Structural Design of the mCCHP-RES System - Design for Micro-Combined Cooling, Heating and Power Systems - page 168

A calculated rating highlights the intrinsic potential of the building while a
measured rating makes it possible to take into account the impact of building
management.
With the term

, the procedure of evaluating a building through the cal-
culation of the energy used by the building for heating, cooling, ventilation, hot
water, and lighting, with standard input data related to climate and occupancy
modes is implied.
With the term

“ asset ”

, the measurement of the energy use (energy
auditing) is implied, with in situ measurements of the performance of building as is
being used, including all the deviations between theoretical and real energy con-
sumption. Although more time consuming, it can lead to more useful feedback on
both the building conditions and the tenants

“ operational ”

' behavior, and on the appropriate

measures that should be taken, so as to ef ciently reduce the energy consumption in

the building sector (and thus the carbon dioxide emissions), which is the final target

of the energy certi cation of buildings.

Since the building is envelope is responsible for its heating and cooling demand,

the estimation of the heat transfer coef

'

cient of building is a very important method

'

for evaluating a building s energy performance.

A. Finding the calculated (asset) overall heat transfer coef cient of the building

The building heat loss coef cient (UA) is found by identifying every route of heat

loss from a building and adding these together. The routes for heat transfer between
the interior and exterior are through the building envelope, air exchange between
inside and outside (in

ltration), and sometimes through the ground (perimeter),
depending on how the building meets the ground (Fig. 15 ).
Fuelling the heating space has to compensate for the losses of heat transmitted
through walls and the roof, and also the losses given by the heated air from the
mechanical or natural ventilation systems.

Fig. 15 Building heat transfer