Environmental Engineering Reference
In-Depth Information
4. For suggesting measures and recommendations for reducing the
energy use
5. To provide the information necessary to make calculations of the
environmental impact due to the energy use (e.g. CO
2
emissions)
6. To describe selected energy properties of the building
7. Give the basis for a common energy performance certification of a
building
Depending on the purpose of the energy declaration, different proce-
dures can be of interest. Different actors need different information. For
example, for benchmarking and for explaining the CO
2
emissions, it can
be enough to read the total energy supply to the building and only adjust
these figures to normal outdoor climate and to the heated area. For giving
relevant advice to the property owner regarding cost-effective measures, a
very careful examination and calculation of the building's energy balance
is necessary.
One way to proceed is to make the energy calculation in different steps
for existing buildings. The first is to collect measured energy use (e.g. from
energy bills) and create a benchmark to decide if the actual building is
better or worse compared to similar buildings. If the energy use seems to
be higher than the average for a comparable grouping of buildings, a sec-
ond step is to make a careful energy calculation that can be compared to
the measured energy use. This has to be done to identify what measures
can be recommended in order to reduce the energy use in the building.
For benchmarking, it might also be of interest to compare the measured
energy use in the building examined with the estimated energy use in
a building that is built with the best available technology. Alternatively,
it could be compared with a building that meets the requirement in the
existing building codes. Some important aspects necessary to take into
consideration when developing a common tool for energy declaration of
buildings are discussed in the next section. The discussion here is focused
on residential buildings, but similar principles are relevant for other types
of buildings.
7.2.2 Energy Declaration of Existing Buildings
For most existing buildings, the energy use usually is well known via the
energy bills. On the other hand, the construction details usually are not very
well documented. Calculations of the energy use will thus in most cases be
very uncertain, and difficulties will occur when giving relevant recommen-
dations of cost-effective energy conservation measures.
The energy declaration needs a combination of tools for calculations based
on the information from the energy bills. For existing buildings, the energy
declarations can be based on measurements and calculations in order to
