Senior Design - Miami Green - Final Draft

Department of Mechanical and Materials Engineering Florida International University, Miami, FL

EML 4905 – Senior Design Project

HVAC Design for Green Building

“Miami Green”

Final Report

Submitted By:

James Klein

Alejandro Franyie

November 28, 2007

FACULTY ADVISOR

x__________________________Dr. Yong X. Tao

This report is written in partial fulfillment of the requirements in EML 4905. The contents represent the opinion of the authors and not the Department of Mechanical and Materials

Engineering.

The Green Machine

The Green Machine is comprised of students from Florida International University’s Department of Mechanical and Materials Engineering. The Green Machine is a committed multi-disciplinary team working together to achieve a final goal. Each team member shall work together in a balanced and dedicated effort to attain the best design possible. Name / Signature

PID # Title

Alejandro Franyie 1305674 Team Leader / Designer / Draftsman

x______________________________

James Klein 1304926 LEED Specialist/ Designer/ Draftsman

x______________________________

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Ethical Design Statement

The Green Machine has thoroughly studied the NSPE Code of Ethics for Engineers and

fully understands the conduct that is expected from an engineer. Furthermore, every member of

the Green Machine vows to be ethical in every aspect of his work and will strive for the highest

ethical behavior. Every member of the Green Machine understands that his ethical behavior is

not only a reflection of himself and the team, but also a reflection of the engineering profession

as a whole.

Environmental Impact Statement

The Green Machine holds human safety and the environment at the paramount of

consideration during design and construction. Each member vows to not deliberately make any

decisions which may negatively influence the life of a human being. Human safety and comfort

will be held in the highest regard.

The main goal of the “Miami Green” project is to reduce the environmental impact

caused by high-rise buildings. The Green Machine vows to eliminate the use or production of

toxic materials and harmful emissions. The Green Machine will strive to make its design as

energy efficient as possible thereby reducing the emission of harmful greenhouse gases.

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Table of Contents

Chapter 1 – Miami Green Overview 1.1 Goal Statement 1.2 Scope 1.3 Miami Green 1.4 Intended Clients 1.5 Design Organization 1.6 Challenges and Constraints

Chapter 2 – Load Calculations

2.1. Concept Overview 2.2. Heating Load 2.3. Cooling Load 2.4. Miami Green Break-Down and Parameters 2.5. Results and Sizes

Chapter 3 – Energy Analysis

3.1. Concept Overview 3.2. Energy Baseline and Optimization 3.3. EQuest and Results

Chapter 4 – Life Cycle Cost Analysis

4.1. Concept Overview 4.2. Input Parameters 4.3. Life Cycle Cost Analysis 4.4. Ownership and Initial Cost 4.5. System Specification and Details

Chapter 5 – LEED Certification

5.1. Overview 5.2. Energy and Atmosphere (EA) 5.3. Indoor Environmental Quality (EQ) 5.4. Conclusion

References

Appendix

Appendix A – Cooling and Heating Loads

Appendix B – Energy Modeling

Appendix C – Economic Analysis

Appendix D – Equipment Specification

Appendix E – Mechanical Drawings

Appendix F – Design Organization

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Chapter 1 – Miami Green Overview

1.1 Goal Statement

The goal of this project is to select and design a preliminary HVAC system for a high-

rise “Green Building” that is both economical and energy efficiency. “Green building” is the

practice of making sustainable buildings that minimize negative impact on the environment and

the inhabitants of the building. For a mechanical engineer this means maximizing energy

efficiency, minimizing refrigerant impact on the environment and improving indoor air quality.

This project will primarily focus on maximizing the energy efficiency of the building but will

also deal with other green concepts such as refrigerant management, increased ventilation, and

indoor pollutant control.

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1.2 Scope

Miami Green is in the preliminary design and development stage where the owner is still

gathering cost and feasibility estimates before pursuing construction. Drawings have been

provided to the mechanical engineers, Green Machine, by the architect to begin schematic

drawings of the HVAC systems design.

The Green Machine has been contracted to calculate heating/cooling loads and perform a

study of different HVAC systems that can be used in Miami Green. The study will include:

energy performance analysis, life cycle cost analysis and schematic drawings of the

recommended system. Also, the mechanical engineer will provide recommended constructions

to be used in the buildings envelope.

Since architectural drawings are still in the design stage and interior space layouts have not

been designed, the scope of the mechanical engineer is to treat Miami Green as a shell building.

Shell building means that the exterior and dividing walls of the building will be treated as

permanent but the space contained is to be designed later. This means that ductwork and space

design will be done as soon as the architect completes interior layouts. Therefore, Green

Machine will only provide a schematic design of the system and not detailed interior layouts.

Also, Green Machine has been contracted to make Miami Green a “green building”. Green

Machine shall design Miami Green using principles provided by the USGBC (United States

Green Building Council.) This will ensure that Miami Green becomes a certified green building

and will comply with the USGBC’s LEED rating method. The LEED rating method is the topic

of chapter 5.

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1.3 Miami Green

Miami Green (Fig. 1.1) is a 13 story, high-rise office/retail building located in Miami,

FL. The first floor contains a double height lobby, retail/office space and equipment rooms. The

second floor contains two offices and a veranda overlooking the lobby. Floors 3-13 are typical

floors that will only be used as office/retail space. The interior layouts of these floors have not

yet been designed by the architect but future plans are to provide different office layout for

future tenants. Potential future layouts will be discussed in the next chapter. Figure 1.2 shows

the shell layout of the typical floors.

Figure 1.1 – Artists rendering of Miami Green

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Figure 1.2 – Typical Floor Layout

There is a central elevator bank located on every floor the opens to public corridors. The

corridors serve at the main entrance to all of the offices. On each extreme of the corridor there is

a stairwell that serves as a secondary link between floors and the primary means of emergency

egress. On the other side of the corridor is a garage that runs from the ground floor to the roof.

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1.4 Intended Clients

The client for Miami Green is the developer that is constructing the building. The

developer has hired Green Machine to provide an economic analysis and schematic plans of the

recommended HVAC. The developer has also hired a structural, electrical, plumbing and civil

engineer, as well as an architect and construction contractor.

The developer is building Miami Green to sell the individual retail spaces upon

completion. This developer is seeking a profit. Therefore, it is upon Green Machine to provide

an economic design to maximize the owner/developers profits.

Also, we must consider the future occupants of the building as clients. We do not work

directly for these people, but we do have a responsibility to them. Our design must keep them

safe and comfortable even if it makes the design more expensive and less desirable for the

developer.

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1.5 Design Organization

Three different HVAC systems will be analyzed to compare energy efficiency, cost, and

“green-ability”. Some primary assumptions that will be made are:

• 100% outside air in the corridors

• Increased outside air supply to other spaces

• Changes shall be made to improve envelope

• High efficiency equipment shall used

• Pursuing LEED certification

• Comply with energy codes (ASHRAE 90.1 and Florida Mechanical Code Ch. 13)

• Interior spaces will be designed later

• Allow flexibility for future interior design

Software shall be used to compute heating/cooling loads, energy performance, and life

cycle cost. The programs used will be discussed in the respective sections of the calculations

mentioned above. Also, AutoCAD shall be used to provide the schematic drawings of the

building with the recommended system.

Appendix F contains a function analysis diagram, a drawing tree, a failure modes and

effects analysis (FMEA) and a project timeline.

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1.6 Challenges and Constraints

In a project such as this, the greatest challenges are unforeseeable. Conflicts with the

architectural layout are inevitable. The main challenge that will arise is where to put all the

equipment necessary to achieve the desired objectives. Often times extra mechanical rooms must

be added to the architectural design to house equipment. Our goal will be to find solutions to

these problems to minimize the change to architectural design and maintain an aesthetic working

and shopping environment for the buildings inhabitants.

The other main challenge of this design is the maximization of energy efficiency. There

are many different techniques and strategies to achieve an energy efficient design, the challenge

will be to find the route that yields the highest efficiency at the most reasonable cost.

Another main challenge of this building is to provide an economical and environmentally

safe design. Economical and environmental are opposites of each other. The more economical

the design the less environmentally safe it is and vice versa. We must find a balance between the

two satisfy both the client and the environment. Also, the design must comply with Florida

Building Code before it can be approved for construction.

The design will be constrained by the following:

• Must comply with Florida Building Code and good engineering practice

• Must achieve a certain indoor design temperature (74ºF winter and 78ºF summer)

o This will correspond to approximately 1 ton cooling capacity per 300 square feet

• Must have high indoor air quality (approximately 30% fresh air)

• Must be economical and environmentally safe

o Pass LEED standard for green building

• Must minimize change to the architectural design

o Reduce need for extra mechanical rooms and chases

• Maximum energy efficiency

o Overall cooling efficiency of over 14 EER

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Chapter 2 – Load Analysis

2.1 Concept Overview

The heating/cooling load is the first major step in designing an HVAC system. All of the

buildings parameters are taken into account to create a minimum measure of the amount of

heating/cooling capacity needed in the building. Building parameters include things such as

floor area, wall/window area, wall construction, orientation and many other key factors. Since

this building is located in Miami, the heating load will be small in comparison to the buildings

cooling load.

This chapter describes the methods used to calculate the heating and cooling loads of a

typical zone. For the Miami Green project, each floor was split up into different zones and

cooling/heating loads were performed using specialized software. Each zone was analyzed and

the cooling/heating loads were calculated using Hourly Analysis Program (HAP). This software

is a well known and widely used tool created by Carrier, an HVAC equipment manufacturer.

The following sections provide the theoretical basis for how this program functions.

2.2 Heating Load

In cold weather there are small variations in the outdoor temperature. This allows the

heat loss to be analyzed as steady state. The heating load consists of two kinds of heat losses that

a zone could experience, the heat transmitted through the walls, ceiling, floor, glass, and other

surfaces, and the heat required to warm outdoor air entering the space. To compute the heating

load the indoor and outdoor design conditions must be defined. The outdoor design condition is

defined by the location of the structure being analyzed. The indoor design condition is defined

by the temperature and humidity that define the comfort level of the occupants.

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The heat losses transferred through the walls, ceilings, roof, window glass, floors and doors is all

sensible heat transfer, referred to as transmission heat loss, and computed using the equation

below. In order to calculate this heat loss, the heat transfer coefficient of the material that make

up the envelope of the structure must also be defined.

( )oittUAq −=

Where:

U = overall heat transfer coefficient (Btu/hr-ft2-F)

A = the net area for the given component for which U was calculated

( )oitt − = the temperature difference on the two sides of the surface being analyzed.

Infiltrating air entering a building must be conditioned to satisfy the indoor design conditions.

The mass flow rate and the specific heat of the air must be determined to calculate the amount of

sensible heat required to condition the infiltrating air. The sensible heat required to heat the

outside air can be calculated with the following equation.

( )oipos ttcmq −=

Where:

om = the mass flow rate of the infiltrating air, lbm/hr

pc = the specific heat of the air, btu/(lbm-F)

( )oitt − = the temperature difference between the infiltrating air and the indoor air.

The enthalpy and the humidity ratio of the infiltrating air affect the humidity of the indoor

conditioned air. The latent heat required to humidify the air is given by the equation below.

( )oifgol WWimq −=

fgi =the latent heat of vaporization at the indoor conditions, Btu/lbmv

( oi WW − ) = the difference in design humidity ratio, lbmv/lbma

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2.3 Cooling Load

Solar radiation has important effects of both heat gain and the heat loss of a building. A

strong transient effect is created because solar radiation varies significantly with time. Thermal

radiation energy falls on the envelope of the structure and is subjected to absorption, reflection

and transmission through transparent bodies. Heat that is absorbed by the surfaces is stored,

causing an appreciable difference between the heat gain of a structure and the heat removed by

the cooling equipment.

In order to size the cooling equipment the heat gain must be computed for the following.

• Solar radiation through fenestrations

• Heat conduction through boundaries with convection and radiation from the inner

surfaces into the space.

• Sensible heat convection and radiation from internal objects.

• Ventilation and infiltration air

• Latent heat gains generated within the space.

The Solar Heat Gain Coefficient method can be used to calculate the heat gain from solar

radiation through fenestrations. A coefficient defined by the glazing of windows is multiplied by

the total irradiation of the sun.

( )SHGCGq ii =

Where:

iG = incident irradiance

(SHGC) = solar heat gain coefficient

To calculate the remaining heat gains, heat balance on each surface that makes up the envelope

of the zone must be analyzed. Every surface of a zone should be analyzed considering energy

balance. Heat is absorbed by the wall from radiation of the sun, radiation of objects near the

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structure, and convection caused by the outside air. The heat balance on an exterior surface can

be calculated considering the equation below.

extradiationextconvectionextsolarheatextconduction qqqq ,,,, '''''''' ++=

Where:

extconductionq ,'' = conduction hear flux through the wall, Btu/(hr-ft2)

extsolarheatq ,'' = absorbed solar heat flux, Btu/(hr-ft2)

extconvectionq ,'' = convection heat flux from the outside air, Btu/(hr-ft2)

extradiationq ,'' = thermal radiation heat flux form other external objects, Btu/(hr-ft2)

The heat absorbed by the envelope of the structure is conducted through the material to

the interior surface. Heat is transferred through convection to the inside conditioned air. Heat is

also radiated to and from inside object to the interior surface. The heat balance on the interior

surface can be calculated considering the equation below.

int,int,int,int, '''''''' radiationconvectionsolarheatconduction qqqq ++=

Where:

extconductionq ,'' = conduction hear flux through the wall, Btu/(hr-ft2)

extsolarheatq ,'' = absorbed radiation from other objects, Btu/(hr-ft2)

extconvectionq ,'' = convection heat flux to the air, Btu/(hr-ft2)

extradiationq ,'' = thermal radiation heat flux to other objects, Btu/(hr-ft2)

Considering that the air inside the building has no thermal storage, the sum of all the heat

transfers is equal to zero. The heat gained/lost by the heating and cooling system must be equal

to the amount of heat gained/lost by convection from the wall, infiltrating air and the heat

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transferred to the conditioned air from the people lights and equipment inside. Finally the heat

balance of the zone air may be represented by the equations below.

0'' ,intint,infint, =++++ convernalradiationsystemiltrationconvection qqqqAq

Where:

A= area of internal surface

iltrationqinf = heat gain due to infiltration, BTU/hr

systemq '' = heat gain to do heating/cooling system, BTU/hr

convernalq ,int'' = convective portion of internal heat gains

The mathematical analysis of the heat balance on the envelope of the structure of a large

building is too tedious to calculate without the aid of computer software. The specifications of

the Miami Green building were determined by using the Carrier software to calculate the heating

and cooling loads. Using the results of the calculations the equipment can be selected.

2.4 Miami Green Break-Down and Design Parameters

As mentioned in the previous section, software shall be used to perform the cooling loads

for Miami Green. The software to be used is called Hourly Analysis Program (HAP) by Carrier.

This software is widely used and respected as the industry standard for accurately calculating a

spaces heating and cooling load.

Even though software will be used to perform the load calculations, the designer must

prepare accurate data to input into the program. This data includes internal loads, material

constructs used and building geometry, which will be organized in a space breakdown table.

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Figure 2.1 and figure 2.2 show floor plan layouts of two typical floors in Miami Green. The

units are called Penthouse, unit “C1” and Unit “C2”.

Figure 2.2 – Layout “Penthouse” Figure 2.2 – Layout “C”

General

Some key elements in performing a cooling/heating load are general parameters that

have to do with the basic geometry of building. Things such as floor area, ceiling height, and

building weight are all crucial to a buildings required cooling and heating. Table 2.1 shows a

breakdown of the different zones and areas to be calculated. Table 2.2 shows the wall/window

area breakdown of the typical floor. The material and the thermal characteristics of the walls and

windows will be specified later.

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Table 2.1 – Area Breakdown

Zone Description Area (Sq. Ft.) Ceiling Height (Ft.)

Typical Floor Entire Conditioned Area 8,355 9

Penthouse Large Layout 7,715 9 C1 Half Layout 2,827 9 C2 Half Layout 4,888 9

Corridor Hallway 640 9

Table 2.2 - Wall and Window (Area and Exposure)

Construct Direction Length (ft) Area U value

N 24.5 220.5 0.52 E 122.25 1100.25 0.52 Glass S 123 1107 0.52 E 21.75 195.75 0.24 S 19 171 0.24 Wall W 41 369 0.24

Corridor Wall - 122 1098 0.24 - 103 927 0.24 Partition - 103 927 0.24

The building weight is assumed to be medium density (70 lb/ft2). This is a standard

assumption for a building made of lightweight concrete and steel. The building weight affects

the thermal retention characteristics of the building and describe how easily cooled/heated a

building is.

Internals

Internal loads deal with heat generated within the buildings envelope. Internal loads are

things such as lighting, electrical equipment, and people. The heat produced by these elements

do not cross the buildings walls and is generated within the cooled space. The following are

some assumptions that have been made for this project:

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• Internal Lighting – 1.2 W/sf

• Electrical Equipment – 0.75 W/sf

• Occupancy – 60 persons per level

• Persons Activity Level – Office Work

o Sensible Load – 245 BTU/ hr

o Latent Load – 205 BTU/ hr

Walls/Partitions

For most spaces, the wall construction is one of the highest transmitters of heat. Since the

exterior of Miami Green is mostly glass, the walls are primary partitions used between the

conditioned corridor and the non-conditioned garage. To calculate the cooling load a typical wall

construction will be used. A typical exterior/partition used in this application is 8” lightweight

concrete, stucco finish and ½” interior gypsum board with ½” air gap. A wall with this

construction has a U-value of 0.24Ffth

BTU2 ⋅⋅

. This U-value has been inserted into table 2.2.

In chapter 3 the overall U-value of the wall will be improved by adding insulation. The

reason the overall U-value is not being considered in the cooling load is because it does not

affect the overall system to be used. It does change the sensible heat load and that is something

that will have to be recalculated before the tenant spaces are built.

Windows/Doors

Windows and doors are also called fenestrations. Since Miami Green is a high rise

building, the only exterior doors to be considered are on the ground floor (lobby entrance).

These doors are made of frameless glass and are considered more as glass than as doors.

Therefore, all the fenestrations in this project will be considered as glass.

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The most important window factors to consider when performing a cooling load are

window area, overall U-value, and solar heat gain coefficient (SHGC). These factors determine

how much heat enters a space by means of radiation due to U and solar radiation due to SHGC.

For this application the SHGC is not used directly. It is used by means of a shading coefficient

(SC). The SHGC and SC is a measure of how much radiation is transmitted, absorbed and

reflected by the glass.

For the purposes of the cooling load we will use an overall U-value of 0.52Ffth

BTU2 ⋅⋅

and

a shading coefficient of 0.78. This corresponds to ½” high impact glass with a tint. In the next

chapter the specification of the glass to be used in Miami Green will be done in much more

detail.

Roof

For most applications, the heat gain through the roof is a significant factor. In Miami

Green this is not as important because only the top floor roof is exposed to the outside. All other

typical levels will not be affected by heat gain through the roof because they are located directly

below a conditioned space. There is zero heat transfer across a surface when the temperature on

both sides is equal.

According to energy codes, the minimum insulation value for a roof in this application is

R-15. Therefore, the cooling load will be performed so that the roof construction has an overall

U-value of 0.063Ffth

BTU2 ⋅⋅

. The conversion between resistance value (R) and heat transfer

coefficient (U) is the following:

R1U =

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Infiltration

Infiltration is the introduction of unconditioned air into a conditioned space or

conditioning system. It is important to take infiltration into account because it is heat added or

removed from the system in the form of convection. Miami Green will be a pressurized building

meaning that all infiltration will be controlled in the form of fresh air supply to the spaces. So

measuring the infiltration into the spaces is a matter of calculating the amount of fresh air that

the design will supply to the spaces.

Fresh air is also called outside air (O/A). Outside air requirements are set forth by

ASHRAE Standard 62. For a building of this type, the O/A is calculated by measuring the

expected occupancy for this type of space and multiplying that quantity by 20 CFM/person of air

supply. The expected occupancy for office space is 7 persons per 1,000 ft2. Table 2.3 shows the

outside air calculations for Miami Green.

Table 2.3 - O/A Calculations

Space Area (S.F.)

Occupancy (Persons)

Requirement (CFM/person)

Min. Air (CFM)

Provided (CFM)

Penthouse 7,715 54 20 1,080 1,404 C1 2,827 20 20 396 500 C2 4,888 34 20 684 884

The above table shows minimum O/A required by code and also shows the air that is going to be

provided in Miami Green. The reason the project is going to be provided with more fresh air is

to improve the indoor air quality (IAQ) and achieve LEED credit points. LEED credit points will

be discussed in chapter 5. Also, it should be noticed that O/A was not calculated for the

corridors. This is because the corridors will be provided with air conditioning units that will

supply 100% outside air. Doing this will greatly improve the IAQ, pressurize the building, and

serve as smoke control in the event of a fire.

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2.5 Results and Sizes

The above parameters were inputted into the Hourly Analysis Program (HAP). HAP then

simulates the building/space parameters according to the weather data from Miami, Florida. The

results of this simulation are detailed summaries of the heat gain and loss to the spaces during

different times of the year. The summaries provide total, sensible and latent cooling as well as

recommended air flow rates and other crucial sizing data. Below, Table 2.3 contains key sizing

information and each space has a suggested equipment layout. As expected, the heating load for

these spaces is relatively low. It is common practice in Miami to provided heating by using

electric strip heaters inside of the air handling units. Therefore, all units in Miami Green will use

electric strip heating.

Table 2.3- Cooling Load and Equipment Data

Space Total Load

(Tons)

Total Load (BTU/h)

Sensible Load

(BTU/h)

Equipment Size & Quantity To Be Used

Penthouse 18.4 221000 179,500 (1) 12.5 Ton & (1) 7.5 Ton Unit

C1 7.2 86100 73500 (1) 7.5 Ton Unit C2 11.3 135700 109400 (1) 12.5 Ton Unit

Corridor 28.5 342,000 280,800 (2) 15 Ton 100% O/A RTU A types 18.4 221000 83200 (5) 5 Ton Units

Appendix A, “Cooling Loads”, contains all the detailed calculations and summaries

calculated by HAP. As can be seen, the cooling load of the penthouse is equal to the sum of the

C units. Also, the last row of the table shows the proposed (5) “A” units shown in figure 2.3,

which also equal a total of 20 tons.

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Figure 2.3 – Layout “A”

As a result of the cooling load calculations and equipment sizing, the following is the

cooling equipment breakdown for all of Miami Green.

• 1st Floor / Lobby

o 22.5 Total Tons of Cooling

(3) 7.5 Ton Units

• 2nd Floor

o 22.5 Total Tons of Cooling

(3) 7.5 Ton Units

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• 11 Typical Floors

o (3) Layout “Penthouse”

20 Total Tons of Cooling

• (1) 12.5 Ton Unit

• (1) 7.5 Ton Unit

o (4) Layout “C”


• (1) 12.5 Ton Unit

• (1) 7.5 Ton Unit

o (4) Layout “A”


• (5) 4 Ton Units

• Corridor

o (2) 15 Ton 100% O/A Roof-Top Units

The system type for these units mentioned above has yet to be determined. The choice of which

system to use will be a result of the next two chapters. From Chapter 2, the size and quantity of

the units that will be used have been determined.

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Chapter 3 – Energy Modeling

3.1 Concept Overview

The energy modeling portion of this project is the most crucial and design intensive. One

of the most important aspects of building “green” is energy conservation and sustainability. Our

goal is to save as much energy as possible. Some of the factors that contribute to a buildings

energy usage are HVAC, lighting, water heating, electrical equipment, and miscellaneous loads.

In South Florida, one of the primary contributors to energy usage is the HVAC system.

Therefore it is critical that the HVAC system is as energy efficient as possible. Computer energy

modeling is the most useful tool for determining HVAC systems energy efficiency. There are

many computer programs designed to this, but for this project eQuest shall be used.

There are three basic cooling systems that will be modeled in this project to determine

which is the most energy efficient and cost effective. The three systems are DX (Air Cooled)

split units, DX Water Cooled system, and chilled water system. For a building this size, it is not

known which system will be the most energy efficient until an energy model is created. Besides

potential energy efficiency, each system has pros and cons in their applications to this building.

Another primary factor in choosing the system to be used is the economical factors of initial cost

and life cycle cost. For all systems, heating will be done by electrical resistance heaters located

within air handler units, because in South Florida, heating loads are relatively small and do not

justify a centralized boiler system.

A direct expansion (DX) split air conditioning system uses a pressurized refrigerant and

expansion valve to create cooling effect at in a cooling coil. It is called a split system because

the four main components of a cooling cycle are divided between the air handler unit (AHU) and

the condensing unit (CU). The AHU contains the expansion valve and the evaporator (cooling)

coil, while the CU contains the compressor and the condenser coil. A DX split system is air-

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cooled, meaning the refrigerant is cooled being blown by the condenser coil. A DX split,

air-cooled system is schematically represented in figure 3.1.

Figure 3.1 – DX Split System

There are many advantages to a DX system. They are available in extremely high EER (Energy

Efficiency Ratio) ratings, meaning much lower energy costs for an individual tenant. DX

systems are easily installed, maintained, and there is less potential for major malfunctions. The

primary disadvantages to high SEER DX systems are extremely high initial cost and quantity of

refrigerant used. Another goal of building “green” is to minimize refrigerant impact on the

ozone layer. Even though current refrigerants, such as R-410a, are much more earth-friendly,

they have an impact on ozone depletion.

A DX Package system (also commonly called condenser water system) has several

packaged water-cooled equipments that use a centralized cooling tower to provide condenser

water. A condenser system is similar to a DX split system in that they both use refrigerant to

cool air. The two systems differ in that the condenser water system uses packaged units where

all four major components are located together. It uses piped water to cool the refrigerant at the

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condenser section. The water is then taken to a cooling tower which transfers heat to the

environment. A DX package, water-cooled system is schematically represented in figure 3.2.

Figure 3.2 – DX Package System

A chilled water system is very different from the previous two systems discussed. The

primary difference is that the cooling coil uses chilled water to directly cool the air as it passes

through to the space. A chilled water system uses a central chiller to chill the water using the

same principles as DX but on a larger scale. Chillers come in a variety of options including air-

cooled (fan and condenser coil) and water-cooled (cooling tower). In this project a water-cooled

chiller will be under consideration because it has the potential of yielding a higher energy

savings. A chilled water, water-cooled is schematically represented in figure 3.3.

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Figure 3.3 – Chilled Water Water-Cooled

3.2 Energy Baseline and Optimization

Measuring the energy efficiency of a building is done by comparing the proposed

building to a baseline model. The method for creating a baseline model is set forth by ASHRAE

Standard 90.1 Energy Standard for Buildings Except Low-Rise Residential Buildings. The

baseline building must use the same building geometry and fundamental zoning definitions. The

baseline building must be modeled using the minimum performance requirement set forth by

90.1. Table 3.1 is a summary of the energy efficiency requirements.

Table 3.1 Minimum Requirements from ASHRAE 90.1

Type Requirement Climate Zone 1

Walls Mass Wall Above Grade – No insulation required Roof Insulation entirely above deck – R-15 Windows Maximum U-1.22 Lighting Maximum of 1.2 W/SF for office space Air Conditioners 10.3 EER

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The baseline building shall be modeled using these minimum requirements to determine

the maximum allowable energy usage for the building. The proposed building will differ from

the baseline by improving mechanical equipment performance, envelope specifications

(insulation, glazing, glass thickness, etc.), and lighting efficiency. By improving these

parameters, the overall building performance improves thereby creating an overall reduction in

energy usage.

Since different HVAC systems will be modeled, the first step shall be to improve the

buildings envelope and lighting characteristics. Improving the buildings envelope and lighting is

a basic step in improving the buildings overall energy performance. These changes to the

building will be constant regardless of the HVAC system chosen.

Envelope

Improving a buildings envelope is a broad statement. For Miami Green the most

important factor is improving the envelope is to improve window performance since the façade

of the building is over 80% glass. This is where the major reduction in energy usage shall occur.

By decreasing the overall U value (heat transfer coefficient) and increasing the shading

coefficient, the heat that enters the condition space by conduction and radiation is reduced. The

reduction in the heat that enters the space is reflected by lowering the amount of electricity

needed to cool the space.

For a high rise building the use of impact resistant glass is mandated by the state of

Florida. Therefore 0.5” impact resistant glass shall be used. This glass not only serves for safety,

but it also drastically reduces heat gain and noise pollution. It has also been specified that the

glass shall be covered in a blue-green tint to further reduce the heat that enters due to radiation.

Also, a second low-e glazing with a 0.5 inch air gap shall be added to reduce the amount of heat

29

that enters due to thermal conduction. Figure 3.4 shows a dimensioned cross-section of the glass

to be used.

Figure 3.4 – Window Section

This specified glass drastically reduces the amount of heat that enters the space. This will

give the proposed Miami Green design a large advantage over the baseline model. The U-Value

of the glass construction specified is 0.42Ffth

BTU2 ⋅⋅

and the shading coefficient is equal to 0.605.

The second most important step in improving the building envelope is to decrease the

overall U value of the exterior walls and partitions. The difference between an exterior wall and

a partition wall is that an exterior wall is exposed to solar radiation while a partition is not. An

exterior wall experiences the combined effects of solar radiation and conduction. A partition

wall only experiences heat conduction. Regardless of the type of wall, the overall U value is

extremely important.

30

Figure 3.5 illustrates the wall section specified for Miami Green. As can be seen, R-20

insulation has been added greatly reduces the baseline U value. The total U-value of the wall

shown in the figure is 0.04Ffth

BTU2 ⋅⋅

.

Figure 3.5 – Window Section

Lighting

Improving lighting efficiency is the easiest way to “go green.” Everyone can change

regular incandescent light bulbs to more energy efficient Compact Fluorescent Light (CFL)

lights. In the scope of Miami Green, all interior and some exterior lights will be fluorescent

lights. Fluorescent lights are more efficient because they produce more Lumens per Watt.

Simply stated, they output more light with less power.

ASHRAE Standard 90.1 allows a maximum of 1.2 W/S.F. for office lighting. Due to

multiple reasons, Miami Green will use approximately 0.9 W/S.F. One of these reasons is the

widespread use of fluorescent lighting instead of incandescent lights. But since ASHRAE has

already assumed the primary use of fluorescents, the energy use reduction is not substantial.

31

The primary reason for the reduction in lighting wattage is as follows. Since Miami

Green is for office/retail usage, its primary use shall be during the day. And since Miami Green

is over 80% glass, the need for interior lighting during the day is greatly reduced. Therefore, the

amount of glass on the building decreases the efficiency of the HVAC system but also reduces

the amount of interior lighting required.

Another way Miami Green is reducing energy is by using smart lighting systems. For

example, bathrooms and closets will be equipped with motion sensors to activate only when

occupied. Basically, reducing the amount of time non-essential lighting is on. Interior smart

lighting will also shut down lighting when the building occupancy is sensed to be low. These

times shall correspond to night time and holidays.

HVAC

The three HVAC systems being used considered in Miami Green were explained in the

previous overview section. The energy efficiency of these three systems differs with different

application. There is no system which is generally more efficient. Within each system there are

varying efficiencies available with a certain cost associated with them. For instance, the

minimum efficiency required for a DX air-cooled system over 65,000 BTU/h cooling capacity is

9.5 EER (Energy Efficiency Ratio). Systems of this type are available with EER values up to 15

but are also much more expensive. The EER of equipment is calculated by the following

formula:

Power(KW)Input (BTU/h)Capacity CoolingEER =

Packaged DX water-cooled systems are also rated by the value of the EER. Package water-

cooled systems are more efficient by also require a cooling tower and water pumps. Generally,

32

for larger scale projects, the water-cooled systems are preferable because they save space and

can sometimes be more efficient. Therefore, the choice is between the two is not clear.

A chilled water system is sometimes more desirable because all refrigeration is localized

to the chiller. In this system the chiller is primarily responsible for energy usage. In Miami

Green the chiller necessary will need to have approximately 300 tons cooling capacity. Chiller

efficiency is measured in COP (Coefficient of Performance). For a 300 ton centrifugal water-

cooled chiller the minimum efficiency required is 5 COP. The conversion from tons of

refrigeration to BTU/H and the formula for COP are shown below. Chiller efficiencies are

available up to 6.5 COP but with significant cost associated with them. Also, chilled water

systems are only feasible in larger scale applications.

BTU/H 12,000 ion RefrigeratTon 1 =

H)Power(BTU/Input TU/H)Capacity(B CoolingCOP =

Since the choice between systems is vague, it is up to the energy modeling and life cycle

cost analysis to determine the system to be used. The life cycle cost analysis is a study of the

economics involved in an HVAC system. Parameters such as initial cost, service life,

maintenance costs and energy costs by a role in the life cycle cost analysis. Often times,

ownership and future plans play a significant role in the choice of the HVAC system to be used.

The importance of the life cycle cost analysis and ownership will be discussed in the next

chapter.

3.3 EQuest and Results

As mentioned at the start of this chapter, eQuest shall be used to measure and analyze the

building’s overall energy usage. EQuest is software based on another energy analysis program

33

called DOE-2. This software began development in the 1970’s with collaborative efforts by

ASHRAE, NASA, the US Postal Service, and energy industry leaders. It was created to answer a

growing concern in the industry, that society as a whole was not leading a sustainable lifestyle.

DOE-2/eQuest is the most widely used and respected software in field of energy

modeling. The results of an energy model cannot be assumed to be 100% accurate but do serve

as a basis of comparison to determine that one alternative is more energy efficient than another.

This will be the usefulness of eQuest in Miami Green. This software will serve as a benchmark

to gauge how energy efficient the proposed building has become in comparison to a baseline

building. The measure of improvement will be shown as a percent reduction in the baseline

energy usage. Below is the formula used to find the percent reduction,

%100 UsageBaseline

UsageProposed- UsageBaselineReduction % ×=

where the energy usage is measured in kWh.

As previously mentioned, the baseline building is modeled using all the minimum

requirements of Table 3.1. The results of this model shall be the basis of comparison for all other

proposed building designs. Below, Figure 3.6 is a summary of the gross energy usage broken

down into different classifications and months of the year

34

Figure 3.6 – Baseline Electric Consumption of Miami Green

As seen in Figure 3.4, the total annual electric consumption of the baseline model is

2,820 MWh. This means that Miami Green will use 2,820 Megawatt-hours of electricity

annually if it is build to minimum standards. Our primary goal is reduce this gross energy usage

as much as possible while maintaining a safe, comfortable environment at a reasonable cost.

Now we will make improvements to the shell/envelope, lighting, and HVAC system. In

order to present the results of our comparisons in an organized fashion, Table 3.2 will show

designations and nomenclature used for different test runs with different specifications.

35

Table 3.2-Nomenclature and Designations Used

Designation Detailed Description

DXS DX Split System Air-Cooled

DXWC DX Packaged System Water-Cooled

CHW Chilled Water System Water Cooled

Shell Only Improvements made to Shell and Lighting only (Min. HVAC efficiency

EER * Improvements made to Shell, Lighting, and HVAC efficiency

COP * Improvements made to Shell, Lighting, and Chiller efficiency

Baseline Building Baseline Model Created according to ASHRAE 90.1

Table 3.3 shows the energy model results for different scenarios. The first model shown

in table is the baseline model shown in detail in figure 3.6. The energy usage of the baseline

model is the basis for measuring the % reduction as previously discussed. The last column

shows the percent reduction of all the different models. Appendix B “Energy Analysis” contains

the complete summary of all the models created and their respective breakdowns and electric

consumptions.

Table 3.3 - Energy Model Results

Model Name Energy Usage %

(kWh x 000) Description Improvement

Baseline 2,820 Model According to ASHRAE 90.1 n/a

DXS Shell 2,328 Sh y ell/LTG Improvement Onl 17.45% DXS EER 12 2,164 Shell and HVAC (12 eer) 23.26% DXWC Shell 2,289 Sh y ell/LTG Improvement Onl 18.83%

DXWC 14 EER 2,107 Shell and HVAC (14 eer) 25.28% CHW Shell 2,277 Sh ell/LTG Improvement Only 19.26%

CHW 6 COP 2,088 Shell and Chiller (6 COP) 25.96%

36

For each different system (DXS, DXWC, and CHW) two models were made. First, the shell

only run, which only improves the building envelope and lighting efficiency while maintaining

the minimum HVAC equipment efficiency allowable by code. The second run makes

improvements upon the HVAC system efficiency.

The data shown in table 3.3 shows that with specifications made the chilled water

system (CHW) is the most energy efficient followed by the DX packaged system and then the

DX split system. Using minimum and maximum efficiency equipment the DX split system is the

least efficient when compared respectably to the other system types. The two other systems are

very close in energy efficiency and the difference is almost negligible.

Also, it should be noted that the greatest improvement in energy efficiency was done by

improving the envelope/shell (walls and windows) and lighting efficiency. This upgrade

accounted for approximated 18% reduction. Improving the HVAC efficiency alone accounted

for only an additional ±6% reduction. Therefore, the primary energy savings is made by

improving the structures thermal properties. Improving equipment efficiencies is a good step but

not as drastic a change.

The choice of which system to use is still not complete. The energy efficiency of the

systems has been measured and a distinction has been made between them. We cannot simply

choose the most efficient system. Other factors such as ownership type, useful life and initial

cost must be accounted for. All of these factors will be weighted and balanced and the system

type will be chosen in the next chapter.

37

Chapter 4 – Cost Analysis and System Selection

4.1 Overview

A cost analysis is one of the most important factors to consider when selecting the

cooling system to be used in a building. For Miami Green, the type of ownership combined with

the initial cost of the building will most likely be the settling factor of which system shall be

chosen. This will be the topic of a later section in this chapter.

Factors to be considered when performing a life cycle cost analysis are things such as

initial cost, life of equipment, operating costs and present worth. Initial cost includes things such

as equipment costs and installation costs. Operating costs include things such as annual

maintenance costs and energy usage.

For the purposes of this project a program called Engineering Economic Analysis by

Carrier will used to perform the life cycle cost analysis. The three different systems under

consideration will be compared by initial cost, annual operation cost and present worth over a

period of time.

4.2 Input Parameters

The life cycle cost of Miami Green will be analyzed over a period 31 years to ensure that

all of the three alternatives must be replaced at least once. A standard assumption of 6%

minimum attractive rate of return will be assumed. Also, the three systems will be analyzed

completely independent of each other. The following is a break-down of the three systems and

the costs associated with them.

Table 4.1 contains the initial cost of the DX Split system for Miami Green. Note that the

unit cost includes air-handler unit (AHU), condenser unit (CU) and installation of all associated

ductwork and equipment. The estimated life of a system of this type is approximately 10 years.

38

At the end of the expected life there are replacement costs. This system must be replaced two

times in a span of 31 years.

Table 4.1 - DXS Cost Equipment (AHU and

CU)

Installed Cost/Unit

($) Quantity Cost ($) Life

(years)

12.5 T. Unit 29,000 7 203,000 10 7.5 T. Unit 17,400 13 226,200 10 4 T Unit 11,600 20 232,000 10

Total Initial Cost = 661,200

The annual costs for DXS include maintenance and energy costs. The annual

maintenance cost for this system can be estimated at $200/AHU for filter, fan and coil

maintenance and $200/CU for refrigerant and compressor maintenance. Since there are 40 AHU

and CU in this proposed design, the average annual maintenance cost for this system is

$16,000/year.

The annual energy usage of this system is the topic of the previous chapter. Using the

results from the last chapter, the local energy costs are applied to find that this system will have

an energy cost of approximately $152,000/year.

Table 4.2 contains the initial cost of the DX package system for Miami Green. Note that

the unit cost includes equipment costs, ductwork, piping and installation. The estimated life of

packaged units (PU) and pumps is approximately 15 years. The estimated life of a cooling tower

is 20 years. Therefore, this system must be replaced once in a span of 31 years. This replacement

cost along with inflation must be taken into account.

39

Table 4.2 - DXWC Cost

Equipment (PU) Installed Cost/Unit


(years)

12.5 T. Unit 30,900 7 216,300 15 7.5 T. Unit 18,500 13 240,500 15 4 T. Unit 12,400 20 248,000 15

Cooling Tower 38,500 1 38,500 20 Pumps 4,200 2 8,400 15


The annual maintenance costs of this system are similar to that of the DXS system. An

average of $400/PU equals to a total of $16,000 per year. Cooling tower maintenance and water

treatment must also be considered for this system. These costs can be estimated at $5,000 per

year. Therefore, the total maintenance cost of the DXWC system is $21,000 per year. Using the

energy usage results from the last chapter, the annual energy cost of this system can be estimated

at $142,000 per year.

Table 4.3 contains the initial cost and life of the chilled water system for Miami Green.

Note that the unit cost includes equipment costs, ductwork, piping and installation. The

estimated life of fan coil units (FCU) and pumps is approximately 15 years. The estimated life of

a cooling tower and chiller is 20 years. Therefore, this system must be replaced once in a span of

31 years. This replacement cost along with inflation must be taken into account.

Table 4.3 - CHW Cost

Equipment (FCU)

Installed Cost/Unit


(years)

12.5 T. Unit 26,500 7 185,500 20 7.5 T. Unit 18,000 13 234,000 20 4 T. Unit 11,000 20 220,000 20

Cooling Tower 38,500 1 38,500 20 Chiller 205,500 1 205,500 20 Pumps 4,200 4 16,800 15


40

The annual maintenance costs of this system much lower than the previous two since

there is one centralized compressor. An average of $200/FCU equals to a total of $8,000 per

year. Cooling tower, Chiller maintenance and water treatment must also be considered for this

system. These costs can be estimated at $6,000 per year. Therefore, the total maintenance cost of

the DXWC system is $14,000 per year. Using the energy usage results from the last chapter, the

annual energy cost of this system can be estimated at $141,000 per year.

4.3 Life Cycle Cost Analysis All of the above parameters were input to the Engineering Economic Analysis software.

The results are summarized below. For the complete results and report see Appendix C

“Economic Analysis.”

• Initial Cost o DXS - $661,200 (winner) o DXWC - $751,700 o CHW - $900,300

• Total Present Worth o DXS - $3,619,000 o DXWC - $3,347,000 o CHW - $3,205,000 (winner)

• Annual Operating Costs o DXS - $168,000 o DXWC - $163,000 o CHW - $155,000 (winner)

The above data shows that the DX split system (DXS) has the lowest initial cost and the

chilled water system (CHW) has the lowest total present worth and annual operating costs. It

should be noted that the DX packaged water-cooled system is in second place in all three

categories. Also, DXS is the worst in total present worth and annual operating costs. Using this

data, the next section will determine which system shall be used.

41

4.4 Ownership and Initial Cost There are essentially two types of builders. The first type of builder is a person or

company that is constructing a building for their own use with intentions of inhabiting and

maintaining the building themselves. This is often the case when a large corporation is planning

on building a headquarters/office or when a university desires to build an additional campus or

building. Also, this kind of developing is found on a large scale in governmental agencies and

institutions. Essentially, building “X” is being built by company “Y” for the use of company

“Y”. The goal of this group is to maintain operating and life cycle costs to a minimum,

regardless of the initial cost of construction. Therefore, for this type of owner, the total present

worth of the HVAC system is of primary concern. This type of owner would most definitely

choose a chilled water system in this situation.

The second type of builder is a private developer that is seeking a profit from selling a

building that he/she has built. For example, Developer “A” is constructing building “B” to later

sell the building and make a profit. This is exactly the case for Miami Green.

Miami Green is being built by a developing company to later lease or sell the spaces to

outside buyers. The main goal of the developer is to maintain the construction cost (initial cost)

to a minimum and maximize the potential profits when the building is sold. Maintenance, energy

and replacement costs are seldom the concern of these types of developers. Therefore, usually

the HVAC system with the lowest initial cost is the one installed.

In this case the system with the lowest initial cost is the DX split system and would

usually be the system installed in this type of application since the lowest initial cost tends to

mean the highest profit for a developer. But this is not the case for Miami Green. Miami Green

will use a DX packaged water cooled system because it is more “green”. Meaning, for only

42

$90,000 more in construction, the DX packaged (DXWC) system will achieve 2 more LEED

credit points that the DX split system does not. The DXWC system will obtain an extra point for

energy efficiency (since it is 2% more efficient than DXS) and an extra point for “Enhanced

Refrigerant Management” that DXS does not get. The basis for LEED points will be further

discussed in the next chapter.

Therefore, even though the DXWC system costs more, the marketability of the label

“Green Building” is out weights the difference in initial costs. The reason the chilled water

system was ruled out is because it does not achieve and extra points over DXWC and costs

$150,000 more.

4.5 System Specification and Details

Now that the system has been chosen, the next task is to make equipment specifications

and create schematic drawing of the system with certain key details. Please note that this section

only summarizes the schematic plans for Miami Green. For complete equipment specifications

and schematic plans, please see Appendix D and Appendix E.

Condenser water lines will be run from the cooling tower on the roof down the building

to the ground floor. Condenser water supply (CWS) and return (CWR) will be supplied piped

across the entire layout of every level. A packaged unit can be inserted anywhere within the

level- and “tap-in” to the condenser water lines. This allows flexibility in layout options for each

floor. All packaged units are manufactured by Trane, a well-known and respected cooling

equipment manufacturer. As mentioned in a previous chapter, all heating will be done by electric

strip heaters inside the packaged equipment. For complete equipment specifications please see

drawings and specifications. A condenser water isometric has been provided to schematically

show the piping and equipment locations.

43

Two (2) 100% outside-air roof-top units located supply the corridors on Miami Green via

shafts throughout the building. Outdoor fresh air is supplied to the packaged units within the

spaces from the roof via a shaft located in the center of the building.

The garage of Miami Green is open to the outside and naturally ventilated. Recirculation

fans guarantee that there are no stagnation points and CO/CO2 levels remain below critical.

Exhaust fans are provided in all bathrooms and equipment rooms. For exact location of all fans

please see drawings.

The drawings provided in Appendix E are only schematic and are not intended as

construction documents. The goal of this project is to provide schematic drawings of the

recommended HVAC system to the owner for his/her approval. The drawings provided are for

the shell layout only. Once approved, the exact interior layouts must be chosen.

NOTE: The drawings provided in Appendix E are scaled to fit inside of this report. A

full sized set of drawings were provided along with the report on the date of completion.

44

Chapter 5 LEED certification

5.1 Overview

A “Green Building” is the measure of how sustainable a building is constructed. This is

done by optimizing the design and construction of the building and minimizing the operations

and maintenance. The United States Green Building Council (USGC) is the US government

organization that developed the “Green Building” rating system through the LEED committee,

Leadership in Energy and Environmental Design. The LEED committee provides the standards

and performance criteria for certifying a sustainable design. The “Green Building” standards

help improve the quality of buildings their impact on the environment, and promote

environmental leadership in the building industry. Though a point system, LEED addresses six

development and construction processes when rating a building as “Green”. These areas include

sustainable sites, water efficiency, energy and atmosphere, materials and resources, indoor

environmental quality and innovation and design process. Each of the six categories has certain

prerequisites that are required and must be achieve to be considered for LEED certification.

LEED awards points for accomplishing certain criteria in each of the six categories. A minimum

of 26 points is needed for the building to be recognized as a “Green Building”.

The six sections addressed by the LEED certification focuses on different development

processes of the construction of the building. The HVAC system is only a portion of the

development processes that LEED focuses on for certification. The design of the HVAC system

of the Miami Green buildings will concentrate on the Energy and Atmosphere and the Indoor

environmental quality sections. In this chapter, the criteria for these sections and the methods

used to achieve the points will be described.

45

5.2 Energy and Atmosphere (EA)

The Energy and Atmosphere prerequisites that are required from the HVAC design are

the “Minimum Energy Performance” and “Fundamental Refrigerant Management”. The

Minimum Energy Performance (EA Prerequisite 2) standard creates an energy baseline for a

construction depending on the building usage set by ASHRAE standard 90.1. This standard

focuses on establishing a minimum level of energy efficiency for the proposed building and

systems. The Fundamental Refrigerant Management (EA Prerequisite 2) standard aims towards

reducing ozone depletion. The use of CFC, Chlorofluorocarbon based refrigerants is prohibited

for new constructions. This is done to phase out refrigerants such as R-22 that once was

commonly used in HVAC systems and is responsible for ozone depletion due to its release of

CFC into the atmosphere. The HVAC system of the Miami Green Building will be designed to

use refrigerant R-410a which is not CFC-based.

The main focus on the Miami Green HVAC design project is to maximize energy

efficiency. In the Energy and Atmosphere section of the LEED certification, credit 1 awards

points dependant upon the percentage of energy usage reduced. This credit focuses on achieving

increasing levels of energy performance above the standard and reducing economic impacts

associated with excessive energy use. The design of the Miami Green HVAC system will

improve the minimum energy usage set by ASHRAE standard 90.1 by 25.28% to collect 5

points from this section. This improvement of energy usage was the focus of Chapter 3.

Summing the total energy cost of the Miami Green building, E-quest calculated and energy that

the usage of 2,820,000 kWh was needed. By using more efficient lighting and insulating glaze

on the windows and better insulation on the envelope the energy usage was decreased. Also a

more efficient HVAC system of 14 EER (Energy Efficiency Ratio) was used. The baseline

energy usage defined by ASHRAE standards were reduced to approximately 2,107,100 kWh.

46

The forth credit in the Energy and Atmosphere section deals with “Enhanced Refrigerant

Management (EA Credit 4). Miami Green achieves this credit by using packaged units designed

to use refrigerant R-410a. Using this refrigerant drastically reduces ozone depletion. Also, using

packaged units reduces the quantity of the refrigerant used, further reducing the environmental

impact. The combined effect of these two factors gives Miami Green a point for EA credit 4.

5.3 Indoor Environmental Quality (EQ) The next section that the Miami Green Building HVAC system design will focus on is

the Indoor Environmental Quality (EQ). The prerequisite that is required is to provide a

“Minimum Indoor Air Quality” (EQ Prerequisite 1). This prerequisite is mandated to contribute

to the comfort and well being of the occupants of the building. ASHRAE standard 62.1 set

minimum requirements of ventilation for acceptable indoor air quality. Mechanical ventilation

systems installed during core and shell construction will be capable of meeting projected

ventilation levels based on tenant requirements.

The first credit in this section (EQ Credit 1) deals with “Outdoor Air Delivery

Monitoring’. To achieve this credit Miami Green will have a mechanical room with computers

equipped to monitor many sensors that are associated with the HVAC system. Naturally

ventilated areas in the Miami green project such as the Garage will have CO2 and CO sensors to

monitor the concentrations of carbon dioxide and carbon monoxide. Fans will be used to

circulate and ventilate outdoor air into these areas. The sensors will alert the operators in the

Mechanical room if an excess of harmful gasses is present were cautions will be addressed.

Mechanical ventilation systems will be placed properly throughout the structure. These

ventilation systems will provide direct air flow do meet at least the minimum ventilation

requirements. The ventilation systems will have sensors to monitor the airflow through the

47

system. The sensors will also alert the mechanical room if the minimum requirement is not met.

If this were to occur, proper cautions will be addressed. This ventilation monitoring system

receives a point for Outdoor Air Delivery Monitoring. The Ventilating systems for the Miami

Green project will be set to provide airflow of 30 percent over the minimum required by

ASHRAE section 62.1. The increased airflow will provide the occupants with better quality air

and achieves a LEED point for increased ventilation (EQ Credit 2).

When the construction of a building is complete the quality of the air initially in the

building is poor due to the processes of the construction of the building. An Indoor Air Quality

Management Plan is made to control the air quality during construction and preoccupancy

periods. This plan is used to take action in following air quality standards and protect absorption

materials from moisture damage. Once the Miami Green Building is constructed, a flush process

will be performed. This process includes flushing the building with 100% outside air for 10 days

and replacing all filtration systems prior to occupancy. This flush process achieves one point

towards the LEED certification (EQ Credit 3).

Finally the air filters used in the packaged units will be of a minimum efficiency rating

value of 13. These air filters will be applied to both the return air and the outside air which is

delivered as supply air. Using these filters achieves another point towards the LEED certification

(EQ Credit 5).

5.4 Conclusion These HVAC designs outlined above conclude that a total of 10 points will be achieved

towards the LEED certification that is associated with the HVAC design. Also another point can

be awarded for having the occupants of the building complete a survey after six months of the

building occupancy. This survey will ask for a detailed description of the occupant’s view of the

thermal comfort of the building. Depending on how the occupants feel, provisions will be taken

48

to maximize the occupant’s thermal comfort. The 11 points accumulated is almost half of the

points necessary to certify the buildings as “Green”. The remainder of the points can be achieved

through architectural and construction processes. Criteria focusing Sustainable sites, Water

Efficiency, and Material and Resources are sections which the architects design and contractor’s

equipment can achieve the remaining points necessary for LEED certification.

Table 5.1 - LEED Credit Summary

Section

Criteria

Points

Requirements

Minimum Energy Performance PreReq Fundamental Refrigerant Management PreReq Optimize Energy Performance 5

Reduce building energy cost by 24.5%

Energy and Atmosphere

Enhance Refrigerant Management 1 Use Zero CFC-based refrigerants Minimum IAQ Performance PreReq Outdoor Air Delivery Monitoring 1 Measure outdoor airflow Increased Ventilation 1 increase ventilation by 30% Construction IAQ Management Plan 1 perform Building "flush out" Indoor Chemical and Pollutant Source Control 1 Use MERV13 filters

Indoor Environmental Quality

Thermal Comfort Verification 1

Create occupant thermal comfort survey

49

References

ACEC, 1982, Consulting Engineering Practice Manual, McGraw-Hill, Inc. New York City, NY. ASHRAE, 2001 ASHRAE Handbook - Fundamentals, American Society of Heating,

Refrigeration, and Air-Conditioning Engineers, Inc., Atlanta, Ga. ASHRAE, 2000 ASHRAE Handbook – HVAC Systems and Equipment, American Society of

Heating, Refrigeration, and Air-Conditioning Engineers, Inc., Atlanta, Ga. ASHRAE, 1999 ASHRAE Handbook – HVAC Applications, American Society of Heating,

Refrigeration, and Air-Conditioning Engineers, Inc., Atlanta, Ga. ASHRAE, 1998 ASHRAE Handbook – Refrigeration, American Society of Heating,

Refrigeration, and Air-Conditioning Engineers, Inc., Atlanta, Ga. ASHRAE, Standard 90.1 Energy Standard for Buildings Except Low-Rise Residential Buildings,

2004, ASHRAE Inc., Atlanta, Ga. ASHRAE, Standard 62 Ventilation for Acceptable Indoor Air Quality, 2001, ASHRAE Inc.,

Atlanta, Ga. Florida Mechanical Building Code 2004, Florida Building Department, Tallahassee, FL. Gladstone, J., 1981, Air Conditioning Testing/Adjusting/Balancing, A Field Practice Manual,

2nd Edition, Van Nostrand Reinhold Company, New York City, NY. Haines, R. W. and Wilson, C. L., 1994, HVAC Systems Design Handbook, 2nd Ed McGraw-Hill,

Inc. New York City, NY. Incropera, F. P., Dewitt, D. P., Bergman, T. L. and Lavine, A. S., 2007, Fundamentals of Heat

and Mass Transfer, John Wiley & Sons, Inc. Hoboken, NJ. McQuistion, F. C., Parker, J. D., and Spitler, J.D., 2005, Heating, Ventilating, and Air

Conditioning, Analysis and Design 6th Ed., John Wiley & Sons, Inc. Hoboken, NJ. Moran, M. J. and Shapiro, H. N., 2004, Fundamentals of Engineering Thermodynamics, John

Wiley & Sons, Inc. Hoboken, NJ. NFPA, 2000, Life Safety Code Handbook, NFPA 101 8th Edition, National Fire Protection

Association, Quincy, Massachusetts. NFPA, 2005, Florida Fire Prevention Code, 2004 Edition, National Fire Protection Association,

Quincy, Massachusetts.

50

Rowe, W. H. III, 1988, HVAC Design, Criteria, Options, Selections, R. S. Means Company, Inc., Kingston, MA.

SMACNA, 1995, HVAC Duct Construction Standards, Metal and Flexible, 2nd Ed. Sheet Metal

and Air Conditioning Contractors’ National Association, Inc., Chantilly, Va.

51

Appendix A

Cooling and Heating Loads

52

Appendix B

Energy Modeling

Project/Run: Miami Green - Baseline Design Run Date/Time: 11/15/07 @ 10:33

eQUEST 3.60.5200 Monthly Energy Consumption by Enduse Page 1

0

100

200

300

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Electric Consumption (kWh)

(x000)

Area LightingTask LightingMisc. Equipment

Exterior UsagePumps & Aux.Ventilation Fans

Water HeatingHt Pump Supp.Space Heating

RefrigerationHeat RejectionSpace Cooling

Electric Consumption (kWh x000)

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Total Space Cool 51.7 53.6 61.3 72.1 83.0 90.7 95.2 97.8 87.2 83.2 67.1 55.4 898.4 Heat Reject. - - - - - - - - - - - - - Refrigeration - - - - - - - - - - - - - Space Heat 1.4 0.0 - - - - - - - - - - 1.4 HP Supp. - - - - - - - - - - - - - Hot Water - - - - - - - - - - - - - Vent. Fans 21.9 20.5 23.8 22.4 22.6 23.1 22.4 23.3 22.2 22.6 21.2 23.0 269.0 Pumps & Aux. 0.0 0.0 0.0 - - - - - - - - 0.0 0.0 Ext. Usage 10.6 8.5 9.4 9.1 7.6 7.4 7.6 10.6 10.3 10.6 10.3 10.6 112.9

Misc. Equip. 61.9 56.4 64.9 62.2 64.4 62.2 62.4 66.9 57.6 64.4 59.2 60.3 742.8

Task Lights - - - - - - - - - - - - -

Area Lights 66.5 60.3 69.7 66.6 69.5 66.6 66.7 72.4 60.9 69.5 63.5 64.0 796.2

Total 214.0 199.3 229.1 232.5 247.0 250.0 254.3 271.1 238.3 250.3 221.3 213.3 2,820.6

Gas Consumption (Btu)

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Total Space Cool Heat Reject. Refrigeration Space Heat HP Supp. Hot Water Vent. Fans Pumps & Aux. Ext. Usage

Misc. Equip.

Task Lights

Area Lights

Total

Project/Run: Miami Green DXS - Shell Only Run Date/Time: 11/21/07 @ 14:51


0

50

100

150

200

250



(x000)







Misc. Equip. 55.7 50.7 58.4 56.0 58.0 56.0 56.1 60.2 51.9 58.0 53.3 54.3 668.7

Task Lights - - - - - - - - - - - - -

Area Lights 48.5 44.0 50.8 48.6 50.6 48.6 48.6 52.8 44.4 50.6 46.3 46.6 580.4

Total 174.3 164.1 187.9 191.5 204.9 207.5 211.6 225.0 197.2 207.1 182.3 174.7 2,328.3



Misc. Equip.

Task Lights

Area Lights

Total

Project/Run: Miami Green DXS - EER 12 Run Date/Time: 11/21/07 @ 15:01


0

50

100

150

200

250



(x000)







Misc. Equip. 55.7 50.7 58.4 56.0 58.0 56.0 56.1 60.2 51.9 58.0 53.3 54.3 668.7

Task Lights - - - - - - - - - - - - -

Area Lights 48.5 44.0 50.8 48.6 50.6 48.6 48.6 52.8 44.4 50.6 46.3 46.6 580.4

Total 164.8 154.1 176.6 178.3 189.7 191.0 194.3 207.3 181.5 191.9 170.0 164.4 2,164.0



Misc. Equip.

Task Lights

Area Lights

Total

Project/Run: Miami Green DXWC - Shell Only Run Date/Time: 11/21/07 @ 14:38


0

50

100

150

200

250



(x000)






Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Total Space Cool 41.8 44.5 49.7 56.3 66.3 70.9 75.1 77.1 68.9 67.1 53.8 45.5 717.0 Heat Reject. 4.8 4.4 5.4 6.3 7.7 8.3 8.1 8.4 8.0 7.7 6.5 4.2 79.8 Refrigeration - - - - - - - - - - - - - Space Heat 1.5 0.1 - - - - - - - - - - 1.6 HP Supp. - - - - - - - - - - - - - Hot Water - - - - - - - - - - - - - Vent. Fans 3.3 3.1 3.6 3.4 3.4 3.5 3.4 3.5 3.3 3.4 3.2 3.5 40.5 Pumps & Aux. 8.8 9.4 11.3 10.7 10.8 11.0 10.7 11.1 10.6 10.8 10.1 10.9 126.2 Ext. Usage 7.1 5.7 6.3 6.1 5.1 4.9 5.1 7.1 6.9 7.1 6.9 7.1 75.2

Misc. Equip. 55.7 50.7 58.4 56.0 58.0 56.0 56.1 60.2 51.9 58.0 53.3 54.3 668.7

Task Lights - - - - - - - - - - - - -

Area Lights 48.5 44.0 50.8 48.6 50.6 48.6 48.6 52.8 44.4 50.6 46.3 46.6 580.4

Total 171.5 162.0 185.5 187.3 201.8 203.2 207.1 220.2 194.0 204.7 180.1 172.1 2,289.5



Misc. Equip.

Task Lights

Area Lights

Total

Project/Run: Miami Green DXWC - EER 14 Run Date/Time: 11/21/07 @ 14:53


0

50

100

150

200

250



(x000)







Misc. Equip. 55.7 50.7 58.4 56.0 58.0 56.0 56.1 60.2 51.9 58.0 53.3 54.3 668.7

Task Lights - - - - - - - - - - - - -

Area Lights 48.5 44.0 50.8 48.6 50.6 48.6 48.6 52.8 44.4 50.6 46.3 46.6 580.4

Total 160.9 150.6 172.8 173.0 185.0 185.3 188.2 200.8 176.6 187.7 166.4 160.5 2,107.9



Misc. Equip.

Task Lights

Area Lights

Total

Project/Run: Miami Green CHW - Shell Only Run Date/Time: 11/21/07 @ 14:45


0

50

100

150

200

250



(x000)







Misc. Equip. 55.7 50.7 58.4 56.0 58.0 56.0 56.1 60.2 51.9 58.0 53.3 54.3 668.7

Task Lights - - - - - - - - - - - - -

Area Lights 48.5 44.0 50.8 48.6 50.6 48.6 48.6 52.8 44.4 50.6 46.3 46.6 580.4

Total 179.1 166.1 191.5 188.6 197.6 196.8 197.3 210.5 188.0 200.2 181.4 179.9 2,277.1



Misc. Equip.

Task Lights

Area Lights

Total

Project/Run: Miami Green CHW - Chiller 6 COP Run Date/Time: 11/21/07 @ 14:47


0

50

100

150

200



(x000)







Misc. Equip. 55.7 50.7 58.4 56.0 58.0 56.0 56.1 60.2 51.9 58.0 53.3 54.3 668.7

Task Lights - - - - - - - - - - - - -

Area Lights 48.5 44.0 50.8 48.6 50.6 48.6 48.6 52.8 44.4 50.6 46.3 46.6 580.4

Total 165.9 153.0 176.3 173.0 181.0 179.6 180.1 192.7 171.2 183.4 166.4 165.5 2,088.2



Misc. Equip.

Task Lights

Area Lights

Total

Appendix C

Economic Analysis

Appendix D

Equipment Specification

Appendix E

Mechanical Drawings

Note: Full size set provided separately

Appendix F

Design Organization

Project Timeline

Category Sub-Category

Jan-07

Feb-07

Mar-07

Apr-07

May-07

Jun-07

Jul-07

Aug-07

Sep-07

Oct-07

Nov-07

Dec-07

Progress Report #1

Progress Report #2

Presentation #1

Progress Report #3

Presentation #2

EML 4551-

Design Org.

Final Report

Progress Report #1

Progress Report #2

Progress Report #3

Senior Project Design

Final Demo

Research Code Resrictions Cooling Loads

Ventilation Design

Equipment Selection

Drafting

Preliminary Review

Re-Design

Code Compliance

HVAC Design

For Miami Green

Final Design

Failure Modes and Effects Analysis (FMEA)

Item #

Component Description Failure Mode Effects Safeguard Actions

Complete Malfunction Uncomfortable Select More

Reliable Equipment

Select Proper Warranty Info

Not Enough Cooling Uncomfortable Better Design Over Design

Humidity Uncomfortable Better Design and Equipment Accurate Design

1 AC

Refrigerant Leak Environmental

Impact; Uncomfortable

Environmentally Safe Refrigerant

Proper Equipment Selection.

Complete Malfunction Check Regularly Select Proper Warranty Info

Insufficient Pressure

Unsafe in event of a fire

Better Design Over Design 2 Stair

Pressurization Fans

Over Pressurization Doors are hard to open Better Design Accurate Design

Duct Leak

Improper Insulation Loss of Cooling;

Loss of Efficiency Check

Construction Contractor Guarantee

3 Ducts

Unsmooth Finish Mold and

Bacteria Growth; Heath

Insure Air Quality Buy Correct Ducts

CO Sensor Failure Unsafe Garage Conditions Redundancy Over Design

Thermostat Failure Uncomfortable Select More

Reliable Equipment

Select Proper Warranty Info 4 Sensors

Fire Damper Failure Unsafe in event of a fire

Select More Reliable

Equipment

Contractor Guarantee

Artistic Rendering of Miami Green in Future Location

Documents

Senior Design - Miami Green - Final Draft