United States	Indoor Environments	EPA-402-S-01-001G
Environmental	Division (6609J)	January 2000
Protection	Office of air and Radiation
Agency	
Energy Cost and IAQ
Performance of Ventilation
Systems and Controls
Report # 7
The Cost of Protecting Indoor Environmental
Quality During Energy Efficiency Projects for
Office and Education Buildings
Integrating Indoor Environmental Quality with Energy Efficiency

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Energy Cost and IAQ Performance of Ventilation Systems
and Controls
Project Report # 7 The Cost of Protecting Indoor Environmental Quality
During Energy Efficiency Projects for Office and
Education Buildings
Integrating Indoor Environmental Quality with
Energy Efficiency
Indoor Environments Division
Office of Radiation and Indoor Air
Office of Air and Radiation
United States Environmental Protection Agency
Washington, D.C. 20460
January 2000
Energy Cost and IAQ Performance of Ventilation Systems and Controls
Energy Cost and IAQ
Report # 7

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Project Report # 7 The Cost of Protecting Indoor Environmental Quality During Energy
Efficiency Projects for Office and Education Buildings
Integrating Indoor Environmental Quality with Energy Efficiency
INTRODUCTION
Purpose and Scope of this Report
Many building owners and managers are under increased pressure from many circles to
provide good indoor environmental quality (IEQ). There are many opportunities to advance IEQ
during the course of energy projects without sacrificing energy efficiency. These opportunities
could provide the energy service companies and other energy professionals with the ability to
gain a competitive edge as they market their services to a clientele that is becoming
increasingly sensitive to indoor environmental quality issues. Many energy professionals believe
that IEQ necessarily leads to significant energy penalties and therefore deliberately ignore it in
their projects.
Relationship between Energy Efficiency and Indoor Environmental Quality
Many actions taken to improve energy efficiency have a secondary effect on the quality of the
indoor environment. This secondary effect may be to improve indoor environmental quality
(IEQ), leave IEQ relatively unaffected (provided that certain cautions and adjustments are
adhered to), or degrade IEQ, sometimes substantially.
The indoor environmental factors that most influence occupant health and welfare are the
thermal conditions, the lighting, and the concentrations of indoor pollutants. Thermal control and
lighting are familiar subjects in energy management. Accordingly, energy professionals are in a
strong position to affect these two important aspects of the indoor environment. However,
energy professionals are often less knowledgeable about the third factor-indoor pollutant
concentrations. Although they are often responsible for the design, control, and modification of
the ventilation systems, energy professionals are often not fully aware of the resulting effects of
these systems on IEQ.
Much of the perceived conflict between IEQ and energy efficiency results from just two elements
of an energy strategy- the tendency to minimize outdoor air ventilation rates, and the willingness
to relax controls on temperature and relative humidity to save energy. Some energy activities
that are compatible with IEQ, either because they are likely to enhance or have little effect on
IEQ if properly instituted, are suggested in Exhibit 1. The compatibility with IEQ is critically
dependent on the cautions and adjustments which are outlined in this exhibit. Some energy
projects may inadvertently or needlessly degrade the indoor environment. The energy project
activities that are judged to have the greatest potential for degrading the indoor environment are
listed in Exhibit 2
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The purpose of this report is to help reconcile the desire to provide a quality indoor environment
that supports the health and comfort of occupants, with the very important objective of reducing
energy use. This report suggests strategies by which energy professionals can design projects
for clients that result in both improved energy efficiency and improved indoor environments.
Background
This is a modeling study, subject to all the limitations and inadequacies inherent in using models
to reflect real world conditions that are complex and considerably more varied than can be fully
represented in a single study. Nevertheless, it is hoped that this project will make a useful
contribution to understanding the relationships studied, so that together with other information,
including field research results, professionals and practitioners who design and operate
ventilation systems will be better able to save energy without sacrificing thermal comfort or
outdoor air flow performance
The methodology used in this project has been to refine and adapt the DOE-2.1 E building
energy analysis computer program for the specific needs of this study, and to generate a
detailed database on the energy use, indoor climate, and outdoor air flow rates of various
ventilation systems and control strategies. Constant volume (CV) and variable air volume
(VAV) systems in different buildings and with different outdoor air control strategies under
alternative climates provided the basis for parametric variations in the database.
Seven reports, covering the following topics, describe the findings of this project:
	Project Report #1: Project objective and detailed description of the modeling methodology
and database development
	Project Report #2: Assessment of energy and outdoor air flow rates in CV and VAV
ventilation systems for large office buildings:
	Project Report #3: Assessment of the distribution of outdoor air and the control of thermal
comfort in CV and VAV systems for large office buildings
	Project Report #4: Energy impacts of increasing outdoor air flow rates from 5 to 20 cfm per
occupant in large office buildings
	Project Report #5: Peak load impacts of increasing outdoor air flow rates from 5 to 20 cfm
per occupant in large office buildings
	Project Report #6: Potential problems in IAQ and energy performance of HVAC systems
when outdoor air flow rates are increased from 5 to 15 cfm per occupant in
auditoriums, education, and other buildings with very high occupant density
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 Project Report #7: The energy cost of protecting indoor environmental quality during energy
efficiency projects for office and education buildings
DESCRIPTION OF THE BUILDING AND VENTILATION SYSTEMS MODELED
A large 12 story office building and an L shaped 2 story education building were modeled in
three different climates representing cold (Minneapolis), temperate (Washington, D.C.), and
hot/humid (Miami) climate zones. The office building has four perimeter zones corresponding to
the four compass orientations, and a core zone. The education building has 6 perimeter zones
representing the four compass directions, and two core zones. A single duct variable volume
(VAV) system was modeled for both buildings. VAV systems alter the supply air volume while
maintaining a constant supply air temperature.
Three basic outdoor air control strategies were employed: fixed outdoor air fraction (FOAF),
constant outdoor air (COA), and a temperature-controlled air-side economizer (ECONt). The
FOAF strategy maintains a constant outdoor air fraction (percent outdoor air) irrespective of the
supply air volume, and is commonly represented in field applications by an outdoor damper in a
fixed position. The COA strategy maintains a constant volume of outdoor air irrespective of the
supply air volume. In a CV system, the FOAF and the COA strategies are equivalent. In a VAV
system, the COA strategy might be represented in field applications by a modulating outdoor
air damper which opens wider as the supply air volume is decreased in response to reduced
thermal demands, or by a dedicated outdoor air fan. Economizers use additional quantities of
outdoor air to provide "free cooling" when the outdoor air temperature (or enthalpy when
enthalpy economizers are employed) is lower than the return air temperature (or enthalpy). The
quantity of outdoor air is adjusted so that the desired supply air temperature (or enthalpy) can
be achieved while using as little chiller energy as possible.
A more detailed description of the building and ventilation systems is provided in Report #1.
APPROACH
Energy simulation modeling using the DOE-2.1 E computer program was used to estimate the
relative energy impacts of various energy efficiency measures and of selected indoor
environmental controls. This was done in the context of a staged energy retrofit program for an
office building and an education building in the three representative climates. The staged
retrofit included operational (tune-up) measures in Stage 1, load reduction measures in Stage
2, air distribution system upgrades in Stage 3, central plant upgrades in Stage 4, and selected
IEQ upgrades in Stage 5. The building and HVAC parameters of the base office and
education buildings that were modeled are presented in Exhibit 3. Elements of Exhibit 1 that
describe adjustments to energy activities required to protect IEQ are implicit in the modeling of
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these activities of Stages 1 -4. Specific improvements to the outdoor ventilation rate and
controls to improve IEQ are modeled in Stage 5.
Both buildings were modeled with a variable air volume ventilation system with an air side
temperature-controlled economizer. The office building has a fixed outdoor air damper set to
circulate 5 cfm of outdoor air per person at design load. The education building was modeled
using damper controls to circulate 5 cfm of outdoor air per occupant at all load conditions
(constant outdoor airflow). Ventilation rates and controls were adjusted in Stage 5 to meet all
the requirements of ASHRAE Standard 62-19991.
RESULTS
Energy Savings from Stages 1-4
Exhibits 4 and 5 present the energy cost results from the staged energy activities for the office
building and the education building respectively. Exhibit 6 presents the percent savings (from
the base and from the previous stage) of total energy costs for both buildings.2 Stage 1
included only a simple seasonal supply air temperature reset strategy which increased the
supply air temperature from 55F to 65F from January 1 to March 31 in each climate.
Therefore, it does not reflect an optimal control logic for the fans and chiller. As a result, the
energy results from stage 1 are not substantial, and do not reflect the values that could be
achieved with a more sophisticated control strategy. For example, in the temperate climate of
Washington D.C., the seasonal supply air temperature reset strategy in Stage 1 resulted in
insignificant reductions (1 %) in total energy costs. A greater potential for savings in this stage
would exist in buildings with significant pre-existing operational problems. Other measures
which are typically included in Stage 1 could either not be modeled or were modeled
independently - not part of the staged energy program. These are discussed in a separate
section below.
The largest savings resulted in Stage 2 where a further reduction of 31 % was achieved through
a lighting retrofit and increased efficiency of office equipment. About one fourth of the savings in
Stage 2 resulted from reduced loads to the HVAC system. Stage 3 upgrades relied solely on
variable speed drives (VSD) which reduced the energy costs an additional 8%. Finally, in
Stage 4, central plant upgrades, including down-sizing the equipment because of reduced
1	This project was initiated while ASHRAE Standard 1989 was in effect. However, since the outdoor air flow rates for
both the 1989 and 1999 versions are the same, all references to ASHRAE Standard 62 in this report are stated as ASHRAE
Standard 62-1999.
2
Total energy costs are defined here to include only energy from HVAC, lighting, and office equipment.
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loads3 added another 13% to the total energy savings, bringing the combined savings to 45%.
These results are consistent with EPA's experience in the Energy Star program where typical
lighting retrofits result in 25%-30% savings, while other retrofits result in 5%-15% savings
depending on the particular retrofit and the context of its application.
The results for the office building in Minneapolis and Miami, also shown in Exhibit 4, are similar
with some exceptions. The seasonal supply air temperature reset in Miami added an energy
penalty due entirely to the increase in fan energy with no offsetting savings in cooling energy.
The lighting retrofit achieved greater overall savings in Miami and lower savings in Minneapolis
because of the attendant effects of reduced internal gains on the cost of heating (increase) and
on cooling (decrease). Similarly, the savings from the VSD retrofit were greatest in Minnesota,
where loads are variable, and lowest in Miami where the loads are more constant.
The results for the education building which are shown in Exhibit 5, are similar to the office
building results with some exceptions. Energy savings from lighting and office equipment
retrofits were lower compared to the office building. Since the lighting and office equipment in
the education building constitute a lower proportion of total loads, the secondary savings on the
HVAC system in Stage 2 were less. Finally, the education building experienced greater energy
savings from improved central plant efficiencies in Stage 4 because of the larger loads
compared to the office building.
While many of these activities implemented in Stages 1 through 4 above could impact IEQ, all
the necessary adjustments identified in Exhibit 1 were made or are implicit in the model's
algorithms to ensure that IEQ would not be degraded. Thus, this modeling suggests that it is
quite feasible to cut the energy budget in the office building by 44% - 45%, and in the education
building by 31 %-45% (see Exhibit 6, Stage 4) without adversely impacting a building's IEQ,
though this does not include the energy impacts of increasing outdoor air ventilation.
3 The equipment was downsized, but the final sizing was designed to accommodate increased
outdoor air flow of 20 cfm/occ for the office building, and 15 cfm per occupant for the education
building as per ASHRAE Standard 62-1999.
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Energy Impacts from Stage 5: Increasing Outdoor Air Ventilation to Meet
ASHRAE Standard 62-1999
The base buildings provided only 5 cfm of outdoor air per occupant (i.e. does not meet the
current ASHRAE ventilation requirements for indoor air quality (ASHRAE Standard 62-1999)).
To meet these requirements, a set of IEQ controls were instituted as part of Stage 5. The first
control was to raise the outdoor air control setting at the air handler to 20 cfm per occupant in
the office building, and 15 cfm per occupant in the education building. This increases the
outdoor air design flow rate, but since the office building has a variable air volume system with
constant outdoor air fraction (VAV(FOAF)) control strategy, ASHRAE Standard 62-1999
requirements are not met at part- load conditions (see Project Report #3). To solve this
problem, the fixed fraction outdoor air strategy was replaced with a constant outdoor air (COA)
flow control in the office building. This control allows the outdoor air flow rate to remain at the
design level even at part-load.
The education building was already modeled with a constant outdoor air flow control in the base
case. However, in order to satisfy the requirement of ASHRAE Standard 62-1999, the following
two additional adjustments were implemented in Stage 5. First, the VAV box minimum settings
in the education building needed to be adjusted upward. In both the office and education
building, the VAV box minimum settings are typically set at about 30% (of peak flow).
Unfortunately, because of the high occupant densities in the education building, when the
outdoor airflow is raised from 5 to 15 cfm per occupant, the outdoor air requirement was
sometimes greater than the supply air needed for thermal comfort alone (see Project Report
#6). In other words, the HVAC controls in education buildings and other buildings with high
occupant density become ventilation-dominated as opposed to thermally- dominated (Report
#6). As a result, the requisite 15 cfm per occupant is only achieved a portion of the time at
typical minimum VAV box settings. Therefore, the minimum flow settings in the VAV boxes were
adjusted upwards to ensure 15 cfm per occupant during all periods.
The second adjustment required for the education building was to increase control over
humidity. The relative humidity at outdoor air ventilation rates of 15 cfm of outdoor air per
occupant can sometimes rise above 60% and occasionally above 70% (Project Report #6).
This situation causes thermal discomfort and adds to the potential for microbiological
contamination. The problem with excess humidity was most dramatic, though not limited, to the
Miami climate. Relative humidity was maintained at 60% or less by lowering the cooling coil
temperature when required to meet the latent load. The VAV box and humidity controls were
instituted for the education building as part of Stage 5.
The results of these ventilation modifications for the office and education building are presented
at the end of Exhibits 4 -6. For the office building, the energy used to increase outdoor air flows
to meet ASHRAE 62-1999 raised total energy cost of the Stage 4 retrofitted building by 3-4% in
all climates- much less than many energy practitioners expect. In fact, when compared to the
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base (pre-retrofitted) building, the energy savings foregone by instituting these controls was only
2% - 3%. These results are consistent with other studies (Project Report #4, Eto and Meyer,
1988, Eto, 1990; Steele and Brown, 1990; Ventresca, 1991). This is because, during a large
portion of the year, bringing in additional outdoor air provides free cooling and reduces cooling
energy use. In HVAC systems with economizers already installed, the energy penalty from
higher outdoor airflows is only experienced in extreme weather conditions, and mostly during
the summer months. In the winter months, economizer operation may still provide 20 cfm of
outdoor air per occupant in office buildings with adequate freeze stat controls, even with outdoor
air temperatures as cold as 0 F (Project Report #4; Ventresca, 1991). In HVAC systems
without economizers, the higher outdoor airflows act as an implicit economizer by providing
some degree of free cooling during most of the year.
In the education building, meeting ASHRAE Standard 62-1999 increased total energy costs of
the retrofitted Stage 4 building by 5% -14%. Compared to the base (pre-retrofitted building),
this means that the energy savings foregone as a result of these controls was only 3% - 9%.
Interestingly, the adjustments for outdoor air and humidity control for the education building had
the highest energy penalty (13-14% from Stage 4) in Washington D.C. and in Minneapolis, but
in Miami, the energy penalty was only 5%. This runs contrary to conventional wisdom but is
explained by the fact that in temperate and cold climates, there is a substantial heating penalty
associated with the outdoor air adjustments which was not present in Miami (Project Report
#4). Another counter-intuitive phenomenon is evident in Miami. Increasing the outdoor air
setting accounted for a substantial energy penalty (7%) from Stage 4. However, the VAV box
and humidity controls reduced the increase to only 5%. This is because by lowering the cooling
coil temperature when needed to control humidity, a considerable reduction in fan energy was
achieved that more than offset the increase in cooling energy.
Raising the outdoor air flow in this energy retrofit scenario also limits how much equipment can
be downsized. The sizing requirements for the boiler and chiller with and without the indoor
environmental controls are presented in Exhibit 7. If the outdoor air adjustments and humidity
controls identified above were not included in this retrofit (no IEQ controls), the chillers could
have been downsized to 75%-77% of the base for the office building and 86% - 90% of the
base in the education building. However, by raising the outdoor air design flow rates, insuring
that rate is achieved under full and part load conditions, and controlling relative humidity to
below 60%, downsizing was limited to 90%-99% of the base in the office building, while in the
education building, the size of the chillers had to be increased from 104%-109% of the base.
Boiler capacity must generally be increased in energy efficiency projects because of the
reduced internal heat gains from more efficient lights, office equipment, and plant, but the IEQ
controls add additional boiler size requirements over the base condition.
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Measures to Mitigate the Energy Cost of Outdoor Air Ventilation
At higher occupant densities, such as in education buildings, satisfying ASHRAE Standard 62-
1999 requires a substantial increase in outdoor air and this can create a substantial energy
penalty. Outdoor air ventilation with an energy recovery system thus becomes an attractive
method for reducing the energy cost of this ventilation requirement. Unfortunately, DOE-2.1 E
does not have capabilities which are sufficiently sophisticated to reliably model energy recovery
technologies (especially latent heat recovery). However, available literature suggests that
energy recovery systems can eliminate or substantially reduce the energy penalty created by
raising outdoor air levels to meet ASHRAE Standard 62-1999 in office buildings in hot and
humid climates (Rengarajan, et al. 1996; Shirey and Rengarajan, 1996). The efficiency of
energy recovery systems range from 50% -75%. Thus, while the cost of increasing outdoor air
ventilation rates to15 cfm year round with humidity controlled in education buildings was 5% -
14% over Stage 4, this could well be reduced to 3% to 7% with the use of energy recovery.
Reductions in capacity requirements would also be possible.
Stage 1 Measures with Potentially Adverse IEQ Impacts
Many energy measures with significant potential to adversely impact IEQ occur in Stage 1, and
involve either relaxing temperature (and humidity) controls and/or reducing HVAC operating
hours. Exhibit 3 identifies modeling scenarios for relaxing daytime temperature controls, night
time temperature controls, and HVAC operating hours. These scenarios were modeled
separately and were not included in the staged energy retrofit project. Exhibit 8 summarizes the
results of these modeling runs.
Widening the day time temperature dead band from 71-77 F to 68-80 F reduced energy costs
by 2% -3% in the office building, and by 7%-8% in the education building. Relaxing the night
time temperature setback from +/-10F to +/-15F reduced energy costs from 1 % - 2% in the
office and from 0% -1 % in the education building. Reducing the HVAC operating time by two
hours (including a reduction of startup time from 2 hours to 1 hour), reduced the energy costs by
0%-1 % for the office building and by 2%-4% in the education building. Had all these measures
been included in Stage 1, the energy reductions in Stage 1 would have increased to 3%-5% for
the office building and to 7%-10% in the education building.
In contrast, other operational measures for Stage 1 that do not degrade IEQ can provide
significantly greater savings. For example, simply commissioning the building to insure that
controls and equipment are functioning properly (not modeled) have been shown to typically
reduce total energy costs by 5%-15%, and also tend to improve IEQ (Gregerson, 1997).
Reducing lighting and office equipment usage during unoccupied hours can also result in
significant savings. The base office building was modeled with lighting during unoccupied
hours operated at 20% of daytime use and office equipment operated at 30% of daytime use.
Exhibit 9 compares the modeling results for this case (20%/30%) with both greater usage
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during unoccupied hours (40% /50%) in Stage 1, and reduced usage (10%/15%) after Stage 4
modifications.
As indicated in Exhibit 9, had the usage of the lighting/office equipment during unoccupied
hours been at 40%/50% of day time levels and then reduced to the 20%/30% that was modeled
in the base building, 12% savings would have been possible in Stage 1 from this activity. This
result is consistent with field data which showed that energy savings of approximately 15% on
average are associated with operational controls (mostly lighting) during unoccupied hours
(Herzog, et al.1992). In addition, an aggressive program to reduce night time use of lights and
office equipment after the building is made energy efficient and IEQ compatible could provide
additional reductions of equal magnitude.
The energy savings from operational controls that could degrade IEQ amounted to only 3% -
10% of total energy costs. Considering the energy savings of 31 % - 45% associated with IEQ-
compatible upgrades through Stage 4, plus the potential for additional savings of 12% or more
from reduced use of lights, and savings of 5% -15% from improved equipment performance,
the energy savings of 3% -10% from controls that are incompatible with IEQ are very small in
comparison. It appears to make little sense to pursue energy reduction activities that
compromise IEQ and run the risk of potential liability of lEQ-related illnesses and complaints,
when the energy saving potential for compatible measures is so much greater in comparison.
CONCLUSIONS
This report suggests that indoor environmental quality need not be detractor to achieving
substantial energy savings in buildings. Energy savings of 31 % - 45% were achieved in a
staged energy retrofit program which was designed to prevent degradation of IEQ. Further
savings in the range of 5% -15% are possible through commissioning (not modeled) plus 12%
or more from reduced lighting and office equipment use during unoccupied hours. Instituting all
the controls needed to meet the outdoor air and humidity requirements of ASHRAE Standard
62-1999 increased the energy cost of the Stage 4 retrofitted building by only 3% - 4% in the
office building, but by 5% -14% in the education building. However, when measured against the
base (pre-retrofitted) building, these increases mean that the energy savings foregone because
of ASHRAE Standard 62-1999 requirements were only 2% -3% for the office, and 3% - 9% for
the education building. Similarly, the outdoor air and humidity requirements limited the degree
to which chillers and boilers could be downsized. However, the use of energy recovery
technology is likely to either eliminate or substantially reduce that penalty, and allow for greater
downsizing of chillers and boilers.
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BIBLIOGRAPHY
Eto, J., 1990. The HVAC costs of increased fresh air ventilation rates in office buildings, part 2.
Proc. Of Indoor Air 90: The Fifth International Conference on Indoor Air Quality and Climate.
Toronto.
Eto, J., and C. Meyer, 1988. The HVAC costs of fresh air ventilation in office buildings.
ASHRAE Transactions 94(2): 331-345.
Gregerson, Joan. 1997. Commissioning Existing Buildings. Tech Update. E Source, Inc. TU-
97-3. March.
Guarneiri, M. 1997. EPA's Energy Star Buildings provides a roadmap to energy efficiency.
Facilities Manager January/February 1997: 39-43
Harriman, L. G., Plager, D., Kosar, D. 1997. Dehumidification and cooling loads from
ventilation air. ASHRAE Journal 39(11): 37-45
Hathaway, A. 1995. The link between lighting and cooling. Engineered Systems Maintenance
July 1995: 18-19.
Herzog, Peter and LaVine, Lance. 1992. Identification and Quantification of the Impact of
Improper Operation of Mid-size Minnesota Office Buildings on Energy Use: A Seven Building
Case Study. Paper presented at the 1992 Conference of the American Council for an Energy
Efficient Economy Pacific Grove, CA.
Meckler, M. 1994. Desiccant-assisted air conditioner improves IAQ and comfort.
Heating/Piping/Air Conditioning October 1994: 75-84.
Rengarajan, K.; Shirey, D. B. Ill, and Raustad, R.1996. Cost-effective HVAC technologies to
meet ASHRAE Standard 62-1989 in hot and humid climates. ASHRAE Transactions, V.
102(1).
Shirey D.B. and Rengarajan, K. 1996. Impacts of ASHRAE Standard 62-1989 on small florida
offices. ASHRAE Transactions, V. 102(1).
Steele,T., and Brown, M. 1990. Energy and Cost Implications of ASHRAE Standard 62-1989.
Bonnyville Power Administration. May.
Ventresca, J. 1991. Operation and maintenance for IAQ: implications from energy simulation
of increased ventilation. IAQ '91: Healthy Buildings. American Society of Heating,
Refrigerating, and Air-Conditioning Engineers Inc. Atlanta.
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USEPA. 1993. Energy Star Buildings Manual. United States Environmental Protection
Agency. Washington, DC:
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Exhibit 1
Energy Measures that are Compatible With IEQ
Measure
Comment
Improve building
shell
- May reduce infiltration. May need to increase mechanically supplied
outdoor air to ensure applicable ventilation standards are met.
Reduce internal
loads (e.g. lights,
office
equipment)
-	Reduced loads will reduce supply air requirements in VAV systems. May
need to increase outdoor air to meet applicable ventilation standards.
-	Lighting must be sufficient for general lighting and task lighting needs
Fan/motor/drives
- Negliqible impact on IEQ
Chiller/ boiler
- Neqliqible impact on IEQ
Energy recovery
- May reduce energy burden of outdoor air, especially in extreme climates
and/or when high outdoor air volumes are required (e.g. schools, auditoria).
Air-side
economizer
-	Uses outdoor air to provide free cooling. Potentially improves IEQ when
economizer is operating by helping to ensure that the outdoor air ventilation
rate meets IEQ requirements.
-	On/off set points should be calibrated to both the temperature and
moisture conditions of outdoor air to avoid indoor humidity problems. May
need to disengage economizer during an outdoor air pollution episode.
Night pre-cooling
- Cool outdoor air at night may be used to pre-cool the building while
simultaneously exhausting accumulated pollutants. However, to prevent
microbiological growth, controls should stop pre-cooling operations if dew
point of outdoor air is high enough to cause condensation on equipment.
Preventive
Maintenance
(PM) of HVAC
- PM will improve IEQ and reduce energy use by removing contaminant
sources (e.g. clean coils/drain pans), and insuring proper calibration and
efficient operation of mechanical components (e.g. fans, motors,
thermostats, controls)..
C02 controlled
ventilation
- C02 controlled ventilation varies the outdoor air supply in response to C02
which is used as an indicator of occupancy. May reduce energy use for
general meeting rooms, studios, theaters, educational facilities etc. where
occupancy is highly variable, and irregular. A typical system will increase
outdoor air when C02 levels rise to 600-800 ppm to ensure that maximum
levels do not exceed 1,000 ppm. The system should incorporate a
minimum outside air setting to dilute building related contaminants during
low occupancy periods.
Reducing
demand (KW)
charges
- Night pre-cooling and sequential startup of equipment to eliminate
demand spikes are examples of strategies that are compatible with IEQ.
Caution is advised if load shedding strategies involve changing the space
temperature set points or reducing outdoor air ventilation during occupancy.
Supply air
temperature
reset
- Supply air temperature may sometimes be increased to reduce chiller
energy use. However, fan energy will increase. Higher supply air
temperatures in a VAV system will increase supply air flow and vice versa.
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Equipment
down-sizing
-	Prudent avoidance of over-sizing equipment reduces first costs and
energy costs. However, capacity must be sufficient for thermal and
outdoor air requirements during peak loads in both summer and winter.
Latent load should not be ignored when sizing equipment in any climate.
Inadequate humidity control has resulted in thermal discomfort and mold
contamination so great as to render some buildings uninhabitable.
-	Energy recovery systems may enable chillers and boilers to be further
downsized by reducing the thermal loads from outdoor air ventilation.
Exhibit 2
Energy Activities That May Degrade IEQ
Energy
Measure
Comment
Reducing
outdoor air
ventilation
- Aoolicable ventilation standards usuallv soecifv a minimum continuous
outdoor air flow rate per occupant, and/or per square foot, during occupied
hours. They are designed to ensure that pollutants in the occupied space are
sufficiently diluted with outdoor air. Reducing outdoor air flow below
applicable standards can degrade IEQ and has low energy saving potential
relative to other energy saving options.
Variable Air
Volume (VAV)
Systems with
fixed percentage
outdoor air
-	VAV systems can yield significant energy savings over Constant Volume
(CV) systems in many applications. However, many VAV systems provide a
fixed percentage of outdoor air (e.g. fixed outdoor air dampers) so that during
part load conditions when the supply air is reduced, the outdoor air may also
be reduced to levels below applicable standards.
-	VAV systems should employ controls which maintain a continuous outdoor
air flow consistent with applicable standards. Hardware is now available from
vendors and involves no significant energy penalty.
Reducing HVAC
operating hours
Delayed start-up or premature shutdown of the HVAC can evoke IEQ
problems and occupant complaints.
- An insufficient lead time prior to occupancy can result in thermal discomfort
and pollutant-related health problems for several hours as the HVAC system
must overcome the loads from both the night-time setbacks and from current
occupancy. This is a particular problem when equipment is downsized.
Shutting equipment down prior to occupants leaving may sometimes be
acceptable provided that fans are kept operating to ensure adequate
ventilation. However, the energy saved may not be worth the risk .
Relaxation of
thermal control
Some energy managers may be tempted to allow space temperatures or
humidity to go beyond the comfort range established by applicable standards.
Occupant health, comfort and productivity are compromised. The lack of
overt occupant complaints is NOT an indication of occupant satisfaction.
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Exhibit 3
Modeling Parameters for the Base Office and Education Building
Building Parameter
Office Building
Education Building

Base
Modification
Base Modification
Stage 1: Operational/Tune-up Measures
Day Temp. Set Points
71-77 F
(68 - 80 F)
71-77 F
(68 - 80 F)
Night Set Back
+/-10 F
(+/-15 F )
+/-10 F
(+/-15 F)
Day HVAC Hours
8am - 6pm
(9 am - 5pm)
7am -10pm
(8am - 9pm)
Seasonal Reset
No
Yes
No
Yes
Entries in parentheses were modeled separately-not part of the retrofit
project
Stage 2: Load Reduction Measures

Lighting
2.5 W/f2
30% reduction
3.0 W/f2 rms
2.0 W/f2 corr
30% reduction
Office Equipment
1.0 W/f2
30% reduction
0.25 W/f2
30% reduction
Stage 3: Air distribution System Upgrades
VSD no
yes no yes
Stage 4: Central Plant U
pgrades
Chiller COP
3.0
5.5
3.0
5.5
Boiler Efficiency
70%
85%
70%
85%
Stage 5: IEQ Ventilation Modifications Required to meet ASHRAE 62-1999
Outdoor Air Setting
5 cfm/occ
20 cfm/occ
5 cfm/occ
15 cfm/occ
Outdoor Air Control
fixed
damper
constant flow
constant flow
const. flow-VAV
box adjustment
Humidity Control
not needed
not needed
not needed
60% RH
*Forthe base education building used for the energy retrofit: infiltration rate = 0.5ach; window U value = 0.99
(Btui/hr ft2 F); and window shading coeff. = 0.90.
Energy Cost and IAQ
14
Report # 7

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Exhibit 4
Energy Cost for Office Building With Energy and IEQ Modifications
Parameter
Washington D.C. ($/f2)
Minneapolis (S/f2)
Miami ($/f2)

Fan
Cool
Heat
Total
HVAC
Light
&Off.
Equip
Total
Fan
Cool
Heat
Total
HVAC
Light
&Off.
Equip
Total
Fan
Coo
I
Hea
t
Total
HVAC
Light
&Off.
Equip
Total
Base Bldg
0.17
0.42
0.05
0.64
0.94
1.58
0.19
0.39
0.10
0.68
0.94
1.62
0.18
0.56
0.00
0.74
0.94
1.68
Stage 1
Seas. Rset
0.18
0.41
0.04
0.63
0.94
1.57
0.19
0.38
0.08
0.66
0.94
1.60
0.21
0.56
0.00
0.78
0.94
1.72
Stage 2
Ltng/OE
0.15
0.30
0.06
0.52
0.57
1.08
0.17
0.29
0.12
0.58
0.57
1.16
0.17
0.40
0.00
0.57
0.57
1.15
Stage 3
VSD
0.09
0.28
0.06
0.43
0.57
1.00
0.08
0.27
0.12
0.47
0.57
1.04
0.13
0.38
0.00
0.52
0.57
1.09
Stage 4
chllr/boilr
0.09
0.16
0.05
0.30
0.57
0.87
0.08
0.15
0.10
0.33
0.57
0.90
0.13
0.22
0.00
0.35
0.57
0.93
Stage 5
OA setting
0.09
0.18
0.06
0.32
0.57
0.89
0.08
0.16
0.11
0.36
0.57
0.93
0.13
0.24
0.00
0.38
0.57
0.95
OA Control
0.09
0.19
0.06
0.33
0.57
0.90
0.08
0.18
0.11
0.37
0.57
0.94
0.13
0.26
0.00
0.40
0.57
0.97
Exhibit 5
for Education Building With Energy and IEQ Modifications
Building
Parameter
Washiri
(S
gton D.C.
?/sf)
Min
rieapolis
[$/sf)
Miami
($/sf)

Fan
Cool
Heat
Total
HVAC
Light &
Off.
Equip
Total
Fan
Cool
Heat
Total
HVAC
Light &
Off
Equip
Total
Fan
Cool
Heat
Total
HVAC
Light &
Off.
Equip
Total
Base Bldg
0.21
0.62
0.28
1.11
0.97
2.08
0.26 0.55 0.62 1.42
0.97
2.40
0.25 0.97 0.01 1.22
0.97
2.19
Stage 1
Seas. Rset
0.21
0.61
0.25
1.07
0.97
2.04
0.26 0.54 0.58 1.38
0.97
2.36
0.28 0.96 0.00 1.23
0.97
2.21
Stage 2
Ltng/OE
0.19
0.53
0.33
1.04
0.67
1.71
0.26 0.48 0.68 1.42
0.67
2.10
0.24 0.83 0.01 1.08
0.67
1.76
Stage 3
VSD
0.11
0.50
0.33
0.94
0.67
1.62
0.15 0.45 0.69 1.30
0.67
1.97
0.18 0.80 0.01 0.98
0.67
1.65
Stage 4
chllr/boilr
0.11
0.29
0.28
0.67
0.67
1.35
0.15 0.26 0.57 0.98
0.67
1.65
0.18 0.46 0.01 0.64
0.67
1.31
Stage 5
OA Setting
0.12
0.35
0.35
0.82
0.67
1.49
0.16 0.31 0.72 1.19
0.67
1.68
0.18 0.54 0.01 0.73
0.67
1.40

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| OA Control 10.13 |0.36 |0.38 |0.87 |0.67 |1.54 |0.16 0.31 0.72 1.20 |0.67 |1.87 |0.14 0.55 0.01 0.71 |0.67 |1.38 |
Energy Cost and IAQ
16

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Exhibit 6:
Percent Savings in Total Energy Cost from Energy and IEQ Modifications
Top figure in each cell is for office building; bottom figure is for education building)

Washington
Minneapolis
Miami

$/f2
From
Base
From
Prev.
Stage
$/f2
From
Base
From
Prev.
Stage
$/f2
From
Base
From
Prev.
Stage
Base Bldg
1.58
2.08


1.62
2.40


1.68
2.19


Stage 1
Seas. Reset
1.57
2.04
1%
2%
1%
2%
1.60
2.36
1%
2%
1%
2%
1.74
2.21
-2%
-1%
-2%
-1%
Stage 2
Ltng/Off
Equip
1.08
171
32%
18%
31%
16%
1.16
2.10
28%
13%
28%
11%
1.15
1.76
32%
20%
33%
20%
Stage 3
VSD
1.00
1.62
37%
22%
7%
5%
1.04
1.97
36%
18%
10%
6%
1.09
1.65
35%
25%
5%
6%
Stage 4
Chi ller/boilr
0.87
1.35
45%
35%
13%
17%
0.90
1.65
44%
31%
13%
16%
0.93
1.31
45%
40%
15%
21%
Stage 5
OA setting
with OA &
RH control*
0.90
1.54
43%
26%
-3%
-14%
0.94
1.87
42%
22%
-4%
-13%
0.97
1.38
42%
37%
-4%
-5%
* Only the office building required OA control while only the education building required RH control (see text)
Energy Cost and IAQ
17
Report # 7

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Exhibit 7:
Sizing requirements for chillers and boilers with and without IEQ controls

Chiller
Boiler
Wash. D.C.
Minneapolis
Miami
Wash. D.C.
Minneapolis
Miami
MBTU
%of
Base
MBTU
%of
Base
MBTU
%of
Base
MBTU
%of
Base
MBTU
%of
Base
MBTU
%of
Base

Office Building
Base
4.29
100
4.33
100
4.35
100
4.67
100
6.19
100
1.96
100
IEQ Control











yes
4.08
95
3.90
90
4.30
99
5.88
126
8.17
132
2.13
109
no
3.20
75
3.17
73
3.37
77
4.74
101
7.18
116
1.99
102

Education Building
Base
1.13
100
1.07
100
1.26
100
2.69
100
3.75
100
0.84
100
IEQ Control











yes
1.23
109
1.11
104
1.43
113
2.93
109
3.99
106
1.13
135
no
0.98
87
0.92
86
1.13
90
2.76
103
3.89
104
0.81
96
Energy Cost and IAQ
18
Report # 7

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Exhibit 8:
nergy costs ($/ft2) with operational measures that may adversely affect IEQ

Washington D.C.
Minneapolis
Miami

Fan
Cool
Heat
Total
HVAC
Light &
Off..Equip
Total
Total
HVAC
Total
Total
HVAC
Total
Base Office Bldq
0.17
0.42
0.05
0.64
0.94
1.58
0.68
1.62
0.74
1.68
Day Temp. Set Pts
0.17
0.40
0.04
0.61
0.94
1.56
0.64
1.58
0.71
1.65
Night Set Back
0.16
0.41
0.04
0.62
0.94
1.56
0.66
1.60
0.72
1.66
Day HVAC Hours
0.17
0.42
0.04
0.63
0.94
1.57
0.66
1.60
0.75
1.69
Base Edu. Bldg.
0.21
0.62
0.28
1.11
0.97
2.08
1.42
2.40
1.22
2.19
Day Temp. Set Pts
0.18
0.55
0.22
0.95
0.97
1.93
1.25
2.23
1.06
2.03
Night Set Back
0.21
0.62
0.27
1.10
0.97
2.07
1.40
2.38
1.22
2.19
Day HVAC Hours
0.20
0.61
0.25
1.06
0.97
2.02
1.34
2.31
1.18
2.15
Exhibit 9: Savings from reduced lights and
office equipment when unoccupied
Operational Control
Office Building in Washing
ton D.C.
% of daytime use during unoccupied hours
En
erav Cost f$/f21
Savina
HVAC
Light/off eguip
Total
S/f2
%
Stage 1





40% lights/50% office eguipment (base
case)
0.71
1.08
1.79


20% lights/30% office eguipment
0.64
0.94
1.58
0.21
12%
Stage 4 (retrofitted building)





20% lights/30% office eguipment
0.33
0.57
0.90


15%lights/20% office eguipment
0.29
0.40
0.70
0.20
22%
Energy Cost and IAQ
19
Report # 7

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