MIL-HDBK-1003/19
where Qint (Btu/day) is the internal heat generation rate. Use of Tb
rather than Tset in heat loss calculations is a simple and reasonably
accurate way to include the effect of internal source heating on building
performance. Unless other information is available, Qint can be taken
equal to 20,000 Btu/day per person.
4.4.1.14 Heating degree days. The heating degree days (DD) is the
hourly summation of the difference between a specified base temperature and
the ambient temperature for a certain time interval, where only positive
terms are included in the summation, and the result is divided by 24. The
units of DD are deg.F-day and the time interval of interest is generally one
month or one year.
4.4.1.15 Effective building heat load. The effective building heat
load (QL) is given by the product of the effective total load coefficient
and the heating degree days for the time period of interest. Thus:
QL = TLCe [multiplied by] DD ,
(Equation 4.14)
where the units of QL are Btu.
4.4.1.16 Net building heat load. The net building heat load (QN) is
the product of the net load coefficient and the heating degree days for the
time period of interest. The defining equation is:
QN = NLC [multiplied by] DD ,
(Equation 4.15)
and the units are Btu.
4.4.1.17 Steady state heat load. The steady state heat load (QSL) is
the actual total heat load for a specified time period. The defining
equation is:
QSL = TLCs [multiplied by] DD
(Equation 4.16)
and the units are Btu.
4.4.1.18 Solar load ratio. The solar load ratio (SLR) is the ratio of
the amount of solar radiation absorbed by the system to the effective
building heat load. The defining equation is
SLR = S [multiplied by] Ac/QL ,
(Equation 4.17)
or
SLR = ST/QL
(Equation 4.18)
For tilted apertures in sunspaces, Ap must be substituted for Ac.
The
solar load ratio is dimensionless.
48
Previous Page
