Residential HVAC
Installation Practices:
A Review of
Research Finding
s
JUNE
2018
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Acknowledgments
Thank you to all of individuals that provided invaluable insights and reviews throughout the organization and
compilation of this literature review.
Will Baker, Midwest Energy
Efficiency
Alliance
Jim Bergmann, Redfish Instruments
Lena Burkett, U.S. Department of Energy
Michael Blasnik, Nest Labs
Abigail Daken, U.S. Environmental Protection Agency
Wes Davis, Air Conditioning Contractors of America
Tom Downey, Proctor Engineering Group
Lieko Earle, National Renewable Energy Laboratory
Dean Gamble, U.S. Environmental Protection Agency
Dale Hoffmeyer, U.S. Department of Energy
James Jackson, Emerson Climate Technologies
David Lis, Northeast Energy Efficiency Partnerships
Casey Murphy, ICF
Jon Passe, U.S. Environmental Protection Agency
John Taylor, Consortium for Energy Efficiency
Chandler von Schrader, U.S. Environmental Protection Agency, Retired
Eric Werling, U.S. Department of Energy
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List of
Acronyms
AC Air Conditioning
ACEEE American Council for an Energy-Efficient Economy
ACCA Air Conditioning Contractors of America
AFUE Annual Fuel Utilization Efficiency
ASHP Air-Source Heat Pump
ASHRAE American Society of Heating, Refrigerating and Air-Conditioning Engineers
BPM Brushless Permanent Magnet
CAC Central Air Conditioning
CEC California Energy Commission
CEE Consortium for Energy Efficiency
CFM Cubic Feet per Minute
COP Co-efficient of Performance
DOE Department of Energy
ECM Electronically Commutated Motor
EER Energy Efficiency Ratio
EM&V Evaluation, Measurement and Verification
EPA Environmental Protection Agency
FDD Fault Detection and Diagnostics
FXO Fixed Orifice
HP Heat Pump
HVAC Heating, Ventilation, and Air Conditioning
IESO Independent Electricity System Operator
MERV Minimum Efficiency Reporting Value
NASEO National Association of State Energy Officials
NIST National Institute of Standards and Technology
NREL National Renewable Energy Laboratory
PARR Partnership for Advanced Residential Retrofit
PSC Permanent Split Capacitor
STAC State Technologies Advancement Collaborative
QI Quality Installation
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QIV Quality Installation Verification
QM Quality Maintenance
R&D Research and Development
STAC State Technologies Advancement Collaborative
TXV Thermostatic Expansion Valves
Table of
Contents
Introduction
1
Background
and Approach
3
Analysis
of
Information
Gathered
3
Research Topic 1:
Quantifying Benefits
of Better Installations
5
Research Topic 2: Scope and
Applicability
of Existing Knowledge Base
5
Research Topic 3:
Availability
of Technology Solutions
5
Research Topic 4:
Prevalence
of Faults by Type
6
Summary
of Findings and Recommendations
7
Appendix
A: Evolution of Research on HVAC Installations
10
Appendix
B:
Annotated
Bibliography
15
Appendix
C: Questions on HVAC
Installation
Practices for Industry Stakeholders
26
List of
Tables
Table 1: Key Findings by Research Topic
4
Table 2: Field Measured Data by Fault Type
6
Table 3: Evolution of Research on HVAC Installations
10
Table 4:
Annotated
Bibliography
15
Table 5: Questions on HVAC
Installation
Practices for Industry Stakeholders
26
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Introduction
This report summarizes relevant findings from available literature and research that were evaluated to better quantify
the potential benefits of improving current installation practices for heating, ventilation, and air conditioning
(HVAC) equipment in existing homes (i.e., equipment replacements). Although some of the findings may be
informative and applicable to the new construction market, this report focuses on analyses specific to the single-
family residential HVAC replacement market. The research findings summarized in this report reveal that improving
the installation of central heating and air conditioning systems has the potential to decrease operating and
maintenance costs, decrease equipment purchase price, improve indoor air quality and overall indoor comfort, and
reduce household energy consumption by mitigating a variety of common system performance issues.
The US Department of Energy (DOE) produced this report in response to industry stakeholder input received during
the May 2016 Residential Central Air Conditioning and Heat Pump Installation Workshop Meeting
1
(https://
energy.gov/eere/buildings/downloads/residential-central-air-conditioning-and-heat-pump-installation-workshop).
DOE hosted the stakeholder discussion workshop to identify and rank research and development (R&D) needs and
critical knowledge gaps related to improving system design, selection, and installation (collectively “installation”).
At the meeting, it was suggested that additional field research may be needed to supplement modeled and lab-based
studies and develop a better understanding of both the prevalence of system performance faults and their cumulative
impact.
One hallmark study from 2014 served as a foundation for this literature review. The National Institute of Standards
and Technology’s (NIST) Sensitivity Analysis of Installation Faults on Heat Pump Performance
2
study assessed the
impacts of installation faults on the energy consumption of refrigerant-based residential heat pump equipment. The
study used computer simulations and laboratory tests to quantify the impact of commonly observed individual faults,
as well as certain combinations of faults. While the study provided unprecedented insight into the potential impact of
improper HVAC installations and performance degradation, it also identified key knowledge gaps. This literature
review, including examination of field-based studies, aims to fill those gaps:
• How would field data, collected under imperfect conditions, change the results?
• What research has been performed on the prevalence of installation faults, and how can the data and
findings from this research inform the need for better HVAC system installation and performance?
• What are the impacts of the studied faults on other types of systems and other aspects of HVAC system
performance (e.g., occupant comfort, indoor air quality, and equipment durability)?
DOE gathered and reviewed 44 reports, focusing primarily on field studies, produced by industry experts, utilities, and
regional energy efficiency organizations that documented the energy performance impacts of common HVAC faults
that occurred because of installation and/or maintenance issues. This collection includes reports published prior to the
2014 NIST study and more recent studies. Findings were supplemented by informal discussions with subject matter
experts in the spring/summer of 2017, and the results of 13 interviews of HVAC industry stakeholders regarding
common practices and the relative impacts of oversizing of HVAC equipment conducted by Oak Ridge National
Laboratory staff in 2015-2016.
DOE’s systematic review underscored that comfort and energy performance in the single family residential HVAC
replacement market are impacted most by improper airflow, incorrect refrigerant charge, and duct performance
1
U.S. Department of Energy—Office of Energy Efficiency and Renewable Energy, Building Technologies Office.
Residential Central Air Conditioning and Heat Pump Installation–Workshop Outcomes. U.S. Department of Energy:
Washington, DC. November 2016. DOE/EE-1496. https://www.energy.gov/sites/prod/files/2016/11/f34/CAC-
CHP%20Installation%20Workshop%20Report%20-%2011-30-16.pdf.
2
U.S. Department of Commerce—National Institute of Standards and Technology, Energy and Environment Division.
Sensitivity Analysis of Installation Faults on Heat Pump Performance. NIST Technical Note 1848. U.S. Department of
Commerce: Washington, DC. September 2014. https://nvlpubs.nist.gov/nistpubs/TechnicalNotes/NIST.TN.1848.pdf.
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issues. It also revealed that the issues often inherent with existing ductwork (e.g., duct leakage, duct insulation, duct
design, and exposure to outdoor conditions) complicate the overall load calculation and sizing process and interfere
with the efficient operation of equipment, even when it is installed with correct airflow and refrigerant charge.
Additionally, the majority of studies reviewed found that the energy savings attributed to proper residential HVAC
equipment sizing may be less than previously estimated for the majority of split-system HVAC equipment installed
in single-family homes. Few studies, however, have addressed performance of advanced technologies or
installations in highly efficient homes (such as low-load or zero net energy homes). Further, some studies show
proper sizing can significantly reduce peak demand, which has benefits for the electricity grid and consumers by
lowering overall energy costs. Under current industry practice, however, the majority of systems—especially those
installed as emergency replacements—are installed without performing detailed load calculations.
Detailed load calculations tend to be imprecise and are likely to be distorted by inefficiencies in the existing duct
system that can be difficult to accurately measure and costly to repair. Given the limited availability of equipment in
sizing increments less than half a ton (6,000 Btuh), it may be difficult to justify the added time and cost of
completing a detailed load and sizing calculation in the vast majority of retrofit installations that are triggered by
equipment failure.
3
A more streamlined and accessible means of properly sizing equipment could help enable large-
scale adoption of proper equipment sizing practices in retrofit applications. In specific applications where improper
sizing has greater impact, detailed load calculations should continue to be used, such as low-load homes and homes
where humidity control is a key consideration.
The availability of multi-stage and variable speed equipment offers a potential solution to the need for detailed load
and sizing calculations in many replacement/retrofit applications. But additional research is needed to better
understand the interplay between comfort, efficient equipment operation, distribution system losses, and optimized
control strategies to support the development of updated sizing, equipment selection, and system design procedures.
This report presents the background and approach for the cited research and lists key findings and recommendations
for further areas of study to promote industry adoption of improved HVAC installation practices. An annotated
bibliography of the publications, reports, and documents considered for this review is included (see Appendix B).
Results from this literature review will inform DOE’s ongoing R&D, field validation, and communication on
advancing the industry adoption of improved HVAC installation practices.
3
Informal discussions with users of Manual J and other load calculation tools, indicate the time required to collect input data
in the field and complete the data entry needed to produce a sizing estimate can range from 90 minutes to as much as 8 hours,
depending on the complexity of the home and the experience level of the technician. The time and expense required to obtain
load calculations further increases when visual observations are supplemented with diagnostic tests (e.g. blower door tests
and duct leakage tests) to improve the accuracy of the input data.
3
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Background
and
Approach
Building on NIST’s work, DOE compiled and reviewed publications, reports, and industry studies that considered
in situ HVAC performance and the impact of installation and maintenance faults. DOE obtained reports from
existing resource repositories, including the Building America Solution Center, the Consortium for Energy
Efficiency Resource Library, the California Energy Commission website, and DOE national laboratories, as well as
from sources mentioned during interviews with industry experts. While the list of studies considered for this report
is by no means exhaustive, it represents a good faith effort to review the existing knowledge base so as to
accurately inform our findings and recommendations. The study addresses the following research topics:
1. Is there sufficient data available to accurately quantify the cost savings, energy savings, and other
measurable benefits resulting from quality installation (QI)? Or, alternatively, is the data available to
accurately quantify the penalty for installation or maintenance faults?
2. Is the research robust enough to extrapolate nationally? What limitations exist?
3. To what extent are technology solutions available in the market (i.e., fault-tolerant HVAC equipment, and/or
automated field verification tools) that could mitigate installation faults?
4. Is there sufficient data to quantify the frequency of faults, by type, existing in the
field?
Are baseline
studies or utility program data available to aid in determining the prevalence of those faults?
This search was coupled with outreach to regional energy efficiency organizations, utility HVAC programs, EPA’s
ENERGY STAR
®
Program, and subject matter experts, including many of the original authors of the cited
research. DOE also gathered input from industry representatives attending DOE’s Building Technologies Office
Peer Review Meeting: Smart Tools for Improving Installed Performance of Residential and Small Commercial
HVAC Systems Expert Meeting held on March 16, 2017.
4
Based on analysis from an initial set of reports, DOE generated a list of questions (see Appendix C) to guide
further input and identify additional source documents to be included in this review.
Analysis
of
Information Gathered
DOE identified and systematically reviewed 44 reports. DOE considered the evolution of the research, examining
the reports chronologically to gauge how industry views on the relative impact of faults on HVAC performance
have shifted over time as technologies and industry’s understanding of the issues have changed. Studies
researching the impact of improper installation on HVAC equipment performance date back to the early 1990s.
Since that time, a number of technology innovations in heating and cooling equipment and diagnostic tools have
come to market and, with some trial and error along the way, many lessons have been learned regarding the impact
of sub-optimal installations. Advancements in HVAC technology innovations (e.g., TXVs, variable speed
components, and modulating equipment) have enabled more energy efficient equipment to be installed in more
homes. Appendix A presents the evolution of research on HVAC installations, categorized by topics addressed
including fault detection methodologies, ducts, refrigerant charge, sizing and load calculations, airflow, peak
demand, building shell (e.g., leakage rates), contractor concerns, and demand concerns (e.g., customer concerns).
The testing methods are also included. Appendix B includes an alphabetized annotated bibliography for each of
the reports reviewed.
Table 1 (below) summarizes our key findings based on the project’s four research topics. A more detailed discussion
of the frequency and net impact of installation and maintenance faults follows.
4
Navigant Consulting, Inc. U.S. Department of Energy’s Workshop on Smart Tools for Improving Installed Performance of
Residential and Small Commercial HVAC Systems Stakeholder Workshop. Navigant Consulting, Inc.: Chicago, IL. March
16, 2017. https://www.energy.gov/sites/prod/files/2017/11/f46/bto-QI-HVAC-Systems-Stakeholder-Workshop-Discussion-
Summary-11-2017.pdf.
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Table 1: Key Findings by Research Topic
Research Topic
Key Findings
1
Quantifying Benefits of
Better Installations
•
Sufficient
data exists to support the need for
improved installation
and
maintenance, but the level of energy and demand savings to be gained varies by
fault type and
climate
zone.
• Information about the prevalence of faults and the distribution of the
magnitude
of
faults by type are also necessary to develop cost and savings estimates. Table 2
attempts
to summarize these
findings,
but direct
comparisons
between studies are
complicated
by the use of varying
metrics
and
measurement
methods used by the
researchers.
• Findings across the studies reveal pervasive incidences of field performance
issues—and savings
opportunities—in refrigerant-
based central cooling and heating
systems.
2
Scope and Applicability of
Existing Knowledge Base
•
Available
field studies cover hot-dry,
mixed-dry,
hot-humid,
mixed-humid,
cold, and
very cold climates.
• Most field studies are small in scale and a variety of
metrics
are used,
making
it
difficult
to
make statistically
valid
extrapolations
and to quantify the wide-scale
impact
of
installation
faults. However, consensus is strong that duct
leakage
is a
nearly universal problem, and the vast
majority
of
refrigerant-based
systems suffer
from
airflow
and/or refrigerant charge faults, regardless of the age of the HVAC
system, or the house.
• It is harder to pinpoint a specific energy or cost penalty, as the scale of the faults
varies by study and the direction of the faults (over or under for sizing,
airflow,
and
refrigerant
charge) may vary by region.
3
Availability of Technology
Solutions
• Researchers are starting to
investigate
the
potential
for
multi-stage
and variable
speed
equipment
to
mitigate
sizing issues but these systems are still
susceptible to
common
faults like refrigerant charge, airflow, and poor duct
design and installation.
• Early research suggests that
complex interactions
between the equipment,
distribution
system
condition, and control settings have a
significant impact
on the
success of
optimizing
the
potential benefits
of these technologies.
•
Automated verification system
tools are suggested in one study
[Appendix
A: 44] as
a
potential
remedy to
mitigate installation
faults as they occur.
4
Prevalence of Faults
• Duct
leakage
is the most
common
source of
performance degradation
of HVAC
systems, with most studies
finding
90-100% of systems tested needing sealing or
repairs to the supply or return air ducts.
• Low
airflow
is found more than 50% of the time in all regions studied, while high
airflow
is a
problem
in 8-15% of systems.
•
Refrigerant
charge faults vary by study approach and region, but range between
29-78% undercharge and 4-50% overcharge.
• The presence of non-condensables in
refrigerant
lines is a
potentially
common
fault that has not been studied
extensively. While
at least one study [Appx A: 23]
identified
the presence of non-condensables as a
potentially important
problem,
additional research is needed to better quantify the prevalence,
magnitude,
and
relative
impact
on
system performance
of this fault type.
5
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Research Topic 1: Quantifying Benefits of Better Installations
The literature provides sufficient data to support the need for improved installation and maintenance practices.
However, the prevalence of specific faults can vary by region, and most studies are limited to a single region. There
is general agreement that airflow and refrigerant charge are the key issues with AC/HP performance. However,
quantifying the exact impact is difficult because the relative impact can vary by region due to climate and/or
construction practices, and because interactions with leaky ductwork confound efforts to accurately predict
potential savings. Occupant behavior also varies significantly, which further challenges predictions about the
energy performance of installed equipment. For instance, for many homeowners in colder climates [Appx A: 18],
commonly accepted assumptions for operating hours are incorrect, with discretionary use of AC resulting in total
run times 25-33% lower than projected and peak afternoon events contributing up to 2.5% additional demand
burden. Additionally, the practice of continuous fan operation has been found in multiple studies to be a significant
factor in exacerbating both energy consumption and demand penalties stemming from installation and maintenance
issues.
Potential benefits associated with repairing existing systems vary with the level of intervention, type of system
(e.g., central air conditioning, heat pumps, fossil fuel furnaces, etc.), and climate demands. In all cases, duct
performance represents a wild card in terms of being able to accurately predict and achieve energy savings targets.
Potential benefits of repairing the studied faults include:
• Duct sealing and insulation: 33% increased cooling capacity, 16-41% increased seasonal system efficiency
[Appx A: 1, 4]
• Duct sealing, insulation, airflow and refrigerant charge correction combined: 12-47% energy savings and
1.2 kW demand reduction [Appx A: 2, 3, 23, 44]
• Static pressure, capacity, efficiency, refrigerant charge, and thermal expansion valves (TXV) repairs: 24%
efficiency improvement in AC/HP systems [Appx A: 21]
• Incremental savings from tuning up existing AC/HP systems are approximately 5% [Appx A: 18]
• Gas furnace tune-up with some duct improvements achieved 23% increased capacity [Appx A: 30].
Research Topic 2: Scope and Applicability of Existing Knowledge Base
The available research covers all major climate zones with the exception of marine climates. While most field
studies are small in scale, the field data largely aligns with predictions based on simulations and lab tests. However,
the condition of the distribution system (i.e., location, leakage rates, static pressure, etc.), occupant thermostat, and
fan settings also greatly impact overall system performance. While additional field study is needed to better
understand how to optimize advanced system design (e.g., ECM motors, multi-stage and variable speed equipment,
and smart controls), it appears that the case has sufficiently been made that duct leakage, incorrect airflow, and
incorrect refrigerant charge are pervasive faults in both new and existing equipment nationwide.
Research Topic 3: Availability of Technology Solutions
Research investigating the potential for advanced HVAC equipment to mitigate the penalties incurred from
common faults is limited. One small-scale study [Appx A: 13] designed to determine the potential for dual-stage
equipment to mitigate penalties incurred from oversizing found that field performance of the systems was
significantly less than lab tests, with actual measured performance of central AC systems at 59-84% of rated SEER.
The same study suggested that there may be both energy consumption and peak demand penalties associated with
downsizing dual-stage equipment, but further study is needed in this area.
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Research Topic 4: Prevalence of Faults by Type
Existing research dating back to the mid-1990s and continuing through 2016 indicate that 70-90% of AC/HP
systems in homes have at least one performance-compromising fault incurred at installation or due to inadequate
maintenance. When duct leakage is considered, these rates rise to 90-100%.
Gas furnaces are less susceptible to installation faults, with gas pressure being the primary adjustment. Low
airflow (indicated by high temperature rise) can also be a problem for fossil fuel furnaces causing systems to
cycle on the high limit, but there is minimal energy impact associated with these issues. The greater effect is on
comfort and system durability.
It is also important to note that the studies do not provide sufficient data to reliably quantify the prevalence of
multiple faults, or the impacts of faults occurring in combination.
Table 2 summarizes the field measured data by evaluated fault type.
Table 2: Field Measured Data by Fault Type
Fault Type
Reports
States
Recommended
Range
5
% of Systems
Testing
Higher than
Recommended
Range
% of Systems
Testing Lower
than
Recommended
Range
Equipment
Sizing
Appx
A: 1, 2, 3, 5,
8, 12, 13, 18, 24
AZ, CA (south),
FL, NJ, NV, TX, WI
33-48% oversize
compared to
Manual J
31-93%
0-9%
Airflow
Appx
A: 1, 2, 3, 8,
24, 44
AZ, CA (north and
south), MN, NJ,
NV, WI
Less than 350
CFM/ton
8-29%
50-93%
Refrigerant
Charge
Appx
A: 2, 3, 8,
24, 44
AZ, CA (north), NJ,
NV, MN, WI
Exceeded
manufacturer
superheat or
subcooling
ranges
4-50%
29-78%
Duct Leakage
Appx
A: 1, 2, 3, 4,
8, 23, 24
AZ, CA (north and
south), NJ, NV, TX
100 CFM25 (to
outside) or more
67-100%
N/A
5
Varying methods and metrics were used to measure the studied faults. The information provided in the table
represents
the
most commonly used metrics to determine out-of-compliance
performance.
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Summary
of
Findings
and
Recommendations
Based on the systematic review and analysis, DOE identified the following findings:
Continued pursuit and support of HVAC quality installation is needed, but new approaches may be
required. Despite extensive research, HVAC quality installation and maintenance practices have not been
widely adopted throughout the HVAC industry. Research indicates that training and standards alone are
insufficient to influence trade practices [Appx A: 38, 41] and consumers are driven primarily by low cost
and fast service [Appx A: 8, 40, 42], particularly in retrofit scenarios. Technology solutions in the form of
advanced equipment, controls, and automated verification tools hold promise but need support to engage
the market. As such, collaboration with industry to research and field validate HVAC system performance
is needed.
The prevalence and impact of non-condensables in the refrigerant lines is still unknown. Additional
field research is needed to better quantify the frequency with which systems are operating with non-
condensable contaminants in the refrigerant line, the magnitude and range of the level of contamination,
and the degree to which the system performance is compromised as a result.
More research is needed to determine the relative impact of faults on HVAC system performance
beyond energy (e.g., occupant comfort, indoor air quality, and equipment durability). Most studies
have focused primarily on energy impacts of improper system design and installation practices. Taking the
extra steps to make the necessary measurements and adjustments as a system is installed adds cost and time
to the job. To justify this added burden on the contractor and customer, it would be worthwhile to better
quantify the potential non-energy related benefits of a proper and verified installation. For example, which
faults cause more wear and tear on the equipment, and to what extent do properly performing systems
maintain more consistent comfort and health conditions?
Additional work is needed to improve duct system performance. Ducts with enough leakage to require
sealing can occur as frequently as 70-100% of existing systems, but duct leakage characteristics vary
regionally and duct performance is increasingly dependent on housing vintage as codes (and enforcement)
get better. In addition to leakage, some duct systems suffer from other design (e.g., restrictive duct
capacity) or installation issues (e.g., incorrectly installed flex duct) which can also adversely impact system
performance. These repairs are not a natural fit for any existing trade, the work can be difficult and labor-
intensive, and there is no consumer market for these services. Technological advancements in duct
materials, design, installation, and sealing techniques, as well as market breakthroughs, are needed to
mitigate this issue.
Evolving sizing and equipment selection practices are needed to better address retrofit scenarios
and support proper design of systems using advanced equipment and control technologies. Efforts
should focus on more accurately assessing the balance between sensible and latent loads for cooling,
establishing procedures for selection of multi-stage and variable speed equipment, and developing
methods or tools that speed up and simplify the load calculation process. Although studies have found
that energy savings attributed to proper residential HVAC equipment sizing may be less than previously
estimated, the number of studies with field-verified data on the impacts of sizing on energy efficiency
and system performance is limited [Appx A: 12, 19]. Moreover, retrofit scenarios present unique
challenges as obtaining accurate input data for load calculations can be complicated, time consuming,
and subject to interpretation. In addition, better sizing, equipment selection, and system design guidance
are needed when specifying multi-stage and variable speed equipment. In the case of basic retrofits, a
quick assessment that estimates acceptable equipment sizing within the margins of what is available
from the manufacturer would be sufficient to avoid gross oversizing without placing undue burden on
the contractor or creating a false sense of precision by asking for detailed inputs that may not be
available to the technician. In the case of multi-stage and variable speed equipment, sizing strategies
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should include consideration of interactions with existing duct systems and control strategies to optimize
system performance. In addition, studies have emerged showing that:
o Even when using best practices, Manual J results can overestimate sensible loads by as much as
50% [Appx A: 5] and also underestimate latent loads [Appx A: 13]; and
o The level of effort and uncertainty associated with input assumptions required to complete a
comprehensive load calculation and determine accurate sizing often outweighs the net benefit in
retrofit situations.
The findings above provide the basis for the following recommendations to advance high performance
HVAC installation practices.
• Develop and define a universally accepted set of methodologies and metrics for measuring the benefits of
applying best installation and maintenance practices to enable more “apples to apples” comparisons among
available field data sets.
• Focus market interventions on the following installation elements to improve performance in residential
retrofits:
- Ensure tools and guidance for proper system design and equipment selection are readily available and
accessible to installers, especially when specifying multi-stage and variable speed equipment.
- Ensure correct airflow by any means possible (i.e., fan speed adjustments are better than not doing
anything even if ducts cannot be repaired) and verify through direct or indirect (i.e., static pressure drops
combined with fan curve data) airflow measurements;
- Ensure correct refrigerant charge using manufacturer recommended methods (i.e., sub-cooling or
superheat); and
- Address the duct system to be designed, sized, sealed, insulated, and constructed cost-efficiently.
• Promote technologies and processes that reduce deployment and implementation costs and make improved
installation practices more accessible and cost-efficient (e.g., automated verification systems and on-board
monitoring and fault detection).
• Develop Quality Control protocols to detect and minimize the opportunity for gaming of data inputs when
using automated verification tools. At a minimum, ensure data checks exist to identify patterns indicating
improper use of tools and intentional gaming.
• Promote high efficiency systems and those which are capable of adapting to varying building load
conditions via multi-stage or variable speed technologies.
• Conduct further research to better understand elements related to load calculations and sizing,
including:
- The role of system sizing practices and advanced controls in managing peak demand and load curves;
and
- Identification of the scenarios in which sizing should be prioritized in relation to comfort and energy
consumption reduction (e.g., low-load homes, high humidity conditions, and as part of an overall system
redesign inclusive of ductwork).
• Define best practices for selecting, specifying, and installing advanced technologies (e.g., multi-stage and
variable speed equipment) with intelligent controls. Coordinate these definitions with equipment
manufacturers developing best practices for equipment sizing, selection, and installation when coupled
with inadequate duct systems that adversely impact equipment and system performance and that cannot
be repaired.
For more information on DOE’s efforts to improve the energy efficiency of new and existing homes, visit
the Residential Buildings Integration site.
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Appendix
A:
Evolution
of
Research
on
HVAC
Installations
Table 3 is organized chronologically to help the reader align each of the 44 reports DOE reviewed with the
HVAC and diagnostic testing technology available at the time each study was completed. The chronological
listing also helps demonstrate the evolution of how industry views have emerged over time in terms of the
relative impact of heating and cooling equipment performance faults. Studies researching the impact of improper
installation on HVAC equipment performance date back to the early 1990s. Since that time, a number of
technology innovations in heating and cooling equipment and diagnostic tools have come to market and, with
some trial and error along the way, many lessons have been learned regarding the impact of sub-optimal
installations. Advancements in HVAC technology innovations (e.g., TXVs, variable speed components, and
modulating equipment) have enabled more energy efficient equipment to be installed in more homes. In
examining each report, DOE’s analysis considered the testing methods applied and how each of the following
topics were addressed:
• Fault Detection Methodologies: includes reports examining the methodology of measuring the
performance of diagnostic tools (handheld and onboard sensors) and/or their accuracy
• Ducts: includes reports examining practices, impacts and/or prevalence of faults related to duct material,
location, design, leakage, and insulation
• Refrigerant Charge: includes reports examining impacts and/or prevalence of improper refrigerant
charge
• Sizing and Load Calculations: includes reports examining practices, impacts and/or prevalence of faults
related to sizing and load calculations
• Airflow: includes reports examining practices, impacts, and/or prevalence of faults related to airflow
• Peak Demand: includes reports examining the impact of proper HVAC installation on peak demand
• Building Shell: includes reports that documented building airflow leakage rates (in cubic feet per minute,
or CFM)
• Contractor Concerns: includes reports examining contractor concerns related to HVAC installation,
verification, and maintenance practices
• Demand Concerns: includes reports examining homeowner concerns and interests related to HVAC
installation practices
10
f
Table 3:
Summary of Reviewed Research Studies on HVAC Installations
Ref
#
Publication
Date
Report
Topics Addressed
Testing Method
Fault D
etection M
ethodologies
Ducts
Refrigerant Charge
Sizing & Load Calculations
Airfl
ow
Peak Demand
Building Shell (Lea
kage Ra
tes)
Contrac
tor Concerns
Demand Concerns (Cus
tomer)
Modeled
Lab
Testing
Field
Testing
Survey
1
1995
Blasnik, M., Proctor, J., Downey, T.
,
Sundal J., & Peterson, G.
Assessment
of HVAC
Installations
in
New Homes in Southern California
Edison’s Service Territory
x
x
x
x
x
x
x
x
2
1995
Blasnik, M., Proctor, J., Downey, T.
,
Sundal, J., & Peterson, G.
Assessment
of HVAC Installations in
New Homes in Nevada Power
Company’s
Service Territory
x
x
x
x
x
x
x
x
3
1996
Blasnik, M., Downey, T., Proctor, J.
,
& Peterson, G. Assessment of HVAC
Installations in New Homes in APS
Service Territory
x
x
x
x
x
x
x
x
4
1996
Jump, D.,
Walker,
I., &, Modera, M.
Field Measurements of Efficiency
and Duct
Retrofit
Effectiveness in
Residential
Forced Air Distribution
Systems
x
x
x
x
5
1998
Proctor, J. Monitored In-Situ
Performance
of
Residential
Air-
Conditioning
Systems
x
x
x
x
x
x
x
x
6
1998
Walker,
I., Sherman, M., Modera, M.,
& Siegel, J. Leakage Diagnostics,
Sealant Longevity, Sizing and
Technology Transfer in Residential
Thermal Distribution Systems
x
x
x
x
7
2000
Siegel, J.,
Walker,
I., & Sherman,
M.
Delivering
Tons to the Register:
Energy
Efficient
Design and
Operation of
Residential
Cooling
Systems
x
x
x
x
x
x
8
2001
Xenergy New Jersey Residential
HVAC Baseline Study
x
x
x
x
x
x
x
x
11
f
Ref
#
Publication
Date
Report
Topics Addressed
Testing Method
Fault D
etection M
ethodologies
Ducts
Refrigerant Charge
Sizing & Load Calculations
Airfl
ow
Peak Demand
Building Shell (Lea
kage Ra
tes)
Contrac
tor Concerns
Demand Concerns (Cus
tomer)
Modeled
Lab
Testing
Field
Testing
Survey
9
2002
Foster, R., South, M., Neme, C.,
Edgar, G., & Murphy, P. Residential
HVAC Quality Installation: New
Partnership Opportunities and
Approaches
x
x
x
10
2003
Walker, I. Register Closing Effects
on Forced Air Heating System
Performance
x
x
x
x
x
11
2004
Wilcox, B. & Larsen, J. Measured
Cooling load, Energy, and Peak
Demand Savings from High-
Performance Glass in a California
Production House
x
x
12
2006
Sonne, J., Parker, D., & Shirley, D.
Measured Impacts of Proper Air
Conditioning Sizing in Four Florida
Case Study Homes
x
x
x
x
x
13
2006
Proctor, J., & Cohn, G. Two-Stage
High Efficiency Air Conditioners:
Laboratory Ratings vs Residential
Installation Performance
x
x
x
x
x
x
x
14
2006
Titus, E. Strategies to Increase
Residential HVAC Efficiency in the
Northeast
x
x
x
x
x
x
x
x
x
x
x
15
2006
Walker, I. Residential Furnace
Blower Performance
x
x
x
x
x
x
16
2007
Henderson, H., & Shirley, D. Closing
the Gap: Getting Full Performance
from Residential Central Air
Conditioners
x
x
x
x
x
17
2007
Wirtschafter, R., Thomas, G., Azulay,
G., Blake, W. and Prahl, R. Do
Quality Installation Verification
Programs for Residential Air
Conditioners Make Sense in New
England?
x
x
x
x
x
x
x
18
2008
Pigg, Scott Central Air Conditioning
in Wisconsin: A compilation of
recent field research.
x
x
x
x
x
x
x
x
19
2009
Proctor, J. AC Sizing, Electrical
Peak, and Energy Savings
x
x
x
x
12
f
Ref
#
Publication
Date
Report
Topics Addressed
Testing Method
Fault D
etection M
ethodologies
Ducts
Refrigerant Charge
Sizing & Load Calculations
Airfl
ow
Peak Demand
Building Shell (Lea
kage Ra
tes)
Contrac
tor Concerns
Demand Concerns (Cus
tomer)
Modeled
Lab
Testing
Field
Testing
Survey
20
2009
Talerico, T., & and Winch, R.
Focus on Energy Evaluation: ECM
Furnace Impact Assessment Report
x
x
x
21
2010
Kim, W. & Braun, J. Impacts of
Refrigerant Charge on Air
Conditioner and Heat Pump
Performance
x
x
22
2010
Hunt, Marshall, Kristin Heinemeier,
Marc Hoeschele, and Elizabeth
Weitzel HVAC Energy Efficiency
Maintenance Study
x
x
x
x
x
x
x
23
2011
Proctor, J., Chitwood, R., & Wilcox,
B. Efficiency Characteristics and
Opportunities for New California
Homes (ECO) PIER Program Final
Project Report
x
x
x
x
24
2011
Rhodes, J. D., Stephens, B.,
& Webber, M.E. Using energy audits
to investigate the impacts of
common air-conditioning design
and installation issues on peak
power demand and energy
consumption in Austin, Texas
x
x
25
2012
Brand, L., & Rose, W. Measure
Guideline: High Efficiency Natural
Gas Furnaces
x
x
x
26
2012
Heinemeier, K., Hunt, M., Hoeschele,
M., Weitzel, E., & Close, B.
Uncertainties in Achieving Energy
Savings from HVAC Maintenance
Measures in the Field
x
x
x
x
27
2012
Walker, I., Dickerhoff, D., Faulkner,
D., & Turner, W. Energy Implications
of In-Line Filtration in California
x
x
x
x
x
28
2012
Yuill, David P., and James E. Braun.
Evaluating Fault Detection and
Diagnostics Protocols Applied to Air-
Cooled Vapor Compression
Air-Conditioners
x
x
13
f
Ref
#
Publication
Date
Report
Topics Addressed
Testing Method
Fault D
etection M
ethodologies
Ducts
Refrigerant Charge
Sizing & Load Calculations
Airfl
ow
Peak Demand
Building Shell (Lea
kage Ra
tes)
Contrac
tor Concerns
Demand Concerns (Cus
tomer)
Modeled
Lab
Testing
Field
Testing
Survey
29
2013
Kim, W. Fault Detection and
Diagnosis for Air Conditioners
and Heat Pumps Based on Virtual
Sensors
x
x
x
x
x
x
x
30
2013
Yee, S., Baker, J., Brand, L., & Wells,
J. Energy Savings from System
Efficiency Improvements in Iowa’s
HVAC Save Program
x
x
x
31
2014
Booten, C., Christensen, C.,
& Winkler, J. Energy Impacts of
Oversized Residential Air
Conditioners--Simulation Study of
Retrofit Sequence Impacts.
x
x
x
32
2014
Rhodes, J. D. Optimal Residential
Energy Consumption, Prediction,
and Analysis
x
x
x
x
x
33
2014
Stephens, B. The impacts of
duct design on life cycle costs of
central residential heating and air-
conditioning systems
x
x
x
x
x
34
2014
Braun, James E., and David Yuill.
Evaluation of the Effectiveness of
Currently Utilized Diagnostic
Protocols
x
x
x
35
2014
Domanski, P. A. , Henderson, H.I., &
W.V. Payne Sensitivity Analysis of
Installation Faults on Heat Pump
Performance
x
x
x
x
x
x
x
36
2015
Brand, L., Yee, S., & Baker, J.
Improving Gas Furnace
Performance: A Field and
Laboratory Study at End of Life
x
x
x
37
2015
Cummings, J., Withers, C., & Kono,
J. Cooling and Heating Season
Impacts of Right-Sizing of Fixed and
Variable-Capacity Heat Pumps with
Attic and Indoor Ductwork
x
x
x
x
x
x
x
38
2015
NMR Group, Inc. Baseline
Characterization Market Effects
Study of Investor-Owned Utility
Residential and Small Commercial
HVAC Quality Installation and
Quality Improvement Programs in
California
x
x
x
x
x
x
x
x
14
f
Ref
#
Publication
Date
Report
Topics Addressed
Testing Method
Fault D
etection M
ethodologies
Ducts
Refrigerant Charge
Sizing & Load Calculations
Airfl
ow
Peak Demand
Building Shell (Lea
kage Ra
tes)
Contrac
tor Concerns
Demand Concerns (Cus
tomer)
Modeled
Lab
Testing
Field
Testing
Survey
39
2015
Parmenter, K., Prijyanonda, J., &
Dorton, D. The Coil & Blade Project:
Combining Field Work and Interval
Data to Measure Impacts
x
x
x
x
40
2015
Steiner, E., & Malinick, T. California
HVAC Quality Installation/Quality
Maintenance Customer Decision-
Making Study
x
x
x
41
2015
Sullivan, M., Smith, J., Afrat, K., &
Bosco, P. Impacts of the OPA HVAC
Installation Optimization Training
Program on Realized Energy
Efficiency in Retrofit AC Systems.
x
x
x
42
2015
Vaidya, R., Fogel, C., Tolkin, B., &
Poulin, B. Swimming Against the
Tide--Gauging HVAC Quality
Installation and Quality
Maintenance Program Efforts to
Establish a Foothold in the Market
x
x
x
x
x
x
x
43
2016
Mallay, D. Compact Buried Ducts in
a Hot-Humid Climate House
x
x
x
x
x
44
2016
Pigg, S., Cautley, D., & Koski, K.
Improving Installation and
Maintenance Practices for
Minnesota Residential Furnaces, Air
Conditioners and
Heat Pumps
x
x
x
x
x
x
x
x
x
15
f
Appendix
B:
Annotated Bibliography
This annotated bibliography presents the evaluated reports with summary annotations (in alphabetical order for
ease of reference). Annotations provided are primarily focused on consideration of the energy performance impacts
of common HVAC faults driven by installation and/or maintenance issues for the single-family residential HVAC
replacement market. If a study was conducted in a specific location, the location is noted after the report URL.
Table 4: Annotated Bibliography
Ref
#
Report
3
Blasnik, Michael, Tom Downey, John Proctor, and George Peterson.
Assessment
of HVAC Installations in
New Homes in APS Service Territory. Report no. 95.111. Proctor
Engineering
Group, Ltd: Phoenix, AZ
April
22, 1996. http://www.proctoreng.com/dnld/95111.pdf (Phoenix, AZ)
This study included a
sample
size of 28 HVAC systems in 22 newly built homes. Key
findings
include: duct
leakage
and existing duct insulation levels reduce overall cooling
efficiency
(reasonable
improvements
can
save 16% of the cooling energy); air conditioners often have
insufficient
air
flow
across the indoor coil and are
frequently
undercharged (proper installation,
following
the
manufacturers installation
instructions, and testing
would remedy these
problems
at a cost of about $70); a
program
that ensures tight,
well-insulated
ducts
and properly installed air conditioners could reduce cooling usage by
approximately
42% and
diversified
peak
demand by 1.2 kW (the
additional
cost is
estimated
to be $210 per unit).
1
Blasnik, Michael, John Proctor, Tom Downey, Jim Sundal, and George Peterson.
Assessment
of HVAC
Installations in New Homes in Southern California Edison’s Service Territory. Report no. 94.113. Proctor
Engineering
Group, Ltd: Palm Springs, CA January 1995. http://www.proctoreng.com/dnld/94113.pdf
(Palm
Springs, CA)
This
investigation
involved field testing duct systems, air handlers, and building shells in ten houses in
Southern
California
Edison’s service territory. Key
findings
include: duct
leakage
and low duct insulation levels
cause an average effective cooling
capacity
loss of 33%; and air conditioners often have
insufficient
air flow
across the indoor coils and are
frequently
undercharged due to
improper
installation procedures. A
program
that ensures tight,
well-insulated
duct systems along with properly installed air conditioners can reduce
cooling usage by
approximately
47% and peak demand by 1.2 kW. In addition, these
modifications
can reduce
the
specified
size of installed systems,
potentially
leading to an
additional
0.4 kW demand savings. The report
also includes
recommendations
for
improving program
design to improve cooling
efficiency
and reduce peak
demand.
2
Blasnik, Michael, John Proctor, Tom Downey, Jim Sundal, and George Peterson.
Assessment
of HVAC
Installations in New Homes in Nevada Power Company’s Service Territory. Final Report. Proctor
Engineering
Group, Ltd: Palm Springs, CA. January 1995. http://www.proctoreng.com/dnld/94113.pdf
(Palm
Springs, CA)
This study covered 40 HVAC (AC) systems in 30 newly built homes. Key
findings
include: duct
leakage
and low
duct insulation levels cause an average loss of 37% in overall cooling
efficiency;
and air conditioners often
have
insufficient
air
flow
across the indoor coils and are
frequently
undercharged due to
improper
installation
procedures (the
problem
can be remedied for
approximately
$68 per house). A
program
that ensures tight,
well-insulated
duct systems along with properly installed air conditioners can reduce cooling usage by
approximately
44% and peak demand by 1.2 kW. In addition, these
modifications
can reduce the
specified
size of installed systems,
potentially
leading to an
additional
0.4 kW demand savings.
16
f
31
Booten, C., C. Christensen, and J. Winkler. Energy Impacts of Oversized Residential Air Conditioners–
Simulation Study of
Retrofit
Sequence Impacts. Report no. NREL/TP-5500-60801. National
Renewable
Energy Laboratory: Denver, CO November 2014
https://www1
.eere.energy.gov/buildings/publications/pdfs/
building_america/energy-impacts-residental-
ac.pdf
This report presents a
simulation-based
study
examining
the
impacts
of oversizing. Key
findings
include:
energy penalties for oversizing are
minimal;
energy penalties in single speed systems have more to do with
parasitic power
consumption
than oversizing; and oversizing penalties are reduced when connected to a
system
with duct losses.
25
Brand, L., and W. Rose. Measure Guideline: High
Efficiency
Natural Gas Furnaces. Report no. DOE/ GO-
102012-3684. National
Renewable
Energy
Laboratory: Denver, CO.
October 2012.
https://www.nrel.gov/docs/fy13osti/55493.pdf
This document is a guideline for practitioners and is based on Partnership for Advanced Residential Retrofit
(PARR) lab-based research. It includes key statements regarding gas furnace sizing, including: high efficiency
furnace annual fuel utilization efficiency (AFUE) (for closed combustion furnaces) is relatively insensitive to
oversizing based on lab testing in the 70% to 120% oversizing range. Even in separating the technologies
(single speed vs modulating), the differences are minimal. For furnaces with permanent split capacitor (PSC)
motors that are connected to tight ducts (high external static pressure above 0.5 inches of water column),
there is a slight decrease in AFUE. For modulating furnaces connected to overly tight/small ducts, there is a
slight increase in power to operate the circulating air blower (more power to overcome the high static
pressure).
36
Brand, L., S. Yee, and J. Baker Improving Gas Furnace
Performance:
A Field and Laboratory Study at End of
Life. Report no. DOE/GO-102015-4626. National
Renewable
Energy
Laboratory: Denver, CO.
February 2015.
https://www
.nrel.gov/docs/fy15osti/63702.pdf
This report presents a field- and lab-based study investigating the impacts of common installation
practices and age-induced equipment degradation on the installed performance of gas furnaces over the
life of the product. Twelve furnaces of various ages and efficiencies were retrieved from Iowa homes and
tested for efficiency in the lab. Prior to their removal, system airflow, static pressure, equipment
temperature rise, and flue loss measurements were recorded for each furnace as installed in the house.
Results indicate that steady-state efficiency in the field was 6.4% lower than that measured for the same
furnaces under Standard 103 in the lab. The study indicates that equipment performance did not
significantly decrease over 15-24 years of operation.
34
Braun, James E., and David Yuill. Evaluation of the Effectiveness of Currently Utilized Diagnostic Protocols.
Purdue University: West Lafayette, IN. February 18, 2014.
http://www.performancealliance.org/Portals/4/Documents/HVAC%20Research/
EffectivenessOfFDDProtocols-Purdue-2014-02
pdf
This paper presents lab and simulation data evaluating the performance of four fault detection
diagnostic (FDD) protocols. This paper also presents an evaluation and findings regarding a fifth protocol.
Key findings include: there is a question of accuracy regarding the protocols’ field testing capabilities.
The results produced high false alarm rates (60-100% overall, with most categories over 95%), high
misdiagnosis rates, high no diagnosis rates, and low missed detection rates (which would suggest the
protocols may be too sensitive). The results also provide some context for what range of performance
might be expected from FDDs.
RESIDENTIAL
HVAC
INSTALLATION
PRACTICES: A
REVIEW
OF
RESEARCH
FINDINGS
37
Cummings,
James, Charles Withers, and
Jamie
Kono. Cooling and Heating Season Impacts of Right-Sizing of
Fixed- and
Variable-Capacity
Heat Pumps With Attic and Indoor Ductwork. Report no. DOE/GO-102015-4678.
National
Renewable
Energy
Laboratory: Golden, CO.
June 2015.
https://www1
.eere.energy.gov/buildings/publications/pdfs/building_america/variable-capacity-heatpum
ps-
indoor-ductwork
pdf
A study funded through the Building
America Partnership
for Advanced
Residential
Construction that examined
the
impact of
sizing on heating and cooling energy
efficiency performance
(including during peak
demand)
f
or
both
variable-capacity
and
fixed-capacity
heat pumps. The research from this study finds that oversizing
residential HVAC systems can be beneficial. Key
findings
include: oversizing residential central air
conditioning
(CAC) and air-source heat pump
(ASHP)
systems can be
beneficial
when using variable speed
equipment;
oversized
variable-capacity
systems can save substantial heating and cooling energy, the
benefits
of which are
even more pronounced with a
well-sealed
duct system, and they can also substantially reduce both heating and
cooling peak demand.
Short-cycling
was not found to be a problem. Heat pump
system
oversizing diminishes
the number of hours per year that the
system
goes into electric resistance backup heating.
35
Domanski,
Piotr A., Hugh I. Henderson, and W. Vance Payne. Sensitivity
Analysis
of
Installation
Faults on Heat
Pump
Performance.
National Institute of Standards and Technology Technical Note 1848. U.S.
Department
of
Commerce: Washington, DC.
September
2014. http://nvlpubs.nist.gov/nistpubs/TechnicalNotes/
NIST.TN.1848.pdf
A study was conducted by NIST to assess and better understand the
impacts
that heat pump
installation
faults
have on
equipment electricity consumption
in a
single-family
residential house application. This study used
computer simulations
and
laboratory
tests to quantify the
impact
of
common
faults. It includes a literature review
of related studies in which the authors note that
many
field studies are not designed with the technical rigor (and
resulting confidence intervals) that are
commonly
achieved in a lab environment. Key
findings
include: duct
leakage,
refrigerant undercharge, oversized heat pump with
nominal
ductwork, low indoor
airflow
due to
undersized ductwork, and refrigerant overcharge have the most
potential
for causing
significant performance
degradation
and increased annual energy consumption.
Additionally,
the
impact
of
simultaneous
faults was
found to be additive.
9
Foster, Rebecca, Mia South, Chris Neme, George Edgar, and
Patrick
Murphy. Residential HVAC Quality
Installation: New Partnership Opportunities and Approaches. ACEEE 2002
Summer
Study on Energy
Efficiency
in
Buildings, Volume 6. American Council for an Energy-Efficient Economy: Washington, DC. 2002.
http://aceee.org/files/proceedings/2002/data/index.htm
This paper provides a historical snapshot of the progress of quality installation (QI) efforts around the country (at both
Federal and local levels): the Consortium for Energy Efficiency’s (CEE) 2000 QI Specification, the ENERGY STAR Cool
Change Promotion, New Jersey’s QI Program, and the Wisconsin QI Program. QI discussed in this paper presents a
model that is very focused on sizing (and avoiding oversizing) and training, but not necessarily on delivered efficiency
savings (capacity delivery).
26
Heinemeier, Kristin, Marshall Hunt, Marc Hoeschele, Elizabeth
Weitzel,
and Brett Close. Uncertainties
in Achieving Energy Savings from HVAC Maintenance Measures in the Field. University of California, Davis: Davis, CA.
June 2012. http://wcec.ucdavis.edu/wp-content/uploads/2013/07/Kristin-Heinemeier-
ASHRAE-2012
pdf
This paper provides an analysis of the uncertainties in the
measurement
of
common
variables (such as dry
bulb, wet bulb, refrigerant
temperatures,
refrigerant pressures,
airflow
and power) as measured in the lab by
evaluation,
measurement,
and
verification
(EM&V) teams, by
participants
in
maintenance programs,
and by
typical contractors. The uncertainties were combined in
calculating
sub-cooling, superheat, energy efficiency
ratio (EER) and annual
kWh
values. A key
finding
is that savings vary widely.
17
RESIDENTIAL
HVAC
INSTALLATION
PRACTICES: A
REVIEW
OF
RESEARCH
FINDINGS
16
Henderson, Hugh I., Jr, and Don B. Shirey, III. Closing the Gap: Getting Full
Performance
from Residential
Central Air Conditioners. University of Central Florida Florida Solar Energy
Center: Orlando, FL.
April
27, 2007.
http://www.fsec.ucf.edu/en/publications/pdf/FSEC-CR-1716-07.pdf
This report provides a
summary
of the National
Association
of State Energy
Officials (NASEO)/
State
Technologies Advancement Collaborative
(STAC) Task 4 to develop
specifications
for a residential
air
conditioner
system optimized
for
hot-humid
climates. The project
complements
efforts by the
California
Energy
Commission
(CEC) and the New York State Energy Research and
Development Authority
to develop residential
AC systems
optimized
for hot-dry and norther
climates,
respectively.
Key
findings
include the following. When a conventional CAC with a seasonal energy
efficiency
ratio (SEER)
of 13 was used to condition
modeled
houses, the periods of low sensible heat ratios resulted in high indoor
humidity.
Indoor
humidity
levels were higher for
high-efficiency
homes (compared to standard homes)
because AC run times were reduced. Adding continuous
ventilation (ASHRAE
62.2 standard)
significantly
increased the amount of time the indoor
humidity
was high (above 60% relative
humidity)
because outdoor
humidity
was introduced into the houses at an accelerated rate. Oversizing increased
comfort
(decreased
supply fan
runtime
lead to decreased outdoor air that was introduced to the building enclosure through leaky
ducts).
Comfort
was increased (with relative
humidity
dropping below 60%) when the thermostat was set
lower and the AC supply airflow was lowered to 300 CFM. A small standalone
dehumidifier
was found to be a
cost-effective way to reduce indoor relative humidity.
22
Hunt, Marshall, Kristin Heinemeier, Marc Hoeschele, and Elizabeth Weitzel. HVAC Energy Efficiency
Maintenance Study. Report no. SCE0293.01. University of California, Davis: Davis, CA. December 29, 2010.
http://www.calmac.org/%5C/publications/HVAC_EE_Maintenance_Final.pdf
This study
examines
the question of
appropriate
savings attributes, especially as they relate to the EM&V
deemed savings processes. The study reviews six EM&V studies that raised questions about the design and
efficacy
of the
implementation
of
programs
focused on single measure rebate
programs
for refrigerant charge,
airflow,
and ducts (testing and sealing) vs.
implementation
with a holistic QI approach. The study includes a
summary
review of key
publications
and reports from past 20+ years and analyzed
laboratory
test data from
HVAC systems operated with and without faults.
4
Jump, David A., Iain S.
Walker,
and Mark P. Modera. Field Measurements of
Efficiency
and Duct Retrofit
Effectiveness in Residential Forced Air Distribution Systems. Lawrence Berkeley National Laboratory: Berkeley,
CA. 1996. http://aceee.org/files/proceedings/1996/data/papers/SS96_Panel1_Paper15.pdf (Sacramento,
CA)
This report includes a field study of 24
California
homes to
determine
the
potential
savings and improved
delivery
efficiency
from air sealing and insulating ductwork that exists outside of the conditioned space (e.g.,
ducts in attics). The study included tests for
infiltration,
register
airflows,
fan air
flow,
duct
leakage,
and home
characteristics. For several metrics, they measured before and after
insulating/air
sealing the ductwork. The
mean cost to
retrofit
was between $635 and $1,069 (and does not include travel time
fixed
costs); labor was
77% of the total cost. The average reduction in energy
consumption
(due to sealing and insulation) was 18%.
29
Kim, Woohyun. “Fault Detection And Diagnosis For Air Conditioners and Heat
Pumps
Based On Virtual
Sensors.” PhD dissertation. Purdue University: West Lafayette, IN. 2013.
http://docs.lib.purdue.edu/open_access_dissertations/153
This study
attempts
to quantify the
impact
of
installation
faults in refrigerant based HVAC systems. Using
simulations
and virtual sensors, simple models were developed to
estimate
energy
consumption
penalties of
various faults (and costs using
fixed sensor
s).
18
RESIDENTIAL
HVAC
INSTALLATION
PRACTICES: A
REVIEW
OF
RESEARCH
FINDINGS
21
Kim, Woohyun and Braun, James E., "Impacts of Refrigerant Charge on Air Conditioner and Heat Pump
Performance." International Refrigeration and Air Conditioning Conference. Paper 1122. Purdue
University: West Lafayette, IN. 2010.
http://docs.lib.purdue.edu/iracc/1122This report studies the
impact
of
improper refrigerant charging
on
cooling capacity, heating capacity, and
efficiency.
Key
findings
include the following. Undercharge or
overcharge can reduce air conditioner life, capacity, and
efficiency.
For systems with a
fixed orifice
(FXO), there
is a rapid reduction in both cooling
capacity
and energy
efficiency
with decreasing refrigerant charge level. For
systems with TXVs, both
capacity
and
co-efficient
of
performance
(COP) do not decrease
significantly
until the
refrigerant charge level reaches around 70%; when the charge level is under 70%, the TXV becomes fully
open and then the
system
acts like a
system
having a FXO. Based on the situations that are
commonly
encountered in the field, refrigerant
undercharging
in the range of 12-19% can lead to an average reduction
of 12.87% in cooling
capacity
and 7.6% in energy efficiency.
43
Mallay, D. Compact Buried Ducts in a Hot-Humid House. Report no. DOE/GO-102016-4796. National
Renewable
Energy
Laboratory: Golden, CO
. January 2016
https://www1.eere.energy.gov/buildings/publications/pdfs/building_america/compact-buried-
ducts-hot-
humid
pdf
A report that outlines research activities by Home Innovation, a U.S.
Department
of Energy Building America
team with the project goal of developing an
alternative
buried duct
system
that performs
effectively
as
ducts
in conditioned space—ducts that are durable, energy
efficient,
and
cost-effective—in
hot humid climates
(International
Energy Conservation Code
warm-humid Climate
Zone 3A). Key
findings
include:
compact
buried
duct layout can be a practical
alternative
to
installing
ducts inside conditioned space (inside the air barrier);
most savings are achieved by a simpler (reduced length) duct layout that
limits leakage,
conduction loses and
pressure drops (static pressure);
minimum recommendation
of R-8 duct insulation and R-30 attic insulation.
38
NMR Group, Inc. Baseline
Characterization
Market Effects Study of Investor-Owned
Utility
Residential and Small
Commercial
HVAC Quality
Installation
and Quality
Improvement Programs
in California.
CALMAC
Study ID
CPU0102.01.
California
Public Utilities
Commission: San Francisco, CA.
January 14, 2015.
http://www.calmac.org/publications/CPUC_HVAC_Baseline_Market_Study_Final_Report.pdf
This study established a baseline of current
installation
and
maintenance
practices using
information from
a
variety of sources (including other studies,
utility
staff interviews, a survey of 500+ customers, a survey of
245+ contractors, and HVAC distributor interviews). Key
findings
include: 42% of residential contractors were
aware of Air
Conditioning
Contractors of
America (ACCA)
Standard 5 and only 14% say they adhered to it; 10%
say they adhere to
ACCA
Standard 4 Quality Maintenance (QM), but none of the 13 techs observed in the field
(for an
ancillary
study) were
knowledgeable
of
ACCA
Standard 4.
39
Parmenter,
Kelly, Joe
Prijyanonda,
and Donney Dorton. The Coil & Blade
Project:
Combining Field Work and
Interval Data to Measure Impacts. International Energy Program Evaluation Conference: Madison, WI. 2015.
https://www.iepec.org/wp-content/uploads/2015/papers/089.pdf
(Oklahoma)
This study included field data collection that incorporated spot
measurements
and data
logging
of HVAC
system components
to measure the
impacts
of key
maintenance
measures as a function of the sequence in
which they were performed. Key
findings
include: a
methodology
to apply field data to
recommend
a set of
deemed savings, and
demonstration
of using interval data to
disaggregate
the HVAC
equipment
from the rest
of the loads in the home by directly
comparing
the logged data of the HVAC
system components
with whole-
home
15-minute
interval data.
18
Pigg,
Scott. Central Air
Conditioning
in Wisconsin: A
Compilation
of Recent Field Research. ECW Report Number
241-1. Focus on Energy: Madison, WI. May 2008. https://focusonenergy.com/sites/default/
files/centralairconditioning_report.pdf
(Wisconsin)
This report
summarizes the results of
several Wisconsin field studies. Key
findings
include the following. One
field study of 2- versus 3-ton systems indicated the
effect
of downsizing on energy savings or humidity control
was inconclusive. One of the sites showed no difference in
weather-normalized
energy
consumption
(reduced
power
requirements
were
almost exactly
offset by increased run time).
19
RESIDENTIAL
HVAC
INSTALLATION
PRACTICES: A
REVIEW
OF
RESEARCH
FINDINGS
44
Pigg,
Scott, Dan Cautley, and Karen Koski. Improving
Installation
and Maintenance
Practices
for
Minnesota Residential Furnaces, Air Conditioners and Heat Pumps. Report no. COMM-201305222-72623.
Minnesota
Department
of
Commerce,
Division of Energy Resources: St. Paul, MN September 30, 2016
http://mn.gov/commerce-stat/pdfs/card-improving-insullation.pdf (Minnesota)
This report
examines
the savings
potential
(and
program
strategies) associated with QI and
maintenance
of
residential CACs,
ASHPs
and natural gas furnaces in Minnesota. The study includes field based research (100
systems),
market
research, interviews with
installation
actors (contractors, distributors, utilities and others),
and a telephone survey of 700
homeowners.
Key
findings
indicate that price and reputation drive consumer
decisions, and that consumers have little awareness, concern for, or understanding of
installation
issues that
affect the
performance
of the systems they purchase. “Quality” is judged by the
technology
of the
equipment
and the cleanliness and professionalism of the servicing technician. More than half of surveyed households
report having their heating and/or cooling
system
serviced in the last five years; 25% have a
maintenance
service contract; and nearly 50% of households practice continuous air circulation at some point during the
year. Field testing reveals nine out of ten HVAC systems have an
installation
or
maintenance
issue that could
be corrected with an average
improvement
of 12% (± 3) or roughly 100
kWh.
Most cooling
system
opportunities
are related to refrigerant charge and
airflow adjustments.
Methods for
measuring airflow
do not
always agree. CACs in new homes appear to run about 50% more hours and use nearly 70% more energy on
average than CACs in older homes. The higher energy
consumption
is
mainly
due to house size (new homes
on average are a third larger). Higher
operating
hours for new homes may
reflect
lack of shade and/or a
greater propensity for occupants to use their cooling systems. The study showed occupants of newer homes
use their CACs on average 14 more days than occupants in older homes).
19
Proctor, John. AC Sizing, Electrical Peak, and Energy Savings. Report no. 92.086. Proctor
Engineering
Group, Ltd.: San Rafael, CA. June 2009. http://www.proctoreng.com/dnld/
ACSizingElectricalPeakandEnergySavings
pdf
A key
finding
of this study is that there are only very small energy savings available to
homeowners
from
downsizing CACs, but downsizing can produce sizable peak reductions for utilities. Therefore, a case could
be
made
that downsizing should be a high priority for society (even if the
benefit
to an individual is
limited).
One way this can be achieved is by accounting for both peak kW and kWh in cost effectiveness
calculations
(whereas
typically
just kWh is accounted for).
5
Proctor, John. Monitored In-Situ
Performance
of Residential
Air-Conditioning
Systems. Report no. SF-
98-30-4. Proctor
Engineering
Group, Ltd.: San Rafael, CA.
http://www.proctoreng.com/dnld/97501B.pdf
This report
examines
three measured factors that affect
performance:
cooling load, capacity, and attic
temperatures.
Key
findings
include: most
common calculations
for sensible heat load gain are
overestimated
by
50%, and
airflow
and refrigerant charge
installation
issues were found in the systems reviewed.
23
Proctor, John, Rick Chitwood, and Bruce A
Wilcox
.
Efficiency Characteristics
and Opportunities for New California
Homes (ECO). Report no. CEC-500-2012-062.
California
Energy
Commission: Sacramento, CA.
March 2011.
http://www.energy.ca.gov/2012publications/CEC-500-2012-062/CEC-500-2012-062 pdf Northern California)
This report presents results of a two-phase field study of 80 homes meant to develop a baseline to support
more accurate life cycle cost and energy savings
calculations.
Key
findings
include: average AC system
performed
well below
expectations,
experiencing
problems
such as high static pressures in return ducts, low
sensible
capacity
and
efficiency,
and issues with TXV and refrigerant charge. AC
system
issues were
particularly
severe in zoned systems and combined hydronic systems. Phase Two showed that post-repair
measurements
on upgrades to nine HVAC units resulted in an average
efficiency improvement
of 24%.
20
13
Proctor, John, and Gabriel Cohn. Two-Stage High
Efficiency
Air Conditioners: Laboratory Ratings vs. Residential
Installation Performance.
American Council for an Energy Efficient Economy: Washington, DC
http://aceee.org/files/proceedings/2006/data/papers/SS06_Panel1_Paper20.pdf
(Atlantic
region)
This project
monitored
four high SEER air conditioners with dual-stage compressors, TXV
metering
devices, and
high
efficiency
air handlers with ECM fans. One
system
with a single- stage compressor was also
monitored.
Data included capacity, power
consumption,
EER,
indoor/outdoor
tem
perature
and relative humidity. The data
were analyzed to assess the
relationship
between laboratory testing and real world
performance.
The
performance
of installed systems was
significantly
lower than their rated
performance,
especially when the fan
was set to operate “continuously.”
Additionally,
there may be energy and peak load penalties if dual-stage air
conditioners are downsized to meet the home’s actual load.
32
Rhodes, Joshua Daniel.
“Optimal Residential
Energy
Consumption,
Prediction, and
Analysis
” PhD
dissertation. University of Texas: Austin, TX. 2014. https://repositories.lib.utexas.edu/handle/2152/33342
This study
examined
a database of 4,971 energy audits on
single-family
homes in Austin, Texas. Key findings
include: there is a need for better
performing
(installed) HVAC systems, and
inefficiencies
associated with poor
residential
air-conditioning performance aggregated
across a city can be
significant,
especially during peak
periods.
24
Rhodes, Joshua D., Brent Stephens, and Michael Webber. “Using Energy Audits to
Investigate
the Impacts of
Common Air-Conditioning
Design and
Installation
Issues on Peak Power
Demand
and Energy Consumption in
Austin, Texas.” Energy and Buildings 43 (2011): 3271-278. http://built-
envi.com/publications/rhodes_etal_eb_2011 pdf (Austin, TX)
This study analyzes the dataset from 4,971 energy audits
performed
on homes in Austin, Texas from 2009–
2010. The study seeks to quantify the prevalence of typical air-conditioner design and
installation
issues such
as low
efficiency,
oversizing, duct
leakage,
and low measured capacity, and
estimate
the
impacts that
resolving
these issues would have on peak power demand and cooling energy
consumption.
Key findings
include: air-conditioner use in
single-family
residences currently accounts for 17–18% of peak demand, and
improving equipment efficiency
alone could save up to 205 MW, or 8%, of peak demand. The study estimated
31% of systems were oversized, leading to up to 41 MW of excess peak demand.
Replacing
oversized systems
with correctly sized higher
efficiency
units has the
potential
for further savings of up to 81 MW. The study
estimates
that the mean
system
could achieve 18% and 20% in cooling energy savings by sealing duct leaks
and servicing their
air-conditioning
units to achieve 100% of
nominal
capacity, respectively.
7
Siegel, Jeffrey, Iain
Walker,
and Max Sherman. Delivering Tons to the Register: Energy
Efficient
Design and
Operation of Residential Cooling Systems. Lawrence Berkeley National Laboratory: Berkeley, CA. May 1, 2000.
http://escholarship.org/uc/item/9mn7j9fp
This paper
examines bringing
the HVAC
system
inside the
thermal
and air
leakage
envelope,
locating
it in a
conditioned attic that is insulated and sealed at the
roofline
and is well connected to the house. A key finding
is that both field
measurements
and
simulation
results show that houses with ducts located in conditioned
attics have
dramatically
increased cooling
performance
and lower energy
consumption
than houses with
ducts in conventional attics. However, the
marginal benefit
of
improving
an air
conditioning system
once it is
in a conditioned attic is small; the largest part of energy savings come from insulating and sealing the attic.
21
RESIDENTIAL
HVAC
INSTALLATION
PRACTICES: A
REVIEW
OF
RESEARCH
FINDINGS
12
Sonne, Jeffrey K., Danny S. Parker, and Don B. Shirley, III. Measured Impacts of Proper Air Conditioning
Sizing in Four Florida Case Study Homes. Report no. FSEC-CR-1641-06. University of Central Florida Florida
Solar Energy Center: Orlando, FL. October 25, 2006. http://www.fsec.ucf.edu/en/ publications/pdf/FSEC-CR-
1641-06.pdf (Cocoa, FL)
This paper presents a
summary
of the
NASEO/STAC
Task 3.2 project
examining
the
benefits
of proper sizing
through field testing of four case study homes in Florida (and additional homes tested in Wisconsin). Of four
right-sized systems, only one saw lower energy use; however, that house’s
system
was not appropriately
installed for a
hot-humid
climate. The authors observed that loads were increased on two of the systems in the
afternoons (late day heat gain), which the authors attribute to return side duct
leakage.
Systems that are right-
sized (lower compared to oversized) need to run longer to
dehumidify.
However, if there is return duct leakage
of
hot/humid
outdoor air can
overwhelm system performance
and may cause increased energy use (the
location of the return ducts can influence this effect, such as return ducts located in the attic). Energy
savings had more to do with
technology
upgrades and SEER
performance
than with right-sizing.
40
Steiner, Ellen, and Todd Malinick. California HVAC Quality
Installation/Quality
Maintenance Customer Decision-
Making Study. EMI Consulting: Seattle, WA.
April
15, 2015. http://www. emiconsulting.com/assets/CDM-
Report-2015-04-15-FINAL.pdf
This study presents anecdotal evidence of how QI (and HVAC in general) are perceived in the
marketplace
from
a
homeowner/customer
perspective and presents the
information
on customer’s
relationship
with the HVAC
marketplace. The purpose of this study is to better understand the
customer
perspective, and how industry
could use this understanding to
improve QI
market penetration
.
33
Stephens, Brent. “The
Impacts
of Duct Design on Life Cycle Costs of Central
Residential
Heating and
Air-Conditioning
Systems.” Energy and Buildings (2014) http://built-envi.com/wp-content/uploads/2012/04/
stephens-2014-enb-lcc-duct-design-unformatted
pdf
This report presents
simulation-
based and predictive
modeling
studies of two typical new
single-family homes
f
or
two separate
climates:
Austin, Texas and Chicago, Illinois. The study tries to predict the
impacts
of various
external static pressure ductwork designs from independent HVAC contractors (using both
flexible
and rigid
sheet
metal
ductwork
materials).
A key
finding
is that lower pressure ductwork is
generally
more efficient,
particularly
in homes with PSC blowers.
41
Sullivan, Michael, Jesse Smith, Kausar
Afrat,
and Phil Bosco. Impacts of the OPA HVAC Installation
Optimization
Training
Program
on Realized Energy
Efficiency
of
Retrofit
AC Systems.
International
Energy
Program Evaluation Conference: Madison, WI. 2015. https://www.iepec.org/wp-
content/uploads/2015/papers/087.pdf
This report supports the need for QI. Key
findings
include: contractor training (a one-day, eight-hour
)
did not
improve
installation
practices; about 20% of the
efficiency
of newly installed air conditioners is lost at the time
of installation.
20
Talerico, Tom, and Rick Winch. Focus on Energy Evaluation: ECM Furnace Impact
Assessment
Report. Focus
on Energy: Madison, WI. January 12, 2009. https://f
ocusonenergy
.com/sit
es/def
ault/files/
emcfurnaceimpactassessment_evaluationreport
pdf
This paper describes a study in Wisconsin designed to update a previous
impact
analysis report for furnaces
with ECMs. The authors interviewed
homeowners
(participants and non-
participants)
and contractors. Key
findings
include:
many homeowners
with furnaces with an ECM
increase the
frequency of
operating
their
furnace fan continuously; advice from HVAC contractors plays a pivotal role in
homeowner’s
decision to
increase fan operation; and HVAC contractors are more
likely
to tell
homeowners
to increase their fan
operation if they install an ECM furnace versus a non-ECM furnace.
22
14
Titus, Elizabeth. Strategies to Increase Residential HVAC
Efficiency
in the Northeast. Northeast Energy
Efficiency
Partnerships: Lexington, MA. May 2006.
https://forum.cee1.org/system/files/library/1330/508.pdf
Recommendations
from this report include: continue central AC rebates but in conjunction with a quality
installation verification
(QIV) requirement, and provide QIV for all central AC installations.
42
Vaidya, Rohit, Cathy Fogel, Betty Tolkin, and Beth Poulin.
Swimming
Against the Tide--Gauging HVAC Quality
Installation
and Quality Maintenance
Program
Efforts to Establish a Foothold in the Market. NMR Group:
Somerville, MA2016. http://www. nmrgroupinc.com/wp-content/uploads/2016/03/Swimming-Against-the-
Tide.pdf
This study
estimated
the proportion of contractors adhering to QI and QM practices, gauged
customer
and
contractor awareness of QI,
identified
barriers to QI, and
examined
contractor QI and QM
compliance
via field
observation. Key
findings
include the following. The field study (for
impact
evaluations) found that the
baseline
assumptions
(f
or
oversizing, duct
leakage,
and
system airflow)
were
generally
not as poor as
assumed by the QI program. The study did not include
examination
of
verification
of refrigerant charge.
Findings suggest that compliance with, awareness of, and
willingness
to pay for QI/QM is weak. Customers
tend to favor contractors who do the job the fastest and for the least amount of money. In California, it was
estimated
that a quarter of the 15,000-19,000 contractors are unlicensed, and that licensed contractors are
therefore “caught between the pincers of a supply side and demand side squeeze.” On the demand side,
customers are not
demanding
(nor
willing)
to pay for QI. On the supply side, licensed contractors are
competing
with unlicensed contractors in the “race to the
bottom.
”
10
Walker,
Iain S. Register Closing Effects on Forced Air Heating System Performance. Report no. LBNL-
54005. Lawrence Berkeley National Laboratory: Berkeley, CA. November 1, 2011. https://www.osti.
gov/scitech/biblio/822806
A lab
oratory
study that that used a test chamber to evaluate the
impact
of closing registers on duct pressures,
duct
leakage,
air handler
airflow,
air handler power
consumption,
and envelope pressure. The study found that
closing registers
generally
does not save energy, unless the ducts are very tight and the envelope is fairly
pourous.
15
Walker,
I.S. Residential Furnace Blower Performance. Report no. LBNL-61467. Lawrence Berkeley National
Laboratory: Berkeley, CA. October 2006. https://eta.lbl.gov/sites/default/files/publications/lbnl-61467.pdf
This study assessed the
performance
of furnace blowers and the
potential
cost-effectiveness of setting
performance
standards in
California
and changing
motor technologies
from PSC blowers—
dominant
in the
market—with
a brushless
permanent
magnet (BPM) blower. The
benefits
of BPM motors depend
strongly
on
interactions
with the rest of the duct system. A key
finding
is that
potential
energy savings for BPM blowers
may not be realized because of existing ductwork, e.g., the high static pressures that are prevalent in existing
residential duct distribution systems. The existing high static pressures are
difficult
to reduce, due to
the presence of
filters
and cooling coils that account for more than half of the
system
static pressure. For both
heating and cooling, pressure reductions can be achieved through these key duct distribution improvements:
• Use of larger or
multiple
returns
• Use of low pressure
filters
–
promote
the use of 4-inch deep pleated filters
• Use of larger air
conditioning
coils to reduce coil pressure drop
• Use of more
compact
duct systems with shorter duct runs
• Careful installation: reduce number of elbows and
make
duct runs as straight as possible
• Encourage use of sheet
metal
duct instead of
flexible
duct
23
RESIDENTIAL
HVAC
INSTALLATION
PRACTICES: A
REVIEW
OF
RESEARCH
FINDINGS
27
Walker,
Iain, Darryl Dickerhoff, David Faulkner, and
Will
Turner. Energy
Implications
of In-Line
Filtration in
California. Report no. CEC-500-2013-081.
California
Energy
Commission: Sacramento, CA.
June 2012.
http://www.energy.ca.gov/2013publications/CEC-500-2013-081/CEC-500-2013-081.pdf
This study
performed measurements
in ten
California
houses to
determine
the effects of
filter performance
on
the energy use of central heating and cooling systems. Multiple
filters
were evaluated covering a range of filter
effectiveness. Generally, the higher
minimum efficiency
reporting value (MERV) correlates to higher airflow
resistance (but
filter
depth can
complicate
that general
statement).
Per the
findings,
general recommendations
are:
•
Recommended
MERV 11 or less –
(moderate
energy impact: less than 5%)
•
Recommended
MERV 16 only be used in low
leakage
duct systems as it pushes blower to the
limit
and
causes excess noise
• Thickness: 4-inch
filters
fare better than 1- or 2-inch filters
6
Walker,
I., M. Sherman, M. Modera, and J. Siegel. Leakage Diagnostics, Sealant Longevity, Sizing and
Technology Transfer in Residential Thermal Distribution Systems. Lawrence Berkeley National Laboratory:
Berkeley, CA. January 1998. https://www.osti.gov/biblio/650258-leakage-diagnostics-sealant-longevity-sizing-
technology-transfer-residential-thermal-distribution-systems
A study of 17 homes in which measured duct
leakage
(to outside of the conditioned space) and sealant
longevity.
A key
finding
is that there was a large range of duct
leakage
from house to house, even in the new
houses that all had the same house and HVAC
system
design, and in some cases the same HVAC contractor.
This large variation indicates that the specific
installation
rather than
system
design is the
determining f
actor
f
or
duct
leakage
and
implies
that any test for duct
leakage
used for
compliance
or screening purposes must be
able to distinguish between individual systems.
11
Wilcox,
Bruce A., and James Larsen. Measured Cooling Load, Energy, and
Peak
Demand Savings from
High-
Performance
Glass in a California Production House.
ASHRAE: Washington, DC.
2004.
http://web.ornl.gov/sci/buildings/conf-rchive/2004%20B9%20papers/129_Wilcox.pdf
This study
examines
the
impacts
of glass glazing and HVAC
system
size in two production houses in California.
For one production house, the AC
system
was downsized (by one ton), but the ducts were not replaced (leaving
them as oversized). Results indicated losses from the extra surface area (of the oversized ducts) slightly
reduced the
efficiency
of the new smaller system. Static pressure and fan energy could have been reduced
with the smaller system, but the better glass actually increased the relative fan energy.
17
Wirtshafter,
Robert M., Greg Thomas, Gail
Azulay, William
Blake, and Ralph Prahl. Do Quality Installation
Verification Programs
for Residential Air Conditioners Make Sense in New England? International Energy
Program
Evaluation Conference: Madison, WI. 2007. https://www
.iepec.org/conf-docs/papers/200
7P
aper
sT
OC/
papers/111_1114_ab_648.pdf
This study examined the effectiveness of QIV
programs
as they relate to peak demand savings
opportunities
in New England. The study concluded that QIV
programs
cannot be justified unless the AC systems have
excess
capacity
at
system
peak, a situation that only occurs in simulations for systems that are more than
40% oversized according to Manual J. If systems have
insufficient capacity
at
system
peak,
efficiency
gains
produced by air
flow
and refrigerant charge will not reduce peak demand.
24
8
XENERGY, Inc. New Jersey Residential HVAC Baseline Study. NJ Clean Energy Program, New Jersey Board
of Public Utilities: Trenton, NJ November 16, 2001.
http://njcleanenergy.com/files/file/Library/Xenergy%20HVAC.pdf (New Jersey)
A baseline study conducted in New Jersey on the supply and demand sides of the HVAC
market
for energy
efficiency
savings. The study includes field data, customer decision
making
data, and contractor segmentation
data. The key
findings
include:
•
Efficiency:
On average, cooling systems were oversized by 23%; 53% of measured
airflows
were less than
the
manufactures recommendation
of 350 cubic feet per
minute
(CFM) per ton. Duct
leakage
data analysis
for this study
estimated
an average outdoor air
leakage
rate of 329 CFM25; 68% of systems were not
charged properly (47% were undercharged and 21% were overcharged). Results of the on-site visits clearly
show that the greatest
potential
to save energy is through reduction of duct
leakage
to outdoors and
refrigerant
charge correction.
•
Contractor/Customer Relationship:
62% of
sample
customers reported that they solicited bids from only one
contractor (and 55%
identified
their contractors through
recommendations
from friends and
family).
At the
same time, 71% reported that their contractor was the only source of
information
they used in
making
their
equipment
selection decisions and
additionally
91% selected the model
recommended
by the contractor.
Ninety-four percent of customers reported they were
satisfied
with the
equipment installation
services they
received (even though most customers surveyed could not
technically define
quality installation).
• Contractor
Segmentation:
The largest 39 contractors (representative of 2% of the contractor
network)
install
nearly 30% of the systems. Ninety-four percent of the contracting
companies
have nine or fewer
employees
(and represent the two
smallest
buckets as far as number of
installations
per company). As a whole, these
companies account for 58% of the installations.
30
Yee, S., J. Baker, L. Brand, and J. Wells. Energy Savings from System
Efficiency Improvements
in Iowa’s HVAC
SAVE
Program.
Report no. DOE/GO-102013-4164. U.S.
Department
of Energy, Building Technologies Office:
Washington, DC
. August
2013. https://
www1.eere.energy.gov/buildings/publications/pdfs/building_america/iowa_hvac_save_project.pdf
A report on a pre- and post-furnace repair field study of 48 homes,
examining installation
faults and their
prevalence. A more in-depth study of ten of the homes with tune-ups or
replaced/modified
ducts was also
conducted. Key findings include the following.
Delivering
up to 23% more energy from the furnace to the
conditioned space via
system
tune-ups with or without furnace upgrades is possible.
Delivering 80%-90%
of
furnace-generated
heat to the conditioned space is possible. Residential HVAC
equipment
should be tested
and
improved
as a
system
rather than a collection of distinct components.
28
Yuill, David
P.
, and James E. Braun. Evaluating Fault Detection and Diagnostics
Protocols
Applied to
Air-Cooled
Vapor Compression Air-Conditioners. Purdue University: West Lafayette, IN. 2012.
http://docs.lib.purdue.edu/cgi/viewcontent. cgi?article=2306&context=iracc
This paper presents lab data from 13 air
conditioning
systems to evaluate how well FDD protocols in tools
perform,
particularly
in the absence of any standard
method
of
measuring
the
performance
of FDD. Key
findings
include the following. As there is no standard
method
(protocol) for creating and
evaluating
faults,
the authors
recommend
a standard protocol be developed. Since tools use different and varying protocols
to diagnose FDD, assessing a tool’s
performance
is
complicated.
Because there is no FDD protocol, the
tools being deployed in the
market
do not measure the same things with the same accuracy, which is
leading to false alarms,
misdiagnosis
alarms, missed detection alarms, and no alarms when conditions
indicated an alarm should have posted.
25
RESIDENTIAL
HVAC
INSTALLATION
PRACTICES: A
REVIEW
OF
RESEARCH
FINDINGS
Appendix
C:
Questions
on HVAC
Installation Practices
for
Industry Stakeholders
DOE gathered input from industry representatives attending DOE’s Building Technologies Office Peer Review
Meeting: Smart Tools for Improving Installed Performance of Residential and Small Commercial HVAC Systems
Expert Meeting held on March 16, 2017. A list of questions was distributed to stakeholders at that meeting as an
aid to guide further input and identify additional source documents to be included in this review. The table below
includes the questions posed during that search process.
Table 5: Questions on HVAC Installation Practices for Industry Stakeholders
1
Are there resources published prior to
September
2014 that were not included in NIST’s report and would add
supplementary information
to DOE’s current efforts?
2
Are there resources published subsequent to
September
2014 that would
supplement
the NIST
findings
and
DOE’s current efforts?
3
Are there
limitations
or concerns with the
methodologies
used in existing research studies that DOE should
consider when assessing the results and
applying regional
results nationally?
4
Field data regarding the prevalence of specific HVAC
system performance degradation
in existing homes is not
widely
available. Are there relevant sources of field data that would provide additional
clarity
around this gap?
5
How resilient is today’s HVAC
equipment?
Can
technology advancements
(e.g. variable speed/capacity
equipment)
help
mitigate
the
impact
of various faults on
electricity consumption
or other
performance
issues?
6
The
majority
of research, study, and
evaluation
has focused on the supply side (contractors and programs) A
recent study by NMR in CA
identified
a need for more demand side work to better understand the barriers and
drivers of customers’ HVAC purchasing decisions Is this approach being pursued in other regions?
7
The issue of
quantifying
savings remains, are there
alternative
means by which EM&V can be
improved
to help
in cost effectiveness tests?
8
Ducts – how
important
are they and when (and where) are they the most
important?
2018 IECC includes
buried ducts and some studies suggest savings are greater for
encapsulating
ducts
(bringing
in the thermal
envelope) than through QI measures (at least in certain
climate
zones).
9
Sizing – how is equipment sizing addressed by the HVAC industry? Has the industry’s approach to sizing been
updated to reflect findings from research on HVAC quality installation practices?
26
27
For more information, visit:
ene
rgy.go
v/eere
DOE/EE-1699 •
May
2018
