Environmental Engineering Reference
In-Depth Information
For example, lower PBP are obtainable if a diesel boiler is installed in the test
house instead of a natural-gas boiler, because the diesel cost in higher. Therefore,
the analysis carried out gives only a very general indication about the convenience
of the installation of BACS and TBM systems.
On the other hand, in this study, the increased market value of the house due to
the improvement of its energy performance class has been neglected. A general
conclusion can be drawn from the results of the calculations: the installation of a
BACS system is as more convenient as higher it is the energy (electrical and
thermal) consumption of the building and as lower is its initial energy class
according to EN 15217.
6.6.2
Passive Measures
For the same test house, the improvement of the energy performance due to the use
of some passive measures as suggested by the Passive House standard is evaluated.
The measure to improve the sealing of the building using a building envelope is
considered. This measure can be actuated realizing a thermal coating as the one
represented in Fig.
6.5
and by replacing the old windows.
In this example, the house is supposed to have originally an Energy Perfor-
mance Class G with a mean global transmittance U = 2.775 W/m
2
K.
After the realization of the thermal coating and the replacement of all the
existing windows (originally with single glass and PVC frame) with new thermal
break windows with double low emission glasses, the mean global transmittance
becomes U = 0.410 W/m
2
K. The new Energy Performance Class is thus C. The
yearly energy saving evaluated according to EEN 9/
2011
is 19,043 kWh/year.
Considering the same electricity and natural gas price of the previous example, the
yearly economic saving obtained is 2072.23 €.
In Table
6.15
the costs for the purchase and the installation of the new windows
and of the thermal coating are reported.
In Table
6.16
the annualized cumulated cash flows (CCF) due to the economic
savings are reported.
In the examined case the Payback Period (PBP) is 23 years.
6.7
Conclusions
The case study presented shows that:
• the installation of a BACS or TBM system is as more convenient as higher it is
the energy (electrical and thermal) consumption of the building and as lower is
its initial energy class;
• the installation of a BACS or TBM system can improve the energy performance
of a building and upgrade its energy class according to EN 15217.
