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DECISION MATRICES FOR HVAC SYSTEMS FOR FLORIDA PUBLIC SCHOOLS

By

KELLY JESSICA MCLAUGHLIN

A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT

OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE IN BUILDING CONSTRUCTION

UNIVERSITY OF FLORIDA

2010

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© 2010 Kelly Jessica McLaughlin

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To my family for their unconditional love and support

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ACKNOWLEDGMENTS

I would like to thank my family for their support and encouragement. I would also

like to thank Dr. Paul Oppenheim for his guidance throughout this study.

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TABLE OF CONTENTS page

ACKNOWLEDGMENTS .................................................................................................. 4

LIST OF TABLES ............................................................................................................ 7

LIST OF ABBREVIATIONS ........................................................................................... 10

ABSTRACT ................................................................................................................... 11

CHAPTER

1 INTRODUCTION .................................................................................................... 13

Background ............................................................................................................. 13 Objective of the Study ............................................................................................. 13 Limitations ............................................................................................................... 14

2 LITERATURE REVIEW .......................................................................................... 15

HVAC System Selection Process ........................................................................... 15 Selection Matrix ...................................................................................................... 16 Life Cycle Cost Analysis ......................................................................................... 19

3 METHODOLOGY ................................................................................................... 25

Introduction ............................................................................................................. 25 Selection of Decision Matrix Criteria ....................................................................... 25

Life Cycle Cost Criteria ..................................................................................... 26 Design Selection Criteria .................................................................................. 27

Organization of HVAC Systems .............................................................................. 28 Development of Decision Matrix ............................................................................. 29 Life Cycle Cost Analysis ......................................................................................... 31

First Costs ........................................................................................................ 33 Energy Costs .................................................................................................... 37 Maintenance Costs ........................................................................................... 39 Replacement Costs .......................................................................................... 40

Replacement of HVAC units ...................................................................... 40 Replacement of miscellaneous equipment ................................................ 40

Life Cycle Cost ................................................................................................. 41 Design Criteria Analysis .......................................................................................... 41

Required Space ................................................................................................ 41 Complexity ........................................................................................................ 42 Life of the Unit .................................................................................................. 42 Noise ................................................................................................................ 45

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Temperature Control ........................................................................................ 46 Humidity Control ............................................................................................... 47

4 DATA ...................................................................................................................... 48

Cost Criteria ............................................................................................................ 48 First Costs ........................................................................................................ 48 Energy Costs .................................................................................................... 50 Maintenance Costs ........................................................................................... 53 Replacement Costs .......................................................................................... 54 Life Cycle Cost ................................................................................................. 56

Design Criteria ........................................................................................................ 59 Required Space ................................................................................................ 59 Complexity ........................................................................................................ 59 Life of the Unit .................................................................................................. 64 Noise ................................................................................................................ 64 Temperature Control ........................................................................................ 65

5 RESULTS ............................................................................................................... 69

DX and Chiller Systems .......................................................................................... 69 Air Distribution Systems .......................................................................................... 69

6 CONCLUSIONS ..................................................................................................... 71

7 RECOMMENDATIONS ........................................................................................... 72

APPENDIX

A INSTALLATION COSTS OF FLORIDA SCHOOLS ................................................ 73

B PRESENT VALUE CALCULATIONS ...................................................................... 75

Energy Costs .......................................................................................................... 75 Maintenance Costs ................................................................................................. 77 Replacement Costs ................................................................................................ 79

LIST OF REFERENCES ............................................................................................... 82

BIOGRAPHICAL SKETCH ............................................................................................ 84

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LIST OF TABLES

Table page 2-1 Decision Matrix for the Comparison of HVAC Systems ...................................... 17

2-2 Decision matrix using both performance and numerical rating ........................... 18

2-3 Decision Matrix with Weight Factors ................................................................... 19

2-4 System selection matrix utilizing both qualitative and quantitative rating methods .............................................................................................................. 21

3-1 HVAC systems included in study ........................................................................ 29

3-3 Life cycle cost parameters .................................................................................. 31

3-2 Example of the proposed decision matrix displaying the color coding and ranking of systems .............................................................................................. 32

4-1 First costs of DX and Chiller units based off of actual supplier quotes ............... 48

4-2 First Cost of Air Distribution devices based off of actual supplier quotes ........... 49

4-3 General quotes of the installation costs of DX systems ...................................... 50

4-4 Summary and ranking of the first cost per ton for DX and Chiller systems ......... 51

4-5 Summary and ranking of the first cost per unit for Air Distribution systems ........ 51

4-6 Calculation of energy costs of DX units .............................................................. 52

4-7 Calculation of energy costs of Chiller systems ................................................... 52

4-8 Summary and ranking of energy costs for the DX and Chiller units .................... 54

4-9 Present value of the cost of maintenance over a 50 year building life ................ 54

4-10 Summary and ranking of unit maintenance costs ............................................... 54

4-11 Calculation of periodic unit replacement costs ................................................... 57

4-12 Calculation of miscellaneous equipment costs ................................................... 58

4-13 Summary and ranking of DX and Chiller replacement costs .............................. 58

4-14 Summary and ranking of Air Distribution replacement costs .............................. 58

4-19 Explanation of rating system for the required space criterion ............................. 59

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4-15 Summary and ranking of the life cycle costs for the DX and Chiller units ........... 60

4-16 Summary and ranking of the life cycle costs for the Air Distribution systems ..... 60

4-17 Space characteristics for typical designs of DX and Chiller systems. ................. 61

4-18 Calculation of the amount of required space needed for DX and Chiller systems. ............................................................................................................. 62

4-20 Space characteristics of typical Air Distribution systems .................................... 63

4-21 Calculation of required space for Air Distribution systems. ................................. 63

4-22 Ranking of the complexity of the DX and Chiller systems .................................. 63

4-23 Ranking of the complexity of the Air Distribution systems .................................. 64

4-25 Potential sources of noise in classroom ............................................................. 65

4-24 Summary of sources examined in the determination of unit service life ............. 66

4-26 Rating of noise characteristics for HVAC systems .............................................. 67

4-27 Ranking of the Air Distribution systems’ ability to control temperature of the space .................................................................................................................. 68

5-1 Completed decision matrix for DX and Chiller systems ...................................... 70

5-2 Completed decision matrix for the Air Distribution systems ................................ 70

A-1 HVAC system component costs for two elementary schools in Pasco County Florida ................................................................................................................ 73

A-2 Total costs for the installation of an air cooled chiller system in Pasco County elementary schools ............................................................................................. 74

B-1 Summary of costs and rates used in the calculation of the total present value of unit energy costs ............................................................................................ 75

B-2 Calculation of total present value of unit energy cost ......................................... 75

B-3 Summary of costs and rates used in the calculation of the total present value of unit maintenance costs ................................................................................... 77

B-4 Calculation of the total present value of unit maintenance cost .......................... 77

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B-5 Summary of costs and rates used in the calculation of the total present value of miscellaneous unit replacement costs ............................................................ 79

B-6 Calculation of the total present value of miscellaneous unit replacement costs . 79

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LIST OF ABBREVIATIONS

AHU Air Handling Unit

ANSI American National Standards Institute

ASHRAE American Society of Heating, Refrigerating and Air-Conditioning Engineers

DX Direct Expansion Systems

CFM Cubic Feet per Minute

EER Energy Efficiency Ratio

EFLOH Equivalent Full Load operating hours

HVAC Heating, ventilating and air conditioning

LCC Life Cycle Cost

LCCA Life Cycle Cost Analysis

VAV Variable Air Volume

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Abstract of Thesis Presented to the Graduate School of the University of Florida in Partial Fulfillment of the

Requirements for the Degree of Master of Science in Building Construction

DECISION MATRICES FOR HVAC SYSTEMS FOR FLORIDA PUBLIC SCHOOLS

By

Kelly Jessica McLaughlin

May 2010

Chair: Paul Oppenheim Cochair: Charles Kibert Major: Building Construction

The purpose of this research was to develop a decision matrix that would aid the

Florida Department of Education in the selection of the most appropriate and cost-

effective HVAC system for Florida public schools. A decision matrix was developed that

included the system selection criteria most pertinent to the needs of school facilities.

This matrix contained both life cycle cost and design criteria. A general life cycle cost

analysis was performed in order to determine the most cost effective HVAC system.

Methods were developed to rate the design criteria. The results of these calculations

were placed in the proposed decision matrix to compare the systems.

From the research conducted it was found that a general life cycle cost analysis of

HVAC systems was not possible to perform. The HVAC industry does not track system

costs on a general basis. As such, the costs used in the life cycle cost calculations were

for the HVAC units only.

The proposed decision matrix effectively presented the HVAC unit performance in

both the cost and design criteria categories. The rating scales developed allowed users

to identify the HVAC system that would best fit their needs. The proposed decision

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matrix could also be adapted to meet the specific needs of individual school districts

throughout the State of Florida.

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CHAPTER 1 INTRODUCTION

Background

Heating Ventilating and Air Conditioning (HVAC) systems are very complex and

require careful design considerations in order to provide a healthy, safe, and

comfortable environment for the building’s occupants. Each project has a unique set of

criteria that should be considered during the design phase in order to select the most

appropriate system for the building function. During the mechanical design phase, such

design criteria will be defined based upon the owner’s specific requirements and needs.

Once defined, engineers will examine the performance capabilities of various HVAC

systems in order to see if they meet these criteria. The systems that successfully meet

the desired criteria are the ones that are considered for implementation in the project.

Traditionally, the HVAC system with the least initial cost is the one selected for the

project. However, this may not be the most cost-effective option over the life of the

system. Other costs such as maintenance, energy use, and replacement costs should

be analyzed in order to get a true sense of the cost of the system over its entire useful

life.

Objective of the Study

This study has two objectives. First, a decision matrix will be proposed that may be

used to assist school board and project team members in the selection of HVAC

systems for new construction projects in Florida public schools. The decision matrix will

contain both design selection criteria and cost criteria. As design criteria and needs vary

by county throughout the state, the matrix will assist users in determining the most

appropriate and cost effective system for the given building in question. A scale will be

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developed to rate the performance levels of each of the criteria in the matrix. Only the

systems that have the greatest potential to be implemented in educational facilities will

be analyzed in this study.

The second objective of this study is to complete the decision matrix for the given

systems in question. A general life cycle cost analysis will be performed on these

systems. Methods of evaluating and rating the design criteria will either be developed or

be based upon standard industry practices.

Limitations

The proposed selection matrix is not intended to provide a definitive selection for the

mechanical system of an educational facility. Its intention is to provide an accurate and

practical tool to aid designers and school district personnel in narrowing the choices for

the selection of the most cost effective and appropriate HVAC system for their facility.

As this is a general study, the recommendations produced within should not replace the

detailed life cycle cost analysis recommendations performed by engineers for a specific

facility.

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CHAPTER 2 LITERATURE REVIEW

HVAC System Selection Process

HVAC systems are responsible for maintaining the desired environmental

conditions of a space. This includes the control of the temperature, humidity, air

movement, and quality of the air in the conditioned space (American Society of Heating,

Refrigerating and Air-Conditioning Engineers (ASHRAE) 2008). There is no one right

system for a building and often there will be multiple systems that meet the design

requirements of a project (Elovitz 2002). The selection of which HVAC system will be

implemented in a building is a critical decision. The responsibility of making this decision

falls upon the design engineer. They must select a system that will satisfy the building

program and design intent of the client (ASHRAE 2008). In order to achieve this, the

design engineer should make a family of decisions that are based upon the

performance of a wide range of criteria (Elovitz 2002).

Criteria can be classified as either gating criteria or comparative criteria. Gating

criteria are those that may be answered with a “yes” or a “no” (Elovitz 2002). These are

aspects that the system in consideration will either meet or not meet. If the system in

consideration does not meet the gating criteria, it cannot be considered for the project

unless the owner changes their criteria (Elovitz 2002). Examples of gating criteria

include system performance, capacity, and spatial requirements. There are also many

requirements that cannot be answered with a simple “yes” or “no” response. Such

criteria is comparative and involves tradeoffs (Elovitz 2002). Comparative selection

criteria include first costs, operating costs, reliability, flexibility, and maintainability.

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For a system selection to be successful, the criteria taken into consideration

should be reflective of the priorities and goals of the owner. These project specific

parameters should be included in the system analysis along with the basic design

constraints (ASHRAE 2008). The design engineer should collaborate with the owner to

identify and organize these criteria. With the desired design goals outlined, the design

engineer must next determine the constraints on the system. System constraints may

include the performance limitations, available capacity, available space, and available

infrastructure of a building (ASHRAE 2008). It should also include the constructability

constraints of the system such as the construction schedule and the ability to phase the

installation of the HVAC system (ASHRAE 2008). Ultimately the goal of the HVAC

system selection process is to narrow down the many choices of HVAC systems to

those that will work and those that will not work for a given project in order to find the

best system for the building (Elovitz 2002).

Selection Matrix

As a means of narrowing the choices of mechanical systems, the designer may

utilize a selection matrix. This matrix should present the advantages and disadvantages

of each of the systems considered for a particular project (Elovitz 2002). The use of

such a tool also allows for owner participation in the selection of the HVAC system

(Oppenheim 1992). It “forces the decision makers to assess what is important to them

for a successful outcome (Janis and Tao 2009).” A grading system should be applied to

the matrix in order to obtain an analytical analysis of the systems in question (ASHRAE

2008). The American Society of Heating, Refrigerating, and Air-Conditioning Engineers

or ASHRAE (2008) suggests two methods of analysis. First, systems may be rated on

their criteria performance levels with descriptive words such as poor, fair, good, and

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excellent. Second, a numerical method may be used to rate the systems. This allows for

a quantitative result where the system with the highest value is that which is selected.

An advantage with the numerical rating method is that weighted multipliers may be

factored into some of the criteria if not all of the criteria carry the same weighted values

(ASHRAE 2008).

As with potential systems, there are numerous ways of evaluating selection criteria

during the design process. There is also no one right way of presenting the results of

the selection study (Elovitz 2002). Oppenheim (1992) presents a simple decision matrix

for the comparison of systems which can be seen in Table 2-1.

Table 2-1. Decision Matrix for the Comparison of HVAC Systems; Adapted from Oppenheim, P. (1992). “A Decision Matrix for Selection of Climate Control Equipment.” National Association of Industrial Technology, 8(4), 42-46.

Decision parameters

Examples of system options

Central four pipe system

Air source heat pump

Water source heat pump PTAC

Costs

First cost Maintenance cost Energy cost Operating cost Life expectancy

Operation

Noise Partial operation Humidity control Varying loads

Other Future needs Space requirements Structural impact

This matrix allows for the comparison of multiple systems based upon system costs,

operation, and other design parameters. These parameters are grouped together for

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easy comparison amongst the systems in question. A specific grading system is not

outlined for use with this matrix, however, a qualitative or quantitative rating method

could be applied. Ottaviano (1993) uses both the performance and numerical rating

methods in his proposed matrix seen in Table 2-2. He associates a performance level

with a number. A “1” indicates that a system has a poor performance level for the given

criteria. Accordingly a “2” represents fair performance, a “3” represents good

performance, and a “4” represents excellent performance.

Table 2-2. Decision matrix using both performance and numerical rating. The table occurs as is in the original reference without any data in it. Adapted from Ottaviano, V. B. (1993). National Mechanical Estimator. The Fairmont Press, Lilburn, GA.

System number

Rating factors 1 2 3 4 5 6 7 8 9 10 11 12

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

Ratings 4 - Excellent 3 - Good 2 - Fair

1 - Poor

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Table 2-3 provides an example of how weighting factors may be applied to the

decision matrix. Each of the criteria is assigned a weight based upon the perceived

importance to the client (Janis and Tao 2009). The systems are then scored on a scale

of one to ten for their criteria performance levels. These scores are multiplied by the

weight factor in order to determine the weighted score. The weighted scores for the

selection criteria are summed in order to determine the system with the highest score.

A more complex selection matrix is presented by Elovitz (2002) in Table 2-4. This

matrix uses a combination of qualitative and quantitative rating methods. A key feature

of this matrix is that summary information for some of the criteria is listed in the table.

For example, the Floorspace design criteria which falls under Space Considerations

lists the equipment that takes up floor space in the table. This form of selection matrix is

an effective way of summarizing a lot of information for comparison.

Life Cycle Cost Analysis

Once potential mechanical systems have been narrowed to those that will satisfy

the owner’s requirements, the systems will be analyzed in order to determine which

would be the most economic option. There are two economic methods commonly used

to evaluate system selection: simple payback period and life cycle cost analysis. The

method of simple payback determines the time period it will take to recoup the initial

cost of implementing a more efficient system through recurring savings in energy (Janis

and Tao 2009). This payback period is determined by dividing the initial extra cost of the

system by the annual difference in operating cost. The system with the shortest

payback period will be the one selected. However, this method does not take into

account all of the associated costs of owning and operating an HVAC system.

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Table 2-3. Decision Matrix with Weight Factors. Adapted from Janis, R. R. and Tao, W. K. Y. (2009). “Mechanical and Electrical Systems in Buildings.”

VAV reheat VAV/Dual duct Multizone Fan-coils

Score Weighted Score Weighted Score Weighted Score Weighted

Criteria Weight Comfort 8 5 40 5 40 5 40 7 56 Flexibility 6 10 60 8 48 1 6 7 42 Initial cost 3 10 30 6 18 4 12 6 18 Energy consumption 6 7 42 7 42 7 42 9 54 Ease of maintenance 6 7 42 9 54 10 60 5 30 Longevity 6 9 54 9 54 9 54 5 30 Acoustics 5 8 40 8 40 8 40 5 25 Total score

308

296

254

255

% score (normalized)

100%

96%

82%

83%

Grade

A+

B

C

C

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Table 2-4. System selection matrix utilizing both qualitative and quantitative rating methods. Adapted from: Elovitz, D. M. (2002). "Selecting the right HVAC system." ASHRAE Journal, 44(1), 24-30.

Heat pump VAV with fan boxes Multiple rooftops Fan-coils Central / Increments

Comfort Considerations

Control options Can be flexible Highly flexible Limited Limited Can be flexible Control type On/Off Modulating On/Off Modulating On/Off Noise Noticeable Quiet Quiet Quiet Note 1 Ventilation Limited Very Good Good Limited Note 2 Overhead heat Yes Yes Yes Note 3 No Glass height Limited Limited Limited Note 3 Above unit only Filtration Low Good Good Low Good/Low

Effect of failure Total local Partial everywhere Total local Either note 4 Either note 5

Space considerations

Floorspace Boiler, pumps, storage tank, MUAU shaft

Shafts, boiler if gas heat Many shafts

MUAU shaft, pumps Shafts

Plenum space Least Medium Medium Least Medium Furniture placement Fully flexible Fully flexible Fully flexible Note 6 Least flexible Maintenance access Above ceiling On roof On roof Note 7 In rooms

Roofscape MUAU, cooling tower One or two large RTUs

Many smaller RTUS

MUAU, maybe chiller Several RTUs

First Costs System cost Depending on Job and Contractor Specifics, Any of These Systems Can be Competitive Cost to add zones Moderate Low Very High Low High Ability to increase capacity Expensive Inexpensive Expensive Inexpensive Expensive

Smoke control Separate system Adaptable Separate system Separate system Adaptable

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Table 2-4. Continued

Heat Pump VAV with fan

boxes Multiple rooftops Fan-coils Central / Increments

Operating cost Energy cost 1 = Highest and 5 = lowest cost Gas 3 2 4 2 4

Electric 3 4 5 4 5

Maintenance cost Moderate Low High Low High

Free cooling Adaptable Inherent Available Adaptable Available Heat recovery Inherent Inherent None Adaptable None

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Other costs that occur over the life of the system, such as operating, maintenance,

and replacement costs, are hard to financially ignore. A life cycle cost analysis (LCCA)

should be performed in order to determine which is the most cost effective option over

the life of the building. Such a method of analysis compares the cumulative costs

incurred over the life of the system from implementation through operating, maintaining

and eventually replacement (American Society of Heating, Refrigerating and Air-

Conditioning Engineers (ASHRAE) 2007). The life cycle cost method is effective in

evaluating the building design alternatives that satisfy a required level of performance

but may have different initial and annual costs (Fuller and Peterson 1996).

The life cycle cost for a building system is calculated by discounting future costs

back to a present value equivalent. Only those costs that are relevant and significant to

the decision need to be included in the life cycle cost analysis. Costs are considered to

be significant when they are large enough to affect the life cycle cost of a project

alternative (Fuller and Peterson 1996). Once these significant costs have been

identified, cost data must be obtained in order to compute the life cycle cost analysis.

The initial first costs for a project are the easiest to obtain since they occur in the

present (Fuller and Peterson 1996). First cost data may be obtained from suppliers and

manufacturers or construction cost estimating guides. Replacement costs may be

estimated by assuming the future costs are equivalent to the initial costs (Fuller and

Peterson 1996). These future costs are then converted into a present value. The

estimation of energy costs requires the calculation of the fuel used by the system.

Computer simulations may be used to estimate a building’s annual energy usage. The

annual energy costs are then obtained by multiplying energy usage and energy prices.

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The maintenance and repair costs of a system are more difficult to estimate than other

system expenditures due to varying operating schedules and standards (Fuller and

Peterson 1996). It is therefore important to use engineering judgment in the estimation

of these costs. Maintenance cost may occur consistently on an annual basis or they

may change at some estimated rate per year (Fuller and Peterson 1996). They may be

computed from cost estimating guides or obtained from direct quotes from contractors

and vendors.

Florida Statutes. According to Section 1013.37(1)(e) of the Florida Statutes, a life

cycle cost analysis shall be performed for new educational facility construction projects

with a total air conditioning load of 360,000 BTUs per hour (30 tons) or greater (Florida

Department of Education (FLDOE) 2003). In this LCCA, at least three schemes of

HVAC systems shall be analyzed. Of these three schemes, one is required to be a

central system (FLDOE 2003). The Life Cycle Cost Guidelines for Materials and

Building Systems for Florida’s Public Educational Facilities report produced by the

Florida Department of Education (1999) lists the possible HVAC system types that may

be considered in the analysis. This report only describes the characteristics of potential

HVAC systems and does not provide any costing information. The system type with the

lowest life cycle cost will be the system that is installed in the new facility (FLDOE

2003). However, if any system alternatives are within four percent of the lowest life

cycle cost, the school district may make the final system selection from the systems that

fall within that range (FLDOE 2003).

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CHAPTER 3 METHODOLOGY

Introduction

There are many different types of HVAC systems that may be utilized in the

construction of Florida public educational facilities. The selection of the mechanical

system to be used is a critical decision and requires the consideration of many different

aspects. The designer must work with the school district to select the most appropriate

system that will fulfill both the owner’s requirements as well as meet all associated

building codes. In order to do this, a wide variety of design criteria should be taken into

account during the design process. An effective way of presenting this information for

the comparison of different HVAC systems is through the use of a selection matrix.

The first objective of this thesis was to develop a decision matrix that can be used

as a tool to assist school board and project team members in the selection of HVAC

systems for the construction of new public educational facilities in Florida. In order to

provide an effective tool, the characteristics of the State of Florida needed to be

considered and understood. Florida is a large state that is comprised of varying sized

counties. Accordingly, school districts are also various sizes. Some counties are located

along the coast while others are located further inland. Some counties are rural, while

other locations have large population centers. Finally, educational facilities vary in size

throughout the state. Elementary and middle schools are a different size than high

schools.

Selection of Decision Matrix Criteria

The first step in the process of developing a decision matrix was to determine

which system selection criteria should be used. The criteria selected should reflect both

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cost and design parameters in order to provide an effective means for the selection of

the most appropriate and cost effective HVAC system. The following are the criteria that

were selected for use in the decision matrix.

Life Cycle Cost Criteria

The associated costs of a system over its useful life are key factors in the selection

process. Florida Statutes require that a life cycle cost analysis be performed on at least

three different HVAC system types as part of the selection process. As such, the

associated costs that comprise the life cycle cost of a system should be included in the

decision matrix. The major categories of the costs that occur over the life of an HVAC

system are First Cost, Energy Cost, Maintenance Cost, and Replacement Cost. These

cost criteria are defined as follows:

First Cost. This is the initial capital cost of materials and installation of an HVAC

system.

Energy Cost. These are the costs associated with running the HVAC equipment

on a day to day basis. This includes the electricity cost to operate a system during

regular and demand hours.

Maintenance Cost. This is the cost associated with performing regular

preventative maintenance on the system so that it will perform at its optimal level. Such

tasks include changing filters and cleaning coils.

Replacement Cost. This is the cost associated with replacing any of the

equipment associated with an HVAC system over the useful life of a building. It includes

the costs to replace the unit at the end of its life as well as the costs to replace any

miscellaneous equipment throughout the life of the unit.

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Life Cycle Cost. This is the cost of the system over its entire useful life. It includes

the system’s first cost, yearly energy and operating cost, yearly maintenance cost, and

replacement costs. The annual costs were converted to a present value in order to

compare system costs.

Design Selection Criteria

Costs are not the only criteria that need to be considered in the selection process.

Project specific parameters dictated by the owner’s needs should also be considered.

There are a wide variety of design criteria that may be analyzed during the selection

process. The needs of educational facilities were considered during the selection of

these parameters. The following factors, denoted as “Other” criteria, were determined to

be most relevant project specific parameters for Florida educational facilities.

Life of the Unit. This is the average useful life of an HVAC unit. The useful life of

a unit will dictate how many times it needs to be replaced over the life of a building

which can affect the life cycle cost of a system.

Required Space. This is the space needed to house the HVAC system. This

includes the footprint of the unit as well as any mechanical rooms needed to house any

associated ductwork and piping in the system. The required space of the system needs

to be accounted for in the design of the facility because some smaller building footprints

might not be able to support a large system.

Complexity of the System. This is the technological sophistication of a system.

This should be considered during the design phase as some counties may not be able

to support sophisticated systems. Location may limit the availability of qualified

maintenance and service personnel needed to maintain the system.

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Noise. This reflects how much noise the system generates during operation. The

noise produced by a system is relevant to quality of the learning environment and will

also dictate design requirements. Acceptable sound levels in classrooms is critical for a

proper learning environment (ASHRAE 2007). The American National Standards

Institute (ANSI) Standard S12.60.2002 requires a maximum background sound level of

35 dB in classrooms (Siebein and Lilkendey 2004).

Temperature Control. This is the level of control the system has in maintaining

the desired air temperature of the conditioned space. This can affect the comfort level

experienced by the room’s occupants.

Humidity Control. How well the system can control and regulate the humidity

within the conditioned space. This parameter needs to be addressed in order to

maintain a proper level of air quality in the conditioned space.

Organization of HVAC Systems

The next step in the process of developing a selection matrix was to determine

which HVAC systems to analyze in the study. The 1999 edition of the Life Cycle Cost

Guidelines report produced by the Florida Department of Education was used as a

starting point in this process. Part 3 of this report outlines the systems that have been

implemented in Florida public schools. This list was analyzed and any outdated

configurations were discarded as options for use in this study. Any systems that were

similar in nature were combined. Systems not included in the 1999 report but with

potential to be implemented in educational facilities were included in the study. A list of

the systems that were analyzed in the study can be seen in Table 3-1.

With the HVAC systems in consideration defined, they were then grouped into

sections of similar system types to better allow for the comparison of the associated life

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cycle costs and decision criteria. Direct Expansion or DX systems were analyzed first.

These types of systems are decentralized and are often suitable for smaller projects.

This section was followed by Chiller systems. Chillers are centralized systems and are

often used for larger facilities. Finally, Air Distribution systems were analyzed. These

systems use various methods to distribute air throughout the conditioned space and can

be used with DX and Chiller systems.

Table 3-1. HVAC systems included in study System classification Unit type DX systems Wall-mounted unit Package rooftop Split systems Water loop heat pump Geothermal heat pump Chiller systems Air cooled chiller Water cooled chiller Air Distribution systems Constant volume Variable air volume (VAV)

Fan-coil units

Development of Decision Matrix

With the decision criteria defined and the systems classified, the next step was to

create a matrix that would effectively display the information. Features of the selection

matrices presented in the literature review were combined to create a matrix that was

appropriate for the intended application. The selection criteria categories of Costs and

Other were clearly outlined for easy reference.

A method of rating the performance of the selection criteria was developed in

order to rate the HVAC systems in question. A combination of numerical ranking and

color coding was used to compare the performance levels of the system selection

criteria. The number scale was used to rank the performance of the unit types within

each selection criteria category. For each criterion, the unit types were numerically

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ranked according to the number of systems in each system classification. For this study,

the DX and Chiller systems were combined into one system classification. These units

are the primary sources of conditioned air. By grouping them into one system

classification allowed these HVAC units to be compared against each other. The Air

Distribution systems were ranked in a separate system classification. These systems

are methods of distributing conditioned air and are therefore not directly comparable

with the DX and Chiller systems. A ranking of “1” denoted the best option for a given

criterion. For example, in the DX and Chiller system classification there were seven

systems being analyzed. Each Cost and Other criterion was ranked on a scale from “1”

to “7”. A ranking of “1” denoted the best unit type for the criteria in question. A tie within

this scale indicated that a significant difference between systems could not be

discerned. Weight factors were not used in this scale as the owner’s requirements will

vary. However, the owner may apply a weight factor to this scale for use in the selection

of equipment if they desire.

The color scale rated the units within each system classification over a range of

performance levels. This scale varied for each of the criteria in question and will be

described in the Data Chapter. The color coding was used to categorize each criterion

into three levels. Each level was represented by a different color: green, orange, or red.

For the Cost criteria, low costs were represented by green, moderate costs were

represented by orange, and high costs were represented by red. Each cost criterion had

different cost ranges. Therefore, the color coding scale for each cost criterion was

determined based on the range of the data collected. For the Other criteria the color

green signified that a system exceeded average performance levels for the given

31

criteria. Orange represented an adequate performance by the system for the given

criteria. Finally, red indicated that a system performed below average performance

levels. These levels applied on an overall basis. An example of both the numerical

ranking and color coding can be seen in Table 3-2.

Life Cycle Cost Analysis

The second objective of this thesis was to complete the decision matrix for the

HVAC systems in question. A general life cycle cost analysis was performed in order to

fill in the cost portion of the decision matrix. Data for this analysis was collected from a

variety of sources. School districts, general contractors, mechanical contractors, and

engineers were consulted for cost data. Once collected, any future costs were

converted into a present value. Table 3-3 shows the life cycle cost parameters that were

used in the computation of the present value of the system costs.

Table 3-3. Life cycle cost parameters Life cycle cost parameter Value Building service life 50 years General inflation rate 2.0% Energy inflation rate 4.0% Non-energy discount rate 2.7% Energy discount rate 3.0%

The present value of future costs were computed using Equation 3-1. For costs

that occur on an annual basis, such as energy and maintenance costs, this equation

was used to compute the present value of the annual cost for each year over the life of

the building. The present value of each year was then summed to get the total present

value for such an annual cost. For costs that occur periodically throughout the life of the

building, such as unit replacement costs, this equation was used to compute the present

32

Table 3-2. Example of the proposed decision matrix displaying the color coding and ranking of systems

Costs Other

Unit type First cost Energy cost

Maintenance cost

Replacement cost LCC

Required space Complexity

Life of unit Noise

Temperature control

Humidity control

System A 1 3 2 1 2 1 1 3 3 3 3 System B 2 2 1 2 1 2 3 2 2 2 2 System C 3 1 2 3 3 2 2 1 1 1 1

33

value for the year at which the cost was incurred. If multiple replacements occurred over

the life of the building, these were summed to get a total present value for the periodic

costs.

Equation 3-1

Where:

P = Present cost

F= Present value of future cost

i = Inflation rate

d= Discount rate

n = Number of periods

The following are descriptions of how the cost data was collected and converted

into a cost per ton for system comparison. Once the costs were in a similar units they

could be ranked according to the method described previously. Any future costs were

converted into a present value.

First Costs

Attempts were made to collect first cost data from manufacturers, engineers, RS

Means, and contractors. However, data was not obtained from all of these sources.

Major manufacturers of HVAC equipment do not produce information on the total

installation costs of mechanical systems. The Trane Company (1991) previously

published the Systems Manual which gave general costing information for different

types of systems in different types of building. A copy of this publication was able to be

obtained, however it was over 15 years old and therefore outdated. The engineers

consulted during the study recommended using RS Means to obtain material and

34

installation costs. RS Means CostWorks (2010) was consulted for data to be used as a

comparison of quotes received from contractors.

Local mechanical contractors were contacted in order to receive pricing quotes. It

was found that these contractors did not maintain a database of approximate prices,

such as cost per square foot or cost per cost per ton, for HVAC systems. This is due to

the uniqueness of each mechanical system. Given this situation, the best way to obtain

first costs was found to be by reviewing actual pricing quotes on pieces of equipment

from manufacturers. These manufacturer quotes only included the cost to furnish the

equipment. Installation costs were not included in these prices. Many of the quotes

reviewed contained multiple pieces of equipment, however only lump sum prices were

listed. This made it difficult to extract the actual costs of the equipment. The

manufacturer quotes that were able to be used to compute the cost per ton of

equipment are considered to be proprietary information. As such, they cannot be printed

in this study. In order to get costs, the total value of the equipment was divided by the

tonnage of the system it was serving. This gave a cost per ton for the piece of

equipment.

It was not possible to obtain a large sample of quotes for each of the systems in

question. Where multiple quotes were available, the costs were averaged. This average

cost was used as the first cost for the material of the unit. However installation costs for

the unit needed to be calculated. The daily labor output found in RS Means CostWorks

(2010) was used in the computation of the installation cost of the unit. Equation 3-2 was

used to calculate the total installation cost of the unit. It was assumed that the hourly

35

labor rate for an installation crew was $75.00/hr. For an eight hour work day this

equated to a $600/day labor rate.

Equation 3-2

The total labor cost of the unit was divided by the approximate unit tonnage to get the

labor cost per ton. The unit material cost per ton determined from the supplier quotes

was added to the labor cost per ton to get the total first cost per ton for the unit. These

costs were compared to the costs found in RS Means CostWorks (2010) in order to

determine if this was a reliable source for costing information. It was found that the

material costs of the units in RS Means were not comparable to the costs of the supplier

quotes.

For the systems where no supplier costing information was able to be obtained,

the first costs for the systems were based off of general quotes obtained from one of the

mechanical contractors that was contacted during the study. Their quotes included the

costs to furnish and install the unit.

For the DX Systems and Chiller Systems the first costs only included the cost per

ton to furnish and install the HVAC unit itself. The costs of ductwork or means of

distributing air were not included in these systems’ first costs. The first costs for the

methods of distributing air were included in the Air Distribution System section. This was

done since the methods of distributing air may be applied to any one of the HVAC units

in question. For the Air Distribution systems, the costs were done on a cost per unit

basis rather than a cost per ton basis. This was done since different quantities of VAV

boxes and Fan-Coil units will be used for different systems. It was also assumed that

the Constant Volume method of air distribution was the baseline cost for all air

36

distribution systems. As such, its first cost was considered to be zero. Ductwork is

needed to supply air to the conditioned space in all of the methods of air distribution.

For similar sized systems the ductwork to supply the air should be relatively the same

size. The only cost difference will come from the air terminal units.

The first costs presented only included the cost to furnish and install the

equipment. Tax, overhead, and markups were not included in these costs. Since school

districts are public entities, they are eligible for the Direct Purchase Program. This

program allows the school district to purchase the materials for the project tax free from

suppliers. The first costs of the systems that were obtained did not need to be converted

because they were already in present value form.

Costs of systems installed in Florida public schools. An attempt was also

made to collect the actual HVAC system costing information for schools that have been

recently built in the State of Florida. However, costing information for only two

elementary schools in Pasco County Florida was able to be obtained. These costs were

the actual prices that were paid by the state for construction of the school. Both of the

elementary schools had an air cooled chilled water system with Variable Air Volume

(VAV) boxes in place. This allowed for the approximate comparison of prices for this

type of system. The prices that were able to be obtained included:

• Cost to purchase the chillers • Cost to purchase the air distribution system • Total material costs (through the Direct Purchase Program) • Total mechanical contractor costs • Total building Costs

The total square footage of the school and tonnage of the chillers were also

obtained for the schools in question. With this data, the cost per ton for the chillers was

37

able to be calculated. Both the total material costs and the total fees for the mechanical

contractor were divided by the tonnage of the system to get an approximate cost per

ton. The total material costs were compared to the total mechanical contractor costs to

get an approximate percentage of the material costs to the costs for installation of the

system as a whole. A percentage difference was also calculated between the total cost

for the mechanical system (summation of the material and contractor costs) and the

total building cost. Since the costing information for only a few schools was able to be

obtained and it was for only one of the systems in question, this data was not able to be

used in the life cycle cost analysis. The costing information for these schools may be

found in Appendix A.

Energy Costs

Energy costs for the systems were computed by doing approximate hand

calculations. More detailed energy calculations may be obtained for a system through

the use of computerized energy models. However, such programs require the input of a

design of a building. Since this is a general study and no set building design was being

used, an energy model was not used to calculate the energy consumption of the HVAC

units. The computed annual energy costs were converted to a present value using

Equation 3-1. Water consumption charges were not included in this study.

The energy consumption costs for the HVAC units were computed by using the

recommended system efficiency rate given by the U.S. Department of Energy’s website.

These efficiency rates are greater than the base rates that are dictated by ASHRAE

Standard 90.1 but they are not the most efficient options available on the market

(USDOE 2008). For DX systems, the efficiency was given in terms of an energy

efficiency ratio (EER). The EER was converted into kW per ton by Equation 3-3.

38

Equation 3-3

The amount of hours that the system operates during the year needed to be

obtained to compute the energy costs. Systems do not always operate at their full load

throughout the entire year. Full load operation is only needed during the time of the year

where peak building cooling loads are experienced. Systems normally operate at partial

load levels throughout the majority of a year. These partial operating loads may be

converted into an equivalent number of hours that the system would have run if it only

operated at its full load. This number of hours is known as the equivalent full load

operating hours (EFLOH). The EFLOH can then be used to calculate system energy

costs. The actual equivalent full load operating hours for a system will vary based on the

overall design of the school and the school’s cooling and heating demands. The EFLOH

for a particular system design may be obtained by running energy modeling programs.

The value obtained will be a constant for the particular school design and will be used to

compute the energy costs for any systems that are considered for installation. For this

study, it was assumed that the EFLOH was 2000 hours as there was no set school

design. Assuming the equivalent full load operating hours allowed for the relative

magnitude of unit electricity costs to be established.

The cost of electricity used was $0.15/kWh. This is the average rate of electricity

for Gainesville, Florida and includes demand charges. The annual energy costs of the

systems were calculated using Equation 3-4.

Equation 3-4

39

Energy costs were only computed for the HVAC units themselves. All other associated

equipment was neglected for this study. Equipment such as pumps, air handlers, or

cooling towers will consume electricity. However, the number and size of such

equipment will be dependent on the system design.

Energy costs for the air distribution systems were not calculated for this study. The

methods used to distribute air can affect the amount of energy used by the HVAC unit

however, exact costs are design dependent and would need to be calculated through

the use of a computer energy model. In general, the method of VAV can reduce energy

costs from 10% to 20% over constant volume systems (USDOE). This is because the

VAV box varies the amount of air that is supplied to a space. This leads to reduced

costs to operate the fans in the system.

Maintenance Costs

Maintenance costs were obtained by receiving general quotes from a mechanical

contractor in the Gainesville area that performs regular maintenance services for local

schools. These quotes were reflective of the costs to perform regular preventative

maintenance. Such maintenance includes changing filters, lubricating bearings and

motors, and inspecting all equipment and controls. These quotes were based on the

contractor’s experience and were reflective of an approximate cost without a system

design. Maintenance costs will vary based on the quantity and type of equipment, the

equipment location and access, system complexity, and whether the units are located in

a harsh environment (ASHRAE 2007). This annual cost was converted to a present

value using Equation 3-1. Maintenance Costs were not available for the Air Distribution

Systems category. According to the quotes received from the mechanical contractors,

40

typical maintenance contracts do not include regular servicing of the devices employed

to distribute air.

Replacement Costs

The replacement costs were divided into the costs to replace the HVAC unit at

the end of its useful life and the costs to replace miscellaneous equipment over the life

of the HVAC unit. These two costs were totaled in order to determine the total present

value of the unit replacement costs.

Replacement of HVAC units

The cost to replace an HVAC unit would only include the price of the unit and the

labor to install it. Thus, the replacement costs for the units were assumed to be the

same price as the first costs of the units. These costs would occur at the end of the

useful service life of the unit. The year(s) of replacement was determined based upon

the life of the unit which is discussed in the Design Criteria Analysis section. For Air

Distribution Systems, it was assumed that the associated ductwork and grilles would not

be replaced during the life of the building. However, the VAV boxes and Fan-Coil units

would need to be replaced over the life of the building. These were the only costs

associated with the replacement of the Air Distribution Systems. The replacement costs

of HVAC units are periodic costs and were converted into a present value using

Equation 3-1.

Replacement of miscellaneous equipment

The costs to replace miscellaneous system equipment reflects the costs to

replace equipment that is needed in order for the HVAC system to work, but is not

critical enough to cause the unit to be replaced. These costs are difficult to predict. For

this study it was assumed that the cost to replace miscellaneous equipment was 6% of

41

the system first cost. This is an annual cost over the life of the unit except for the first

year after installation. The contractor and/or manufacturer will normally provide the first

year’s parts and labor warranty.

Life Cycle Cost

The life cycle cost was determined by summing the present worth values of the

first costs, energy costs, maintenance costs, and replacement costs. The HVAC unit

types in the DX and Chiller system classification and the Air Distribution system

classification were then ranked according to the scale described previously.

Design Criteria Analysis

The design criteria were evaluated by either developing simple rating methods or

by using standard industry practices. The following are descriptions of how the design

criteria were collected and calculated.

Required Space

The required space of the system was based upon the size and location of major

system components. A rating method needed to be developed in order to allow for the

ranking of the systems. The DX and Chiller systems were analyzed separately from the

Air Distribution systems for this design criterion.

First, typical design layouts for the systems were examined, and their space

characteristics were summarized in a table. For the DX Systems and Chiller Systems,

the summary table listed the typical size of the unit, any associated equipment, the

placement of the unit and associated equipment, required piping, required ductwork,

and mechanical rooms needed. Approximate dimensions of HVAC units were found by

looking at manufacturer specifications of typical unit sizes. This summary table was

used to complete a rating table that was used to compute an average score for the

42

required space of the DX and Chiller systems. The systems were rated on the size of

the unit, the piping in the system, the mechanical room space required, and the outdoor

space required. These criteria were rated on a scale of one to three with one being the

least amount/space and three being the most. Exact descriptions of the rating criteria

are given in the Data chapter. An average value for each system was taken and the

systems were ranked according to these averages.

The summary table for the Air Distribution systems listed any associated

equipment, the approximate size of that equipment, the required piping, and the

equipment placed in the ceiling space. A unit size was not associated with this rating

since the air distribution methods may be applied to any one of the HVAC units. This

summary table was used to complete a rating table that was similar to the one used for

the DX and Chiller systems. The Air Distribution systems were rated on the amount of

piping needed and the amount of equipment located in the ceiling space. An average

value for each system was taken and the systems were ranked according to these

averages.

Complexity

The complexity of the system was based upon the number of major components

that needed to be installed and how many points of maintenance the system has. The

summary tables that were created in determining the required space of the systems

were referred to in the rating of the systems. Each characteristic was rated on a scale of

one to three and were then averaged in order to determine a ranking of the systems.

Life of the Unit

There is no exact science to predicting the useful life of an HVAC unit. Service life

will be dependent upon a number of factors that are hard to accurately predict. Among

43

these factors is how well the system is maintained throughout its life and whether the

unit is located in a corrosive environment (ASHRAE 2007). The 2007 ASHRAE

Applications Handbook provides a table of median service life for mechanical

equipment. This table lists the estimated service life for various HVAC system

components that was based upon a 1978 ASHRAE funded research project by Akalin.

However, ASHRAE warns that these estimates may be outdated due to changes in

technology, materials, manufacturing techniques, and maintenance practices (ASHRAE

2007). As such, ASHRAE funded a project to develop an internet database to collect

HVAC equipment service life which was based on the findings of Abramson et al.

(2005). From these findings, survival curves were able to be created giving the median

service life for the HVAC equipment. These curves reflect the units still in service for a

given age and the units that are replaced at each age (ASHRAE 2007). The median

service life indicates the highest age that the survival rate stays at or above 50% while

the sample size is 30 or greater. At the time of this study, there was not enough data to

create accurate survival curves for all of the equipment in consideration.

The estimated service life for HVAC equipment was analyzed in a variety of ways

for this study. The findings of the methods tried during the study are summarized in

Chapter 4. First, a literature review was conducted in order to determine the estimated

service life recommended in HVAC design references. Through the literature review, it

was found that service life was generally given in a range of years. Also, most of the

available HVAC design references were over fifteen years old (Colen 1990; Ottaviano

1993; Akalin 1978). As stated previously, these estimates may be outdated and not

accurately reflect the mean service life of equipment.

44

Next, the internet database created from Abramson et al.’s (2005) findings was

examined for potential use in the estimation of median service life (ASHRAE 2010). The

database allows users to search for equipment through a variety of criteria. Among

these criteria are system type, building type, and state. A search was conducted to

determine if there was equipment service life information for schools from the State of

Florida. This search returned zero matches. Another search was conducted to

determine how many pieces of equipment from the State of Florida were available in the

database. This search returned 1470 equipment matches. From there a search on the

pieces of equipment in schools was conducted which returned 3,620. Individual

equipment types were analyzed to determine the available data. It was found that the

differences on the available data for each type of equipment varied significantly in total

pieces of equipment and location. It was concluded that statistically accurate median

service life data could not be extracted for the means of this study from this database

because of these differences.

The mechanical contractors that were asked to provide cost quotes were also

asked to provide an estimate on equipment service life for the study. However such

opinion based surveys produce age at replacement information (Hiller 2000).

Replacement of units can be for a number of reasons including failure, reduced

reliability, excessive maintenance costs, or changed system requirements (ASHRAE

2007). The age of replacement of units is different from the equipment service life (Hiller

2000).

Finally, the Median Service Life tables found in Chapter 36 of the 2007 ASHRAE

Handbook – HVAC Applications were analyzed. These tables listed the median service

45

life of equipment from the ASHRAE funded research projects by Akalin (1978) and

Abramson et al. (2005). The available median service life from Abramson’s (2005) study

was compared to the median service life given by Akalin (1978). It was found that most

of the differences were on the order of one to five years, with Abramson et al.’s findings

having the longer median service life (ASHRAE 2007). The result of Abramson et al.’s

(2005) findings was deemed to be the most accurate estimate of equipment service life

for this study since the results were based upon survival curves. However, at the time of

this study, there was not enough data available to create survival curves for all the

equipment in question. The median service life for the equipment that was available was

used as the life of the unit for this study. All other unit lives were taken from the

ASHRAE table. These median service life values were consistent with the other sources

examined and are the most credible source until more data is collected from the internet

database.

Noise

Noise generated by HVAC systems may be caused by a number of factors. Most

of these factors are determined by the design of the HVAC system. The HVAC units

generate noise during operation which may be transmitted to the space through the air,

walls, windows, doors, ductwork or ceilings (Siebein and Lilkendey 2004). Noise may

also be generated in the ductwork as air travels through it. There are a number or

methods that may be employed to reduce the noise generated by HVAC systems, but

they specifically pertain to the system’s design. ANSI Standards mandate that the

maximum background sound levels for classrooms be equal to 35 dB or less. The

design professional must take measures to reduce the noise generated by HVAC

system operation in order to meet the required background sound levels.

46

Since the noise heard in the classrooms is dependent upon system design and

this is a general study, the units were rated based on their potential to produce noise in

the classroom. This was done by analyzing the system components that generate noise

during operation and their relative location to the classroom. A summary table was

created to highlight the system noise characteristics. The summary table listed the

equipment located within the classroom space, equipment near the classroom space,

and any other potential sources of noise in the classroom. This summary table was then

used in the rating of the system’s potential to generate noise in the classroom. The

systems were rated on the sources of noise in the classroom, near the classroom, and

other potential noise. Each noise characteristic was rated from one to three with one

being no noise, two being a potential noise source, and three being a noise source. An

average value for each noise characteristic was taken and the systems were ranked

according to these averages.

Temperature Control

The comfort level in the conditioned space depends on the temperature and

humidity of the supply air, the velocity of the supply air as it leaves air terminals, and the

movement of air throughout the conditioned space. These are all factors that are

attributed to the design of a system as a whole. The individual HVAC units are

responsible for conditioning the air to the required temperature and humidity

specifications needed based on the cooling loads of the building. The units that are

installed are selected based upon these specifications. The process of regulating

temperature falls more under the method used to distribute the air throughout the

space. As such, only the Air Distribution systems were rated on their ability to control

the temperature of the conditioned space. The required space design criteria was

47

removed from the DX and Chiller system decision matrices since it is not applicable to

the units themselves. The Air Distribution systems were ranked according to their ability

to control the comfort level of multiple rooms throughout the conditioned space. This

was dependent on the thermostat control type.

Humidity Control

Humidity control is related to the amount of ventilation that is provided for the

conditioned space. ASHRAE Standards require that classrooms have a minimum of 15

cfm per person of ventilation (ASHRAE 2007). Ventilation is provided by supplying fresh

outdoor air to the space in order to remove indoor air pollutants generated by the room’s

occupants. Schools have a high occupant density which in turn results in large volumes

of outdoor air having to be supplied to the conditioned space (Fischer and Bayer 2003).

Florida has a very humid climate and this can put strain on the HVAC system to

properly condition the large levels of required ventilation air. Conditioning large volumes

of ventilation air must be taken into account during the design on the HVAC system of a

building. Some systems may experience part load humidity build up during operation.

This occurs as the unit cycles on and off. The moisture that condenses on the coiling

coil during operation may evaporate back into the air stream when the coiling coil is

cycled off unless the condensate pan is correctly sloped and the condensate drains

properly from the pan. The full latent capability of the unit is realized when the cooling

coil reaches its design temperature.

Part load build up of humidity is dependent upon the design of the system as a

whole. For this general study, a method for rating the systems on their ability to remove

humidity in the space was unable to be created. As such, this design criterion was

removed from the decision matrix for all of the systems in question.

48

CHAPTER 4 DATA

The following is the data that was collected during the study in order to complete

the decision matrix presented in the previous chapter.

Cost Criteria

First Costs

Table 4-1 lists the cost per ton for DX and Chiller units that was able to be obtained

from looking at equipment quotes. This table also shows the computation of the

installation costs of the units. These labor costs were based on the daily output given in

RS Means. Equation 4-1 was used to calculate the total labor cost to install the unit.

Equation 4-1

Table 4-1. First costs of DX and Chiller units based off of actual supplier quotes

Unit material cost per ton

Daily output

Labor rate ($/day)

Total unit labor cost

Labor cost per ton

Total first cost per ton of the unit

Wall- mounted unit $ 1,065.00 4 $ 600.00 $ 150.00 $ 150.00 $ 1,215.00

Split system

$ 633.00

$ 838.00

$ 960.00

$ 810.33 0.5 $ 600.00 $ 1,200.00 $ 240.00 $ 1,050.33

Air cooled chillers

$ 454.00

$ 431.00

$ 442.50 0.21 $ 600.00 $ 2,857.14 $ 19.05 $ 461.55 Water cooled chiller $ 495.00 0.13 $ 600.00 $ 4,615.38 $ 30.77 $ 525.77

It was assumed that the hourly labor rate for an installation crew was $75.00/hr. For an

eight hour work day this equated to a $600/day labor rate. The total labor cost to install

49

the unit was divided by the approximate unit tonnage to get the labor cost per ton. The

material cost per ton determined from the supplier quotes was added to the labor cost

per ton to get the total first cost per ton for the unit.

Table 4-2 shows the calculations of the first cost per unit of the Air Distribution

devices. The unit material costs were obtained by looking at equipment quotes from

suppliers. The labor rate to install the units and the total unit first cost was calculated in

the same manner as the DX and Chiller units. The first costs for these system types

were done on a cost per unit basis rather than a cost per ton basis because different

quantities of VAV boxes and Fan-Coil units will be used for different systems. It was

assumed that the Constant Volume method of air distribution was the baseline cost for

all air distribution systems. As such, its first cost was considered to be zero. Ductwork is

needed to supply air to the conditioned space in all of the methods of air distribution.

For similar sized systems the ductwork to supply the air should be relatively the same

size. The only cost difference will come from the air terminal units.

4-2. First cost of Air Distribution devices based off of actual supplier quotes

Material cost per unit Daily output

Labor rate ($/day)

Total labor cost per unit

Total unit first cost

VAV

$ 630.00

$ 643.00

$ 746.00

$ 673.00 9.00 $ 600.00 $ 66.67 $ 739.67

Fan-coil $ 1,119.00

$ 1,437.00

$ 1,278.00 7.00 $ 600.00 $ 85.71 $1,363.71

50

Since not all of the first costs of the DX systems in the study were able to be

obtained from actual supplier quotes, Table 4-3 shows the quotes that were obtained

from a local mechanical contractor for a general estimate on the cost to furnish and

install DX units.

Table 4-3.General quotes of the installation costs of DX systems

Unit type First cost of units (5 ton) First cost per ton

DX Systems

Wall-mounted unit $5,000.00 $1,000.00 Enhanced Wall-mounted unit $7,400.00 $1,480.00 Package rooftop - electric $5,800.00 $1,160.00 Package rooftop -Gas $6,500.00 $1,300.00 Split systems $6,500.00 $1,300.00 Enhanced split system $7,800.00 $1,560.00 Water source heat pump $4,500.00 $900.00 Geothermal heat pump $6,200.00 $1,240.00

An enhanced unit is one that provides ventilation as well as conditioned air. For this

study, the cost of the basic unit was used.

Table 4-4 gives a summary and ranking of the first cost per ton of the DX and

Chiller systems that were used for this study. Table 4-5 gives a summary and ranking of

the first cost per unit for the Air Distribution systems. The first costs listed for these

systems were rounded to the nearest ten dollars of the calculated costs. This was due

to the accuracy that was able to be obtained from the data.

Energy Costs

Table 4-6 and Table 4-7 show the calculation of the unit energy costs over the life of the

building for the DX and Chiller systems. These costs only reflect the energy usage of

the units themselves. The energy usage of other associated equipment, such as air

handlers, pumps, or cooling towers, have been neglected in the calculations. These are

only estimated energy costs to show the relative magnitude of energy savings from

systems with a higher efficiency. Water consumption charges were not included in this

51

study. The energy costs of the Air Distribution systems were not calculated for this study

as they will be dependent upon the design of the school.

Table 4-4. Summary and ranking of the first cost per ton for DX and Chiller systems

Unit type

First cost ($/ton) Rank

DX systems

Wall-mounted unit $ 1,220.00 6

Package rooftop $ 1,160.00 5

Split system $ 1,050.00 4

Key

Water loop heat pump $ 900.00 3

$0 to $600

Geothermal heat pump $ 1,240.00 6

$601 to $1000

Chiller systems

Air cooled chiller $ 460.00 1

$1001 and up

Water cooled chiller $ 530.00 2

Table 4-5. Summary and ranking of the first cost per unit for Air Distribution systems

Unit type First cost ($/unit) Rank

Key

Air Distribution

systems

Constant volume $ - 1

$0 to $500

VAV box $ 790.00 2

$501 to $1000

Fan-coil unit $ 1,360.00 3

$1001 and up

The unit efficiency rates used in the calculations were taken from the U.S.

Department of Energy’s website (USDOE ). These recommended rates are greater than

the base rates that are dictated by ASHRAE Standard 90.1 but they are not the most

efficient options available on the market. For the DX systems, the efficiency was given

in terms of an energy efficiency ratio (EER). The EER was converted into kW per ton by

Equation 4-2.

Equation 4-2

52

Table 4-6. Calculation of energy costs of DX units

Unit type EER kW/ton

Cost per kWh

Annual EFLOH operating hours

kWh per ton per year

Annual Energy Cost per ton

Inflation rate (%)

Discount rate

PV energy cost over 50 years

DX systems

Wall-mounted unit 11 1.09 $0.15 2000 2182 $330 4% 2.7% $21,111

Package rooftop 11 1.09 $0.15 2000 2182 $330 4% 2.7% $21,111

Split systems 12 1.00 $0.15 2000 2000 $300 4% 2.7% $19,192 Water loop heat pump 12 1.00 $0.15 2000 2000 $300 4% 2.7% $19,192 Geothermal heat pump 14.1 0.85 $0.15 2000 1702 $260 4% 2.7% $16,663

Table 4-7. Calculation of energy costs of Chiller systems

Unit type kW/ton Cost per kWh

Annual EFLOH operating hours

kWh per ton per year

Annual energy cost per ton

Inflation rate (%)

Discount rate

PV energy cost over 50 yrs

Chiller systems

Air cooled chiller 0.98 $0.15 2000 1960 $290 4% 2.7% $18,552

Water cooled chiller 0.49 $0.15 2000 980 $150 4% 2.7% $9,596

53

For this study, it was assumed that the units operated for 2,000 equivalent full load

operating hours. The cost of electricity used was $0.15/kWh and this included demand

charges. The annual energy costs of the units were calculated using Equation 4-3.

Equation 4-3

The annual energy costs listed for these systems were rounded to the nearest ten

dollars of the calculated costs due to the accuracy of the available data. The present

value of this annual cost was computed for each year over the life of the building. These

present values were summed to get the total present value of the unit energy cost over

the 50 year building life. These calculations can be found in Appendix B. Table 4-8

gives a summary and ranking of the cost per ton for the HVAC units.

Maintenance Costs

Table 4-9 shows the calculation of the unit maintenance costs over the life of the

building for the DX and Chiller systems. These costs were based off of general quotes

from mechanical contractors to perform regular preventative maintenance on the units

such as changing filters, lubricating bearings and motors, and inspecting all equipment

and controls. The maintenance cost of the Air Distribution systems were not included in

this study as normal maintenance contracts do not include regular servicing of the

devices that distribute the conditioned air.

The present value of this annual cost was computed for each year over the life of

the building. These present values were summed to get the total present value of the

unit maintenance cost over the 50 year building life. These calculations can be found in

Appendix B. Table 4-10 shows the ranking of maintenance costs for the units.

54

Table 4-8. Summary and ranking of energy costs for the DX and Chiller units

Unit type Annual energy cost per ton Rank

DX systems

Wall-mounted unit $ 330.00 5

Package rooftop $ 330.00 5

Key

Split systems $ 300.00 4

$0 - $150

Water loop heat pump $ 300.00 4

$151 - $300

Geothermal heat pump $ 260.00 2

$301 or greater

Chiller systems

Air cooled chiller $ 290.00 3 Water cooled chiller $ 150.00 1

Table 4-10. Summary and ranking of unit maintenance costs

Unit type

Annual maintenance cost per ton ($/ton) Rank

DX systems

Wall-mounted unit $ 160 4

Package rooftop $ 160 4

Key

Split systems $ 90 2

$0 - $50

Water loop heat pump $ 120 3

$51 - $150

Geothermal heat pump $ 120 3

$151 and up

Chiller systems

Air cooled chiller $ 9.30 1

Water cooled chiller $ 9.30 1

Replacement Costs

Table 4-11 gives the calculation of the present value of the periodic replacement

costs of the HVAC units. These occur at the end of the service life of the HVAC unit.

The replacement costs for the units were assumed to be the same price as the first

costs of the units. The year(s) of replacement was determined based upon the life of the

unit. For Air Distribution Systems, it was assumed that the associated ductwork and

grilles would not be replaced during the life of the building. However, the VAV

55

Table 4-9. Present value of the cost of maintenance over a 50 year building life

Unit type

Annual cost for 5 ton unit

Cost per year ($/ton)

Inflation rate (%)

Discount rate (%)

PV of maintenance costs over 50 years

($/ton)

DX systems

Wall-mounted unit $ 800.00 $ 160 2% 2.7% $ 6,799

Package rooftop $ 800.00 $ 160 2% 2.7% $ 6,799

Split systems $ 450.00 $ 90 2% 2.7% $ 3,824

Water loop heat pump $ 600.00 $ 120 2% 2.7% $ 5,099

Geothermal heat pump $ 600.00 $ 120 2% 2.7% $ 5,099

Chiller systems

Air cooled chiller $ - $ 9.30 2% 2.7% $ 395

Water cooled chiller $ - $ 9.30 2% 2.7% $ 395

56

boxes and Fan-coil units would need to be replaced over the life of the building. These

were the only replacement costs associated with the Air Distribution Systems.

Table 4-12 shows the calculations of the cost to replace miscellaneous unit

equipment. For this study it was assumed that the cost to replace miscellaneous

equipment was 6% of the system first cost. This is an annual cost over the life of the

unit except for the first year after installation. The contractor and/or manufacturer will

normally provide the first year’s parts and labor warranty. The present value of this

annual cost was computed for each year over the life of the building. These present

values were summed to get the total present value of the miscellaneous equipment

replacement cost over the 50 year building life. These calculations can be found in

Appendix B.

Table 4-13 gives a summary of the total replacement costs for the DX and Chiller

units. Table 4-14 gives a summary of the total replacement costs for the Air Distribution

systems. The total replacement costs were found by summing the present value of the

periodic unit replacement costs and the present value of the miscellaneous equipment

costs.

Life Cycle Cost

Table 4-15 summarizes all of the associated costs for the DX and Chiller units

over the life of the building. The life cycle costs of the unit include the first costs, energy

costs, maintenance costs, replacement costs. These costs were summed to get the

total life cycle cost for the unit. Table 4-16 summarizes all of the associated costs for the

Air Distribution systems over the life of the building. The only life cycle costs associated

with the Air Distribution systems were the first costs and the unit replacement costs.

57

Table 4-11. Calculation of periodic unit replacement costs

Unit Type Life of unit

# of replacements over 50 years Replace at year First cost per ton

PV of replacements ($/ton)

DX systems

Wall-mounted unit 15 3 15, 30, 45 $ 1,220.00 $ 2,992

Package rooftop 15 3 15, 30, 45 $ 1,160.00 $ 2,844

Split systems 15 3 15, 30, 45 $ 1,050.00 $ 2,575

Water loop heat pump 24 2 24, 48 $ 900.00 $ 1,412

Geothermal heat pump 24 2 24, 48 $ 1,240.00 $ 540

Chiller systems

Air cooled chiller 25 1 25 $ 460.00 $ 388

Water cooled chiller 25 1 25 $ 530.00 $ 447

The replacement costs for Air Distribution systems are given in cost per unit

Air Distribution

system

Constant volume 50 0 - $ - $ -

VAV 20 2 20, 40 $ 790.00 $ 1,290

Fan-coil units 20 2 20, 40 $ 1,360.00 $ 2,221

58

Table 4-12. Calculation of miscellaneous equipment costs

Unit type First cost per ton

Annual misc. replacement costs (6% of first cost)

PV of misc. replacement costs ($/ton)

DX systems

Wall-mounted unit $ 1,220 $ 73 $ 3,037

Package rooftop $ 1,160 $ 70 $ 2,888

Split systems $ 1,050 $ 63 $ 2,614

Water loop heat pump $ 900 $ 54 $ 2,241

Geothermal heat pump $ 1,240 $ 74 $ 3,087

Chiller systems

Air cooled chiller $ 460 $ 28 $ 1,145

Water cooled chiller $ 530 $ 32 $ 1,319

Table 4-13. Summary and ranking of DX and Chiller replacement costs

Unit Type

Total PV of replacement costs per ton Rank

DX systems

Wall-mounted unit $ 6,029 6

Package rooftop $ 5,732 5

Split systems $ 5,189 4

Key

Water loop heat pump $ 3,652 3

$0 to $2000 Geothermal heat pump $ 3,627 3

$2001 to $5,000

Chiller systems

Air cooled chiller $ 1,533 1

$5,001 or greater

Water cooled chiller $ 1,766 2

Table 4-14. Summary and ranking of Air Distribution replacement costs

Unit type Total PV of replacement costs per unit Rank

Key

Air Distribution

Constant volume $ - 1

$0 to $500

VAV $ 1,290 2

$501 to $2,000

Fan-coil units $ 2,221 3

$2,001 or greater

59

Design Criteria

Required Space

The required space of the system was based upon the size and location of major

system components. Table 4-17 gives a summary of the space requirements for typical

DX and Chiller systems. This summary table was used in the ratings of the required

space of the DX and Chiller systems which can be seen in Table 4-18. Each space

characteristic was rated on a scale of one to three with one requiring the least space.

Table 4-19 lists the meaning of the rating level for each of the space characteristics.

Table 4-19. Explanation of rating system for the required space criterion

Rating

Criteria 1 2 3 Size of the unit Small Medium Large Piping No piping Refrigerant piping Chilled water piping

Mechanical room space required

No mechanical room

Small mechanical room

Large mechanical room

Outdoor equipment space required

Little or no outdoor space

Moderate outdoor space Large outdoor space

Amount of equipment in ceiling space Basic ductwork

Typical air terminal units

Large air terminal units

Table 4-20 gives a summary of the space requirements for typical Air Distribution

Systems. This table was used in the rating of the required space of the Air Distribution

Systems which can be seen in Table 4-21. The space characteristics of a system were

rated on a level of one to three with one requiring the least space. The meaning of the

rating level for each of the space characteristics can be seen in Table 4-19.

Complexity

Table 4-22 shows the calculation of the ranking of the complexity of the DX and

Chiller systems. Table 4-17 was used as a reference in the completion of this table.

60

Table 4-15. Summary and ranking of the life cycle costs for the DX and Chiller units

Unit type First cost

PV energy cost

PV maintenance cost

PV replacement cost Life cycle cost Rank

DX systems

Wall-mounted unit $ 1,220 $ 21,111 $ 6,799 $ 6,029 $ 35,158 5

Package rooftop $ 1,160 $ 21,111 $ 6,799 $ 5,732 $ 34,802 5

Key

Split system $ 1,050 $ 19,192 $ 3,824 $ 5,189 $ 29,255 4

$0 to $25,000

Water loop heat pump $ 900 $ 19,192 $ 5,099 $ 3,652 $ 28,843 4

$25,001 to $30,000

Geothermal heat pump $ 1,240 $ 16,633 $ 5,099 $ 3,627 $ 26,599 3

$30,001 or greater

Chiller systems

Air cooled chiller $ 460 $ 18,552 $ 395 $ 1,533 $ 20,940 2

Water cooled chiller $ 530 $ 9,596 $ 395 $ 1,766 $ 12,287 1

Table 4-16. Summary and ranking of the life cycle costs for the Air Distribution systems

Unit type First cost NPV replacement cost Life cycle cost Rank Key

Air Distribution

systems

Constant volume $ - $ - $ - 1

$0 to $1,000

VAV box $ 790 $ 1,290 $ 2,080 2

$1,001 to $2,000

Fan-coil unit $ 1,360 $ 2,221 $ 3,581 3

$2,001 or greater

61

Table 4-17. Space characteristics for typical designs of DX and Chiller systems.

Unit type

Typical size of unit (H x W x D)

Associated equipment

Placement of unit / equipment Required piping

Ductwork / ceiling space

Mechanical room / closet needed

DX

syst

ems

Wall-Mounted Unit (1 ton) 48" x 32" x 15" N/A Mounted on wall No piping

No ductwork No

Package rooftop (20 ton) 55" x 133" x 91" N/A On roof No piping Typical No

Split systems (5 ton)

Condensing unit: 45" x 37" x 34" AHU: 58" x 24" x 21"

Condensing unit and AHU

Outside condensing unit and indoor AHU

Refrigerant piping between condensing unit and AHU Typical Yes

Water Loop Heat Pump (5 ton)

Condensing unit: 27" x 59" x 29" AHU: 58" x 24" x 21"

Boiler, cooling tower, pump

Unit, boiler, and pump in mechanical room / cooling tower outside

Piping from unit to boiler and cooling tower Typical Yes

Geothermal Heat Pump (5 ton)

Condensing unit: 27" x 59" x 29" AHU: 58" x 24" x 21" Pump

Unit and pump in mechanical room

Piping from ground to unit Typical Yes

Chi

ller s

yste

ms Air cooled

chiller (150 ton) 100" x 95" x 88"

Pumps, AHUS

Chiller and pumps in outside service area / AHUs in mechanical rooms throughout building

Chilled water piping to central AHUS Typical Yes

Water cooled chiller (150 ton) 75" x 170" 34"

Cooling tower, pumps, AHUS

Chiller & pumps in central mechanical room / outside cooling tower / AHUs in mechanical rooms throughout building

Chilled water piping to cooling tower and central AHUS Typical Yes

62

Table 4-18. Calculation of the amount of required space needed for DX and Chiller systems.

Unit type

Size of the unit

Piping required

Mechanical room space required

Outdoor space required Average Rank

DX systems

Wall-mounted unit 1 1 1 1 1.00 1

Package rooftop 2 1 1 2 1.50 2

Key

Split systems 2 2 2 2 2.00 3

1.00

Water loop heat pump 2 3 2 2 2.25 4

1.00 to 2.50

Geothermal heat pump 2 3 2 1 2.00 3

2.50 to 3.00

Chiller systems

Air cooled chiller 3 3 2 3 2.75 5

Water cooled chiller 3 3 3 3 3.00 6

63

Table 4-20. Space characteristics of typical Air Distribution systems

System

Associated equipment

Size of equipment (H x W x D)

Required piping

Equipment in ceiling space

Air Distribution

systems

Constant volume N/A N/A No piping

Ductwork only

VAV VAV boxes 13" x 34" x 10" (250 cfm) No piping

VAV boxes and ductwork

Fan-coil Fan-coil units 16" x 36"x 31" (1,000 cfm)

Chilled water piping to each fan-coil

Fan-coil units, piping and ductwork

Table 4-21. Calculation of required space for Air Distribution systems.

System type Piping

Amount of equipment in ceiling space Average Rank

Key

Air Distribution

systems

Constant volume 1 1 1.00 1

1.00

VAV 1 2 1.50 2

1.00 to 2.50

Fan-coil units 3 2 2.50 3

2.75 to 3.00 Table 4-22. Ranking of the complexity of the DX and Chiller systems

Unit type

Components to install

Points of maintenance Average Rank

DX systems

Wall-mounted unit 1 1 1.00 1

Package rooftop 1 1 1.00 1

Key

Split system 2 1 1.50 2

1.00 to 2.00

Water loop heat pump 3 3 3.00 4

2.00 to 3.00

Geothermal heat pump 2 2 2.00 3

3.00

Chiller systems

Air cooled chiller 3 3 3.00 4 Water cooled

chiller 3 3 3.00 4

1: Little to none 2: Average 3: Excessive

64

Each system complexity characteristic was rated on a scale from one to three with one

being the least complex.

Table 4-23 shows the calculation of the ranking of the complexity of the Air

Distribution systems. Table 4-20 was used as a reference in the completion of this table.

Each system complexity characteristic was rated on a scale from one to three with one

being the least complex.

Table 4-23. Ranking of the complexity of the Air Distribution systems

Unit type Components to install

Points of maintenance Average Rank

Air Distribution

systems

Constant volume 1 1 1.00 1

Key VAV 2 2 2.00 2

1.00 to 2.00

Fan-coil units 3 2 2.50 3

2.00 to 3.00

1: Little to none 2: Average 3: Excessive

3.00

Life of the Unit

Table 4-24 summarizes the sources that were examined in order to determine the

service life of units. The Air Distribution systems were rated separately from the DX and

Chiller systems but still follow the same key. It was found that unit life ranged from 15

years to 30 years. Any units with a life of 15 years up to 20 years were considered to be

poor. Units with a service life of 20 years up to 25 years were considered to have an

average service life. Units with a service life of 25 years or greater were deemed to

have an above average service life.

Noise

Table 4-25 summarizes the potential sources of noise heard in the classroom. This

table was used in the rating of the noise characteristics of the HVAC systems which are

calculated in Table 4-26. Each noise characteristic was rated on a scale of one to three.

65

Table 4-25. Potential sources of noise in classroom

Unit type

Equipment in classroom

Equipment near classroom

Other sources of noise in classroom

DX systems

Wall-mounted unit Fan

Compressor and condenser on outside wall of classroom

Vibration of building structure

Package rooftop None None Rooftop rumble

Split system None

AHU in mechanical closet; condensing unit outside None

Water loop heat pump None AHU in mechanical closet None Geothermal heat pump None AHU in mechanical closet None

Chiller systems

Air cooled chiller None AHU in central mechanical room / closet None

Water cooled chiller None

AHU in central mechanical room / closet None

Air Distribution

systems

Constant volume Ductwork above ceiling None

Air moving through ductwork

VAV

VAV boxes above ceiling (no fan)

Potential placement of VAV above corridor

Air moving through ductwork

Fan-coil Units

Fan-coil above ceiling or in mechanical closet

Potential placement of fan-coil above corridor

Air moving through ductwork

It should be advised that these rankings do not guarantee that a system will fall

within the required 35 dB sound level. It only highlights the potential of the system to

generate noise in the classroom. The design professional must take measures to

reduce system generated noise in the specific design of the system.

Temperature Control

Temperature control was only able to be determined for the Air Distribution

systems. Table 4-27 shows the ranking of these systems’ ability to control temperature

in the conditioned space.

66

Table 4-24. Summary of sources examined in the determination of unit service life

Unit type

From literature review

Contractor's estimate

From ASHRAE table (2007)

From Abramson et al. (2005)

Service life used in study Rank

DX systems

Wall-mounted unit 92 16+ 15 N/A 15 4

Package rooftop 10 to 151, 122 15 15 N/A 15 4

Split systems 122 12 to 15 15 N/A 15 4

Water loop heat pump 10 to 151, 122 16 to 18 19 >24 24 2

Key

Geothermal heat pump N/A 18 19 >24 24 2

25 or greater

Chiller systems

Air cooled chiller (centrifugal) 25 to 301 10 to 15 20 N/A 20 3

20 - 25

Water cooled chiller (centrifugal) 25 to 301 15 to 20 20 >25 25 1

15 - 20

Air Distribution systems were ranked separately from the DX and Chiller systems

Air Distribution

systems

Constant Volume (ductwork) N/A N/A 30 N/A 50 1

VAV box 162 N/A 20 N/A 20 2

Fan-coil unit N/A N/A 20 N/A 20 2

1 Colen (1990); 2 Ottaviano (1993)

67

Table 4-26. Rating of noise characteristics for HVAC systems

Unit type

Sources of noise in classroom

Sources of noise near classroom

Other sources of noise in classroom Average Ranking

DX systems

Wall-mounted unit 3 3 3 3.00 3

Package rooftop 1 1 2 1.33 1

Split system 1 3 1 1.67 2

Key

Water loop heat pump 1 2 1 1.33 1

1.00 to 1.50

Geothermal heat pump 1 2 1 1.33 1

1.50 to 2.00

Chiller systems

Air cooled chiller 1 2 1 1.33 1

2.00 to 3.00

Water cooled chiller 1 2 1 1.33 1 Air Distribution systems were rated separately from the DX and Chiller systems

Air Distribution

systems

Constant volume 1 1 2 1.33 1

VAV 1 1 2 1.33 1

Fan-coil units 2 2 2 2.00 2

1: No noise from equipment 2: Possible source of noise 3: Source of noise

68

Table 4-27. Ranking of the Air Distribution systems’ ability to control temperature of the space

Unit type Control type Rank

Air Distribution systems

Constant volume On/Off 2

VAV Modulating 1

Fan-coil units Modulating 1

The constant volume air method is considered to be the standard method of air

distribution. It delivers air to the space by cycling the HVAC unit on or off as needed.

Both the VAV and Fan-Coil methods of air distribution use modulating controls to

regulate the temperature of the conditioned space. This allows for better control of the

temperature of the space.

69

CHAPTER 5 RESULTS

The following are the completed decision matrices based on the calculations in the

previous chapter.

DX and Chiller Systems

Table 5-1 gives that completed decision matrix for the DX and Chiller systems.

This table is a summary of all the color and numerical rankings for both the cost and

design criteria. The values obtained for the costs of these systems in this general study

did not have a large variation. However, three different ranges in costs were seen.

These ranges are represented by the color scale. Due to the accuracy of the costs that

were able to be obtained during this study, the color scale is the more accurate of the

two scales used in the matrix. It allows the user to quickly identify which range of costs

the system falls within. The numerical ranking of the matrix would be more effective for

use with a specific building design versus a general study such as this one.

Air Distribution Systems

Table 5-2 gives the completed decision matrix for the Air Distribution systems.

This table is a summary of all the color and numerical rankings for both the cost and

design criteria. The variation in costs was not as large for these systems as with the DX

and Chiller systems. However, the color scale again allows the user to quickly identify

which range of costs the system falls within.

70

Table 5-1. Completed decision matrix for DX and Chiller systems

Costs Other

Unit type First cost Energy cost

Maintenance cost

Replacement cost LCC

Required space Complexity

Life of unit Noise

Wall-mounted unit 6 5 4 6 5 1 1 4 3

Package rooftop 5 5 4 5 5 2 1 4 1

Split system 4 4 2 4 4 3 2 4 2

Water loop heat pump 3 4 3 3 4 4 4 2 1

Geothermal heat pump 6 2 3 3 3 3 3 2 1

Air cooled chiller 1 3 1 1 2 5 4 3 1

Water cooled chiller 2 1 1 2 1 6 4 1 1

Table 5-2. Completed decision matrix for the Air Distribution systems

Costs Other

Unit type First cost

Replacement cost LCC

Required space Complexity

Life of unit Noise

Temperature control

Constant volume 1 1 1 1 1 1 1 2

VAV 2 2 2 2 2 2 1 1

Fan-coil units 3 3 3 3 3 2 2 1

71

CHAPTER 6 CONCLUSIONS

From the research conducted it was found that a general life cycle cost analysis of

HVAC systems was not possible to perform. Because each system is unique to the

design of a building, only the approximate costs for the HVAC units were able to be

obtained for this study. Even then costs varied based upon the size and placement of

the unit. Exact cost data was found to be difficult to obtain as the HVAC industry does

not track general cost information. Pricing is done for a specific system according to its

design specifications.

The decision matrix created proved to be a valuable tool in the selection of an

HVAC system for Florida public schools. It effectively presented the HVAC unit

performance in both the cost and design criteria categories so that the units may be

compared. The color scale allows the user to quickly identify the units that fall within the

desired performance levels. The numerical scale allows the user to determine the best

choice within these performance levels. However, the numerical ranking would be more

effective for use with a specific building design versus a general study such as this one.

The proposed decision matrix could be adapted to meet the specific needs of individual

counties in Florida.

72

CHAPTER 7 RECOMMENDATIONS

This study was based on a broad scope. For future studies it would be effective to

narrow the scope to individual counties. Obtaining the costs of HVAC systems that are

constructed in a particular county would provide a more accurate analysis of the costs

for a specific region. The matrix developed in this study could be further developed or

changed to accurately reflect the specific needs of the school district being analyzed.

One of the difficulties of this study was finding accurate cost data for individual

system components and systems as a whole. Further research could focus on collecting

a larger source of quotes of HVAC units. This would provide a more accurate estimate

of the cost per ton of a unit. The first costs of entire HVAC systems could also be

analyzed. A life cycle cost analysis of an entire HVAC system would more accurately

reflect the costs that a school district would incur.

Median service life of HVAC systems could also be analyzed. The median service

life used in this study was based off of ASHRAE’s recommendations. However, this

service life was calculated using the time of replacement for units all over the United

States. The replacement of units in other climatic regions could be different than those

for the State of Florida. A database could be created to track the year at which

equipment is installed in schools and the year when it is replaced. The creation of such

a database would better help the state estimate life cycle costs.

73

APPENDIX A INSTALLATION COSTS OF FLORIDA SCHOOLS

Table A-1 lists the costs of the major HVAC equipment that was put installed in

two schools in Pasco County, Florida. Both schools used the same HVAC system

design of an air cooled chiller with VAV units for air distribution. The materials for these

systems were purchased through the Direct Purchase Program. This allows the State to

purchase materials tax free.

Table A-2 gives a summary of the total costs of the HVAC systems that were

installed in the schools. It calculates the cost per ton of the materials and the installed

cost per ton. It also shows the percentage of material costs to the total mechanical

system cost and the percentage of the mechanical system costs to the total school cost.

Table A-1. HVAC system component costs for two elementary schools in Pasco County Florida

System component costs Cost Tons Cost per ton

Watergrass Elementary (LEED Gold

Certified)

2Aair cooled chillers $ 136,027.00 300 $ 453.42

AHU, VAVs, blower coils $ 71,922.42

2 DX mini-splits $ 11,355.00

Ductwork $ 5,789.34

Total air distribution $ 96,387.00

Gulf Trace Elementary

(LEED Silver Certified)

2 Air cooled chillers $ 129,115.24 300 $ 430.38

AHU, VAVs, blower coils $ 72,340.40

Ductwork $ 4,920.00 Total air distribution $ 80,590.00

74

Table A-2. Total costs for the installation of an air cooled chiller system in Pasco County elementary schools

Total costs Cost per ton

Wat

ergr

ass

Elem

enta

ry

Total material cost $ 486,521.04 $ 1,621.74

Total mechanical contractor amount $ 1,191,478.96 $ 3,971.60

Total cost for HVAC system $ 1,678,000.00 $ 5,593.33 Total construction cost of school $ 11,322,720.00

Percentage of material cost to total mechanical cost 41%

Percentage of mechanical system cost to total construction cost 15%

Gul

f Tra

ce E

lem

enta

ry

Total material cost $ 357,997.16 $ 1,193.32 Total mechanical contractor amount $ 1,131,202.84 $ 3,770.68

Total cost for HVAC system $ 1,489,200.00 $ 4,964.00 Total construction cost of school $ 11,820,540.91

Percentage of material cost to total mechanical cost 32%

Percentage of mechanical cost to total construction cost 13%

75

APPENDIX B PRESENT VALUE CALCULATIONS

Energy Costs

Table B-1 gives a summary of the annual unit energy costs that were used in the

calculation of the total present value of the energy cost. It also gives the inflation rate

and the discount rate. Table B-2 shows the calculation of the total present value of the

annual energy costs for the HVAC units over the 50 year building life.

Table B-1. Summary of costs and rates used in the calculation of the total present value of unit energy costs

Unit HVAC unit Annual energy cost 1.0 Wall-mounted unit $ 330 2.0 Package rooftop $ 330 3.0 Split systems $ 300 4.0 Water loop heat pump $ 300 5.0 Geothermal heat pump $ 260 6.0 Air cooled chiller $ 290 7.0 Water cooled chiller $ 150 Inflation rate 4.0% Discount rate 3.0%

Table B-2. Calculation of total present value of unit energy cost Year 1.0 2.0 3.0 4.0 5.0 6.0 7.0 0 $ 330 $ 330 $ 300 $ 300 $ 260 $ 290 $ 150 1 $ 333 $ 333 $ 303 $ 303 $ 263 $ 293 $ 151 2 $ 336 $ 336 $ 306 $ 306 $ 265 $ 296 $ 153 3 $ 340 $ 340 $ 309 $ 309 $ 268 $ 299 $ 154 4 $ 343 $ 343 $ 312 $ 312 $ 270 $ 301 $ 156 5 $ 346 $ 346 $ 315 $ 315 $ 273 $ 304 $ 157 6 $ 350 $ 350 $ 318 $ 318 $ 276 $ 307 $ 159 7 $ 353 $ 353 $ 321 $ 321 $ 278 $ 310 $ 160 8 $ 357 $ 357 $ 324 $ 324 $ 281 $ 313 $ 162 9 $ 360 $ 360 $ 327 $ 327 $ 284 $ 316 $ 164 10 $ 363 $ 363 $ 330 $ 330 $ 286 $ 319 $ 165 11 $ 367 $ 367 $ 334 $ 334 $ 289 $ 323 $ 167 12 $ 371 $ 371 $ 337 $ 337 $ 292 $ 326 $ 168

76

Table B-2. Continued Year 1.0 2.0 3.0 4.0 5.0 6.0 7.0 13 $ 374 $ 374 $ 340 $ 340 $ 295 $ 329 $ 170 14 $ 378 $ 378 $ 343 $ 343 $ 298 $ 332 $ 172 15 $ 381 $ 381 $ 347 $ 347 $ 301 $ 335 $ 173 16 $ 385 $ 385 $ 350 $ 350 $ 303 $ 338 $ 175 17 $ 389 $ 389 $ 354 $ 354 $ 306 $ 342 $ 177 18 $ 393 $ 393 $ 357 $ 357 $ 309 $ 345 $ 178 19 $ 396 $ 396 $ 360 $ 360 $ 312 $ 348 $ 180 20 $ 400 $ 400 $ 364 $ 364 $ 315 $ 352 $ 182 21 $ 404 $ 404 $ 367 $ 367 $ 318 $ 355 $ 184 22 $ 408 $ 408 $ 371 $ 371 $ 322 $ 359 $ 186 23 $ 412 $ 412 $ 375 $ 375 $ 325 $ 362 $ 187 24 $ 416 $ 416 $ 378 $ 378 $ 328 $ 366 $ 189 25 $ 420 $ 420 $ 382 $ 382 $ 331 $ 369 $ 191 26 $ 424 $ 424 $ 386 $ 386 $ 334 $ 373 $ 193 27 $ 428 $ 428 $ 389 $ 389 $ 337 $ 376 $ 195 28 $ 433 $ 433 $ 393 $ 393 $ 341 $ 380 $ 197 29 $ 437 $ 437 $ 397 $ 397 $ 344 $ 384 $ 199 30 $ 441 $ 441 $ 401 $ 401 $ 347 $ 388 $ 200 31 $ 445 $ 445 $ 405 $ 405 $ 351 $ 391 $ 202 32 $ 450 $ 450 $ 409 $ 409 $ 354 $ 395 $ 204 33 $ 454 $ 454 $ 413 $ 413 $ 358 $ 399 $ 206 34 $ 458 $ 458 $ 417 $ 417 $ 361 $ 403 $ 208 35 $ 463 $ 463 $ 421 $ 421 $ 365 $ 407 $ 210 36 $ 467 $ 467 $ 425 $ 425 $ 368 $ 411 $ 212 37 $ 472 $ 472 $ 429 $ 429 $ 372 $ 415 $ 214 38 $ 476 $ 476 $ 433 $ 433 $ 375 $ 419 $ 217 39 $ 481 $ 481 $ 437 $ 437 $ 379 $ 423 $ 219 40 $ 486 $ 486 $ 442 $ 442 $ 383 $ 427 $ 221 41 $ 490 $ 490 $ 446 $ 446 $ 386 $ 431 $ 223 42 $ 495 $ 495 $ 450 $ 450 $ 390 $ 435 $ 225 43 $ 500 $ 500 $ 455 $ 455 $ 394 $ 439 $ 227 44 $ 505 $ 505 $ 459 $ 459 $ 398 $ 444 $ 229 45 $ 510 $ 510 $ 463 $ 463 $ 402 $ 448 $ 232 46 $ 515 $ 515 $ 468 $ 468 $ 406 $ 452 $ 234 47 $ 520 $ 520 $ 472 $ 472 $ 409 $ 457 $ 236 48 $ 525 $ 525 $ 477 $ 477 $ 413 $ 461 $ 239 49 $ 530 $ 530 $ 482 $ 482 $ 417 $ 466 $ 241 Total PV $ 21,111 $ 21,111 $ 19,192 $ 19,192 $ 16,633 $ 18,552 $ 9,596

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Maintenance Costs

Table B-3 gives a summary of the annual unit maintenance costs and that were

used in the calculation of the total present value of cost. Table B-4 shows the

calculation of the total present value of the annual maintenance costs for the HVAC

units over the 50 year building life.

Table B-3. Summary of costs and rates used in the calculation of the total present value of unit maintenance costs

Unit HVAC unit Annual maintenance cost per ton

1.0 Wall-mounted unit $ 160

2.0 Package rooftop $ 160

3.0 Split systems $ 90

4.0 Water loop heat pump $ 120

5.0 Geothermal heat pump $ 120

6.0 Air cooled chiller $ 9.30 7.0 Water cooled chiller $ 9.30 Inflation rate 2.00% Discount rate 2.70%

Table B-4. Calculation of the total present value of unit maintenance cost Year 1.0 2.0 3.0 4.0 5.0 6.0 7.0 0 $ 160 $ 160 $ 90 $ 120 $ 120 $ 9 $ 9 1 $ 159 $ 159 $ 89 $ 119 $ 119 $ 9 $ 9 2 $ 158 $ 158 $ 89 $ 118 $ 118 $ 9 $ 9 3 $ 157 $ 157 $ 88 $ 118 $ 118 $ 9 $ 9 4 $ 156 $ 156 $ 88 $ 117 $ 117 $ 9 $ 9 5 $ 155 $ 155 $ 87 $ 116 $ 116 $ 9 $ 9 6 $ 154 $ 154 $ 86 $ 115 $ 115 $ 9 $ 9 7 $ 153 $ 153 $ 86 $ 114 $ 114 $ 9 $ 9 8 $ 151 $ 151 $ 85 $ 114 $ 114 $ 9 $ 9 9 $ 150 $ 150 $ 85 $ 113 $ 113 $ 9 $ 9 10 $ 149 $ 149 $ 84 $ 112 $ 112 $ 9 $ 9 11 $ 148 $ 148 $ 83 $ 111 $ 111 $ 9 $ 9 12 $ 147 $ 147 $ 83 $ 111 $ 111 $ 9 $ 9 13 $ 146 $ 146 $ 82 $ 110 $ 110 $ 9 $ 9

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Table B-4. Continued Year 1.0 2.0 3.0 4.0 5.0 6.0 7.0 14 $ 145 $ 145 $ 82 $ 109 $ 109 $ 8 $ 8 15 $ 144 $ 144 $ 81 $ 108 $ 108 $ 8 $ 8 16 $ 143 $ 143 $ 81 $ 108 $ 108 $ 8 $ 8 17 $ 142 $ 142 $ 80 $ 107 $ 107 $ 8 $ 8 18 $ 141 $ 141 $ 80 $ 106 $ 106 $ 8 $ 8 19 $ 141 $ 141 $ 79 $ 105 $ 105 $ 8 $ 8 20 $ 140 $ 140 $ 78 $ 105 $ 105 $ 8 $ 8 21 $ 139 $ 139 $ 78 $ 104 $ 104 $ 8 $ 8 22 $ 138 $ 138 $ 77 $ 103 $ 103 $ 8 $ 8 23 $ 137 $ 137 $ 77 $ 103 $ 103 $ 8 $ 8 24 $ 136 $ 136 $ 76 $ 102 $ 102 $ 8 $ 8 25 $ 135 $ 135 $ 76 $ 101 $ 101 $ 8 $ 8 26 $ 134 $ 134 $ 75 $ 100 $ 100 $ 8 $ 8 27 $ 133 $ 133 $ 75 $ 100 $ 100 $ 8 $ 8 28 $ 132 $ 132 $ 74 $ 99 $ 99 $ 8 $ 8 29 $ 131 $ 131 $ 74 $ 98 $ 98 $ 8 $ 8 30 $ 130 $ 130 $ 73 $ 98 $ 98 $ 8 $ 8 31 $ 129 $ 129 $ 73 $ 97 $ 97 $ 8 $ 8 32 $ 129 $ 129 $ 72 $ 96 $ 96 $ 7 $ 7 33 $ 128 $ 128 $ 72 $ 96 $ 96 $ 7 $ 7 34 $ 127 $ 127 $ 71 $ 95 $ 95 $ 7 $ 7 35 $ 126 $ 126 $ 71 $ 94 $ 94 $ 7 $ 7 36 $ 125 $ 125 $ 70 $ 94 $ 94 $ 7 $ 7 37 $ 124 $ 124 $ 70 $ 93 $ 93 $ 7 $ 7 38 $ 123 $ 123 $ 69 $ 93 $ 93 $ 7 $ 7 39 $ 123 $ 123 $ 69 $ 92 $ 92 $ 7 $ 7 40 $ 122 $ 122 $ 68 $ 91 $ 91 $ 7 $ 7 41 $ 121 $ 121 $ 68 $ 91 $ 91 $ 7 $ 7 42 $ 120 $ 120 $ 68 $ 90 $ 90 $ 7 $ 7 43 $ 119 $ 119 $ 67 $ 89 $ 89 $ 7 $ 7 44 $ 118 $ 118 $ 67 $ 89 $ 89 $ 7 $ 7 45 $ 118 $ 118 $ 66 $ 88 $ 88 $ 7 $ 7 46 $ 117 $ 117 $ 66 $ 88 $ 88 $ 7 $ 7 47 $ 116 $ 116 $ 65 $ 87 $ 87 $ 7 $ 7 48 $ 115 $ 115 $ 65 $ 86 $ 86 $ 7 $ 7 49 $ 114 $ 114 $ 64 $ 86 $ 86 $ 7 $ 7 Total PV $ 6,799 $ 6,799 $ 3,824 $ 5,099 $ 5,099 $ 395 $ 395

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Replacement Costs

Table B-5 gives a summary of the annual costs to replace miscellaneous unit

equipment. It also gives the inflation and discount rates that were used in the calculation

of the total present value of these costs.

Table B-5. Summary of costs and rates used in the calculation of the total present value of miscellaneous unit replacement costs

Unit HVAC unit Annual miscellaneous replacement cost

1.0 Wall-mounted unit $ 73

2.0 Package rooftop $ 70

3.0 Split systems $ 63

4.0 Water loop heat pump $ 54

5.0 Geothermal heat pump $ 74

6.0 Air cooled chiller $ 28

7.0 Water cooled chiller $ 32 Inflation rate 2.00% Discount rate 2.70%

Table B-6 shows the calculation of the total present value of the miscellaneous

equipment replacement costs for the HVAC units over the 50 year building life. The

replacement cost for the first year after installation (year zero) has been neglected in

these calculations as the manufacturer or mechanical contractor will provide a one year

warranty on the parts and labor of any replacements.

Table B-6. Calculation of the total present value of miscellaneous unit replacement costs

Year 1.0 2.0 3.0 4.0 5.0 6.0 7.0 1 $ 73 $ 69 $ 63 $ 54 $ 74 $ 27 $ 32 2 $ 72 $ 69 $ 62 $ 53 $ 73 $ 27 $ 31 3 $ 72 $ 68 $ 62 $ 53 $ 73 $ 27 $ 31 4 $ 71 $ 68 $ 61 $ 53 $ 72 $ 27 $ 31 5 $ 71 $ 67 $ 61 $ 52 $ 72 $ 27 $ 31 6 $ 70 $ 67 $ 60 $ 52 $ 71 $ 26 $ 31

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Table B-6. Continued Year 1.0 2.0 3.0 4.0 5.0 6.0 7.0 7 $ 70 $ 66 $ 60 $ 51 $ 71 $ 26 $ 30 8 $ 69 $ 66 $ 60 $ 51 $ 70 $ 26 $ 30 9 $ 69 $ 65 $ 59 $ 51 $ 70 $ 26 $ 30 10 $ 68 $ 65 $ 59 $ 50 $ 69 $ 26 $ 30 11 $ 68 $ 65 $ 58 $ 50 $ 69 $ 26 $ 29 12 $ 67 $ 64 $ 58 $ 50 $ 69 $ 25 $ 29 13 $ 67 $ 64 $ 58 $ 49 $ 68 $ 25 $ 29 14 $ 67 $ 63 $ 57 $ 49 $ 68 $ 25 $ 29 15 $ 66 $ 63 $ 57 $ 49 $ 67 $ 25 $ 29 16 $ 66 $ 62 $ 56 $ 48 $ 67 $ 25 $ 29 17 $ 65 $ 62 $ 56 $ 48 $ 66 $ 25 $ 28 18 $ 65 $ 62 $ 56 $ 48 $ 66 $ 24 $ 28 19 $ 64 $ 61 $ 55 $ 47 $ 65 $ 24 $ 28 20 $ 64 $ 61 $ 55 $ 47 $ 65 $ 24 $ 28 21 $ 63 $ 60 $ 55 $ 47 $ 64 $ 24 $ 28 22 $ 63 $ 60 $ 54 $ 46 $ 64 $ 24 $ 27 23 $ 63 $ 59 $ 54 $ 46 $ 64 $ 24 $ 27 24 $ 62 $ 59 $ 53 $ 46 $ 63 $ 23 $ 27 25 $ 62 $ 59 $ 53 $ 46 $ 63 $ 23 $ 27 26 $ 61 $ 58 $ 53 $ 45 $ 62 $ 23 $ 27 27 $ 61 $ 58 $ 52 $ 45 $ 62 $ 23 $ 26 28 $ 60 $ 57 $ 52 $ 45 $ 61 $ 23 $ 26 29 $ 60 $ 57 $ 52 $ 44 $ 61 $ 23 $ 26 30 $ 60 $ 57 $ 51 $ 44 $ 61 $ 22 $ 26 31 $ 59 $ 56 $ 51 $ 44 $ 60 $ 22 $ 26 32 $ 59 $ 56 $ 51 $ 43 $ 60 $ 22 $ 26 33 $ 58 $ 56 $ 50 $ 43 $ 59 $ 22 $ 25 34 $ 58 $ 55 $ 50 $ 43 $ 59 $ 22 $ 25 35 $ 58 $ 55 $ 50 $ 43 $ 59 $ 22 $ 25 36 $ 57 $ 54 $ 49 $ 42 $ 58 $ 22 $ 25 37 $ 57 $ 54 $ 49 $ 42 $ 58 $ 21 $ 25 38 $ 56 $ 54 $ 49 $ 42 $ 57 $ 21 $ 25 39 $ 56 $ 53 $ 48 $ 41 $ 57 $ 21 $ 24 40 $ 56 $ 53 $ 48 $ 41 $ 57 $ 21 $ 24 41 $ 55 $ 53 $ 48 $ 41 $ 56 $ 21 $ 24 42 $ 55 $ 52 $ 47 $ 41 $ 56 $ 21 $ 24 43 $ 55 $ 52 $ 47 $ 40 $ 55 $ 21 $ 24 44 $ 54 $ 52 $ 47 $ 40 $ 55 $ 20 $ 24 45 $ 54 $ 51 $ 46 $ 40 $ 55 $ 20 $ 23

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Table B-6. Continued Year 1.0 2.0 3.0 4.0 5.0 6.0 7.0 46 $ 53 $ 51 $ 46 $ 39 $ 54 $ 20 $ 23 47 $ 53 $ 50 $ 46 $ 39 $ 54 $ 20 $ 23 48 $ 53 $ 50 $ 45 $ 39 $ 54 $ 20 $ 23 49 $ 52 $ 50 $ 45 $ 39 $ 53 $ 20 $ 23 Total PV $ 3,037 $ 2,888 $ 2,614 $ 2,241 $ 3,087 $ 1,145 $ 1,319

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LIST OF REFERENCES

Abramson, B., Herman, D., and Wong, L. (2005). Interactive Web-based owning and operating cost database (TRP-1237). ASHRAE Research Project, Final Report.

Akalin, M.T. (1978). “Equipment life and maintenance cost survey (RP-186).” ASHRAE Transactions, 84(2), 94-106.

American Society of Heating, Refrigerating and Air Conditions Engineers (2010). “ASHRAE: HVAC Maintenance Cost Database.”, <http://xp20.ashrae.org/publicdatabase/maintenance.asp> (Feb. 27, 2010).

American Society of Heating,Refrigerating and Air Conditioning Engineers , and Knovel. (2008). 2008 ASHRAE handbook [electronic resource] : heating, ventilating, and air-conditioning systems and equipment. ASHRAE, Atlanta, Ga.

American Society of Heating,Refrigerating and Air Conditioning Engineers, and Knovel. (2007). 2007 ASHRAE handbook [electronic resource] : heating, ventilating, and air-conditioning applications. ASHRAE, Atlanta, Georgia.

Colen, H. R. (1990). HVAC systems evaluation. R.S. Means Company, Kingston, MA.

Elovitz, D. M. (2002). "Selecting the right HVAC system." ASHRAE J., 44(1), 24-30.

Fischer, J. C., and Bayer, C. W. (2003). "Report Card on Humidity Control." ASHRAE J., 45(5), 30-2, 34, 36-9.

Florida Department of Education (2003). Instructions for Life Cycle Cost Analysis of School HVAC Systems. <http://www.fldoe.org/edfacil/pdf/lcca.pdf> (Feb. 27, 2010)

Florida Department of Education (1999). Life Cycle Cost Guidelines for Materials and Building Systems for Florida’s Public Educational Facilities.

Fuller, S. K., and Peterson, S. R. (1996). "Life-Cycle Costing Manual for the Federal Energy Management Program." U.S. Government Printing Office, Washington, DC.

Hiller, C. C. (2000). "Determining equipment service life." ASHRAE J., 42(8), 48-54.

Janis, R. R., and Tao, W. K. Y. (2009). "Mechanical and Electrical Systems in Buildings." Prentice Hall, Upper Saddle River, NJ, 15-16.

Oppenheim, P. (1992). "A Decision Matrix for Selection of Climate Control Equipment." National Association of Industrial Technology, 8(4), 42-46.

Ottaviano, V. B. (1993). National Mechanical Estimator. The Fairmont Press, Lilburn, GA.

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RS Means (2010). “CostWorks.”, <http://www.meanscostworks.com/> (Feb. 27, 2010).

Siebein, G. W., and Lilkendey, R. M. (2004). "Acoustical Case Studies of HVAC Systems in Schools." ASHRAE J., 46(5), 35-6, 38-9, 41-2, 44, 46-7.

The Trane Company (1991). Systems Manual.

US Department of Energy (2009). “Purchasing Specifications for Energy-Efficient Products.”, <http://www1.eere.energy.gov/femp/technologies/eep_purchasingspecs.html> (Feb. 27, 2010).

84

BIOGRAPHICAL SKETCH

Kelly McLaughlin was born and raised in West Palm Beach, Florida. She is the

daughter of Jack and Nadean McLaughlin and has a younger brother Stephen. She

attended the University of Florida where she obtained her Bachelor of Science in

Mechanical Engineering in 2008. She then pursued a Master of Science in Building

Construction. Upon graduation Kelly plans to work for Walt Disney World as a

construction project manager.