evaluation of energy efficient hvac

i

CONSULTANT REPORT

EVALUATION OF ENERGY EFFICIENT

HVAC

ELECTRICAL MOTOR SYSTEMS IN

BUILDINGS

Prepared for: California Energy Commission

Prepared by: UCR Riverside Center for Environmental Research and Technology

MARCH 2015

CEC-CIEE SUBAWARD NO POE F01-R09

ii

Prepared by:

Primary Author(s):

Sadrul Ula, Ph.D.

Alfredo A. Martinez-Morales, Ph.D.

UC Riverside Center for Enviromental Research and Technology

1084 Columbia Ave.

Riverside, CA 92507

951-781-5791

www.cert.ucr.edu

Contract Number: CEC-CIEE Subaward NO. POEF01-R09

Prepared for:

California Energy Commission

Jeffrey Doll, P.E.

Contract Manager

Sadrul Ula, Ph.D.

Project Manager

DISCLAIMER

This report was prepared as the result of work sponsored by the California Energy Commission. It

does not necessarily represent the views of the Energy Commission, its employees or the State of

California. The Energy Commission, the State of California, its employees, contractors and

subcontractors make no warrant, express or implied, and assume no legal liability for the information

in this report; nor does any party represent that the uses of this information will not infringe upon

privately owned rights. This report has not been approved or disapproved by the California Energy

Commission nor has the California Energy Commission passed upon the accuracy or adequacy of

the information in this report.

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ABSTRACT

This project conducted research on electrical energy efficiency of building systems in California.

While most of the current building efficiency efforts are focused on lighting and insulation, the

largest building energy users are actually large Heating Ventilating and Air Conditioning

(HVAC) motors running 24 hours a day throughout the year. Depending on the environment,

building motors may last 20 years or more, meaning an inefficient motor continues to waste

energy for a very long time.

This work focused on the following:

Review of software used by architectural and engineering firms on designing HVAC

systems

On-site testing of HVAC motor systems in use

Develop large motor testing facilities at the University of California, Riverside

Most commonly and widely used HVAC design software were reviewed. On-site testing of

HVAC motors were performed on multiple office, industrial, and commercial buildings. Results

of these on-site testing are presented in this report.

A testing facility was developed capable of efficiency and load testing of electric motors up to 25

hp capacity. This facility also has an ability to test efficiency of Adjustable Speed Drive (ASD)

up to 100 hp. The facility can also measure electrical system harmonics. This is the first

independent electric motor testing center in the state of California capable of providing

unbiased evaluation of motor efficiency at various operating conditions. This facility is available

for use by the industry professionals, academics and other stake holders.

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TABLE OF CONTENTS

Abstract.................................................................................................................................................... iii

Executive Summary ............................................................................................................................... 1

1.0 Introduction .................................................................................................................................. 3

1.1 background and Overview ......................................................................................... 3

1.2 Goal of the proposed Project ...................................................................................... 4

1.3 Objective of the Project ................................................................................................ 4

1.4 Benefits to California ................................................................................................... 5

2.0 Software used by Architectural and Engineering Firms on Designing HVAC Systems ... 6

2.1 Introduction .................................................................................................................. 6

2.2 Impact of Large Safety Factor in HVAC systems .................................................... 7

2.3 The Design Process ...................................................................................................... 8

2.3.1 Typical Sizing Procedure ............................................................................... 8

2.3.2 Sizing Tools ...................................................................................................... 10

2.4 Tools for HVAC System Design and Analysis ........................................................ 12

2.4.1 Hourly Analysis Program (HAP) ................................................................. 12

2.4.2 HAP System Design Load ............................................................................. 13

2.4.3 TRACE 700 ....................................................................................................... 13

2.4.4 System Analyzer ............................................................................................. 13

2.4.5 EnergyPro ........................................................................................................ 14

2.4.6 RHVAC............................................................................................................. 14

2.4.7 HVAC-Calc ...................................................................................................... 15

2.5 Conclusion .................................................................................................................... 15

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3.0 HVAC Motor Systems in Use and On-Site Motor Testing ..................................................... 17

3.1 Introduction .................................................................................................................. 17

3.2 On-Site Testing of HVAC Motors in an Office Building ........................................ 17

3.3 Electrical Layout and Connected Loads ................................................................... 17

3.4 Power Measurement and Analysis for the Office Building ................................... 18

3.5 Oversizing of HVAC Motors ...................................................................................... 18

3.6 Analysis of Electrical Bills ........................................................................................... 19

4.0 Capabilities of Large Motor Testing Facility Including Test Results of Sample Motors .... 37

4.1 Introduction .................................................................................................................. 37

4.2 Motor Efficiency Test Setup ........................................................................................ 37

4.3 Motor Efficiency Calculations .................................................................................... 42

4.4 Motor Efficiency Test Results ..................................................................................... 42

5.0 Conclusion ..................................................................................................................................... 45

6.0 Reference ....................................................................................................................................... 46

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LIST OF FIGURES

Figure 3.1 The electrical layout of the office building 480 V, 600 A 3-phase main feed……….20

Figure 3.2 Office Building HVAC Location Schematic……………………………………………21

Figure 3.3 Running Characteristics of a 2 Ton Roof-Mounted HVAC Unit…………………….22




Figure 3.7 Running Characteristics of a 7.5 Ton Roof-Mounted HVAC Unit…………………..26

Figure 3.8 Electrical Demand for an Office Building for 4 Days………………………………....27

Figure 3.9 Electrical Demand for an Office Building for 4 Hours……………………………….28

Figure 3.10 Electrical Demand for an Office Building for 4 Hours – Highlighted areas for

zooming………………………………………………………………………………………………..29

Figure 3.11 Electrical Demand for an Office Building for 30 Minutes…………………………..30

Figure 3.12 Electrical Demand for an Office Building for 30 Minutes with HVAC Unit

Values Labeled…..................................................................................................................................31

Figure 3.13 Running Characteristics of Air Handler 1 of an Industrial Building……...............33

Figure 3.14 Running Characteristics of Air Handler 2 of an Industrial Building………….…..33

Figure 3.15 Running Characteristics of Air Handler 3 of an Industrial Building……………...34




Figure 4.1 Block Diagram of Motor Efficiency Test Bench……………………………………….37

Figure 4.2 Motor Efficiency Test Bench…………………………………………………………....38

Figure 4.3 Induction Motor 25hp 480V 3-Phase…………………………………………………...39

Figure 4.4 Torque Transducer………………………………………………………………………39

Figure 4.5 Loading Alternator 240V 3-Phase 1800RPM 60Hz 26kW…………………………..40

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Figure 4.6 Variable Frequency Drive 100hp……………………………………………..…….....41

Figure 4.7 Load Bank 240V 3-Phase 9-15kW……………………………………..........................41

Figure 4.8 Torque Transducer Output Results for 3 Loading Conditions…………………….43

Figure 4.9 Input Power Results for 3 Loading Conditions………………………………...…....43

LIST OF TABLES

Table 2.1 Software tools for HVAC systems…………………………………………………..….11

Table 3.1 HVAC Units Total Power, Individual Power Use, and Time of Occurrence………32

Table 3.2 Percent Loading of Air Handler Motors in an Industrial Building…………………36

Table 4.1 Results from Motor Efficiency Test Experiment ……………………………………...44

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NOMENCLATURE

ACCA Air Conditioning Contractors of America

ASD Adjustable Speed Driver

ASHRAE American Society of Heating, Refrigerating and Air-Conditioning

Engineers

CEC California Energy Commission

DOE Department of Energy

EERE Energy Efficiency & Renewable Energy

EUI Energy Use Intensity

HAP Hourly Analysis Program

HVAC Heating, Ventilation, and air conditioning

LEED Leadership in Energy & Environmental Design

MPG Miles Per Gallon

OEM Original Equipment Manufacturer

R&D Research and Development

RTU Rooftop Unit

US EPA US Environmental Protection Agency

VFD Variable Frequency Drive

1

EXECUTIVE SUMMARY



largest building energy users are actually large Heating Ventilating and Air Conditioning

(HVAC) motors running 24 hours a day throughout the year. Depending on the environment,

building motors may last 20 years or more, meaning an inefficient motor continues to waste

energy for a very long time. On-site efficiency testing of HVAC motors is needed for evaluation

and proper replacement, both in existing and new buildings, even those which are Leadership

in Energy and Environmental Design (LEED) certified.

A large motor usually fails due to electrical insulation or bearing failure, often without warning.

With building maintenance personnel under tremendous pressure to bring the HVAC system

back in operation, any available motor is an acceptable replacement, including larger-sized

motors that are far too powerful for the system; and, once the system is operational, there is

little interest in going back and replacing it with a proper-sized motor. As a result, buildings

end up with oversized motors, much higher magnetic and no-load losses, and lower efficiency.

The energy wasted by these oversized motors is also compounded when considering that they

last 20+ years.

Many building managers also choose to repair and rewind the old damaged motors locally both

for convenience and cost reduction. But rewind motors typically lower efficiency and repeated

rewind can lower efficiency significantly. New buildings can also end up with large, oversized

motors; this occurs during the design stage and is due to the complicated multidisciplinary

nature of motor applications.

Actual testing of motors by an independent testing facility is the only way of ascertaining the

true operating efficiency of a motor used in a building application. The ability to test on-site in

real world operating condition is also needed to evaluate existing motor stock.

This project reviewed available commercial software for building design to identify causes of

oversizing HVAC motors at the design stage including use of inflated safety factors. Another

aspect of this project was to test numerous HVAC motors operating at existing commercial and

industrial buildings. These motors’ electrical characteristics were recorded in real time and

several oversizing operations were identified and documented.




2




3

Evaluation of Energy Efficient HVAC Electric Motor

Systems in Buildings

1.0 Introduction

1.1. Background and Overview


largest building energy users are actually large HVAC motors running 24 hours a day

throughout the year. Depending on the environment, building motors may last 20 years or

more, meaning an inefficient motor continues to waste energy for a very long time. On-site

efficiency testing of HVAC motors is needed for evaluation and proper replacement, both in

existing and new buildings, even those which are Leadership in Energy and Environmental

Design (LEED) certified.

Buildings use 40% of all primary energy in the US. California’s commercial sector alone uses

121 billion kWh annually, 46.7% of total state electricity, compared to 36.3% for this sector

nationally. While HVAC motors consume the largest amounts of building energy, motor

related efficiency requirements are relatively lax, spanning a wide range of efficiency bands. In

addition, there is no independent verification of motor efficiency, leaving individual motor

manufacturers the task of claiming satisfactory target efficiency; this is equivalent to allowing

car manufacturers to claim their own fuel economy miles per gallon (mpg) in highway and city

driving, instead of the US EPA independently providing it.

A large motor usually fails due to electrical insulation or bearing failure, often without warning.

With building maintenance personnel under tremendous pressure to bring the HVAC system

back in operation, any available motor is an acceptable replacement, including larger-sized

motors that are far too powerful for the system; and, once the system is operational, there is

little interest in going back and replacing it with a proper-sized motor. As a result, buildings

end up with oversized motors, much higher magnetic and no-load losses, and lower efficiency.

The energy wasted by these oversized motors is also compounded when considering that they

last 20+ years.

Many building managers also choose to repair and rewind the old damaged motors locally both

for convenience and cost reduction. But rewind motors typically lower efficiency and repeated

rewind can lower efficiency significantly. Actual testing of motors by an independent testing

facility is the only way of ascertaining the true operating efficiency of a motor used in a building

application.

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New buildings can also end up with large, oversized motors; this occurs during the design

stage and is due to the complicated multidisciplinary nature of motor applications. HVAC

applications require thermal, fluid, and mechanical pump backgrounds, while the drive motor

requires a 3-phase electrical background. Yet, there is a serious shortage of electrical engineers

graduating with electrical power or energy backgrounds from either California or US

institutions. In fact, most universities have been slowly reducing, and ultimately eliminating,

electrical power offerings due to the expansion of new areas like electronics (during 1960s),

communications (1970s), and computers (1980s). Most universities, including the ten-campus

UC System, responded to increased interest in the new areas by allotting classroom and lab

space previously used for the less glamorous electrical power/energy area to the new areas. A

handful of campuses opted for only computer modeling based instruction and lab experiments,

while others maintained undergraduate instruction in the power area; yet, Ph.D. level activities

helping sustained R&D all but disappeared.

As few engineers now possess the composite background needed to understand large three-

phase motors, the general practice followed by design and architectural firms is to use a large

safety factor in sizing HVAC motors. Firms do not want to have their air conditioning system

fail due to a smaller sized motor, so they opt for larger motors. The oversized motors may be

running inefficiently, but there is no chance they will fail since they are only carrying a partial

load.

In addition to on-site testing for proper sizing of motors in established buildings, there is a need

to stream line the design process for sizing electrical motors, especially checking the safety

factor multiplier used in commercially available software used by design firms.

1.2. Goal of the Proposed Project

The goal of the project is to reduce electrical power (kW) and energy (kWh) use in California’s

buildings by evaluating HVAC drive motors. The goal will be achieved by quantifying energy

waste due to the: (i) use of lower efficiency motors, (ii) use of oversized motors in existing

buildings, and (iii) selection of oversized motors in the architectural and engineering design

stage of new buildings. It is vitally important to make the information available to consumers,

who can then use the information to make informed choices. Mediums through which the

information could be made available include the CEC web-site, as it is now provided for

appliances. An additional, though longer-term goal, would be to work with motor

manufacturers and OEMs to produce future HVAC products which are proven energy savers.

1.3. Objective of the Project

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The first objective of the project is to measure and document energy use of large HVAC motors

on-site under actual operating conditions. The objective will be accomplished by collecting

actual operational energy use data of HVAC motors in use in office, institutional and

commercial buildings. The University of California – Riverside (UCR) College of Engineering –

Center for Environmental Research and Technology (CE-CERT) will implement the project

using commercially available measuring instruments. Both graduate and undergraduate

students will collect and analyze data under the supervision of experienced faculty and staff.

The second objective is to set up a large motor testing facility at UC-Riverside that is capable of

testing either new and old HVAC motors, as well as the Variable Frequency Drives (VFDs) or

Adjustable Speed Drives (ASDs) used for energy savings in many HVAC applications. The new

independent test facility will be a first of its kind in California, and will prevent potential users

from having to ship their motors to North Carolina or Oregon for efficiency testing. UCR’s

CERT has been a leader in automobile emissions testing for 20 years; existing equipment

includes three vehicle dynamometers one of which could be adapted for large motor testing, if

funding is available.

The third objective is to evaluate commercial and in-house software used by architectural and

engineering firms designing HVAC systems for inflated safety factors used in calculating three-

phase motor sizes for buildings.

1.4. Benefits to California

Out of the total US electrical energy consumption of 3,597 billion kWh, California used 259.6

billion kWh or 7.22% in 2009, of which 121.11 billion kWh (46.7%) were used in commercial

buildings [EIA USDOE, 2011]. Yet, no studies, to date, have quantified HVAC motor power

consumption in larger office and commercial buildings. According to a report by the National

Research Council of Canada’s Institute for Research in Construction, approximately 28% to 35%

of Leadership in Energy and Environmental Design (LEED) certified buildings use more energy

than conventional buildings. The study was based on a re-analysis of data supplied by the US

Green Building Council, the organization which certifies LEED buildings, from a project on

measured energy data from 100 LEED certified commercial buildings. The study report states

under the sub-title in page 3: Measured Performance in Relation to Modeling, “Some buildings do

much better than anticipated, as evidenced by those in Figure ES-4 with measured Energy Use Intensity

(EUI) below the dotted line. On the other hand, nearly an equal number are doing worse – sometimes

much worse.” It reports that the median measured EUI was 69 kBtu/sf, and it is noteworthy that

USGBC/NBI came to this conclusion after arbitrarily excluding an additional 21 LEED certified

buildings which reported much “more energy use than the predicted code baseline modeling.” For

6

these buildings “.. had EUIs up to nearly 700 kBtu/sf, with a median of 238.” Such revelations have

led stakeholders to file a class action suit in federal court against USGBC, charging fraud.

Building energy use issues impact California more than the other states due to California’s

much higher energy use in commercial buildings, 46.7% compared to the national average of

36.3%. Some experts, including UCR CERT experts, believe that the lack of attention to the

proper sizing and efficiency evaluation of large HVAC motors may be one of the major causes

of the higher energy use. The proposed project will quantify both energy use and sizing of

motors by actual field measurements. Results will help building owners and decision makers to

take appropriate steps towards future reduction in building energy use. For example, even a

5% reduction in energy uses in California’s commercial sector is equivalent to 6 billion kWh

savings per year, or equivalent to the annual output of two to three typical power plants

[lbl.gov/today/2006/Mar/14].

2.0 Software Used by Architectural and Engineering

Firms on Designing HVAC Systems:

2.1. Introduction

At the residential and small commercial level, rooftop units (RTUs) are the most commonly

used heating ventilation and air conditioning (HVAC) systems, and therefore, represent a

suitable starting point toward understanding and researching the issue of oversizing in HVAC

systems. A previous study determined that in Northern California, RTUs represented more

than 2.3 million tons of air conditioning capacity, covering around 70% of the commercial

cooling [1].. Additionally, it is calculated that on a yearly basis, about 40 million square feet (ft2)

of new California construction are fitted with small HVAC systems (i.e. RTUs), and by applying

design principles that address the issue of oversizing, a reduction in energy consumption and

costs of 25% to 35% could be achieved [2].

A study on the oversizing of HVAC systems [3]discusses the findings of prior research in

California, which shows that over 60% of RTUs surveyed had a cycling rate of at least 3

cycles/hour, a clear signature that a RTU is oversized. Furthermore, the same study also shows

that more than 40% of the RTUs studied were more than 25% oversized and about 10% were

considerably greater than 50% oversized [4]. The study only labeled RTUs as 'oversized' if they

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were at least 25% oversized because many HVAC engineers consider oversizing by 25% as a

“safe and acceptable practice” for oversizing [5].

2.2. Impact of Large Safety Factor in HVAC Systems

As mentioned above, it is common practice for design engineers to oversize HVAC systems by

introducing a safety factor, as a precaution, intended to manage periods of operation that are

more extreme (e.g. heat wave) than the specific design conditions [1]. Unfortunately, oversizing

of HVAC systems, and therefore the indirect oversizing of motors, can easily become excessive.

The design engineer, by minimizing the risk of a HVAC system failing prematurely or during a

time of stress, will inflict cost and operational costs and penalties to the owner of the HVAC

system. These costs and penalties are:

1) Increased capital cost of HVAC unit − if a HVAC system is oversized the initial cost for

such system will be higher compared to a rightsized system;

2) Increased capital cost in the distribution system − an oversized HVAC system will require a

larger distribution system and incur higher capital cost;

3) Decreased in operational efficiency − due to operation under partial load at non-rated

conditions, the efficiency of the HVAC system will be less that if it was to run as designed;

4) Higher energy consumption − while in operation, an oversized HVAC system will consume

more energy in terms of kWh, even though it is continuously cycling;

5) Higher cost of energy, particularly in peak demand charges due to kW;

6) Decreased in power factor − by oversizing HVAC system, a bigger motor is used, and this

motor due to its inductive nature will further decrease the power factor at the facility. When

the loss of power factor is significant, it must be corrected by adding a capacitor bank.

7) Generation of harmonics

8) Shortening of HVAC system reliability and lifetime − the high compressor cycling rate (i.e.

frequent/continuous starting and stopping) can lead to premature failure of the HVAC

system;

9) Poor humidity control − if a cooling system is oversized, it may not energize long enough

(e.g. short cycling) to properly dehumidify the space. This could result in significant

humidity-related issues including mold and mildew;

10) Poor in-door air quality − short cycling limits the total amount of air circulation

throughout the space (e.g. each room) and can lead to poor indoor air quality;

8

11) Decreased in ability of HVAC system to provide simultaneous economizer and

compressor operation; and,

12) Intensify problems with distribution system fan power

All of the associated costs, penalties and issues listed above are derived from “short cycling” in

both heating and cooling modes. Short cycling is a characteristic of an oversized HVAC system.

To reach peak operational efficiency and effectiveness, a HVAC system should run for as long

as possible to satisfy cooling and heating demand loads.

2.3. The Design Process (a.k.a. Sizing Procedure)

The design process is of particular importance because the choices made at this stage will have a

direct impact on the installation, maintenance, and operation for the lifetime of HVAC systems.

In addition to being critical at the front end of the design process for a new system, properly

sizing HVAC systems is also critical during replacement of a failed or poorly performing unit.

From a practical perspective, the problem of HVAC oversizing is a systematic problem

augmented by the indiscriminate use of rules of thumb and arbitrary choices in the amount of

safety factor used.

2.3.1. Typical Sizing Procedure

The first step in the design of a HVAC system is to perform an accurate heating and cooling

load calculation. Load calculations have a direct impact on energy efficiency, indoor air quality,

building comfort level, and building durability. The load calculation process is an iterative and

detailed analysis that at the end dictates the selection of equipment and the design of the duct

system. During the load calculation step, it is critical to make sure that calculations are accurate.

Although the HVAC system must be sized for weather extremes (i.e. design days), so that the

system has enough capacity to adequately cool on the hottest day and comfortably heat on the

coldest night, emphasis needs to be put toward considering the implications of making

inaccurate adjustments during the load calculation process (i.e. avoiding excessive/arbitrary

safety factor) [6]. The recognized standard for design day temperatures is the Design

Conditions for Selected Location table, found in the ASHRAE Fundamentals Handbook [7].

Because the air conditioning size is based on the design day, inadvertently the majority of the

time the HVAC system will operate below rating conditions at a lower load. The partial load

operation of HVAC systems is inherently inefficient as HVAC units do not operate as efficiently

9

at partial-load (compared to operation at rated conditions). Furthermore, when the HVAC is

oversized due to a safety factor, then the partial-load condition is amplified.

In the commercial building design industry, a variety of HVAC sizing techniques and

methodologies exist, ranging from the application of "rules of thumb" (i.e. based on ft2/ton) ,

manual calculations (i.e. Manual J), and load calculation software (i.e. Trane Trace). The load

calculating programs, perform a room by room analysis on an hour-by-hour basis in order to

identify heating and cooling peaks. Using the room characteristics in terms of floor area, roof

area, wall area, physical orientation, number of occupants, lighting type, miscellaneous power

loads, construction materials and characteristics of the roof, floor, walls, windows, existing load

avoidance strategies, and historical weather data, these software packages can calculate with

great precision the hour of the year on which peaks will occur. Unfortunately, these packages

are also susceptible to providing incorrect results when the information used for the

calculations is incorrect, or arbitrarily adjusted.

A number of those interviewed for this report, expressed concern in this area:

"[..], but there is plenty of room for "gaming" I wished they would remove. "

"Cheating the software...Anything Non ACCA 5 Protocol Is Gaming...IE Adding loads that are not

permitted , non accurate inputs--Too Many use Manual J for a Dog and Pony Sales Tool"

A survey of design practices in the small commercial building market showed that although

load calculation software is used more prevalently over manual methods, or even "rules of

thumb", assumptions used during the calculation are conservative with respect to the building

shell, lighting design, and occupant densities [2]. So, it is particularly critical to include any type

of load avoidance strategies into the load calculations. Otherwise, the calculated HVAC system

will be larger than what is needed.

A well accepted and widely used method for carrying out load calculations is the Air

Conditioning Contractors of America (ACCA) Manual J Version 8 (MJ8), which also references

information provided by the American Society of Heating, Refrigerating and Air-Conditioning

Engineers (ASHRAE). Therefore, a number of load calculation software are ACCA approved

Manual J. Specific to the State of California, Title 24 compliance drives design, and compliance

software (i.e. Energy Pro) is also widely used for the design of HVAC systems.

10

With regards to the oversize of HVAC systems due to the addition of a safety factor, The ACCA

MJ8 says:

"Manual J calculations should be aggressive, which means that the designer should take full

advantage of legitimate opportunities to minimize the size of estimated loads. In this regard, the

practice of manipulating the outdoor design temperature, not taking full credit for efficient

construction features, ignoring internal and external window shading devices and then applying an

arbitrary "safety factor" is indefensible.”

“No additional safety factors are required when load estimates are based on accurate information

pertaining to the envelope construction and duct system efficiency. Large errors are possible if there is

uncertainty about insulation levels, fenestration performance, envelope tightness or the efficiency of

the duct runs installed in the unconditioned space.”

2.3.2. Sizing Tools

Over the past several decades, hundreds of building energy programs have been developed,

and are widely used by professionals in the building energy community. The main purpose of

these programs is to provide designers with key building performance indicators such as

energy demand, energy use, temperature, humidity, and costs. In 2005, the Department of

Energy (DOE), working with the University of Wisconsin-Madison, the University of

Strathclyde, and the National Renewable Energy Laboratory prepared a report contrasting the

capabilities of twenty

major building energy simulation programs [8]

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Table 2.1. Software tools for HVAC systems.

Software Software Type Description Developer

HAP Design Collection of software programs created specifically for

the HVAC system designer.

Carrier Corporation [9]

HAP System Design

Load

Calculation Similar to HAP. Omits energy simulations Carrier Corporation [9]

TRACE 700 Modeling Assess energy and economic impacts Trane [10]

System Analyzer Design Comparative analysis tool for preliminary evaluations

of HVAC systems based on energy and economic

performance

Trane [10]

EnergyPro Design California Title 24, LEED, ASHRAE 90.1, compliance

software, energy simulation, commercial, residential

EnergySoft [11]

RHVAC Design Calculates peak heating and cooling loads for

residential and small commercial buildings in

accordance with the 8th. edition of the ACCA Manual

J.

Elite Software Development,

Inc. [12]

HVAC-Calc Design Calculate heat loss and heat gain, both residential and

commercial.

HVAC Computer Systems

Ltd. [13]

12

2.4. Tools for HVAC System Design and Analysis

The Building Energy Software Tools Directory provides information on 417 building software

tools for evaluating energy efficiency, renewable energy, and sustainability in building [14]. The

directory is sponsored by the U.S. Department of Energy (DOE) and managed through the

Office of Energy Efficiency & Renewable Energy (EERE). The type of energy tools listed in the

directory include databases, spreadsheets, component and systems analyses, as well as whole-

building energy performance simulation programs.

In this section we present a summary of currently available and widely used software for

performing HVAC design, sizing and simulations. The software tools are designed with the

intent to improve the performance of HVAC systems, reduce overall energy consumption, and

to meet indoor quality guidelines and requirements. The selected energy tools in Table 2.1, are a

summary based on a review on the web and the literature.

The information listed is from the DOE's Building Energy Software Tools Directory.

2.4.1. Hourly Analysis Program (HAP)

In a single software package, the HAP software, developed by Carrier Corporation, offers both

a system design tool and an energy simulation tool. HAP's design module uses a system-based

approach to HVAC load estimation, by tailoring the sizing procedure and results based on the

specific type of system being analyzed.

Building heat flow is calculated by using the ASHRAE Transfer Function Method. Furthermore,

HAP performs an hour-by-hour simulation of building loads and equipment operation for all

8,760 hours in a year, taking into account the unique weather and operating schedules for each

day of the year. This provides superior accuracy versus other methods that use averages or

typical days for each month.

Strengths: Technical sophistication is combined with ease of use. HAP can communicate

electronically with Carrier to import equipment performance data.

Weaknesses: Limited used for research scientist since the software is closed source.

Safety Factor: A safety factor of 10% for cooling loads and 20% for heating loads is used in

calculations [12].

13

2.4.2. HAP System Design Load

Similar to HAP, this software package also offers load estimating and system design features.

By omitting the energy simulations of HAP, the HAP System Design Load is simpler, and more

efficient tool for performing system design.

Strengths: Technical sophistication is combined with ease of use. HAP can communicate

electronically with Carrier to import equipment performance data.

Weaknesses: Limited used for research scientist since the software is closed source.

Safety Factor: A safety factor of 10% for cooling loads and 20% for heating loads is used in

calculations [15].

2.4.3. TRACE 700

Trane's TRACE 700 brings the algorithms recommended by the ASHRAE to the Windows

operating environment. This software is used to assess the energy and economic impacts of

building-related selections, including HVAC equipment selections. In this software the designer

is able to compare up to four scenarios for a single project by modeling different options of the

air distribution and mechanical system/control choices. Additionally, the designer can choose

from seven different ASHRAE cooling and heating methodologies, including the Exact Transfer

Function.

Strengths: Customizable libraries and templates simplify data entry and allow greater modeling

accuracy. Documentation includes detailed online Help and a printed modeling guide.

Weaknesses: New users are recommended to take formal training.

Safety Factor: TRACE 700 does not have any one single entry dedicated to providing a factor of

safety. The program results can be as moderate or conservative as the user sees fit. It is the

user's responsibility to account for safety factors by using conservative information while

inputting the values in the different sections of the program. [16].

2.4.4. System Analyzer

The System Analyzer develop by TRANE is a comparative analysis tool for preliminary

evaluations of HVAC systems based on energy and economic performance [17]. This software

package can be used to quickly evaluate any combination of air distribution system(s) and

cooling/heating equipment for a specific building type and weather location.

14

Strengths: The intuitive and user-friendly interface provides built-in templates for creating

accurate and comprehensive reports.

"The TRANE System Analyzer software is an excellent tool to do a quick Life Cycle Cost Analysis of

several HVAC system alternatives. It does the heating/cooling loads, system/equipment part load

simulation for an entire year, has equipment and system cost data, utility rates for cities all over the

world and templates of various building types that can be easily modified to more closely model your

particular building."

Weaknesses: This program lacks some of the features available in the TRACE suite.

Safety Factor: TRANE does not include one single entry dedicated to providing a factor of

safety. The program results can be as moderate or conservative as the user sees fit. It is the

user's responsibility to account for safety factors by using conservative information while

inputting the values in the different sections of the program. [16].

2.4.5. EnergyPro

EnergyPro is a comprehensive energy analysis program that can be used to perform several

type of calculations, including California Title 24 energy analysis of nonresidential buildings, as

well as Leadership in Energy & Environmental Design (LEED) and ASHRAE 90.1 calculations.

Energy Pro's interface includes a building tree, a set of libraries, and a database of state-certified

equipment directories.

Strengths: The extensive use of Wizards allows most users to start creating reports.

Weaknesses: Some advanced concepts encompassed by DOE-2 are not handled by EnergyPro.

Safety Factor: EnergyPro does not have any one single entry dedicated to providing a factor of

safety.

2.4.6. RHVAC

Developed by Elite Software, RHVAC calculates peak heating and cooling in accordance with

ACCA Manual J. Additionally, RHVAC has a built-in database for design weather data for over

1,500 cities. For equipment selection, RHVAC is provided with a database for thousands of

equipment models from over 80 HVAC manufacturers.

Strengths: Suitable for light commercial applications because it allows for additional loads not

covered in Manual J such as lighting, latent equipment, and ventilation air loads.

15

Weaknesses: More input values are required than for other load calculating programs.

Safety Factor: RHVAC allows for the use of a safety factor by the user. Care is recommended

when adding a safety factor.

2.4.7. HVAC-Calc

This software comes with many features that easily calculates both Heat Loss and Heat Gain.

Online and software documentation explains how to size Furnaces and Air Conditioners. In

addition the software includes Duct Sizing and Hot-Water Baseboard sizing. With clear and

uncluttered screens for entering house information, it is simple to perform calculations by just

following the on screen numbered steps.

Strengths: Easy to use

Weaknesses: Not ACCA approved. Not possible to declare different zone temperatures.

Safety Factor: HVAC-Calc does not have an entry for safety factor.

2.5. Conclusion

Even though oversizing of HVAC systems (i.e. RTUs) is a prevalent problem in the building

industry, currently design engineers and firms do not have any incentive to rightsize these

units. On the contrary, by oversizing HVAC systems designers are able to avoid the potential

risk of having a HVAC system fail due to overloading. Previous studies have made

recommendations on how to increase the performance of an installed RTU and how to properly

design RTUs. In this chaper we focused on acknowledging the critical role that the addition of a

safety factors play in the oversizing of RTUs. Therefore, there is a need for an accurate and

repeatable method for rightsizing RTU during the design phase, or during replacements and

during rezoning efforts.

In addition properly sizing HVAC systems, on-site testing for proper assessment of HVAC

system size in operating buildings is needed, as well as there is a need to stream line the design

process for sizing HVAC systems, especially for checking safety factors/multiplier used in

commercially available software used by design firms. Most of the software packages do not

include a safety factors, as they are designed to make accurate load calculations, but designers

will add this safety factor "just in case".

16

In order to examine the prevalence of HVAC over sizing, it is important to examine this issue

both from a design perspective as well as from a practical perspective. Furthermore, the

accurate and repeatable field monitoring and evaluation are needed components in quantifying

the amount and penalty costs associated with over sizing existing HVAC systems.

17

3.0 HVAC Motor Systems in Use and On-Site Motor

Testing

3.1. Introduction

Electric motors in HCAC systems typically last for many years. In many office buildings located

in relatively cleaner environment it is not unusual for HVAC motors to last 10-20 years. Any

inefficiencies due to oversized and/or poorer quality motors can add up to large energy loss

over the life of the motor. For many practical reasons HVAC motor oversizing occurs

frequently. For example, when a HVAC motor breaks down during a hot and humid day, the

maintenance manager is under pressure to bring it back to operation as soon as possible. If a

local motor dealer does not have a similar sized motor in stock a higher sized motor may be

installed due to its availability. Nobody ever goes back and reinstalls the proper sized motor

after this temporary fix is achieved and this oversized solution becomes permanent. The only

way to find out HVAC motor oversizing and inefficient operation is to perform on-site motor

testing. But on-site testing is challenging due to the location of HVAC motors in building attics

and basements coupled with the risks associated with high voltage and current prevalent in

motor controllers and breakers. Another challenge is the lack of availability of professionals and

consultants capable of performing safe on-site testing of HVAC motors.

3.2. On-Site Testing of HVAC Motors in an Office Building

An evaluation of electrical energy use for the HVAC system of an office complex in Riverside,

California was performed over a four and a half day period including a weekend (Jun 28 – July

2, 2013) during the summer. The electrical power for one of the office buildings is supplied by

the local utilities electrical feeder into two transformers. Transformer 1 (T1) supplies power for

lighting and other loads; transformer 2 (T2) supplies power for the air conditioning units. The

building is temperature controlled by 16 packaged HVAC units located on the roof. The HVAC

units come in different sizes and service different parts of the building. This study has five

major components as listed below:

1. Updated electrical sketch identifying all major connected electrical devices.

2. Measurements at breaker.

3. Identifying the load profile of differently sized HVACs.

4. Analysis of power usage during peak hours.

5. Analysis of power company’s electrical bills.

18

3.3 Electrical Layout and Connected Loads

The electrical layout of the office building is shown in Figure 3.1 and the mechanical schematic

of the roof-mounted HVAC units is shown in Figure 3.2. The 480 V, 600 A 3-phase main feed

after going through meter # 104966, is split into two transformer feeds – T1 for lighting and plug

loads, and T2 for 16 roof top HVAC units. Transformer T2 was instrumented with a Fluke 435 II

meter to record electrical readings.

3.4. Power Measurement and Analysis for the Office Building

A 6,500 square feet single story office building in a commercial area in southern California is

served by 16 roof-mounted HVAC packaged units. The units consist of 3 x 2 ton, 3 x 3 ton, 5 x 4

ton, 4 x 5 ton, and 1 x 7.5 ton. The electrical power use characteristics of each of these sizes are

given in figures 3.3 – 3.7.

Electrical demand for the office building HVAC units were measured by a recording meter for a

4.5 day period from June 27th to July 2nd and is shown in Figure 3.8. The maximum demand on

weekday afternoons were approximately 69 kW while the nighttime minimums were about 3

kW. The weekend maximum was approximately 65 kW. Figure 3.9 shows the power usage

trend zoomed in on the afternoon of June 28, 2013. We can see that the peak usage on a

weekend is approximately the same as the peak usage during a weekday, despite the

significantly reduced activities and almost nobody in the building. Figure 3.10 highlights the

areas that we zoom into and analyze further, which are shown in figures 3.11 and 3.12.

In figure 3.11, we analyze a thirty minute interval with the highest power usage. In this interval

we see that at one point all 16 HVAC units are turned on. With the data we recorded, we are

able to identify the size of the HVAC unit that turned on by looking at the difference in power

between steady readings. These power differences are labeled in figure 3.12 and summarized in

table 3.1.

Looking at the data we recorded, we see that there are multiple times during each day where all

16 HVAC units are on. We also see that during the times before and after these peaks occur,

there are many valleys. Using this data, we are planning to clamp the peaks to fill in the valleys.

3.5. Oversizing of HVAC Motors

A number of HVAC motors were tested on-site for possible oversizing. The power consumption

characteristics of six of these air handlers are given in figures 3.13 – 3.18. The percentage

operating load of these motors is given by

19

𝑃𝑚𝑒𝑎𝑠𝑢𝑟𝑒𝑑 = 𝑘𝑊

746= ℎ𝑝𝑚𝑒𝑎𝑠𝑢𝑟𝑒𝑑 (3.1)

𝑃𝑒𝑟𝑐𝑒𝑛𝑡𝑎𝑔𝑒 𝑂𝑝𝑒𝑟𝑎𝑡𝑖𝑛𝑔 𝐿𝑜𝑎𝑑 = ℎ𝑝𝑚𝑒𝑎𝑠𝑢𝑟𝑒𝑑

ℎ𝑝𝑟𝑎𝑡𝑒𝑑 × 100 (3.2)

The percentage loadings were calculated using the above equations and the results are given in

Table 3.2. Air handler 4 was found to be operating at only 17% of rated load while air handler 3

was operating at under 50% loading. Light load operations are inefficient due to proportionally

higher bearing and electromagnetic losses.

3.6. Analysis of Electrical Bills

To reduce the electrical costs of the building, we need to understand how the utilities company

charges for their service. The bill shows that there are two main portions of the electric bill that

we are able to control. We are able to control the amount of electricity used, measured in KWH,

and the peak demand of electricity, measured in KW. For the first stage of implementing our

HVAC controlling hardware, we are controlling the peak demand of the building.

For the month of June 2013, the peak demand of the building was 72.4 KW and was billed

$10.48 per KW. The HVAC usage peaks around 65KW, meaning that the remaining 7.4KW of

usage came from other building loads such as lighting and computers. Using the implemented

control system, we will limit the HVAC usage peak to 50kW which is a 15KW reduction from

before. Given that the peak demand rate stays the same, we will save approximately $157.20 per

month. The projected savings for one year and five years are $1,886.40 and $9,432, respectively.

We can further reduce the electricity bill by reducing electrical consumption. Possible methods

of doing so could be to limit HVAC usage by turning off units that cool rooms which are not in

use, or, to create cooling schemes that keep HVAC usage to a minimum while keeping the

building at a comfortable temperature. The savings would be more difficult to accumulate but

would still make a difference nonetheless.

To reduce electric bills, the following steps are recommended;

1. Reduce non-essential electricity use during on peak hours (turn off AC for conference

rooms not in use).

2. Implement control schemes to limit maximum kW demand in any 15 minute period (45-

50kW).

3. Limit usage during weekends and holiday

20

Figure 3.1: The electrical layout of the office building 480 V, 600 A 3-phase main feed

21

Figure 3.2: Office Building HVAC Location Schematic

22

Figure

3.3: Running Characteristics of a 2 Ton Roof-Mounted HVAC Unit

23

Figure 3.4: Running Characteristics of a 3 Ton Roof-Mounted HVAC Unit

24


25


26

Figure 3.7: Running Characteristics of a 7.5 Ton Roof-Mounted HVAC Unit

27

Figure 3.8: Electrical Demand for an Office Building for 4 Day

28

Figure 3.9: Electrical Demand for an Office Building for 4 Hours

29

Figure 3.10: Electrical Demand for an Office Building for 4 Hours – Highlighted areas for zoomin

30

Figure 3.11: Electrical Demand for an Office Building for 30 Minutes

31

Figure 3.12: Electrical Demand for an Office Building for 30 Minutes with HVAC Unit Values Labeled

32

Table 3.1: HVAC Units Total Power, Individual Power Use, and Time of Occurrence

33

Figure 3.13: Running Characteristics of Air Handler 1 of an Industrial Building


34



35



36

Table 3.2: Percent Loading of Air Handler Motors in an Industrial Building

Air Handlers Approx kW Load HP kW rated %load

AH1 13.45 25 20.04 67.09

AH3 6 15 12.027 49.88

AH4 4 30 24.05 16.62

AH5 0.72 1 0.08 89.79

AH6 6.4 10 8.018 79.8

37

Section 4: Capabilities of Large Motor Testing Facility

Including Test Results of Sample Motor

4.1. Introduction

To verify independently efficiency of an electric motor, a testing facility was set up at CE-CERT

of UC Riverside. Accurate measurement of both input and output powers is necessary to find

operating efficiency of a motor. Input power measurement is relatively easy with electrical

power/watt meters, but measurement of output power is complicated due to the output being

mechanical, hydraulic, thermal, and various pumping systems. To isolate and measure actual

motor output measurements at the shaft of the motor is needed. This is achieved by separating

the load from the motor and inserting a torque transducer between them.

4.2. Motor Efficiency Test Setup

The block diagram of the motor efficiency test setup is shown in Figure 4.1. A power of 480V, 3-

phase, 60 Hz source is connected to a breaker to a 100-hp variable frequency drive (VFD). The

output of the VFD is connected to a 25-hp, 480 V, 3-phase induction motor. The shaft output of

the motor is coupled to a precision torque transducer whose output is coupled to a 240 V, 3-

phase, 1800 RPM, 60 Hz, 26 kW loading alternator. The alternator is loaded by a 3-phase, 240 V

variable load bank.

38

Source480V 3-Phase

60HzBreaker

Variable Frequency

Drive 100hp

Induction Motor25hp 480V 3-Phase

Torque Transducer

Loading Alternator 240V 3-Phase

1800RPM 60Hz 26kW

BreakerLoad Bank 240V 3-Phase 9-15kW

Figure 4.1: Block Diagram of Motor Efficiency Test Bench

Figure 4.2 shows the actual motor efficiency test setup. The motor is shown in the bottom left

and next to it is the torque transducer. The loading generator is shown in the middle while the

VFD is shown in the right along with the two FLUKE Power analyzers. Figure 4.3 shows the

close-up of the 25 hp, 480 V, 3-phase induction motor under testing. Figure 4.4 shows the torque

transducer. Figure 4.5 shows the 240 V, 3-phase, 1800 RPM, 60 Hz, 26 kW loading alternator.

Figure 4.6 shows the 100 hp variable frequency drive, while Figure 4.7 shows the 3-phase, 240 V

variable load bank.

39

Figure 4.2: Motor Efficiency Test Bench

Figure 4.3: Induction Motor 25hp 480V 3-Phase

40

Figure 4.4: Torque Transducer

Figure 4.5: Loading Alternator 240V 3-Phase 1800RPM 60Hz 26kW

41

Figure 4.6: Variable Frequency Drive 100hp

42

Figure 4.7: Load Bank 240V 3-Phase 9-15kW

4.3: Motor Efficiency Calculations

The electric motor efficiency is given by the following equations:

𝐸𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑐𝑦, 𝜂 = 𝑃𝑜𝑢𝑡

𝑃𝑖𝑛× 100% (4.1)

𝑃𝑜𝑢𝑡 = 𝜔𝜏 =2

𝑃𝑜𝑙𝑒𝑠× 2𝜋𝑓 (4.2)

Where,

Pout = output power of the motor at the shaft calculated by equation 4.2

Pin = input power of the motor measured by power meters

ω = angular frequency in radians per second

τ = torque in newton-meter

Poles = number of electromagnetic poles of the motor

f = frequency of the electrical grid power

43

4.4. Motor Efficiency Test Results

A 25 hp industrial motor commonly used for HVAC applications was tested under various

loading conditions in this newly developed motor testing facility. Figures 4.8 and 4.9 show the

torque transducer values and input power watt meter readings, respectively, for 3 loading

conditions: (1) 9 kW load setting, (2) 12 kW load setting, and (3) 15 kW load setting. These are

not the actual operating loads – as the operating voltage is lower than the design voltage of the

load banks. Actual load values are given by the torque transducer readings as shown in Table

4.1.

Figure 4.8: Torque Transducer Output Results for 3 Loading Conditions

-10

0

10

20

30

40

50

60

70

80

90

0 200 400 600 800 1000 1200 1400 1600

Torq

ue

(N-m

)

Time (Seconds)

Torque Transducer Data

9 kW Load Setting

12 kW Load Setting

15 kW Load Setting

44

Figure 4.9: Input Power Results for 3 Loading Conditions

Table 4.1: Results from Motor Efficiency Test Experiments

9 kW Load 12 kW Load 15 kW Load

Output Frequency (Hz) 59.7 60.0 59.5

Input Power (kW) 8.447 11.312 14.279

Output Torque (Nm) 43 57 72

Efficiency (%) 95.48 94.34 94.25

-2

0

2

4

6

8

10

12

14

16

18

20

0 200 400 600 800 1000 1200 1400 1600

Inp

ut

Po

wer

(kW

)

Time (Seconds)

Input Power Data

9 kW Load Setting

12 kW Load Setting

15 kW Load Setting

45

5.0. Conclusions


The focus was electrical energy use by Heating Ventilating and Air Conditioning (HVAC)

motors – as a group the largest energy users in the building, running 24 hours a day throughout

the year.

When a large motor usually fails building maintenance personnel are under tremendous

pressure to bring the HVAC system back in operation, any available motor is an acceptable

replacement, including larger-sized motors that are far too powerful for the system; and, once

the system is operational, there is little interest in going back and replacing it with a proper-

sized motor. Many building managers also choose to repair and rewind the old damaged

motors locally both for convenience and cost reduction. But rewind motors typically lower

efficiency and repeated rewind can lower efficiency significantly. New buildings can also end

up with large, oversized motors; this occurs during the design stage and is due to the

complicated multidisciplinary nature of motor applications.

This project reviewed available commercial software for building design to identify causes of

oversizing HVAC motors at the design stage including use of inflated safety factors. Another

aspect of this project was to test on-site numerous HVAC motors operating at existing

commercial and industrial buildings. Numerous oversized motors were identified to be

operating in the existing buildings.







46

6.0. REFERENCES

[1] Djunaedy, E., Van Den Wymelenberg, K., Acker, B., Thimmana, H., 2010. Right Sizing of

Rooftop HVAC Systems, Technical Report, 20090208-01, Integrated Design Lab, University of

Idaho, Boise, ID.

[2] Pete Jacobs. Architectural Energy Corporation. 2003. Small HVAC System Design Guide.

California Energy Commission. Publication Number: CEC-500-2003-082.

[3] Djunaedy, E., Van Den Wymelenberg, K., Acker, B., Thimmana, H. (n.d.). Oversizing of

HVAC System: Signatures and Penalties. Energy and Buildings, In Press, Accepted Manuscript.

doi:10.1016/j.enbuild.2010.10.011 <http://dx.doi.org/10.1016/j.enbuild.2010.10.011>.

[4] Felts, D., & Bailey, P. (2000). The state of affairs—packaged cooling equipment in California.

In Proceedings of the 2000 ACEEE Summer Study on Energy Efficiency in Buildings (Vol. 3, pp. 137-

147).

[5] McDowall, R. (2007). Fundamentals of HVAC systems: SI edition. Academic Press.

[6]Arlan Burdick. IBACOS, Inc. 2011. Strategy Guideline: Accurate Heating and Cooling Load

Calculations. U.S. Department of Energy. (doi://www.nrel.gov/docs/fy11osti/51603.pdf)

[7] D.J. Wessel (Ed.). 2001. ASHRAE Fundamentals Handbook 2001 (SI Edition), American

Society of Heating, Refrigerating, and Air-Conditioning Engineers.

[8] Crawley, .B., Hand, J.W., Kummert, M., Griffith, B.T. Contrasting the capabilities of building

energy performance simulation programs. Building and Environment, 43 (4) (2008), pp. 661–673.

[9]

http://www.commercial.carrier.com/commercial/hvac/general/0,,CLI1_DIV12_ETI495,00.html

[10] http://www.trane.com/commercial/north-america/us/en/products-systems/design-and-

analysis-tools/analysis-tools/system-analyzer.html

[11] http://www.energysoft.com/

[12] http://www.elitesoft.com/web/hvacr/elite_rhvacw_info.html

[13] http://www.hvaccalc.com/main.asp

[14] http://apps1.eere.energy.gov/buildings/tools_directory/

[15] Carrier Corporation Software Systems Network. HAP Quick Reference Guide. 2003.

[16] Trane. Frequently Asked Questions. http://www.trane.com/commercial/north-

america/us/en/products-systems/design-and-analysis-tools/c-d-s--help/cds-software-

news/october-2008.html. Accessed on 11/17/2014.

[17]Trane. System Analyzer. http://www.trane.com/commercial/north-america/us/en/products-

systems/design-and-analysis-tools/analysis-tools/system-analyzer.html. Accessed on 11/23/14

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