United States
Environmental
Protection
Indoor Environments
Division (6609J)
Office of air and Radiation
EPA-402-S-01 -001 E
January 2000
Aganry	
Energy Cost and IAQ
Performance of Ventilation
Systems and Controls
Project # 5
Peak Load Impacts of Increasing Outdoor Air
Flows from 5 cfm to 20 cfm per Occupant in
Large Office Buildings

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Energy Cost and IAQ Performance of Ventilation Systems
and Controls
Project Report # 5: Peak Load Impacts of increasing Outdoor Air Flows
from 5 to 20 cfm per Occupant in Large Office
Buildings
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

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Energy Cost and IAQ Performance of Ventilation Systems and Controls
Project Report #5: Peak Load Impacts of increasing Outdoor Air Flows from 5 to 20 cfm
per Occupant in Large Office Buildings
INTRODUCTION
Purpose and Scope of this Report
In order to achieve acceptable indoor air quality in office environments, ASHRAE Standard 62-
1989 (and subsequently ASHRAE Standard 19991) raised the recommended outdoor air
ventilation rates from 5 cfm/occupant to 20 cfm/occupant. This four-fold increase has raised a
number of questions concerning the feasibility and cost of implementing this standard.
A companion paper (Project Report # 4) quantifies the energy and energy cost impact of raising
outdoor air ventilation rates in office buildings. That report suggests that raising outdoor air flow
rates from 5 to 20 cfm/occupant only modestly changes energy costs by $0.02 - $0.06 per square
foot in most cases. However, in extreme cases, energy costs were reduced as much as $0.02 per
square foot, and increased by as much as $0.19 per square foot. High occupant density and
extended operating hours had the most profound effects on the energy cost impact.
The purpose of this report is to examine the peak load impacts which occur when outdoor air flow
rates are raised. This issue is important for both new and existing buildings. First, downsizing is
an important feature of many energy conscious designs and retrofit strategies. This report sheds
light on the extent to which downsizing is possible when buildings operate at elevated outdoor air
flow rates. Second, owners of existing buildings which may have been designed to operate at
relatively low outdoor air flow rates are being asked to raise these rates in order to improve indoor
air quality. This report also addresses the extent to which such increases are feasible for these
buildings, and identifies situations in which serious problems may occur if capacity issues are not
properly addressed.
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.
Energy Cost and IAQ
1
Report # 5

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Background
This report is part of a larger modeling project to assess the compatibilities and trade-offs between
energy, indoor air, and thermal comfort objectives in the design and operation of HVAC systems in
commercial buildings, and to shed light on potential strategies which can simultaneously achieve
superior performance on each objective. It is hoped that this project will contribute to the body of
new data needed by professionals and practitioners who design and operate ventilation systems
as they attempt to reduce costs and 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:
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 airflow rates from 5 to 20 cfm per
occupant in large office buildings
•	Project Report #5: Peak load impacts of increasing outdoor airflow 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 airflow rates are increased from 5 to 15 cfm per occupant in
auditoriums, education, and other buildings with very high occupant density
•	Project Report #7: The energy cost of protecting indoor environmental quality during energy
efficiency projects for office and education buildings
Energy Cost and IAQ
2
Report # 5

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DESCRIPTION OF THE BUILDINGS AND VENTILATION SYSTEMS MODELED
A large 12 story office building (Building A), along with 13 additional parametric variations
(Buildings B-N) were modeled in three different climates representing cold (Minneapolis),
temperate (Washington D.C., and hot/humid (Miami) climate zones. All buildings have an air
handler on each floor servicing four perimeter zones corresponding to the four compass
orientations, and a core zone. A dual duct constant volume (CV) system, and a single duct variable
volume (VAV) system with reheat were modeled using alternative outdoor air control strategies.
Constant volume systems control the thermal conditions in the space by altering the temperature of
a constant volume of supply air, while VAV systems alter the supply air volume while maintaining a
constant supply air temperature. The building and HVAC parameters used in this analysis are
described in Exhibit 1.
The basic outdoor air control strategy which was modeled for both CV and VAV systems is one
that provides the design outdoor air flow during all operating conditions. To this basic strategy, a
temperature air-side economizer strategy is also presented. To avoid humidity problems, the
economizer is shut off at outdoor temperatures above 65°F. The outdoor air flow rate reverts to its
base level (5 or 20 cfm per occupant) when the economizer is in the "off" mode.
A more detailed description of all the buildings and ventilation systems modeled in this project is
provided in Report #1.
APPROACH
The CV and VAV systems were each modeled for the entire year for each HVAC system in each of
the three climates using 5 cfm and 20 cfm of outdoor air per occupant. From the data, the peak
hourly load on the heating coil, cooling coil, and preheat coil were identified. Comparisons were
then made between the two runs (5 cfm and 20 cfm per occupant) to determine the impact of an
increased outdoor air flow on these peak loads.
RESULTS
Exhibits 2 and 3 presents the peak load impacts of raising outdoor air flow rates in CV systems
(with and without economizers) in each of the three climates. Exhibits 4 and 5 presents the same
data for VAV systems.
Peak Cooling Loads
Peak Coiling Loads at 5cfm Per Occupant
Peak cooling loads for CV and VAV systems were similar, except that CV systems experienced
peak cooling loads which were generally 5-10% higher in all climates compared to VAV systems.
Energy Cost and IAQ
3
Report # 5

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A low efficiency shell and a high perimeter to core ratio raised the peak cooling load, since these
buildings are most affected by outdoor climate conditions. Buildings with a high exhaust rate
experienced a higher peak cooling load because they have a higher flow of replacement air which,
during the heat of the summer, will raise the peak cooling load. Similarly, buildings which operate
over 24 hours tend to had higher peak cooling loads because there are a larger number of hours
where the peak may occur. The highest peak cooling loads were experience by the high occupant
density building. Occupants generate heat which increases the demand for cooling, so that the
peak cooling load rises as occupant density rises. Economizers do not affect peak cooling loads
because when the peak occurs, the economizer is shut off. In addition, the peak cooling load is not
predictably affected by climate. The peak cooling load in Minneapolis, for example, was not much
different than the peak cooling load in Miami or Washington, D.C. even though the overall weather
patterns are substantially different.
Impact of Higher Outdoor Air Flow Rates on Peak Cooling Load
Raising outdoor airflow rates from 5 cfm to 20 cfm per occupant typically increased peak cooling
loads by 15%-25% with the highest increases in the Miami climate. CV and VAV systems had
comparable increases in peak cooling load. Economizers made no difference, since the
economizer was not operating when the peak cooling load occurs.
The one notable exception is that occupant density had a dramatic influence, increasing the peak
cooling load impact to 41% for both CV and VAV systems in Miami, and approximately 30% in
Washington, D.C. and Minneapolis. The dramatic effect that occupant density had on the impact
on peak cooling loads from increased outdoor airflow rates raises potentially serious issues
concerning the viability of raising outdoor airflow in very high density buildings such as education
buildings, auditoriums, and theaters. These issues are explored in detail in a companion report
(Project Report #6).
Peak Heating Loads
Peak Heating Loads at 5 cfm Per Occupant
Unlike peak cooling loads that were not significantly affected by outdoor climate, peak heating
loads were significantly affected by outdoor climate, especially for CV systems. For example, the
peak heating load for the CV system of the base building in Miami was only 191 kBTU/h while it
was 6,649 kBTU/h for the same building in Minneapolis. The effect of climate on peak heating
loads for VAV systems was much less dramatic than for CV systems because the VAV system
modeled here uses a zone reheat system, which heats the supply air at the VAV box after it has
been cooled. The heatng coil load is therefore less dependent on outdoor weather conditions.
Thus, for the VAV system, the same building experienced peak heating loads of 1,940 kBTU/h in
Miami and 6,131 kBTU/h in Minneapolis.
Energy Cost and IAQ
4
Report # 5

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In contrast to the cooling coil, economizers significantly increased the peak load on the heating coil,
though this is true only for the CV systems. For example, the peak heating coil load for the CV
system in the base building in Washington, D.C. without economizer was 2,572 kBTU/h. Adding
an economizer increased this to 3936 k BTU/h. This is because the economizer increases the flow
of outdoor air in the winter to take advantage of free cooling. This increased the heating
requirement in zones requiring heat. In VAV systems, the economizer did not affect the peak
heating load because heating needs are accommodated by reheating 55°F air at the VAV box,
and this is not affected by an economizer.
As expected, buildings with low shell efficiency and high perimeter to core ratios experienced
higher peak heating loads than buildings with high shell efficiency and low perimeter to core ratios.
Impact of Higher Outdoor Air Flow Rates on Peak Heating Coil Loads
Raising the outdoor airflow rate from 5 cfm to 20 cfm per occupant typically raised the peak
heating coil load by 5% - 20%, but sometimes this increase was as high as 40-45%. The most
important feature which can drive the heating coil impact up appears to be high occupant density.
However, low perimeter to core ratios and high efficiency shell resulted in high heating coil impacts.
The absolute impact of higher outdoor flow rates in Miami was small, but it was sometimes
proportionally high because the base peak heating coil loads were generally low.
The data present some odd results which are not easily predicted or explained. For example, in
some buildings with CV systems, the peak heating load impact was reduced. An examination of
the data reveals that the peak typically occurred at start-up. Since the system only occasionally
cycles on at night, the indoor climate conditions at start up are highly dependent on when the
system was last on before start-up. Raising the outdoor air flow rate from 5 to 20 cfm per occupant
could affect the on/off cycle at night and therefore the indoor climate conditions at start-up, and this
could present counterintuitive results on the peak heating coil. For example, some CV systems
without economizers in Miami experienced a decrease in peak heating coil load when outdoor air
flow rates were increased.
Peak Preheat Coil Loads
Peak Preheat Coil Loads at 5 cfm Per Occupant
The preheat coil for both CV and VAV systems in all buildings in all climates experienced no load
when outdoor flow rates were at 5 cfm per occupant.
Impact of Higher Outdoor Air Flow Rates on the Preheat Coil Load
Even when the outdoor air flow rates are raised from 5 cfm to 20 cfm per occupants, none of the
CV systems experienced a preheat coil load in any climate. This is because the preheat coil
loads only occur when the mixed air temperature is below 45°F. Since return air is at or above
Energy Cost and IAQ
5
Report # 5

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room air temperature, the mixed air temperature can only fall below 45°F if the outdoor air
temperature is cold and the outdoor air fraction is high. Since CV systems have high winter
supply air flow rates relative to VAV systems, the outdoor air fraction of the CV systems was
evidently not high enough to trigger the need for preheat coils, even in the cold climate of
Minneapolis.
However, VAV systems have much lower outdoor air fractions, so that in almost every VAV
building in the Minneapolis climate, the system experienced a preheat coil load when the outdoor
air flow rate was raised to 20 cfm per occupant. The loads which typically appeared at 20 cfm per
occupant ranged from 700 to 1500 kBTU/h. However, both the medium and high occupant density
building were above this range, resulting in loads of 2700 and 5800 kBTU/h respectively.
Economizers made no meaningful difference in peak preheat coil load impact.
In general, the preheat peak loads experienced are moderate and may well fall within the excess
capacity range of existing systems or within the safety factor of most new system designs.
However, many existing buildings do not have preheat coils. Raising the outdoor air flow rate to 20
cfm in these building, even in temperate climates, runs the risk of damaging the coil, particularly for
medium or high occupant density buildings, or buildings that operate with extended operating
hours. This is an especially high risk for cold climates, though buildings in cold climates are more
likely to have some preheat coil capacity.
SUMMARY AND CONCLUSIONS
With the exception of very low occupant density buildings, every HVAC system in every building in
every climate experienced a large peak load increase in one of the three coil systems.
Because many buildings have excess capacity precisely in order to avoid unexpected problems,
this analysis may overstate the potential problem in many buildings. However, in individual cases,
this analysis suggests that it would be extremely unwise for owners of existing buildings to raise
outdoor air flow rates without first carefully performing a load analysis.
Occupant density was the single most important factor in determining the increase in peak coil
loads when outdoor air flow rates are increased. This suggests that buildings with exceptionally
high occupant densities, such as education buildings, auditoriums, or theaters may have significant
capacity issues associated with high outdoor airflow rates. These issues are examined in detail in
a companion report (Project Report #6).
Buildings that were built with energy efficiency in mind may have the least excess capacity and
therefore may have the greatest difficulty in raising outdoor airflow rates to meet current ASHRAE
standards. In addition, this report suggests that downsizing as an energy conservation strategy
ought to be judiciously applied, taking into account the increased capacity needed to
accommodate outdoor airflow rates consistent with indoor air quality.
Energy Cost and IAQ
6
Report # 5

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BIBLIOGRAPHY
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.
Meckler, M. 1994. Desiccant-assisted air conditioner improves IAQ and comfort. Heating/Piping/Air
Conditioning October 1994: 75-84.
Rengarajan, K., Shirey, D. B., Raustad, R. A. 1996. Cost-effective HVAC technologies to meet ASHRAE
Standard 62-1989 in hot and humid climates. ASHRAE Transactions 102(1): 3949.
Shirey, D. B., Rengarajan, K. 1996. Impacts of ASHRAE 62-1989 on small Florida offices. ASHRAE
Transactions 102(1): 3948
Energy Cost and IAQ
7
Report # 5

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Exhibit 1
Building and HVAC Characteristics
Building Configuration
Window
R-Value
Window
Shading
Coeffic.
Roof
Insulation
Infiltration
Rate
Chiller
COP
Boiler
Effic.
(%)
Occup.
Density
(Occup/
1000 SF)
P/C
Ratio
Exhaust
Flow
Rate
(cfm)
Daily
Operating
Hours
(hrs/day)
A. Base Case
2.0
0.8
10
0.5
3.5
70
7
0.5
750
12
B. High Effic. Shell
3.0
0.6
20
0.75
3.5
70
7
0.5
750
12
C. Low Effic. Shell
1.0
1.0
5
0.25
3.5
70
7
0.5
750
12
D. High Effic. HVAC
2.0
0.8
10
0.5
4.5
80
7
0.5
750
12
E. Low Effic. HVAC
2.0
0.8
10
0.5
2.5
60
7
0.5
750
12
F. High Occup.Density
2.0
0.8
10
0.5
3.5
70
15
0.5
750
12
G. Med Occup. Density
2.0
0.8
10
0.5
3.5
70
10
0.5
750
12
H. High P/C Ratio
2.0
0.8
10
0.5
3.5
70
7
0.8
750
12
I. Low P/C Ratio
2.0
0.8
10
0.5
3.5
70
7
0.3
750
12
J. High Exhaust Rate
2.0
0.8
10
0.5
3.5
70
7
0.5
1500
12
K. Low Occup Density
2.0
0.8
10
0.5
3.5
70
5
0.5
750
12
L. Very Low Occ. Density
2.0
0.8
10
0.5
3.5
70
3
0.5
750
12
M. Extended Oper. Hours
2.0
0.8
10
0.5
3.5
70
7
0.5
750
18
N. 24 Hour Operation
2.0
0.8
10
0.5
3.5
70
7
0.5
750
24
Energy Cost and IAQ
Report # 5

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Exhibit 2
Changes in Peak Coil Load Due to Increased Outdoor Air Flow Rates From 5 to 20 cfm per
Occupant: CV Systems without Economizers {cv(foaf)>


Miami, FL

Washington, DC
Minneapolis, MN
Building Configuration
Cooling
Heating
Preheat
Cooling
Heating
Preheat
Cooling
Heating
Preheat

(kBtu/H)
(kBtu/H)
(kBtu/H)
(kBtu/H)
(kBtu/H)
(kBtu/H)
(kBtu/H)
(kBtu/H)
(kBtu/H)
A. Base Case @5
9258
191
0
9017
2572
0
9288
6649
0
increase
1876
443

1752
1047

1421
649

Percent Increase
20%
232%
None
19%
41%
None
15%
10%
None
B. High Eff. Shell @5
8662
37
0
8110
1023
0
8307
4298
0
Increase
1851
-12

1856
2000

1398
1864

Percent Increase
21%
-31 %
None
23%
196%
None
17%
43%
None
C. Low Eff. Shell @5
10482
1267
0
10368
5160
0
10361
8818
0
Increase
1845
133

1553
445

1442
71

Percent Increase
18%
10%
None
15%
9%
None
14%
1%
None
D. High Eff. HVAC @5
9258
191
0
9017
2572
0
9296
6649
0
Increase
1876
443

1752
1047

1423
649

Percent Increase
20%
232%
None
19%
41%
None
15%
10%
None
E. Low Eff. HVAC @5
9258
191
0
9017
2572
0
9296
6649
0
Increase
1876
443

1752
1047

1423
649

Percent Increase
20%
232%
None
19%
41%
None
15%
10%
None
F. High P/C Ratio @5
10301
919
0
10277
4007
0
10414
8349
0
Increase
1812
-339

1521
763

1401
380

Percent Increase
18%
-37%
None
15%
19%
None
13%
5%
None
G. Low P/C Ratio @5
8056
55
0
7940
1452
0
7899
4427
0
Increase
1995
206

1668
1305

1439
1217

Percent Increase
25%
377%
None
21%
90%
None
18%
28%
None
H. High Exhaust @5
9817
305
0
9465
2886
0
9727
6917
0
Increase
1317
330

1314
733

993
382

Percent Increase
13%
108%
None
14%
25%
None
10%
6%
None
1. High Occ. Dens. @5
10775
129
0
10927
2923
0
10509
7059
0
Increase
4384
547

3522
1532

3206
1158

Percent Increase
41%
424%
None
32%
52%
None
31%
16%
None
J. Medium Occ. Dens. @5
9741
168
0
9665
2803
0
9644
6777
0
Increase
2929
472

2465
1099

2192
666

Percent Increase
30%
281 %
None
26%
39%
None
23%
10%
None
K. Low Occ. Dens. @5
9034
221
0
8949
2704
0
9041
6643
0
Increase
1192
421

953
594

960
909

Percent Increase
13%
190%
None
11%
22%
None
11%
14%
None
L. Very Low Occ. Dens. @5
8811
222
0
8893
2661
0
8786
6566
0
Increase
494
93

247
279

400
406

Percent Increase
6%
42%
None
3%
10%
None
5%
6%
None
M. Extended Op. Hours @5
9066
810
0
9003
2679
0
8986
5975
0
Increase
1975
316

1572
1482

1490
588

Percent Increase
22%
39%
None
17%
55%
None
17%
10%
None
N. 24 Hour Operation @5
9621
759
0
8903
3106
0
8896
6657
0
Increase
1331
353

1569
2186

1453
1992

Percent Increase
14%
47%
None
18%
70%
None
16%
30%
None
Energy Cost and IAQ
9
Report # 5

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Energy Cost and IAQ	10	Report # 5

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Exhibit 3
Changes in Peak Coil Load Due to Increased Outdoor Air Flow Rates From 5 to 20 cfm per
Occupant: VAV Systems without Economizers (VAV(COA)}


Miami, FL

Washington, DC
Minneapolis, MN
Building Configuration
Cooling
Heating
Preheat
Cooling
Heating
Preheat
Cooling
Heating
Preheat

(kBtu/H)
(kBtu/H)
(kBtu/H)
(kBtu/H)
(kBtu/H)
(kBtu/H)
(kBtu/H)
(kBtu/H)
(kBtu/H)
A. Base Case @5
8670
1940
0
8517
4638
0
8688
6131
0
increase
1862


1659


1320
456
897
Percent Increase
21%
None
None
19%
None
None
15%
7%
Increase
B. High Eff. Shell @5
8010
967
0
7855
3552
0
7966
4868
0
Increase
1881


1695
101

1303
479
745
Percent Increase
23%
None
None
22%
3%
None
16%
10%
Increase
C. Low Eff. Shell @5
9591
3066
0
9360
6168
0
9580
8795
0
Increase
1697


1621
345

1332
50
514
Percent Increase
18%
None
None
17%
6%
None
14%
1%
Increase
D. High Eff. HVAC @5
8670
1940
0
8517
4638
0
8688
6131
0
Increase
1862


1659


1320
456
897
Percent Increase
21%
None
None
19%
None
None
15%
7%
Increase
E. Low Eff. HVAC @5
8670
1940
0
8517
4638
0
8688
6131
0
Increase
1862


1659


1320
456
897
Percent Increase
21%
None
None
19%
None
None
15%
7%
Increase
F. High P/C Ratio @5
9567
2680
0
9672
5641
0
9666
7862
0
Increase
1759


1425


1298
613
382
Percent Increase
18%
None
None
15%
None
None
13%
8%
Increase
G. Low P/C Ratio @5
7551
1158
0
7476
3490
0
7427
4834
0
Increase
2029


1597
153

1390
515
864
Percent Increase
27%
None
None
21%
4%
None
19%
11%
Increase
H. High Exhaust @5
9238
1940
0
8971
4637
0
9106
6127
0
Increase
1293


1196


934
457
896
Percent Increase
14%
None
None
13%
None
None
10%
7%
Increase
I. High Occ. Dens. @5
10119
1981
0
10128
5598
0
9944
6314
0
Increase
4190
262

3290
979
1539
2899
899
5801
Percent Increase
41%
13%
None
32%
17%
Increase
29%
14%
Increase
J. Medium Occ. Dens. @5
9151
1981
0
9110
4876
0
9098
6203
0
Increase
2782
13

2081
423
451
1993
783
2743
Percent Increase
30%
1%
None
23%
9%
Increase
22%
13%
Increase
K. Low Occ. Dens. @5
8407
1938
0
8496
4576
0
8436
5900
0
Increase
1198


972


878
493

Percent Increase
14%
None
None
11%
None
None
10%
8%
None
L. Very Low Occ. Dens. @5
8168
1936
0
8282
4550
0
8262
5859
0
Increase
503


407


368


Percent Increase
6%
None
None
5%
None
None
4%
None
None
M. Extended Op. Hours @5
8363
2321
0
8433
4498
0
8389
6337
0
Increase
1772


1474
114
15
1273
547
1386
Percent Increase
21%
None
None
17%
3%
Increase
15%
9%
Increase
N. 24 Hour Operation @5
8249
2214
0
8336
4827
0
8228
6659
0
Increase
1725
64

1471
24
36
1265
618
1494
Percent Increase
21%
3%
None
18%
1%
Increase
15%
9%
Increase
Energy Cost and IAQ
11
Report # 5

-------
Energy Cost and IAQ	12	Report # 5

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Exhibit 4
Changes in Peak Coil Load Due to Increased Outdoor Air Flow Rates From 5 to 20 cfm per
Occupant: CV Systems with Economizers (CV(FOAF)Econ}


Miami, FL

Washington, DC
Minneapolis, MN
Building Configuration
Cooling
Heating
Preheat
Cooling
Heating
Preheat
Cooling
Heating
Preheat

(kBtu/H)
(kBtu/H)
(kBtu/H)
(kBtu/H)
(kBtu/H)
(kBtu/H)
(kBtu/H)
(kBtu/H)
(kBtu/H)
A. Base Case @5
9258
3446
0
9017
3936
0
9288
6707
0
increase
1876


1755
35

1421
623

Percent Increase
20%
None
None
19%
1%
None
15%
9%
None
B. High Eff. Shell @5
8406
2715
0
8110
2786
0
8307
4326
0
Increase
2010


1855
246

1398
1839

Percent Increase
24%
None
None
23%
9%
None
17%
43%
None
C. Low Eff. Shell @5
10482
3817
0
10368
5532
0
10361
8901
0
Increase
1845
30

1553
135

1442


Percent Increase
18%
1%
None
15%
2%
None
14%
None
None
D. High Eff. HVAC @5
9258
3446
0
9017
3936
0
9296
6707
0
Increase
1876


1755
35

1423
623

Percent Increase
20%
None
None
19%
1%
None
15%
9%
None
E. Low Eff. HVAC @5
9258
3446
0
9017
3936
0
9296
6707
0
Increase
1876


1755
35

1423
623

Percent Increase
20%
None
None
19%
1%
None
15%
9%
None
F. High P/C Ratio @5
10301
4546
0
10277
5451
0
10414
8476
0
Increase
1812


1536
-61

1401
299

Percent Increase
18%
None
None
15%
-1%
None
13%
4%
None
G. Low P/C Ratio @5
8056
1950
0
7940
2360
0
7899
4461
0
Increase
1995
22

1668
412

1439
1190

Percent Increase
25%
1%
None
21%
17%
None
18%
27%
None
H. High Exhaust @5
9817
3446
0
9465
3949
0
9727
6967
0
Increase
1317


1317
32

993
364

Percent Increase
13%
None
None
14%
1%
None
10%
5%
None
I. High Occ. Dens. @5
10775
3238
0
10927
3067
0
10509
7110
0
Increase
4384


3522
1407

3206
1261

Percent Increase
41%
None
None
32%
46%
None
31%
18%
None
J. Medium Occ. Dens. @5
9741
3371
0
9665
3974
0
9644
6834
0
Increase
2929
-58

2445


2192
626

Percent Increase
30%
-2%
None
25%
None
None
23%
9%
None
K. Low Occ. Dens. @5
9034
3580
0
8949
3996
0
9041
7006
0
Increase
1192


953


960
588

Percent Increase
13%
None
None
11%
None
None
11%
8%
None
L. Very Low Occ. Dens. @5
8811
3155
0
8893
3940
0
8786
6952
0
Increase
494


248


400
276

Percent Increase
6%
None
None
3%
None
None
5%
4%
None
M. Extended Op. Hours @5
9067
3232
0
9003
3575
0
8986
6031
0
Increase
1975


1572
591

1490
562

Percent Increase
22%
None
None
17%
17%
None
17%
9%
None
N. 24 Hour Operation @5
9621
3056
0
8903
4528
0
8896
9783
0
Increase
1331


1569
2062

1453
1748

Percent Increase
14%
None
None
18%
46%
None
16%
18%
None
Energy Cost and IAQ
13
Report # 5

-------
Energy Cost and IAQ	14	Report # 5

-------
Exhibit 5
Changes in Peak Coil Load Due to Increased Outdoor Air Flow Rates From 5 to 20 cfm per
Occupant: VAV Systems with Economizers (VAV(COA)Econ}


Miami, FL

Washington, DC
Minneapolis, MN
Building Configuration
Cooling
Heating
Preheat
Cooling
Heating
Preheat
Cooling
Heating
Preheat

(kBtu/H)
(kBtu/H)
(kBtu/H)
(kBtu/H)
(kBtu/H)
(kBtu/H)
(kBtu/H)
(kBtu/H)
(kBtu/H)
A. Base Case @5
8670
1949
0
8517
4638
0
8688
6148
0
increase
1862


1659


1336
444
897
Percent Increase
21%
None
None
19%
None
None
15%
7%
Increase
B. High Eff. Shell @5
8010
967
0
7855
3552
0
7962
4868
0
Increase
1881


1694
101

1364
479
745
Percent Increase
23%
None
None
22%
3%
None
17%
10%
Increase
C. Low Eff. Shell @5
9591
3064
0
9360
6168
0
9580
8806
0
Increase
1697


1621
355

1331

514
Percent Increase
18%
None
None
17%
6%
None
14%
None
Increase
D. High Eff. HVAC @5
8670
1949
0
8517
4638
0
8688
6148
0
Increase
1862


1659


1336
444
897
Percent Increase
21%
None
None
19%
None
None
15%
7%
Increase
E. Low Eff. HVAC @5
8670
1949
0
8517
4638
0
8688
6148
0
Increase
1862


1659


1336
444
897
Percent Increase
21%
None
None
19%
None
None
15%
7%
Increase
F. High P/C Ratio @5
9567
2691
0
9672
5641
0
9662
7875
0
Increase
1759


1425


1298
602
382
Percent Increase
18%
None
None
15%
None
None
13%
8%
Increase
G. Low P/C Ratio @5
7551
1082
0
7476
3490
0
7427
4834
0
Increase
2029
-17

1596
153

1390
515
864
Percent Increase
27%
-2%
None
21%
4%
None
19%
11%
Increase
H. High Exhaust @5
9238
1949
0
8971
4637
0
9106
6141
0
Increase
1293


1196


947
448
897
Percent Increase
14%
None
None
13%
None
None
10%
7%
Increase
I. High Occ. Dens. @5
10119
1984
0
10128
5598
0
9961
6325
0
Increase
4190
262

3290
979
1539
2903
888
5801
Percent Increase
41%
13%
None
32%
17%
Increase
29%
14%
Increase
J. Medium Occ. Dens. @5
9151
1956
0
9110
4876
0
9114
6218
0
Increase
2782


2082
423
451
1995
767
2743
Percent Increase
30%
None
None
23%
9%
Increase
22%
12%
Increase
K. Low Occ. Dens. @5
8407
1947
0
8496
4576
0
8436
5900
0
Increase
1198


972


878
493

Percent Increase
14%
None
None
11%
None
None
10%
8%
None
L. Very Low Occ. Dens. @5
8168
1935
0
8282
4550
0
8262
5859
0
Increase
503


407


368


Percent Increase
6%
None
None
5%
None
None
4%
None
None
M. Extended Op. Hours @5
8363
2331
0
8433
4500
0
8389
6337
0
Increase
1772


1474
121
18
1273
547
1386
Percent Increase
21%
None
None
17%
3%
Increase
15%
9%
Increase
N. 24 Hour Operation @5
8249
2344
0
8335
4921
0
8228
6659
0
Increase
1725


1472

37
1265
618
1494
Percent Increase
21%
None
None
18%
None
Increase
15%
9%
Increase
Energy Cost and IAQ
15
Report # 5

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Energy Cost and IAQ	16	Report # 5

-------