Table 3-1. Building Heat Loss Rates

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Design: Solar Heating of Buildings and Domestic Hot Water

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:

The ASHRAE Handbook of Fundamentals describes the basic method for

calculating heat losses in a chapter entitled "Heating Load."

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.