Civil Engineering Reference
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building, there will be some outdoor temperature, below the occupied set point
temperature, at which the heating system will not need to run. At this point the
casual gains equal the heat loss. This temperature will be the base temperature for
the building. If the outdoor temperature is below the base temperature, then it is
required heat from the heating system. Heating degree-days are a measure of the
amount of time when the outside temperature falls below the base temperature.
They are the sum of the differences between outside and base temperature whenever
the outside temperature falls below the base temperature. The number of degree
days for a heating season is determined with relation:
X
day
ð#
b
#
e
;
i
Þ
C day
HDD ¼
for
#
b
#
e
;
i
½
ð
4
Þ
Heating degree-days for a geographical site between given dates correspond to a
time integral of
D
#
bal
¼
#
b
#
e
;
i
in which only positive values of the difference are
counted.
The number of heating degree-days in EU countries (Fig.
5
) is in a range from
700
-
°
-
°
800 [
C day] for Cyprus and Malta to 4,000
5,000 [
C day] in Nordic and
Baltic countries.
Fig. 6 Correlation between temperatures and degree-days [
2
]
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