Structural Design of the mCCHP-RES System - Design for Micro-Combined Cooling, Heating and Power Systems - page 170

Expressing the design energy consumption of a building for heating as:

UA ref
g h

Q design ¼

ð# i # e Þ design ð 21 Þ

Comparing it to the annual energy consumption gives the following relation
between energy consumption at design conditions and the annual energy
consumption:

Q heating ; year
Q design ¼

HDD
ð# i # e Þ design

ð 22 Þ

where
ð# i # e Þ design

-

is the design indoor outdoor temperature difference.

The annual energy need for heating can be determined by integration (or by
summation over daily or hourly averages) as follows:

Z

Q heating ; year ¼ UA ref ð# b # i Þ dt 0 : 024 UA ref HDD kWh ½ = year ð 23 Þ

Similarly calculated is the annual cold consumption, Q C , the difference resides
only in that the formula for calculation becomes the following:

Q C ¼ 0 : 024 UA ref CDD kWh ½ = year ð 24 Þ

The total building heat loss coef cient UA ref is given by relation:

UA ref ¼ UA envelope þ UA AirChange þ UA perimeter ð 25 Þ

The conductive heat transfer through all elements of the building envelope from
one side to the other (walls, floor, roof, windows, doors, etc.) is given by the

following relationship:

m 2 K m 2 UA envelope ¼ U ½ W = A ½ ð 26 Þ

find in Table 9 the U-value
for each element of the building envelope, multiply this value by the area of
element, and then summing the UA values thus obtained.
In

To calculate the UA value for whole building, may

ltration is the exchange through leaks, cracks, and ventilation. This represents
a loss of energy through the replacement of conditioned interior air with (colder)