal panels, louvers, and operable windows or vents.

Curtain walls differ from storefront systems in that they are designed to span multiple floors, and take into consideration design requirements such as: thermal expansion and contraction; building sway and movement; water diversion; and thermal efficiency for cost-effective heating, cooling, and lighting in the building.

. Maintenance and repair

Curtain walls and perimeter sealants require maintenance to maximize service life. Perimeter sealants, properly designed and installed, have a typical service life of 10 to 15 years. Removal and replacement of perimeter sealants require meticulous surface preparation and proper detailing.

Aluminum frames are generally painted or anodized. Factory applied fluoropolymer thermoset coatings have good resistance to environmental degradation and require only periodic cleaning. Recoating with an air-dry fluoropolymer coating is possible but requires special surface preparation and is not as durable as the baked-on original coating.

Anodized aluminum frames cannot be "re-anodized" in place, but can be cleaned and protected by proprietary clear coatings to improve appearance and durability.

Exposed glazing seals and gaskets require inspection and maintenance to minimize water penetration, and to limit exposure of frame seals and insulating glass seals to wetting.

AutomationAutomation is the use of control systems (such as numerical control, programmable logic control, and other industrial control systems), in concert with other applications of information technology (such as computer-aided technologies [CAD, CAM, CAx]), to control industrial machinery and processes, reducing the need for human intervention.[1] In the scope of industrialization, automation is a step beyond mechanization. Whereas mechanization provided human operators with machinery to assist them with the muscular requirements of work, automation greatly reduces the need for human sensory and mental requirements as well. Processes and systems can also be automated.

Automation plays an increasingly important role in the global economy and in daily experience. Engineers strive to combine automated devices with mathematical and organizational tools to create complex systems for a rapidly expanding range of applications and human activities.

Many roles for humans in industrial processes presently lie beyond the scope of automation. Human-level pattern recognition, language recognition, and language production ability are well beyond the capabilities of modern mechanical and computer systems. Tasks requiring subjective assessment or synthesis of complex sensory data, such as scents and sounds, as well as high-level tasks such as strategic planning, currently require human expertise. In many cases, the use of humans is more cost-effective than mechanical approaches even where automation of industrial tasks is possible.

Specialised hardened computers, referred to as programmable logic controllers (PLCs), are frequently used to synchronize the flow of inputs from (physical) sensors and events with the flow of outputs to actuators and events. This leads to precisely controlled actions that permit a tight control of almost any industrial process.

An Introduction to Indoor Air QualityVolatile Organic Compounds (VOCs)

Volatile organic compounds (VOCs) are emitted as gases from certain solids or liquids. VOCs include a variety of chemicals, some of which may have short- and long-term adverse health effects. Concentrations of many VOCs are consistently higher indoors (up to ten times higher) than outdoors.  VOCs are emitted by a wide array of products numbering in the thousands. Examples include: paints and lacquers, paint strippers, cleaning supplies, pesticides, building materials and furnishings, office equipment such as copiers and printers, correction fluids and carbonless copy paper, graphics and craft materials including glues and adhesives, permanent markers, and photographic solutions.

Organic chemicals are widely used as ingredients in household products. Paints, varnishes, and wax all contain organic solvents, as do many cleaning, disinfecting, cosmetic, degreasing, and hobby products. Fuels are made up of organic chemicals. All of these products can release organic compounds while you are using them, and, to some degree, when they are stored.

EPA's Office of Research and Development's "Total Exposure Assessment Methodology (TEAM) Study" (Volumes I through IV, completed in 1985) found levels of about a dozen common organic pollutants to be 2 to 5 times higher inside homes than outside, regardless of whether the homes were located in rural or highly industrial areas.  TEAM studies indicated that while people are using products containing organic chemicals, they can expose themselves and others to very high pollutant levels, and elevated concentrations can persist in the air long after the activity is completed.

Sources

Household products including: paints, paint strippers, and other solvents; wood preservatives; aerosol sprays; cleansers and disinfectants; moth repellents and air fresheners; stored fuels and automotive products; hobby supplies; dry-cleaned clothing.

Health Effects

Eye, nose, and throat irritation; headaches, loss of coordination, nausea; damage to liver, kidney, and central nervous system. Some organics can cause cancer in animals; some are suspected or known to cause cancer in humans.  Key signs or symptoms associated with exposure to VOCs include conjunctival irritation, nose and throat discomfort, headache, allergic skin reaction, dyspnea, declines in serum cholinesterase levels, nausea, emesis, epistaxis, fatigue, dizziness.

The ability of organic chemicals to cause health effects varies greatly from those that are highly toxic, to those with no known health effect. As with other pollutants, the extent and nature of the health effect will depend on many factors including level of exposure and length of time exposed. Eye and respiratory tract irritation, headaches, dizziness, visual disorders, and memory impairment are among the immediate symptoms that some people have experienced soon after exposure to some organics. At present, not much is known about what health effects occur from the levels of organics usually found in homes. Many organic compounds are known to cause cancer in animals; some are suspected of causing, or are known to cause, cancer in humans. 

Search EPA's Integrated Risk Information System (IRIS) (a compilation of electronic reports on specific substances found in the environment and their potential to cause human health effects)

Drinking Water regulations - Contaminant Specific Fact Sheets: Volatile Organic Chemicals

Review information on VOCs in water sources developed by the U.S. Geology Survey's National Water-Quality Assessment (NAWQA) Program and their Toxic Substances Hydrology Program: Toxic Program Research on VOCs

Levels in Homes

Studies have found that levels of several organics average 2 to 5 times higher indoors than outdoors. During and for several hours immediately after certain activities, such as paint stripping, levels may be 1,000 times background outdoor levels.

Steps to Reduce Exposure

Increase ventilation when using products that emit VOCs. Meet or exceed any label precautions. Do not store opened containers of unused paints and similar materials within the school. Formaldehyde, one of the best known VOCs, is one of the few indoor air pollutants that can be readily measured. Identify, and if possible, remove the source. If not possible to remove, reduce exposure by using a sealant on all exposed surfaces of paneling and other furnishings. Use integrated pest management techniques to reduce the need for pesticides.

Use household products according to manufacturer's directions.

Make sure you provide plenty of fresh air when using these products.

Throw away unused or little-used containers safely; buy in quantities that you will use soon.

Keep out of reach of children and pets.

Never mix household care products unless directed on the label.

Follow label instructions carefully.

Potentially hazardous products often have warnings aimed at reducing exposure of the user. For example, if a label says to use the product in a well-ventilated area, go outdoors or in areas equipped with an exhaust fan to use it. Otherwise, open up windows to provide the maximum amount of outdoor air possible.

Throw away partially full containers of old or unneeded chemicals safely.

Because gases can leak even from closed containers, this single step could help lower concentrations of organic chemicals in your home. (Be sure that materials you decide to keep are stored not only in a well-ventilated area but are also safely out of reach of children.) Do not simply toss these unwanted products in the garbage can. Find out if your local government or any organization in your community sponsors special days for the collection of toxic household wastes. If such days are available, use them to dispose of the unwanted containers safely. If no such collection days are available, think about organizing one.

Buy limited quantities.

If you use products only occasionally or seasonally, such as paints, paint strippers, and kerosene for space heaters or gasoline for lawn mowers, buy only as much as you will use right away.

Keep exposure to emissions from products containing methylene chloride to a minimum.

Consumer products that contain methylene chloride include paint strippers, adhesive removers, and aerosol spray paints. Methylene chloride is known to cause cancer in animals. Also, methylene chloride is converted to carbon monoxide in the body and can cause symptoms associated with exposure to carbon monoxide. Carefully read the labels containing health hazard information and cautions on the proper use of these products. Use products that contain methylene chloride outdoors when possible; use indoors only if the area is well ventilated.

Keep exposure to benzene to a minimum.

Benzene is a known human carcinogen. The main indoor sources of this chemical are environmental tobacco smoke, stored fuels and paint supplies, and automobile emissions in attached garages. Actions that will reduce benzene exposure include eliminating smoking within the home, providing for maximum ventilation during painting, and discarding paint supplies and special fuels that will not be used immediately.

Keep exposure to perchloroethylene emissions from newly dry-cleaned materials to a minimum.

Perchloroethylene is the chemical most widely used in dry cleaning. In laboratory studies, it has been shown to cause cancer in animals. Recent studies indicate that people breathe low levels of this chemical both in homes where dry-cleaned goods are stored and as they wear dry-cleaned clothing. Dry cleaners recapture the perchloroethylene during the dry-cleaning process so they can save money by re-using it, and they remove more of the chemical during the pressing and finishing processes. Some dry cleaners, however, do not remove as much perchloroethylene as possible all of the time. Taking steps to minimize your exposure to this chemical is prudent. If dry-cleaned goods have a strong chemical odor when you pick them up, do not accept them until they have been properly dried. If goods with a chemical odor are returned to you on subsequent visits, try a different dry cleaner.

Standards or Guidelines

No standards have been set for VOCs in non industrial settings. OSHA regulates formaldehyde, a specific VOC, as a carcinogen. OSHA has adopted a Permissible Exposure Level (PEL) of .75 ppm, and an action level of 0.5 ppm. HUD has established a level of .4 ppm for mobile homes. Based upon current information, it is advisable to mitigate formaldehyde that is present at levels higher than 0.1 ppm.

Additional Resources

Indoor Air Fact Sheet No. 4 (revised) - Sick Building Syndrome

Explains the term "sick building syndrome" (SBS) and "building related illness" (BRI). Discusses causes of sick building syndrome, describes building investigation procedures, and provides general solutions for resolving the syndrome.

HTML Version

[EPA 402-F-94-004, April 1991]

Indoor Air Pollution: An Introduction for Health Professionals

Assists health professionals (especially the primary care physician) in diagnosis of patient symptoms that could be related to an indoor air pollution problem. Addresses the health problems that may be caused by contaminants encountered daily in the home and office. Organized according to pollutant or pollutant groups such as environmental tobacco smoke, VOCs, biological pollutants, and sick building syndrome, this booklet lists key signs and symptoms from exposure to these pollutants, provides a diagnostic checklist and quick reference summary, and includes suggestions for remedial action. Also includes references for information contained in each section. This booklet was coauthored with the American Lung Association, the American Medical Association, and the U.S. Consumer Product Safety Commission.

SICK BUILDING

Introduction

The term "sick building syndrome" (SBS) is used to describe situations in which building occupants experience acute health and comfort effects that appear to be linked to time spent in a

building, but no specific illness or cause can be identified. The complaints may be localized in a particular room or zone, or may be widespread throughout the building. In contrast, the term "building related illness" (BRI) is used when symptoms of diagnosable illness are identified and can be attributed directly to airborne building contaminants.

A 1984 World Health Organization Committee report suggested that up to 30 percent of new and remodeled buildings worldwide may be the subject of excessive complaints related to indoor air quality (IAQ). Often this condition is temporary, but some buildings have long-term problems. Frequently, problems result when a building is operated or maintained in a manner that is inconsistent with its original design or prescribed operating procedures. Sometimes indoor air problems are a result of poor building design or occupant activities.

Indicators of SBS include:

Building occupants complain of symptoms associated with acute discomfort, e.g., headache; eye, nose, or throat irritation; dry cough; dry or itchy skin; dizziness and nausea; difficulty in concentrating; fatigue; and sensitivity to odors.

The cause of the symptoms is not known.

Most of the complainants report relief soon after leaving the building.

Indicators of BRI include:

Building occupants complain of symptoms such as cough; chest tightness; fever, chills; and muscle aches

The symptoms can be clinically defined and have clearly identifiable causes.

Complainants may require prolonged recovery times after leaving the building.

It is important to note that complaints may result from other causes. These may include an illness contracted outside the building, acute sensitivity (e.g., allergies), job related stress or dissatisfaction, and other psychosocial factors. Nevertheless, studies show that symptoms may be caused or exacerbated by indoor air quality problems.

Causes of Sick Building Syndrome

A Word About Radon and Asbestos...

SBS and BRI are associated with acute or immediate health problems; radon and asbestos cause long-term diseases which occur years after exposure, and are therefore not considered to be among the causes of sick buildings. This is not to say that the latter are not serious health risks; both should be included in any comprehensive evaluation of a building's IAQ. 

See www.epa.gov/radon  and  www.epa.gov/asbestos

The following have been cited causes of or contributing factors to sick building syndrome:

Inadequate ventilation: In the early and mid 1900's, building ventilation standards called for approximately 15 cubic feet per minute (cfm) of outside air for each building occupant, primarily to dilute and remove body odors. As a result of the 1973 oil embargo, however, national energy conservation measures called for a reduction in the amount of outdoor air provided for ventilation to 5 cfm per occupant. In many cases these reduced outdoor air ventilation rates were found to be inadequate to maintain the health and comfort of building occupants. Inadequate ventilation, which may also occur if heating, ventilating, and air conditioning (HVAC) systems do not effectively distribute air to people in the building, is thought to be an important factor in SBS. In an effort to achieve acceptable IAQ while minimizing energy consumption, the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) recently revised its ventilation standard to provide a minimum of 15 cfm of outdoor air per person (20 cfm/person in office spaces). Up to 60 cfm/person may be required in some spaces (such as smoking lounges) depending on the activities that normally occur in that space (see ASHRAE Standard 62-1989).

Chemical contaminants from indoor sources: Most indoor air pollution comes from sources inside the building. For example, adhesives, carpeting, upholstery, manufactured wood products, copy machines, pesticides, and cleaning agents may emit volatile organic compounds (VOCs), including formaldehyde. Environmental tobacco smoke contributes high levels of VOCs, other toxic compounds, and respirable particulate matter. Research shows that some VOCs can cause chronic and acute health effects at high concentrations, and some are known carcinogens. Low to moderate levels of multiple VOCs may also produce acute reactions. Combustion products such as carbon monoxide, nitrogen dioxide, as well as respirable particles, can come from unvented kerosene and gas space heaters, woodstoves, fireplaces and gas stoves.  For more information, see VOCs; Carbon Monoxide; Formaldehyde; Nitrogen Dioxide; Respirable Particles.

Chemical contaminants from outdoor sources: The outdoor air that enters a building can be a source of indoor air pollution. For example, pollutants from motor vehicle exhausts; plumbing vents, and building exhausts (e.g., bathrooms and kitchens) can enter the building through poorly located air intake vents, windows, and other openings. In addition, combustion products can enter a building from a nearby garage.

Biological contaminants: Bacteria, molds, pollen, and viruses are types of biological contaminants. These contaminants may breed in stagnant water that has accumulated in ducts, humidifiers and drain pans, or where water has collected on ceiling tiles, carpeting, or insulation. Sometimes insects or bird droppings can be a source of biological contaminants. Physical symptoms related to biological contamination include cough, chest tightness, fever, chills, muscle aches, and allergic responses such as mucous membrane irritation and upper respiratory congestion. One indoor bacterium, Legionella, has caused both Legionnaire's Disease and Pontiac Fever.  For more information, see Biologicals and Mold.

These elements may act in combination, and may supplement other complaints such as inadequate temperature, humidity, or lighting. Even after a building investigation, however, the specific causes of the complaints may remain unknown.

Top of page

Building Investigation Procedures

The goal of a building investigation is to identify and solve indoor air quality complaints in a way that prevents them from recurring and which avoids the creation of other problems. To achieve this goal, it is necessary for the investigator(s) to discover whether a complaint is actually related to indoor air quality, identify the cause of the complaint, and determine the most appropriate corrective actions.

An indoor air quality investigation procedure is best characterized as a cycle of information gathering, hypothesis formation, and hypothesis testing. It generally begins with a walkthrough inspection of the problem area to provide information about the four basic factors that influence indoor air quality:

the occupants

the HVAC system

possible pollutant pathways

possible contaminant sources.

Preparation for a walkthrough should include documenting easily obtainable information about the history of the building and of the complaints; identifying known HVAC zones and complaint areas; notifying occupants of the upcoming investigation; and, identifying key individuals needed for information and access. The walkthrough itself entails visual inspection of critical building areas and consultation with occupants and staff.

The initial walkthrough should allow the investigator to develop some possible explanations for the complaint. At this point, the investigator may have sufficient information to formulate a hypothesis, test the hypothesis, and see if the problem is solved. If it is, steps should be taken to ensure that it does not recur. However, if insufficient information is obtained from the walk through to construct a hypothesis, or if initial tests fail to reveal the problem, the investigator should move on to collect additional information to allow formulation of additional hypotheses. The process of formulating hypotheses, testing them, and evaluating them continues until the problem is solved.

Although air sampling for contaminants might seem to be the logical response to occupant complaints, it seldom provides information about possible causes. While certain basic measurements, e.g., temperature, relative humidity, CO2, and air movement, can provide a useful "snapshot" of current building conditions, sampling for specific pollutant concentrations is often not required to solve the problem and can even be misleading. Contaminant concentration levels rarely exceed existing standards and guidelines even when occupants continue to report health complaints. Air sampling should not be undertaken until considerable information on the factors listed above has been collected, and any sampling strategy should be based on a comprehensive understanding of how the building operates and the nature of the complaints.

Top of page

Solutions to Sick Building Syndrome

Solutions to sick building syndrome usually include combinations of the following:

Pollutant source removal or modification is an effective approach to resolving an IAQ problem when sources are known and control is feasible. Examples include routine maintenance of HVAC systems, e.g., periodic cleaning or replacement of filters; replacement of water-stained ceiling tile and carpeting; institution of smoking restrictions; venting contaminant source emissions to the outdoors; storage and use of paints, adhesives, solvents, and pesticides in well ventilated areas, and use of these pollutant sources during periods of non-occupancy; and allowing time for building materials in new or remodeled areas to off-gas pollutants before occupancy. Several of these options may be exercised at one time.

Increasing ventilation rates and air distribution often can be a cost effective means of reducing indoor pollutant levels. HVAC systems should be designed, at a minimum, to meet ventilation standards in local building codes; however, many systems are not operated or maintained to ensure that these design ventilation rates are provided. In many buildings, IAQ can be improved by operating the HVAC system to at least its design standard, and to ASHRAE Standard 62-1989 if possible. When there are strong pollutant sources, local exhaust ventilation may be appropriate to exhaust contaminated air directly from the building. Local exhaust ventilation is particularly recommended to remove pollutants that accumulate in specific areas such as rest rooms, copy rooms, and printing facilities. (For a more detailed discussion of ventilation, read Fact Sheet: Ventilation and Air Quality in Offices)

Air cleaning can be a useful adjunct to source control and ventilation but has certain limitations. Particle control devices such as the typical furnace filter are inexpensive but do not effectively capture small particles; high performance air filters capture the smaller, respirable particles but are relatively expensive to install and operate. Mechanical filters do not remove gaseous pollutants. Some specific gaseous pollutants may be removed by adsorbent beds, but these devices can be expensive and require frequent replacement of the adsorbent material. In sum, air cleaners can be useful, but have limited application.

Education and communication are important elements in both remedial and preventive indoor air quality management programs. When building occupants, management, and maintenance personnel fully communicate and understand the causes and consequences of IAQ problems, they can work more effectively together to prevent problems from occurring, or to solve them if they do.