MIL-HDBK-1003/13A
Table 3-1.
Building Heat Loss Rates.
Net Loss Coefficient
Construction
(Btu/ft degree-day)
A. Brick veneer, 4-bedroom house, asphalt roof,
15.3
storm windows, no insulation, 15 mph wind
B. Same as A, but with 3-1/2-inch batts in walls
9.3
and attic
C. Same as B, but with 6 inches insulation in attic
8.7
D. Same as B, but with 12 inches insulation
8.4
in attic
E. Stucco over frame, 4-bedroom house, shake roof,
14.1
3-inch insulation in attic only
F. Frame, 3-bedroom, heated basement, 3-1/2-inch
11.7
batts in walls, 5-1/2-inch batts in ceiling
If Table 3-1 is not used, or if space heating loads for other types of
buildings are desired the following sources give details on how to calculate
loads:
a.
The ASHRAE Handbook of Fundamentals describes the basic method for
calculating heat losses in a chapter entitled "Heating Load."
b.
U.S. Dept HUD (1977), page 16, Section 3.3.1, describes a modified
degree-day method for space heating loads.
Table 3-2 contains degree-day data for use in Worksheet C-1. This data is
excerpted from Solar Energy Research Institute (1980). Additional locations
are available in U.S. NOAA (1968) and U.S, NAVFACENGCOM (1978). Hot water
usage is calculated on Worksheet C-2 (see Section 3.4) and transferred to
Worksheet C-1. Net DHW use is desired; if gross figure based on fuel usage
is the starting point, then it must be multiplied by heater efficiency to get
net DHW load. Utilization efficiency rather than an equipment efficiency
should be used (see DM-3). Total net heating load is sum of space and DHW
loads.
3.4 Demand calculations - DHW - worksheet C-2. Worksheet C-2 summarizes
DHW demand determined by conventional methods: Manual DM-3, chapter 1. Table
2-9 (Section 2.3) gives hot water demands for various buildings. Table 3-3
gives temperature of water mains for various locations. Net DHW load, Qd x
No, (Qd is Btu/day hot water demand) is transferred to column (W),
Worksheet C-1, if a combined space heating DHW system is being designed. If
hot water demand is calculated from fuel bills, a gross figure is obtained,
which is entered in column (U), Worksheet C-1. Net demand = gross x
[eta]w, where [eta]w = heater utilization efficiency.
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