User Manual

112
4.4.4. Sample calculation for an office building
Application of the BACS efficiency factors when calculating the impact of BACS and TBM on overall
energy efficiency of a medium-sized office building (length 70 m, width 16 m, 5 floors). BACS
efficiency class C is used as the reference. Improvements to energy efficiency by changing to
BACS efficiency class B are calculated.
Description
No.
Calcu-
lation
Unit Heating Cooling
Ventila-
tion
Lighting
Thermal energy
Energy demand
1
kWh
m
2
· a
100
80
Plant losses
Reference case
2
kWh
m
2
· a
22 28
Energy expense for
Reference class C
3 S 1+2
kWh
m
2
· a
122 108
BACS factor thermal
Reference class C
4
1 1
BACS factor thermal
Actual case (Class B)
5
0.80 0.80
Energy expense
Actual case class B
6
3

∙

5
4
kWh
m
2
· a
98 86
The expense of thermal energy must be distributed among various energy carrier to complete the calculation.
Electrical energy
Auxiliary energy class C
7a
kWh
m
2
· a
5 20 21
Lighting energy
7b
34
BACS factor electrical
Reference class C
8 1 1 1 1
BACS factor electrical
Actual case (class B)
9 0.93 0.93 0.93 0.93
Auxiliary energy
Actual case (class B)
10
7 ∙
9
8
kWh
m
2
· a
4.6 18.6 19.5 31.6
Results
After transforming the office building by updating BACS functions from the BACS efficiency class C
to class B, energy consumption per BACS efficiency factors published in EN 15232 were reduced as
follows:
· Heating energy 98 kWh/m
2
· a instead of 122 Reduction to 80 %
· Cooling energy 86 kWh/m
2
· a instead of 108 Reduction to 80 %
· Electrical energy 74 kWh/m
2
· a instead of 80 Reduction to 93 %
These improvements in energy efficiency lead to annual energy savings of 291,200 kWh for
the entire building (5,600 m
2
).