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Chapter –01 Introduction to the Buildings Sector
Jan F. Kreider “Introduction to the Buildings Sector”
Handbook of Heating, Ventilation, and Air Conditioning
Ed. Jan F. Kreider
Boca Raton, CRC Press LLC. 2001
© 2001 by CRC Press LLC
Introduction to the
1
Buildings Sector
1.1
Energy Use Patterns in Buildings in the U.S
Jan F. Kreider
Commercial Buildings • Industrial Processes
and Buildings • Residential Buildings
Kreider
&
Associates, LLC
1.2
What Follows
Introduction
Buildings account for the largest sector of the U.S. economy. Construction, operation, and investment in
buildings are industries to which every person is exposed daily. One of the major expenditures in the life
cycle of a building is the operation of its space conditioning systems — heating, ventilation, and air
conditioning (HVAC) — dwarfing the initial cost of these systems or of even the entire building itself.
Therefore, it is important to use the best, most current knowledge from the design phase onward through
the building life cycle to minimize cost while maintaining a productive and comfortable indoor environment.
HVAC systems are energy conversion systems — electricity is converted to cooling or natural gas is
converted to heat. Because it is important to understand from the outset the nature of energy demands
placed on HVAC systems, that subject is discussed immediately below. The chapter closes with a short
outline of the rest of the book with its coverage of HVAC design, commissioning, operation, and
problem diagnosis.
1.1 Energy Use Patterns in Buildings in the U.S.
It is instructive to examine building energy use, sector by sector, to get an idea of the numbers and to
clarify the differences between large and small buildings as well as between industrial and office buildings.
The next several sections discuss each.
1.1.1 Commercial Buildings
In 1997, there were 4.6 million commercial buildings, occupying 58.8 billion square feet of floor space
(PNNL, 1997). These buildings consumed 126.5 thousand Btu of delivered energy use (or 252.4 thousand
Btu of primary energy) per square foot of space.
Figure 1.1
shows that of the four main census regions,
the South contains the highest percentage of commercial buildings, 38%, and the Northeast contains the
least, 16%.
Commercial Buildings Disaggregated by Floor Space
Sixty percent of U.S. commercial buildings range between 5,000 and 100,000 square feet, 82% range
between 1,000 and 200,000 square feet. The size class with the largest membership is the 10,000–25,000
square foot range.
Table 1.1
shows the size distribution in the U.S.
© 2001 by CRC Press LLC
Total Number of Buildings: 4.6 Million
Total Floor space: 58.8 Billion Square Feet
25
24
16
20
NORTHEAST
MIDWEST
21
20
38
35
WEST
Percent of Buildings
Percent of Floor space
SOUTH
FIGURE 1.1
Commercial building geographical distribution. (From the
1995 Commercial Buildings Energy Con-
sumption Survey
.)
TABLE 1.1
Size Distribution of U.S. Commercial Building Space
Commercial Building Size as of 1995
(percent of total floor space)
Square Foot Range
Percent
1,001 to 5,000
10.80%
5,001 to 10,000
12.80%
10,001 to 25,000
19.80%
25,001 to 50,000
13.10%
50,001 to 100,000
13.60%
100,001 to 200,000
11.50%
200,001 to 500,000
9.40%
Over 500,000
9.00%
100%
Commercial Energy Consumption and Intensity by Square Footage (1995)
Total consumption is fairly evenly distributed across building size categories; only the largest size
category (over 500,000 square feet per building) showed a significant difference from any of the other
categories. Buildings in the 10,001–25,000 square feet per building category have the lowest energy
intensity of all categories.
Commercial Buildings Disaggregated by Building Type and Floor Space
The usage to which building space is put is a key influence on the type and amount of energy needed.
Of the total square footage of commercial office space, 67% is used for mercantile and service, offices,
warehouses and storage places, or educational facilities. The average square footage for all building types
ranges between 1,001 and 25,000 square feet. The largest building types, between 20,000 and 25,000 square
feet, are lodging and health care facilities. Medium sized building types, between 10,000 and 20,000
square feet, are public order and safety, offices, mercantile and service, and public assembly. Small building
types, less than 10,000 square feet, include warehouse and storage facilities, education facilities, food
service, and sales.
Table 1.2
summarizes sector sizes and typical floor sizes.
Commercial End-Use Consumption
Mercantile and service, and office buildings consume almost 40% of total commercial energy, in terms
of Btu per square foot. Education and health care facilities, lodging, and public assemblies also consume
© 2001 by CRC Press LLC
Intensity Consumption
Over 500,000
200,001 to 500,000
100,001 to 200,000
50,001 to 100,000
25,001 to 50,000
10,001 to 25,000
5,001 to 10,000
1,001 to 5,000
120100 80 60 40 20 0 200 400 600 800
1,000 Btu/sq. ft.
Trillion Btu
FIGURE 1.2
Energy consumption and usage intensity for eight commercial building size categories. (From the
1995
Commercial Buildings Energy Consumption Survey.
)
TABLE 1.2
Commercial Building Sector Size and Typical Floor Area
1995 Average and Percent of Commercial Building by Principal Building Type (1)
Building Type
Floor Space
(%)
Average
Floor Space/Building
(SF)
Mercantile and Service
22%
11260
Office
18%
12870
Warehouse/Storage
14%
6670
Education
13%
1770
Public Assembly
7%
12110
Lodging
6%
22900
Health Care
4%
22220
Food Service
2%
4750
Food Sales
1%
4690
Public Order and Safety
2%
14610
Vacant (2)
9%
18480
Other
2%
—
a large amount of energy, making up another 40% of total commercial energy consumption.
Table 1.3
summarizes the energy use intensities for the 12 most important categories.
End Use Consumption by Task
Finally, one must know the end use category — space heating, cooling, water heating, and lighting. Space
heating and lighting are generally the largest energy loads in commercial office buildings. In 1995, energy
consumed for lighting accounted for 31% of commercial energy loads. Space heating consumed 22%, and
space cooling consumed 15% of commercial energy loads. On average, water heating is not high at 7%;
actual load varies greatly according to building category. Health care facilities and lodging are unique in
their high water heating loads; however, offices, mercantile and service facilities, and warehouses require
minimal hot water.
Figure 1.3
shows the distribution of energy end use by sector for 1995. Another way of
considering the data in
Figure 1.3
is to consider the end uses aggregated over all buildings but further
disaggregated over the nine main end uses in commercial buildings.
Figure 1.4
shows the data in this way.
Commercial Energy Consumption and Intensity by Principal Building Activity (1995)
Commercial buildings were distributed unevenly across the categories of most major building charac-
teristics. For example, in 1995, 63.0 percent of all buildings and 67.1 percent of all floor space were in
© 2001 by CRC Press LLC
TABLE 1.3
End Use Consumption Intensity by Building Category
1995 Commercial Delivered End-Use Energy Consumption Intensities by Principal Building Type
(1000 Btu/SF)
Building Type
Space
Heating
Space
Cooling
Wa t e r
Heating
Lighting
Total
2
Percent of
Total
Consumption
Office
24.3
9.1
8.7
28.1
97.2
19%
Mercantile and Service
30.6
5.8
5.1
23.4
76.4
18%
Education
32.8
4.8
17.4
15.8
79.3
12%
Health Care
55.2
9.9
63
39.3
240.4
11%
Lodging
22.7
8.1
51.4
23.2
127.3
9%
Public Assembly
53.6
6.3
17.5
21.9
113.7
8%
Food Service
30.9
19.5
27.5
37
245.5
6%
Warehouse and Storage
15.7
0.9
2
9.8
38.3
6%
Food Sales
27.5
13.4
9.1
33.9
213.5
3%
Vacant
3
38
1.4
5.5
4.5
30.1
3%
Public Order and Safety
27.8
6.1
23.4
16.4
97.2
2%
Other
4
59.6
9.3
15.3
26.7
172.2
3%
All Buildings
29
6
13.8
20.4
90.5
100%
Notes:
Parking garages and commercial buildings on multibuilding manufacturing facilities are excluded from CBECS 1995.
Includes all end-uses.
Includes vacant and religious worship.
Includes mixed uses, hangars, crematoriums, laboratories, and other.
Source:
EIA, Commercial Building Energy Consumption and Expenditures 1995, April 1998, Table EU-2, p. 311.
four building types: office, mercantile and service, education, and warehouse. Total energy consumption
also varied by building type. Three of these — health care, food service, and food sales — had higher
energy intensity than the average of 90.5 thousand Btu per square foot for all commercial buildings.
Figure 1.5
shows the 13 principal building types and their total consumption and intensity.
Commercial Building Energy Consumption by Fuel Type
Five principal energy types are used in U.S. commercial buildings:
Natural gas
Fuel oil
Liquefied petroleum gas (LPG)
Other and renewables
On-site electric
Table 1.4
s
hows the relation between end use type in
Figure 1.5
and the corresponding energy sources.
Space heating, lighting, and water heating are the three largest consumers of energy. Natural gas and
electricity directly competed in three of the major end uses — space heating, water heating, and cooking.
In each of these three, natural gas consumption greatly exceeded electricity consumption.
Table 1.5
shows expected commercial sector energy use growth in the U.S.
1.1.2 Industrial Processes and Buildings
The industrial sector consists of more than three million establishments engaged in manufacturing,
agriculture, forestry, fishing, construction, and mining.
In 1997, these buildings occupied 15.5 billion
square feet of floor space and 37% (34.8 quadrillion Btus) of total U.S. primary energy consumption.
After the transportation sector, the manufacturing sector consumes the most energy in the U.S. Of
the 37% of primary energy consumption in the industrial sector in 1997, 33% was used for manufacturing
purposes and 4% was used for nonmanufacturing purposes. Thus, manufacturing establishments con-
sume the majority of the energy in the industrial sector even though they are far outnumbered by
nonmanufacturing establishments. Because there is a lack of information regarding nonmanufacturing
© 2001 by CRC Press LLC
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