1The Glass Innovation SeriesBr

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India’s first & premier learning platform for glass & glazing.

Glass Academy’s vision is to achieve knowledge dissemination and empower the various stakeholders in the construction landscape – including Architects, students of architecture, Consultants for facade installations, Energy and HVAC, Fabricators, Developers, Project managers,

Installation companies and Glass processing companies in their chosen areas.

Glass Academy is governed by an elite Advisory Board with zeal and commitment to constantly better its achievements create a global knowledge repository and authority for Glass.

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Dear Reader,

Every successful individual follows one mantra -— Continuing Education. As simple as it may sound, Continuing Education is Continuing Evolution.

Eight years ago, we looked around to see a lack of educational platforms in building industry that support learning beyond the folds of formal education. Idea sparked, we set out to creating a platform that brought together a community of people, who together redefined the architectural landscapes of urban India; A Community that would together learn, share and evolve to build Indian Habitats towards Sustainability, Modernity, and Globalization. The Glass Academy was founded.

What began as an online portal — The Glass Academy, has diversified and diverged to reaching out to the current & future professionals through its revolutionary ideas and initiative. Be it Glass Explore — a student Research Fellowship programme, or Skill Gurukul — a Skill-Development program for the rural youth, every Glass Academy initiative has created a platform for learning, unlearning and sharing of new ideas.

The Enlightened Spaces is yet another step by Glass Academy towards Continuing Education. In the era of search engines, where information is easily available and in abundance, there is a need for expert wisdom and curation of information to ensure clear and complete learning. Enlightened Spaces is an attempt to reach expert intelligence on Sustainable and Smart Building Practices to the builders of tomorrow — You.

We were overwhelmed with the response our initiative met. Habitat experts were enthused by the idea, eager to share their knowledge and chose ‘Daylighting’ as the theme for the first season of Webinars. ‘Daylighting is the most easy and effective measure towards sustainability which also ensures occupancy comfort’ they declared. We agreed.

Their enthusiasm to share was met with enthusiasm to learn — hundreds of people from across India joined our webinar sessions to interact, and explore new ideas. The result — a wealth of information, we simply couldn’t resist but publish and share. This journal is a compilation of expert perspectives and practices on Daylighting, shared in our Enlightened Spaces sessions, to help you build your complete understanding of Daylighting for buildings.

We look forward to the exploration of many more interesting topics on modern buildings, future habitat & architecture in the seasons to come. I welcome you to be part of our Journey in Continuing Education. And Evolution.

I, also, welcome you to write to us at glassacademyindia@gmail.com and let us know of your suggestions for Enlightened Spaces or avail the many more journals to come.

Warm regards,

Mr. A. R. UnnikrishnanSecretary - Advisory Board, Glass Academy Foundation(National Head - Sales & MarketingSaint-Gobain India Private Limited)

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Architecture is the masterful, correct and magnificentplay of volumes brought together in light.

- Le Corbusier“

“

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EnlightEnEd SpacES

Glass Academy, the world’s largest glass learning platform, brings to you, an exclusive record of ideas on daylighting shared on ‘Enlightened Spaces’ — the most popular series of Webinars presented by the Energy Experts and Architectural Gurus of India.

Get ready to explore new possibilities with light that can bring to life creative building ideas.

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Padmashree ar. C. N. raghaveNdraN PARTNER,

C. R. NARAYANA RAo ARCHITECTS AND ENGINEERS

dr. vishal garg ASSoCIATE PRoFESSoR,

INDIAN INSTITUTE oF INFoRMATIoN TECHNoLoGY,

HYDERABAD.

mr. TaNmay TaThagaT DEPUTY ExECUTIVE DIRECToR,

ENVIRoNMENTAL DESIGN SoLUTIoNS (EDS)

PG.08

PG.16

PG.26

topic Daylighting and Artificial Lighting Controls

KEy pointS diScuSSEd Why daylight in buildings Issues and problems with daylight Why daylighting fails How to control daylight in buildings Dynamic facades Exterior and interior control measures Daylight modelling

topic Daylighting - Basic Concepts and Green Building Requirements

KEy pointS diScuSSEd Daylighting Basics Daylighting terminologies Daylighting quantification Daylighting factor Daylighting design steps & problems Daylighting benefits Strategies for daylighting design- Active & passive Energy efficiency and daylighting

topic An insight into DAYLIGHT HARVESTING

KEy pointS diScuSSEd Light and Architecture Aims of Daylighting Daylight Methods Passive Daylight Harvesting Systems Shading Systems Daylight Harvesting Automatic Daylight Harvesting Control System Daylight Sensor Placement Guidelines Building Standards and Daylighting

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mr. TaNmay TaThagaT DEPUTY ExECUTIVE DIRECToR,

ENVIRoNMENTAL DESIGN SoLUTIoNS (EDS)

PG.32

PG.40

PG.44

topic Green Buildings- All About people

KEy pointS diScuSSEd Challenges today Need for green buildings Building operation costs Key attributes for creating and enhanced environment Day lighting in Green Buildings

topic Daylighting and GRIHA

KEy pointS diScuSSEd About GRIHA Impacts of GRIHA Daylighting in GRIHA (versions) Examples Details on daylighting criteria in Version 2015

topic Role of Daylighting in Enhancing Human Comfort and Well-being

KEy pointS diScuSSEd Physiological and psychological benefits of daylighting Circardian rhythm and cycles Effects on internal body system Daylighting and body clock Daylighting in schools, offices, and other different segments Daylighting in industries Daylighting addressed in green buildings

04 05 06ms. deePa saThiaram LEED FELLoW,

ExECUTIVE DIRECToR, EN3 SUSTAINABILITY SoLUTIoNS.

KNoWLEDGE PARTNER - USGBC.

mr. sriNivas DEPUTY ExECUTIVE DIRECToR,

INDIAN GREEN BUILDING CoUNCIL.

ms. mili majumdar SENIoR DIRECToR - SUSTAINABLE HABITAT DIVISIoN, TERI.

SECRETARY & TREASURER - THE GRIHA CoUNCIL.

Building for light. Building for SuStainaBility.as old as architecture, is the concept of daylighting in architecture.

from Prehistoric habitats, to the earthy iranian dwellings, to the regal Mahals of india, to the grand Pantheon at rome — every architectural marvel celebrated is a creation designed for daylight. it is the art of lighting up your interiors naturally, with the controlled admission of daylight, reducing the need for artificial electric lighting.

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Padmashree ar. C. N. raghaveNdraN PARTNER - C. R. NARAYANA RAo ARCHITECTS

AND ENGINEERS

Padma Shri. Ar. C. N. Raghavendran, the Globally Reputed Architect-Leader from

India is the Chairman of CII – LEED India, a committee to Indianize the Green Building rating for Energy Efficient Buildings in India; Chairman of the Southern Chapter of Indian

Institute of Architects, Tamil Nadu for the years 1979 to 1984;

Fellow of Indian Institute of Architects.International Association Member of American

Institute of Architect; andMember of Governing Council of National

Institute of Design, Ahmedabad.

With the increasing need to lower energy consumption and build for a sustainable future, Daylighting today has gained more relevance than ever. A habitat optimized for Daylighting can create a visually stimulating and productive environment for building occupants. Here’s where an Architect’s understanding of the benefits and limitations of Daylighting helps create structures that optimize this abundantly and naturally available energy.

MEthodS of day lighting.

The two classic methods by which light can stream into building spaces are Top lighting and Side lighting. A building can be top-lit by allowing natural light to enter from the top of a building through Skylights, clerestories, monitors, and saw-tooths or other scoop-shapes; and side-lit by allowing light to enter through side window-walls and fenestration. The strong directionality involved in this technique may result in Visual Glare, which will have to be controlled. While Side lighting allows to light the corner rooms and perimeter areas, Top Lighting brings light deep into the building.

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Building for daylight.

For a building form highly aesthetic and functional, daylighting must begin at the conceptualization stage where Daylighting Systems can be integrated within the design of the building. There is a wide-range of Day-lighting Systems with diverse design alternatives within each choice for you to choose from. Here are a few that can help you design an architectural Form that is unique, aesthetic and high-in-comfort,

light ShElvESA light shelf is a classic daylighting system, which is designed to shade and reflect light on its top surface and to shield direct glare from the sky. The lower the height of a light shelf, the greater is the light reflected onto a ceiling, but also the incidence of glare is likely to increase.

louvrES and Blind SyStEMSLouvres and blinds are traditional daylighting systems that can be applied for solar shading, to protect against glare and to redirect daylight. They are located on the exterior or interior of a window, or between the panes of glass.

priSMatic panElS Prismatic panels are thin, planar, saw tooth devices made of clear acrylic that are used in temperate climates to redirect or refract daylight. When used as a shading system, they refract direct sunlight but transmit diffuse skylight. Used in fixed or sun-tracking arrangements, to façades and skylights, and used to guide diffuse daylight or sunlight.

laSEr-cut panElS A laser-cut panel is a daylight-redirecting system produced by making laser cuts in a thin panel made of clear acrylic material. The laser-cutting divides the panel into an array of rectangular elements. Each cut surface then becomes a small internal mirror that deflects light passing through the panel. An advantage of the panel is that in between the cuts, a view to outside of the window is maintained, although this is somewhat distorted.

light-guiding ShadES Light-guiding shades are external shading systems that redirect sunlight and skylight onto the ceiling. They are designed to improve the daylighting of rooms in subtropical buildings that have often have deep external shading from wide eaves to reduce radiant heat gain through windows. Highly reflective material must be used for their inner surfaces.

Sun-dirEcting glaSS The main component of a sun-directing glass system is a double-glazed sealed unit that holds concave acrylic elements. These elements are stacked vertically within a double-glazed unit and redirect direct sunlight from all angles of incidence onto the ceiling.

ZEnithal light-guiding glaSS with holographic optical ElEMEntSZenithal light-guiding glass redirects diffuse skylight into the depth of a room. The main component is a polymeric film with holographic diffraction gratings, which is laminated between two glass panes. The holographic element redirects diffuse light coming into the building from the zenithal region of the sky.

anidolic cEilingSAnidolic ceiling systems use the optical properties of compound parabolic concentrators to collect diffuse daylight from the sky. The primary objective is to provide adequate daylight to rooms under predominantly overcast sky conditions and is designed for side lighting of non-residential buildings.

anidolic Solar BlindS Anidolic solar blinds consist of a grid of hollow reflective elements, each of which is composed of two three-dimensional compound parabolic concentrators. The blinds are designed for side lighting and provide angular-selective light transmission to control sunlight and glare. The innovative feature of Solar Blind, in comparison with other Andolic Systems, is their used of three-dimensional reflective elements and their small scale. The optics of the admitting portion of the blinds are designed to reject most high-solar-altitude rays from direct sun but to transmit lower altitutde diffuse light or winter sunlight.

a sensor-less lEd dimming system based on daylight harvesting with Bipv systemsThe amount of daylight in clear sky is explicitly larger than that of daylight in overcast sky, but after passing through the window surface the daylight distribution decreases exponentially with respect to the distance from the window. The amount of daylight at the surface of window can be expected by the amount of electric power generated by BIPV system because the amount of daylight outside is closely related to generating electric power of BIPV system. Furthermore, the electric power generated by BIPV system can be used to operate the light-emitting diode (LED) lights without any conversion processes, leading to improving the energy savings in terms of energy efficiency.

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harvESting daylight.

Daylight Design becomes complete when there are measures to control the Daylight that streams in. In tropical countries like India, where the abundance in Sunlight leads to over-illumination and wastage of Light Energy, rises the need for strategic Daylight Harvesting measures. This begins with understanding Daylight Harvesting.

Daylight Harvesting is an advanced lighting control strategy that minimizes energy costs and consumption. It involves designing the building and its lighting systems for an even illumination that meets ideal lux levels.

Building an EffEctivE daylight harvESting SyStEM:

A building optimized for daylight can contribute to obtaining points in several LEED credit categories. The Mandates laid by the various Building and Energy Efficiency codes — Title 24 codes (Section 130.1[d]) and ASHRAE 90.1 standards (Section 9.4.1.4 and 9.4.1.5) — are met through a system of occupancy Sensors, Integrated Room Controller (IRC) and Relay Control Panels. Smart monitoring and actuation can significantly reduce cost and improve the building’s energy performance.

Zoning:It is difficult to achieve even lighting merely with the help of Windows and Skylight. We need an effective Daylight Harvesting System which can dim or turn off the artificial lights installed, based on the levels of Ambience light available or occupancy within the interiors. This can be achieved by sectioning your interiors into zones of light or shade, with lighting and lighting control systems that work in harmony to maintain even light levels. This way the interior is never too dark or too bright.

Thus, studying the fall of light within these Zones and their distance from ambient light sources — windows and skylights, can help gauge the dimming & switching of lighting loads and create an ideal Daylight Harvesting System.

Sensor placement:Be it any daylighting system employed in a building — Switched, Bi-Level or Continuous Daylighting Systems — it is the placement of Sensors and Fixtures that leads to achieving ideal lux levels. It is important to ensure the sensor maximizes the ratio of natural light to artificial light, and is not constantly washed out with sunlight. Here are a few sensor placement guidelines you can adapt for different interior locations,

gEnEral SEnSor placEMEnt guidElinES:

Allocate one sensor for each partitioned space in a closed office environment, and at least one sensor covering 30 linear feet of window-wall in an open office environment. Similarly, allocating a sensor for every individually controlled shade group will provide an ideal daylighting behavior.

Point the Sensor arrow towards the nearest window, and place at a distance that is one-to-two times the effective window height (H). The effective window height (H) is measured from the window sill or 3 ft (1 m) from the floor — whichever is higher — to the top of the window.

The view of the daylight sensor must not be obstructed by ceiling fans or pendant fixtures.

Avoid placing the sensor in direct light from fixtures in the space. This brings inaccuracy in the sensor readings and hinders with the Daylight Efficiency.

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corner office:

If working with a small corner office, point the sensor toward one of the window opening.

If working with a large corner space either use: Two sensors, one pointed towards each façade. A single sensor close to the corner, pointed at either façade

MultiplE ShadES / opEn officE

Inconsistent shade (manual or electric) positions will affect the amount of light coming into the space from one section of the office to another. You will need more than one sensor, as the lights/shades will only respond to the sensor that is receiving the natural light, leaving the rest of the space under lit. The addition of another sensor ensures that the entire space will be properly lit.

narrow privatE officE or hallway

In this application, if you place the sensor closer than 1 window height, the sensor will receive too much sunlight and won’t be able to operate the electric lights with precision. Try placing the sensor against the window, facing in toward the space.

SENSOR

SEN

SOR

North Window

East Window

North Window

SENSOR

East Window

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SKylightS

Mount the sensor as close as possible to the skylight with the field of view oriented toward the floor, under the skylight opening. Avoid positioning the sensor inside skylight.

high windowS, SlantEd cEiling

The guidelines for high slanted ceilings depend on the structure of the space and will have to be adapted to suit its Form.

fixturE fEEdBacK When light from a fixture contributes to the over all light on a sencer the sencer might not be giving true results. High levels of fixture feedback can result in unexpected behavior including light oscillation or under-lit areas. To minimize fixture feedback, position sensors in such a way so they don’t receive direct light from the fixture.

SpEcial conSidErationS

Not enough light at the sensorBefore calibrating, ensure at least 25% of the desired light level reaches the sensor during calibration. Place a light meter on the ceiling in the same location as the sensor, and move the sensor closer to the natural light source or calibrate the sensor at a different time of day.

Sensor washed out with sunlightIf the sensor is in a location where its washed out with sunlight, the calibration will most likely result in a too low gain. Make sure the sensor placement matches the spec. This will most likely result in under lit spaces during certain times of the year, or certain weather conditions. You can avoid this by shifting the sensor to a different location.

Reflective surfacesReflective surfaces can provide unexpected spikes in daylight sensor readings. This could result in the light level changing dramatically without a significant change of work surface light. You will need to move the sensor out of the reflection’s path

Window treatmentsWindow treatments will greatly affect the daylight penetration curve in the space, especially blackout shades. Remove or open all window treatments when placing the sensor. Then replace or close window treatments to test Daylighting behavior at varying light levels.

SKY LIGHT

SKY LIGHT

?

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IECC 2012, International Energy Conservation Code Building code created by the International Code Council in 2000 in buildings for a Sustainable future, IECC 2012 certification requires,

Daylight Zone Control (405.2.2.3)

Multiple daylight zones must be separately controlled from the general area lighting and can be controlled either manually or via an automatic daylight sensor.

Building codES and daylighting StandardS.

In the Contemporary World of Construction new codes and standards are being introduced on the local municipal, state and national levels to conserve energy and create a Sustainable future. With Artificial Lighting consuming nearly 30 percent of our commercial electricity use, Daylighting has become an important factor by which the efficiency of a building is assessed.

LEED: Leadership in Energy and Environmental Design (LEED), the famous American third-party certification program for design, operation and construction of high performance green buildings demands a building save Energy,

optimize daylight and provide unobstructed views. The choice of daylight sensor and its efficacy can contribute up to 19 possible points in the LEED 2009 NC rating system.

ASHRAE 90.1 – 2010: A global society advancing human well-being through sustainable technology for the built environment, ASHRAE certifies the energy standard in commercial buildings. Here are a few norms by which ASHRAE certifies,

Parking Garage Lighting Control (9.4.1.3)

Transition lighting and lights within certain parameters with relation to natural light must be automatically reduced in response to daylighting.

Automated Daylighting Controls for Sidelighted Areas (9.4.1.4)

The lamps for general lighting must be controlled by at least one multilevel daylight control in any enclosed space that has more than 250 ft2 of window lit area.

Automated Daylighting Controls for Toplighted Areas (9.4.1. 5)

The lamps for general lighting must be controlled by at least one multilevel daylight control in any enclosed space that has more than 900 ft2 of skylight lit area.

Exterior Lighting Control (9.4.1.7)

Exterior lighting must automatically be turned off when sufficient daylight is available.

Title 24 – 2013 Part 6 (California’s energy standard) Standards set by the Californian Energy Commission, Title 24 focuses on Energy Savings from a Building. The Standard that has saved Californians more than $74 billion in reduced electricity bills

since 1977, demands from an Energy Efficient Building,Automatic daylighting controls: SECTIoN 130.1- Indoor Lighting Controls That Shall Be InstalledAutomatic daylighting controls must be used to provide multi-level or continuous dimming in spaces with more than 250 ft2 of daylight area.

IGCC IGCC — International Green Construction Codes set by the International Code Council expects in a Green Building,

Automatic Daylight Controls (609.5)

Automatic daylight controls shall be provided for all daylight zones.

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thE dynaMiC WayS of daylight & dESign.Inspiring young minds as Associate Professor

in IIIT, Hyderabad, Dr. Vishal Garg is a research specialist in Task control of lightning,

heating, air-conditioning using fuzzy logic; Smart occupancy sensors; Fuzzy logic based

protocol for wireless sensors network and Intelligent Building. I.T. in Building science.

dr. vishal garg ASSoCIATE PRoFESSoR,

INDIAN INSTITUTE oF INFoRMATIoN TECHNoLoGY, HYDERABAD.

timeless, unchanging, yet dynamic is the nature of the Sun - the nature of light itself. Creating a nourishing environment that optimizes natural light, begins with the understanding of daylight - the Sun-directional Paths, radiation levels and the Color temperature of Sunlight that affect the geography of a habitat. it is the direction of the Sun’s movement, the seasons, and the weather that determines the quality of light that streams into your life-spaces.

challEngES in daylighting:

When a building is designed to capture daylight aplenty, but is not properly equipped to control the amount of daylight that streams into it, then the purpose of daylighting cannot be achieved. Non-uniform distribution of daylight, Glare and increase in cooling energy consumption, the changing requirements for daylight within the building — are all challenges that impress the need for Architectural Design with Light Controls.

control SyStEMS for daylighting:

Control Systems integrated in building design can help control the entry of daylight through facades. There are four types of control systems,

ExtErior controlS in-BEtwEEn panE controlS intErnal controlS light pipE with apErturE control

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01. ExtErior controlS

The most energy efficient method of controlling heating issues that result in Daylighting, Exterior Control Systems block heat waves before they reach the window making them a heat-reducing, energy-efficient solution for Daylight Management.

a. ExtErior ShadES & BlindS:

The heat from the daylight that pass through shades and blinds are absorbed as short wave, and later emitted as long wave. Using interior shades and blinds increases interior temperature as the long waves emitted by the shades are trapped within the room, while installing exterior blinds controls daylight and keeps the heat radiation outside the building.

b. louvErS:Exterior Shutter Mechanisms that shift from being partially to fully closed, Louvers are ideal for high-rise buildings where exterior shades or blinds become difficult to maintain.

c. awningSAwnings are projections from the exterior of a wall that can control daylight without obstructing the view. Awnings are exterior control systems that are ideal to be used on windows to effectively eliminate glare.

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02. in-BEtwEEn panE controlS

In Between Pane Controls are Glass Facade and Fenestrations Systems that are specially designed for Daylight and Solar Control in Buildings

a. BlindS BEtwEEn glaSS:A Control system where a blind is placed in between the two glass panes — Blinds between Glass systems trap the heat absorbed within the glass panes. Here, the blinds are not exposed to dust, water and wind, and thereby don’t require maintenance.

b. ElEctrochroMic glaSSThe Electrochromic glass helps control the amount of radiation and light that passes through the glass, through electrical voltage. The glass is electronically tintable. It can be programmed to dynamically change its tint - based on the external temperature and internal occupancy. It is an aesthetic way to control sunlight without shades or blinds, so you can manage glare and heat while maintaining a connection to the outdoors.

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03. intErior controlS

Interior Control Methods are the most simple, cost-effective and commonly employed Daylight Control Method.

a. autoMatEd BlindS:Automated blinds can control the amount and angle of the light that enters a building. The Mechanised Blinds can redirect the natural light towards the ceiling or the floor helping the user control and channelize natural light to best suit one’s needs.

b. autoMatEd rollEr ShadES:Mechanisms that can roll up and down, Automated Roller Shades can help balance between Controlling DayLight and enjoying an unobstructed view.

c. rEflEcting porouS faBricA Breakthrough in Light Control, the Reflecting Porous Fabric is a control system which shades the interiors, allowing views from the inside through its porous surface, while its highly-reflective exterior surface reflects the heat waves keeping the building cool and energy efficient. Based on the amount of light one wants controlled, one can choose from the Wide range of fabrics that are available commercially.

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04. light pipE with apErturE control:

Light Pipes and optic Fibre systems can light up every inch of your life-space with the Sun. When light enters the light pipe with a high internal reflectivity, it is reflected several times within the pipe until it reaches the destination it is to light up. A Dimming arrangement at the end of the light pipe can add to the control a user has over the amount of light that fills the interior space. In optical Fibre Systems, light gets captured from the roof through specially designed devices and is passed on to optical Fibre Systems that can be installed for the perfect light experience.

Efficacy of light SourcES:

The efficiency of a light source is assessed by its luminous efficacy. The luminous efficacy of a source is a measure of the efficiency with which the source provides visible light from electricity. It is assessed and expressed as the number of lumens a light source emits for one watt of heat. While incandescent light emits 14 lumens with one watt of heat, natural sunlight emits 105 lumens per watt, which means that percentage of light emitted by the sunlight is higher than the percentage of light emitted by the incandescent light for the same amount of heat - one watt. Interestingly, the Sunlight that streams through Low-E High-Performance glass systems that block the heat radiation from entering the interiors provides 175 lumens per watt becoming the coolest source of light - artificial or natural.

artificial light controlS for daylight dESign:

Where the optimum level of light is not met, arises the need for Artificial Lighting Methods that complement a building’s daylighting design. The dynamic nature of natural lighting calls for dynamic artificial lighting and control systems that can be controlled as per the requirement of your interiors. We need a system that can study the daylight that enters a building and controls the amount of artificial lighting that will be required to maintain the required amount of light. Based on the Daylight that enters a room and the various surfaces it illuminates, a photo sensor signals an artificial light controller that will level the dimming units and the light emitted by the fixtures accordingly.

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thE nEEd for artificial lightS in daylighting:

When light enters through the windows, it is only natural that the spaces closer to the windows are more lit than the spaces away from the daylight. The lighting design will have to be planned to maintain an even luminance across the interior space, where the space closest to the windows need no lighting, to a gradual increase in illuminating the shade areas with artificial lighting systems.

artificial light control MEthodS:

The artificial controllers can adapt to two different control methods in illuminating shade areas - Dimming or Switching.

a. diMMing:Dimmers are devices that lower the brightness of a light source, allowing a wide range of light output.

b. Switching:Switching happens with light fixtures that hold several lamps, where different lamps will be switched on or off to achieve the required amount of light intensity. The more the number of lights within a fixture, the wider the light intensity options it offers.

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optiMiZing uSE of luMinariES:

A cost-efficient alternate to fixtures with a wide light intensity range, is Control arrangements that can maintain light levels from an array of luminaires in a space.

a. altErnating luMinairES: Every alternate luminaire is switched on or off to control the amount of light. Though the methods affects the uniformity in lighting, it is simple to execute and cost-effective.

b. altErnating laMpS: Fixtures with three lamps are rewired to have their ballasts that control all three lights to switch on alternate lamps of different light fixtures, allowing uniformity in lighting and access to different light intensities.

c. diMMing: Luminaires in which all the ballasts are dimmable, are the most effective of Light Controls allowing uniformity in lighting and offering a full range of light intensity. However, in dimming the amount of power consumed is higher than the amount of light emitted, resulting in low efficacy.

undErStanding autoMatEd controlS and logic:

Daylight harvesting automated controls measure the daylight contribution on the task surface and operate the artificial light system to ensure uniform lighting. The two Types of Control Systems are,

a. cloSEd loop SyStEMS:Closed Loop Systems measure the contribution to the overall lighting level from available daylight and from electric light output, and then adjust the electric light output to maintain the desired level of overall illumination. As the photo sensor measures both the available daylight contribution as well as the electric light output, it ‘sees’ the results of its own adjustment, which could make the assessment of the room’s illuminance inaccurate.

b. opEn loop SyStEMS:open Loop Systems measure the incoming daylight, not the electric lighting. The photo sensor should be mounted either inside a skylight light well, between the blinds and glazing or outside, so that it does not see any electric light. There is no feedback from the task surface and is called an open Loop.

c. partial opEn loop SyStEMS:A combination of the open loop and closed loop systems, where predominantly the closed loop controller works but when there is a high difference between the open loop and closed loop controllers, the open loop controller takes precedence.

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controlling artificial lightS in daylighting SyStEMS:

The designed Daylight systems need controllers that can function to suit the changing needs of the interiors. The System can constitute

a. Manual controlS:Simple Manual Switches that can be used to turn the luminance off or on, and also to switch between required light intensities.

b. occupancy SEnSorS: Devices which switch lights on and off based on detection of motion within room or area.

c. tiMErS: Devices that are simply time clocks that are scheduled to turn lamps or lighting off on a set schedule. If spaces are known to be unoccupied during certain periods of time, timers are extremely cost-effective devices.

d. dEMand rESponSE:For Demand Response, where consumers reduce or shift the electricity usage during peak periods electric light levels may be reduced temporarily from recommended levels.

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MASTERLIGHTING

CoNTRoLLER

ExTERNALTIMING DEVICEoR CENTRAL

oN/oFF SYSTEM

DIMMINGPHoToSENSoR

oCCUPANCYSENSoR

CoNTRoLSTATIoN

INPUT:Does user wantto switch ordim lights?YES/No

INPUT:Is spaceoccupied?YES/No

INPUT:Is target lightlevel reacheddue to daylightcontribution?YES/No

INPUT:Is it thescheduled timeto switch thelights?YES/No

oUTPUTS:If YES, switch or dim lightsIf No, do nothingIf YES, turn on lightsIf No, turn off lightsIf YES, dim lightsIf No, do nothingIf YES, switch the lightsIf No, do nothing

LIGHTINGLoAD

Branch lighting circuit Switched circuit

Control wire

13 StEpS towardS dESign for daylight:An idea designed for Daylighting without a well-equipped and well-executed Light Control Design increases the building’s energy consumption and fails to achieve the purpose of daylighting - occupancy Comfort and Energy Efficiency. The effects of Daylight on a building can be accurately analyzed with Daylight Simulation tools like Radiance and designed with Daylight Modeling tools such as Energy Plus to create an effective Light Control Strategy and a high-impact daylight design. Here are the steps to designing an energy-efficient Lighting Control System,

Select the artificial light control Method: dimming vs. SwitchingSelect the degree of automation: Manual vs. automatedSelect the daylight control System (open vs. closed loop)Select the System (a large System vs. Stand-alone)Select the photo sensorEstablish control zonesplace photo sensorsplace controllersEstablish set-pointsintegrate the daylighting controls with other controlsSpecify the control systemcommissioningoccupants acceptance

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logic SyStEM of a light controllEr:

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EnErgy EffiCiEnCy and daylighting.an architect’s aim, across ages, has been to naturally light spaces that improve productivity levels, enhance aesthetics and heighten comfort levels within a building. advancements in science and increasing need for Sustainable Practices have brought to life various ways with which daylighting can transform our living spaces into Zones of Energy Efficiency.

mr. TaNmay TaThagaT DEPUTY ExECUTIVE DIRECToR,

ENVIRoNMENTAL DESIGN SoLUTIoNS (EDS)

Mr. Tanmay Tathagat leads the Environmental Design Solutions’ [EDS] team of consultants working on climate change policies, energy

efficient building design, building code development, energy efficiency policy

development, energy simulation and green building certification process. He has

received the LEED (Leadership in Energy and Environmental Design) Fellow accreditation from the US Green Buildings Council. He is

working closely with the Indian Green Building Council and GRIHA for development of green building standards in India, and for supporting

green building projects worldwide.

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A myth that commonly prevails is that daylighting in interiors increases the heat levels within. However, the fact remains that the Solar Radiation Spectrum is a combination of heat and light radiation, which can be classified as,

uv radiation viSiBlE radiation infrarEd radiation

Visible Radiation is the light spectrum that is independent of heat and is the source of daylight. The luminosity of light is measured as Lux units — luminous flux per unit area. Construction materials - especially Glass - have evolved to allow Visible Light, while blocking Heat Radiations from entering a building, making way to light up interiors sans the discomfort of heat.

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thE BaSicS of dESigning for daylighting:

Daylighting design for your building begins with the understanding of three factors that can help optimize your building in achieving Energy Efficiency and the diverse comforts of Daylighting -

oriEntation forM conStruction MatErialS

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01. oriEntation:

Daylight Design is the art of composing a Building’s response to the natural light, which is unique to the geography of a region. This begins with the study of Daylight that is natural to the region - its movements, intensity, color, etc. The movement of the earth around the sun naturally changes the movement of light upon a building, changing the angles, intensity and direction from which sunlight impacts the building at different periods of time.

Similarly, the Path and characteristics of Sunlight is different at different geographical co-ordinates. observing these factors is essential in planning a building orientation apt for daylight optimization.

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02. forM:

The Shape and Configuration of a building – its FoRM, rules the play of light within the building. It is the factor that helps in attaining the Goals of Daylighting - provide sufficient illuminance, minimize glare, provide overall visual comfort, improve aesthetics, improve occupant comfort, productivity and health, and reduced energy usage. All of these benefits and more can be experienced with a building form, created and designed for Daylight.

The most commonly used method for Daylighting is Fenestration. The shape, size, orientation and material property of your fenestration decides the quantity and quality of daylight that streams into your building. Ideally, the Window-Wall Ratio (WWR) and Skylight Roof Ratio (SRR) are ascertained based on the quantity and distribution of daylighting you would prefer in your life-space. In addition to bringing in light, a well-planned Fenestration brings the comfort of fresh air and great views.

a. daylighting factor:

Beyond the permittance of Sunlight into a building, the aim is to be able to achieve an even and uniform lighting within a building by harvesting natural light. This quality of daylight distribution and even luminance in a building is referred as its Daylight Factor. Daylight illuminance distribution across a room is usually a high variable, and the success of a design lies in its ability to evenly distribute natural light. It is wise to design for the lowest possible daylight factor of a region, as low light conditions result in the use of artificial lighting, thereby defying the purpose of daylighting. on the contrary, excessive daylight conditions are easy to control.

iESna df(%)office 2 (for the entire area)

Warehouse 1.5

Factory (depends on the function) 5

Public areas 1

Sp-41 df (%)office 1.9

School - classroom 1.9-3.8

Library - reading room 1.9 - 3.75

*Recommended Daylight Factor

daylighting factor =indoor illuMinancE in lux unitS

x 100outdoor illuMinancE in lux unitS

*Lower VLT requirements offset the increased heat transfer through the WWR

window wall ratio Min vlt0 - 0.3 0.27

0.31 – 0.4 0.20

0.41 – 0.5 0.16

0.51 – 0.6 0.13

0.61 – 0.7 0.11

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b. glarE and Shading EfficiEncy: While low daylight conditions affect productivity, excessive daylight causes visual glare and affects occupant comfort. Based on the nature of Daylight unique to a region, there are many types of glare that can affect your interiors - high angle direct, low angle direct, reflected or veiling reflections and screen glare. It is important to integrate measures that control glare and excessive brightness in the building design.

Light or Shade - the Solar accessibility of a building lies in its form. By studying the nature of daylight - Daylight Autonomy & Analyzing the Glare in a geographical location, the form can be built to shade actively and passively. Actively by the use of various Daylight controls such as Exterior Shades, Blinds, BIPV and Solar Collecting methods. Passively by the form itself having horizontal and vertical shades and materials that block excessive heat.

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03. conStruction MatErialS:

Choosing a Construction material designed for daylight efficiency, is the easiest and most effective method of Daylight optimization. The most common yet incorrect method used to prevent glare and heat gain through fenestration is the use of Tinted Windows. Tinted Glass simply colors the Visible Light Spectrum reducing the brightness of light, and does not lower the Heat Gain. on the other hand, Energy Efficient Glass is specially optimized to allow a High Visual Light Transmission and maintain a Low Solar Gain. This ensures that your building enjoys the comfort of light without the discomfort of heat, reducing energy consumption on cooling and artificial lighting; lowering your energy bills.

Know thE factorS that affEct daylight:Here are a few factors that can help deliver on the promise of Comfort through Daylight,

Size of daylight apertures (windows, skylights, etc.)location of daylight apertures (side lighting, top lighting, etc.)access to daylight (considering the site, building, and room contexts)room geometry (height, width, and depth)location of the point of interest relative to aperturesvisible transmittance (vt) of glazingreflectance of room surfaces and contentsreflectance of exterior surfaces affecting daylight entering the aperturethe effects of daylighting enhancements (such as light shelves).

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a challEngE for changE:The changing nature of Daylight gives way to challenges in Daylight optimization. However, understanding the nature of light, the factors that affect light and the various scientific advances that help optimize it, can create a productive and healthful living space.

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rolE of day lighting in EnhanCing huMan CoMfort and WEll BEing

ms. deePa saThiaram LEED FELLoW,

ExECUTIVE DIRECToR, EN3 SUSTAINABILITY SoLUTIoNS.

KNoWLEDGE PARTNER - USGBC.

The 1st woman outside of the United States to be awarded the LEED Fellow

recognition, Ms. Deepa Sathiaram is a leading international sustainable design expert working with diverse project teams and

creating sustainable habitats in the U.S., India, Europe and Middle East.

She is the Past President of the ASHRAE South India Chapter and also the Past

National Environment Chair for the Young Indians (Yi) arm of the Confederation of Indian

Industry (CII)

day lighting is an architectural statement of a building. in addition to energy saving, day lighting has a huge non energy related benefit that results in Physiological and Psychological benefits for the occupants of the building. Positive attitude, reduced eye strain, stress and fatigue, lesser mistakes at work, reduced depression at work places, improved sleep rhythm and ease of pain among patients in the hospitals are examples of such benefits.

the u.S. green Building Council (uSgBC) is committed to transforming the way our buildings are designed, constructed and operated through lEEd — the top third-party

verification system for sustainable structures around the world.through their community network, continuous collaboration with industry experts, market research publications and lEEd professional credentials, uSgBC remains a key driving force in the green building sector.

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While discussing the effect of day light on the wellbeing of people, an understanding about the Electromagnetic spectrum becomes necessary. The spectrum is divided into 7 regions in order of wavelength. (See diagram)

Visible light falls between ultraviolet (UV) and infrared (IR) rays and have wavelengths between 380 Nano meters and 740 Nano meters. Visible light is electromagnetic radiation, just like other radiation like from a nuclear spill or from your cell phone. The closer you get to the sources the stronger the radiation.

Each light source produces a different spectrum of visible light. on the contrary, daylight provides a better lighting environment than all the external light fixtures because daylight very closely matches the visual response that humans have come to compare with all other light. Majority of humans prefer day lit environment because of its balanced spectrum of color

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thE iMportancE of circadian rhythM

Light falling on the retina of the eye and being transmitted to the hypothalamus controls our circadian rhythms. Circadian Rhythm can be explained as the body’s reaction to different time zones within the day. This synchronizes our internal clock to 24 hours. For example our body experiences high alertness at 10 a.m., best coordination is achieved at 2.30 p.m., the highest cardio vascular efficiency and muscular movement is around 5 p.m. and the deepest sleep is attained at 2 a.m. in the morning. our work culture, therefore, should coincide with this body rhythm to achieve maximum efficiency. If the internal rhythms do not match the workday rhythms, one feels drowsy, tired, and distracted. For example, for individuals working during night shifts, a 24-hour cycle that keeps most people awake and alert in the day and sleepy in the night would result in fatigue and a complete inability to perform during the night shift. Studies have shown prolonged exposure to artificial light sources induce abnormal circadian rhythms.

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pinEal and pituitary glandS

Light entering eye correlates with the functioning of pineal glands. Light energy influences the pituitary gland which in turn influences our coping mechanisms, emotions, stress and depression. Melatonin levels in the body determine a person’s activity and energy level. Where daylight or artificial light is inadequate during the day, the natural suppression of melatonin production fails to occur and is accompanied by feelings of depression. Hence it is important that one is exposed the right amount of light and day light in particular.

light’S contact with thE huMan Body haS two typES of EffEctS:

Light reaching the retina modifies individual endocrine, hormone, and metabolic state of the body. Visual retinal responses influence a number of neuro endocrine hormonal functions and consequently has psychological effects.

Light falling on the skin stimulates vitamin D production, skin tanning, and dissociation of bilirubin. Physiological disorders occur if body does not receive solar radiation for long periods of time. Vitamin D deficiency means weakened body defenses and lack of melanin pigment in skin means higher chances of skin cancer.

In today’s living conditions most of the times we are inside a building, be it our house, office, restaurants or other places. The condition of the buildings does have an impact on us indirectly. Hence it is important for us to learn in what way buildings affect us and as designers we need to be conscious of these factors while designing the building.

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thE Body clocK

There are eight facts that will help us appreciate the importance of being housed in a well designed building as it is ultimately relating to our body and our well being.

The Impact of Artificial light: Darkness is Mother Nature’s way of communicating to us that it is time for us to rest. It is one reason why our forefathers resorted to an ‘early to bed and early from bed’ routine and maximized the advantage of functioning during day light and derived the benefits of what natural light offers to our body. Artificial light, irrespective of its source like the Lamp, TV or Cell phone, confuses our biological clock into thinking that it is still not time to rest. This can disturb one’s body rhythm and cause harmful effects as the body is forced to alter its natural rhythm. This is why we experience drowsiness and headaches getting up late in the morning after a late night movie or party. While use of artificial light has become necessary in our current life style of working extended hours, we have to limit our exposure to artificial light so that it doesn’t impede natural body conditions.

Scientists and Therapists have often recommended ‘Camping’ as a resetting process for people, especially for city dwellers, who are constantly exposed to higher levels of

artificial lighting. Camping, in a natural surrounding with its natural light – dark cycle, gives a signal to body to comeback to normalcy and provides the recuperative treatment to the abused body mechanism.

‘Jet lag’, a condition that affects people who return to their original time zone after a long stay in a country that had a different time zone, is a classic example of how our internal biological clock is distorted because of disruption to our normal sleeping patterns. This is termed Circadian rhythm disorder. our internal personal clock is disturbed due to mismatched internal or external cues leading to insomnia or excessive sleep.

Some of our ‘Genes’ and ‘Genetics’ operate on internal clocks. Genes have an overwhelming control on our body and naturally when sleep patterns are affected the genes are affected too. This has an impact on our body temperature, blood sugar and even mood swings. Therapeutic yoga and meditation help rejuvenate the body mechanism as it sets

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the body clock to its natural rhythm by slowing it down to its normal cycle.

Some Genes affect our immune system as well.

Research has shown that a disturbance in the ‘Circadian rhythm’ affects a woman’s fertility as well. Women, who are pregnant and who are hoping to conceive, should keep their bedroom free of artificial light as far as possible. Interaction with clients, especially in the BPo sector, has revealed the fact that a lot of women who constantly travel and whose work cycles are awry have trouble in conceiving.

A disrupted body clock can also lead to depression. Research has shown that the quality and timing of sleep have an impact on the mental state of a person. Studies indicate that clinically depressed people have disturbed body clocks. Even Vegetables and Fruits have their own internal clocks that keep ticking even after days of their harvesting. An interesting study done in an University in the U.S suggests that they respond to their environment for several days and that natural light during certain times of the day can make more cancer fighting anti-oxidants in them.

It is clear that body clocks respond to external stimuli and day light being one big stimulus has a big role to play in maintaining a harmonious body condition. That is why in recent times, beyond the regular green building requirements of energy savings and other considerations the aspect of human well-being due to day light conditions have gained importance. More studies are being undertaken to study how day light can help us attain a natural body rhythm.

Light can cure medical conditions. Improved interior lighting can help alleviate common problems such as over sleeping, over eating, energy loss and work disturbances. Ultra violet radiation from sunlight triggers production of Vitamin D in the skin and can prevent or cure rickets and osteomalacia.

Light plays a very important role in curing Seasonal Affective Disorder (SAD) a condition that arises due to disturbed body rhythms. This is common with people who are in cold regions and is widely prevalent in the Northern Hemisphere as it gets very little day light for many months in a year. Symptoms of SAD could include fatigue, irritability and sadness. It can also lead to clinical depression and melancholic state. Natural light has proven to be a much better alternative to any kind of medication for SAD.

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glarE one major problem of improper day lighting is glare. In many cases, glazed surfaces provided in the building results in too much glare. Eventually we end up putting blinds in these building to block the excessive day light. This defeats the benefit of proper day lighting. Today when architects design a building our focus is not just on glazing and the lux level that is brought into the building but more importantly the element of ‘how much glare we are bringing in’. There are software that help us analyze and make suitable adjustments in positioning the computer monitors and work stations at a particular angle so that the glare does not affect the working conditions.

daylighting in SchoolSTraditionally Indian schools have been functioning under a natural environment of day light with plenty of windows that allow sunlight and air and without

air conditioners. School environments have developed substantially. The use of smart devices like LED Screens, White boards, Use of power point presentations as a methodology for teaching have led to a situation of arresting day light in the class rooms. Modern day schools prefer an undisturbed; air conditioned environment and class rooms are being built with lesser or practically no windows. This could impact the students psychologically and stunt growth in children. The impact of poor lighting on our children can manifest as disorders which cannot be even recognized in the earlier stages. We cannot afford to close the avenues of natural light and hence it is very important to harvest day light in schools. It is imperative on the part of designers to educate the clients the importance of day lighting in our schools.ொொ

day lighting in rEtailThe impact of day lighting on sales in retail outlets can be illustrated through an interesting experiment conducted in Walmart, U.S.A. A comparative analysis between two groups of stores, one with

a good exposure to day light and the other with practically no connection to the external environment, was carried out. It was found that customers spent 18% extra time in the store that had more day light exposure compared to the one which has no allowance for day light. It was evident that the shoppers felt comfortable being connected to a comparatively natural environment and hence spent more time shopping that translated to increased sales for the stores.

day lighting in hEalth carEDay lighting in hospitals results in benefits of not only lower operating costs but also faster patient recovery due to a better environment. Many hospitals in the U.S

have banned the use of cool-white fluorescent light for the same reason. A higher day light restores the natural circadian rhythm which is important for certain ailments like Alzheimer and many hospitals are redesigning the space so that they get more natural lights in their premises. The importance of day light in health care can be illustrated through an estimate made in any senior care facility for assisted living that correlates natural light to human well-being. Studies show that the average requirement of day light for a patient, who is 60 years old, is twice as much as a patient of 20 years and a patient who is 86 years old, needs five times more light than that of a 20 year old. A better day light environment offers easing of pain and reduced mental and physical pain for patients.

day lighting in induStryA factory environment with lesser window space , as studies have shown, has a huge impact on the physiological well being of the workers as indicated

by a study in Sweden which in the late 1950’s had built a lot of underground factories with no windows and light penetration. Their employees faced several health related issues. A window less claustrophobic environment also results in absenteeism and vandalism because of agitated negative attitude of the employees. Today we have factories all over the world that harvest 100% of the day light as there is increasing awareness on the benefits of a good factory environment.

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All external glazing less than 7 feet from the floor must be provided with blinds/external shading systems/electro chromic glass for glare control as uneven levels of brightness can cause visual discomfort. The ideal situation is to have day light without blinds. Blinds can actually defeat the very purpose of daylight requirement as users tend to pull down the blinds even in ideal conditions of day light. What matters is quality light and not just direct day light.

To minimize glare on workstations, all computer screens within desk level located within 15 feet of the glazing are to be oriented within a 20 degree angle perpendicular to the plane of the nearest window or glazing. This along with external systems like shading, users can ensure that the entire glare component is eliminated.

The WWR (Window Wall ratio) on external wall elevations should be between 20% and 60%. In case it is more than 40%, external shading or adjustable opaque glazing is to be provided to control excessive heat.

If the user is exceeding the 40% threshold the excess should necessarily be daylight glass which is at least 7 feet above the floor level.

Glazing, above 7 feet from the floor, must have a Visual Light Transmitter (VLT) of 60% or more.

All glazing below 7 feet from the floor must have a VLT of 50% or more for maximum day light penetration.

In addition to quality of light, there is an additional requirement of wavelengths of light transmissions under WELL specifications. The VLT of wavelengths between 400- 650 Nano meters, as we see in the visible light spectrum must not vary by more than a factor of 2 for uniform color transmittance.

daylighting in officEThere is a direct correlation between daylight and general well-being. Increased productivity, health, reduction in absenteeism and attrition levels, Improvement in employee morale and

day light rEquirEMEntS aS pEr grEEn StandardS

LEED requirements specify that 75% of the regularly occupied spaces be lit with Day light.

As per IGBC Green homes requirements, it is mandatory for every residential development to provide daylight for 50% of the regularly occupied spaces.

A minimum LUx level of 200- 300 is specified as per most standard requirements.

day lighting rEquirEMEntS aS pEr wEll Building rating

There is a new rating system called ‘WELL building rating’ which indicates a ‘wellness coefficient’ of a building. The focus of ‘Green ratings’ is energy conservation, water conservation, waste management and indoor environment quality. A building can still fulfill all the green rating requirements but still have people who are unhappy due to its low wellness co efficient. Well building rating, recently launched in the U.S and still in its pilot version, talks about various aspects of wellness namely air quality, water quality light quality, comfort because of natural light , acoustic comfort, food and nutrition, fitness and exercises and comfort of the body and soul.

WELL building rating requires a minimum of 75% of the regularly occupied seats to be within 25 feet of an atrium or windows to get better lighting. The focus is the location of the seats in a building, in addition to the earlier norm of 75% of the occupied spaces being lit with day light. This norm goes a step further and creates a direct connect to the people working in a building to day light, which is a far more effecting tool of measurement and has a direct impact on the wellness of the people. When we talk about day light we deal with two aspects. Firstly, the harmonic and metabolic impact on the people and secondly, the light falling on the body which has distinct health benefits.

55% of the regularly occupied spaces must receive a minimum of 300 lux of daylight for at least 50% of the operating hours each year. The focus is on ‘operating hours’ which means that the day light exposure must be spread throughout the year.

Additionally no more than 10% of the spaces can receive more than 1000 lux for 250 hours each year. This is to prevent over exposure of day light that can cause discomfort.

WELL specifications are a paradigm shift in design practices of green buildings. The emphasis is not just on energy savings and maintenance cost but on the wellness of the occupants of the buildings. Due considerations are to be given to improve health, safety and productivity in addition to increasing the Physiological and Psychological wellbeing of the user of the building by harvesting day light.

Day lighting criteria ensures satisfaction for both building owners and more importantly to its occupants. We have to ensure that we are creating spaces that are healthier to live because as designers, we are designing buildings for people.

turnover are some of the positive aspects of improved day light in the office.

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daylighting in grEEn BuildingS: thE MythS & rEalitiES

the indian green Building Council (igBC), part of the Confederation of indian industry (Cii) was formed with the vision, “to enable a sustainable built environment for all and facilitate india to be one

going green is more than just a call for action. it is the only way forward to address climate change. With nations uniting across the world for ‘responsibility’ and ‘accountability’, the need is to create ideal living habitats that are transformative, futuristic and importantly contributing to a sustainable, symbiotic lifestyle in the planet.

of the global leaders in the sustainable built environment by 2025”. the council offers a wide array of services which include developing new green building rating programmes, certification services and green building training programmes.

mr. sriNivas DEPUTY ExECUTIVE DIRECToR,

INDIAN GREEN BUILDING CoUNCIL.

S. Srinivas heads the Green Building division in IGBC and leads a team of Architects and Engineers involved in Green buildings and

rating systems. He has an experience of over 28 years of which he has been with the CII for 15 years. He holds a Master’s Degree in Energy Management, with an Under Graduation in Mechanical Engineering.

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Building. for pEoplE.

The people of today have become more aware about their health and wellbeing. There are papers from Harvard Public School and Michigan State University which says that productivity gains from better indoor environment can be as high as 43-235 billion dollars. It is a hypothesis that green buildings are for the people and by the people. However, it is vital to explore the possibilities as to how green buildings can connect to people.

frESh air:There are buildings which are deprived of fresh air due to split air-conditioning units which have no provision to permit fresh air. It is important for Consultants and designers to come up with ideas to draw fresh air into the living spaces.

low EMiSSion indoor MatErialS External Pollution is not the only factor that can impact the Indoor Air Quality of your buildings. Every material used in building construction cause emissions that can affect the quality of your air. The

huMan coMfort:Thermal comfort is always an adaptation issue. The standards created by International green building conference (IGBC) state that overcooling of space had a drop in performance by 4 percent and overheating of space resulted in 6

acouSticS: When it comes to acoustics, IGBC codes states that if you have an office which is very clamorous, there will be a drop in performance by 66 percent. Noise should be addressed by having double glazed windows which reduces sound level by 30-40 decibels.percent drop in performance. We need to configure our living

spaces to the optimum temperature that will enhance the productivity.

use of materials Low in VoC improves your indoor air quality and productivity levels.

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daylighting & connEctivity to ExtErior EnvironMEnt:

It is also very important to design buildings with sufficient day lighting and connectivity because offices equipped with appropriate windows, daylight and ventilation have been able to induce healthier sleep patterns among employees.

With the advent of LED lighting technology, 1.5W per square feet has been reduced to 0.8W per square feet in most of the green buildings. This figure will drop furthermore to 0.4 or 0.45W per square feet in the next five years due to the penetration of LED lights in many of these buildings.

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glaZing. for a grEEn futurE.

Glass is a material that can create comfort at all these levels. Glazing has become a highly important aspect for buildings to go green and offer multi-comfort. Glazing is an aesthetic and functional solution that provides day light, thermal comfort, acoustic comfort, and is Low in VoC. American society of heating, refrigerating and Air-conditioning engineers (ASHRAE) and Energy Conservation Building Code (ECBC) recommend 40-50 percent use of glazing in a widow-wall ratio. We need to select glass made for good visual light transmission and solar gain. Today, with +3356 projects and over 3 billion sq. ft. of Green Building Footprint, India ranks 2nd in Building Green. Gone are the days where we lacked expertise in moving toward green technology. 25 years ago, 1 million square feet was designed for 10 megawatt. However, today, one million square feet is being designed for 7 megawatt. 30-40 percent savings have been achieved in few green buildings with respect to basic lines like ASHRAE 90.1 or ECBC. We have done pretty well in terms of electrical energy, water, glazing and many more. We still have a long way to go. It is a wakeup call for judicious use of green resources.

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grEEn rating for intEgratEd haBitat aSSESSMEnt

griha, an acronym for grEEn rating for intEgratEd haBitat aSSESSMEnt, is a rating system developed by tEri (the Energy and resources institute) that is

griha is a tool to facilitate the designing, construction and the operation of green buildings. it would, especially be, applicable for new constructions and will measure and certify the ‘greenness’ of a building. griha ratings are very critical in the current backdrop of a general market perception that green buildings do not perform or perform much lower than expectations. hence there is increased focus on performance yardsticks being met. the ratings are given only after ensuring that the yardsticks are met.

recognized as india’s national system for rating green buildings.

ms. mili majumdar SENIoR DIRECToR - SUSTAINABLE HABITAT

DIVISIoN, TERI.SECRETARY & TREASURER - THE GRIHA CoUNCIL.

Ms. Mili Majumdar, Director, Sustainable Habitat Division, is an Architect - Building

Technology professional with specialization in energy efficiency and development of

sustainable habitats. She has led the initiative on development of GRIHA (Green Rating for Integrated Habitat Assessment) that has now been adopted as a National Green Building

Rating System.

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GRIHA is specifically applicable to India as the measuring parameters are based on Indian regulations and standards. Hence all the codes that apply to ‘Green’ or ‘Environmentally friendly’ constructions under the National Building Codes (NBC), Energy Conservation Building Codes (ECBC) and Bureau of Indian standards are embedded in GRIHA ratings. GRIHA ratings assume a lot of importance, in the backdrop of the oncoming CoP 21 under which each country has to prepare its own INDC (Intended Nationally Determined Contributions) and enumerate the steps that are going to be taken to reduce emission intensity/standards. It is a matter of pride that GRIHA ratings has been referred to as India’s own rating system as part of its declaration in INDC.

typES of Building

The types of buildings that are covered are Residential, Commercial,Institutional, Hospitals and Hotels except Factories and other Industrial units that have very high process loads. However administrative buildings within a factory complex would be covered by the rating. The criteria’s are customized for different climate zones and regions of India with focus on an integrated design approach.

residential Commercial institutional hospitals hotels

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thE Evolution of griha guidElinES

The guidelines have evolved over a period time. It was known as TERI GRIHA when it was started in 2005. The Ministry of New Renewable energy recognized it as a national rating agency in 2007. Several states, cities and organizations in India have since adopted GRIHA standards that have helped us steer the green building movement forward. Different levels of incentives are provided by each state to incentivize the construction of Green buildings. Green buildings have reduced the load on Municipal services by reducing the infrastructure and maintenance cost of the buildings due to their conformity to energy saving norms. Currently we have 675 ongoing projects representing close to 250 Million Sq. feet built up area out of which 30 projects have been rated.

The positive impact of GRIHA ratings are evident from the impressive record these 30 projects have managed to show case. We have achieved energy savings of 74000 MWh/annum. Renewable energy installed is 14.5 MWp and Co2 emissions offset are 78516 tCo2/annum in these 30 projects put together. Coming months will see a quantum leap in the above as we have signed 100 Expression of Interests for new buildings.

variantS of griha ratingS

There are three variants of our ratings based on the size of the project.

SVAGRIHA applies to smaller projects of

> 2500 Sq meters

GRIHA is for projects measuring

< 2500 Sq meters

GRIHA LD for projects

< 50 hectares.

grading

In the first two versions the SHGC controls that did not consider the aspect of shading. Even when the designers were able to effectively shade a window, which is the basic purpose of SHGC, we were not able to give due credits to the project. Hence a concept of Shading was introduced in 2010 in Version 2 & 3 as an alternative compliance path to SHGC.

Again, the GRIHA V 2015 version saw a major reorganization in criteria based on feedback from the market that the four existing criteria put a lot of pressure on designers and did not meet the client requirement in many cases. After a lot of research we introduced the concept of UDI (Uniform Daylight Illuminance) which can be followed, as an alternative compliance route, instead of all the four existing criteria (WWR, SRR, SHGC and DF). The clients could either choose between meeting mandatory criteria of WWR, SRR, SHGC and DF or alternatively choose UDI as the criteria to meet GRIHA standards.

The day light factor was a standard set way back in 1987 and it is important that user inputs and research are taken into account to develop a more dynamic DF factor in the projects in the years to come, especially in tropical regions.

* The rating is based on a scale of 1 to 5.

day lighting

Day lighting is an important criterion in GRIHA ratings. It aims to combine visual comfort with energy efficiency. It has evolved over a period of time through a participative process of gathering user inputs and integrating the same in the rating process so that the users are able to meet the intent of the criteria. We have also used alternative compliance routes to achieve the objective of useful daylight within day light working hours. This became necessary as we found that the users are not able to use direct daylight due to excessive heat and glare. It is a very common sight in office buildings that even during bright day lights the blinds are put and internal lighting is switched on during day time.

It is important that comfort levels are not compromised in an effort to save energy. Merely switching off lights, in a bid to save energy, would be counterproductive if it affects visual comfort. Hence meeting visual comfort levels is a mandatory requirement. The intent is to reduce heat gain through direct sunlight through fenestrations and optimize availability of diffused daylight to reduce the need for artificial light during day light hours.

Day lighting criteria have evolved from 2007 to 2015. The mandatory parameters set in the first three versions were:

Window to Wall ratio (WWr) Skylight roof ratio (Srr) Solar heat gain co efficient (ShgC) daylight factor (df)

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window to wall ratio

Window to Wall ratio, which refers to the ratio of total fenestrations to the gross wall area are pegged at 40%- 60%, as per ECBC recommendations. This means that the desirable limit of windows in a wall is 40% and one cannot provide a window area exceeding 60% of the overall gross wall area.

The reason for limiting the window area as per the above norm is because of the U factor which is the conduction threshold. The heat gain through the skin of the building primarily through opaque structures is through conduction. The heat gain through direct sunlight exposure is much more for a Glazed or glass dominated structures than that of a wall. Secondly even among glass there are various energy efficient walls available in which the U factor ranges between 1.4 and 1.9 w/sq.m.-C. Hence the more control the user puts on the glazed surface, the more control he will have on the heat gain. The determination of the glazed area not only depends on the aesthetics but also on the usefulness of the glazing. The challenge for designers, therefore, is to strike a balance between the two.

Solar hEat gain coEfficiEnt

Solar Heat Gain Coefficient refers to the ratio of the solar heat that passes through the glazing surface compared to the total solar radiation. The lower the SHGC the lesser the direct heat gain from the glazed surface. A lower solar gain can be achieved by two ways; one by the use of glass that have an imbedded property of lower heat gain co efficient or by a judicious mixture of shading and a less efficient glass surface.

The GRIHA rating standards were not different between commercial and residential buildings in Phase 1. These were stringent values that had a significant impact on the cost of the residential projects. Based on market feedback, we modified the requirements for residential project and introduced the changes in the subsequent versions. With the result, the windows of non living spaces like Toilets and Store rooms etc were exempt from compliance with SGHC/ shading requirements. For residential buildings with operable windows the ECBC thresholds were also revised to accommodate a considerable relaxation on the SHGC/Shading threshold. There are also allowances made for colder regions as one would want more solar gain in such regions.

The reduction in criteria between Commercial and residential buildings is something that GRIHA has allowed to allow some flexibility in design and it is not an allowance given by ECBC

It is not necessary to comply with a SHGC requirement for each window or each façade of the building. The compliance is allowed through a composite or Weighted Façade average. Hence there is a flexibility of allowing different shading systems and different glass types across different facades in a building. What matters is the overall SHGC of all the facades. Similarly WWR also can be a weighted average ratio.In version 3 the criteria of shading requirement was added. Under criterion 13 two alternative strategies were incorporated. one is recommended shading as per SP 41 or alternatively to conduct a solar path analysis for windows for AC as well as non AC spaces to ensure that the windows are shaded between 10 am to 3 pm on all days between 1st April and 30th September.

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day light factor

DF factor is defined as 1% of outdoor illuminance. The recommended DF factor depends on each building and on each type of room within the same building based on the intended use of the room and the critical requirement of light in each type of room. To illustrate with an example, the DF factor of the reading room in a library would be higher than the stack room and the DF factor of a Pathological laboratory in a hospital would be much higher than the General ward. The table gives the different room types and the required DF factor as part of SP 41 guidelines. However for spaces not listed it can be assumed that the Day light factor is exempt for such spaces.

DF factor is continually being evolved to accommodate technological changes. A case in point is schools where presentations are made through electronic boards and LED screens which require a lesser DF factor compared to a conventional black board class environment.

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Shading SyStEMS

Shading systems can be different for different buildings with intent of controlling the heat so that a lot of design flexibility is allowed. Even shading by an adjacent external building is taken into consideration so that the user doesn’t have to invest in additional shading devices.

there are quite a few examples of effective shading systems and buildings with good df factor certified with a 5 star rating by griha.

CESE building at IIT Kanpur was the first project to get a 5 start TERI GRIHA rating where a combination of shading devices and Glass selection ensured that direct sunlight was blocked into the space of the building and yet spaces achieved sufficient day light levels without the use of blinds. There is no glare or direct heat coming into the space and also the use of electric lamps were completely eliminated during day time.

Suzlon, one earth Pune is another 5 star graded building in which the shading was done through multiple louvers where the louvers prevented direct entry of sunlight and allowed only diffused day light and eliminated the use of artificial lighting during day time.

Infosys and IPE Hyderabad also use an innovative shading design to allow even the use of computer monitors in the day time with natural light without any glare.

These are good examples of buildings with a combination of good shading designs, glass selection and architectural layout which has ensured sufficient levels of illuminance within a building without glare.

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griha version 5

Based on projects reviewed and discussions with stake holders in which the earlier criteria relating to Window Wall ration were seen as restrictive in nature, Version 5 saw a reorganization of the criteria.

In the new version an alternative path in the form of UDI, as a measurable yardstick, was introduced. UDI refers to Useful Daylight Illuminance which is defined as those illuminances that fall within the range of 100- to 2000 lx. This range was arrived at after research and comprehensive data from filed studies. A building with less than 100 lx would be termed insufficient daylight and more than 2000 lx would be defined as excessive day light.

There are two methods to achieve the day light requirements. The earlier method will continue to use the WWR, SRR, SHGC and DF as the measurement Criteria whereas the 2nd method will offer design flexibility and will allow the use of UDI as an alternative criteria. The user can choose one between the two.

In the first method at least 25% of the living area should achieve Daylight factor as mentioned in the SP 41. In the second method too, the user has to demonstrate that 25% of the total living area achieves the UDI requirement of 100- 2000 lx. Again, in both the paths the fulfillment of additional 25% of the criteria earns an additional 2 points for the user.

There are specialized software tools available to simulate and measure UDI. Hence if one wants to use UDI as a criteria then the use of these specified software tools become necessary.

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df ( daylight factor) analysis and udi analysis

DF analysis is done for a specific date and time whereas UDI analysis is conducted for all daylight hours of the year. In UDI the lower and upper limits (100- 2000 lx) are established and only if the user falls with the limits the certification will be done.

GRIHA ratings, evolved over a period of time to allow design flexibility have proved to be an important and effective tool to measure the greenness of the projects. The success of GRIHA ratings have stemmed from the underlying belief that ‘What gets measured will ultimately be managed’.

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