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JarekKurnitskiTallinn University of Technologyjarek.kurnitski@ttu.ee | KalleKuuskTallinn University of Technology | Raimo SimsonTallinn University of Technology |
To
understand the status on the ground QUALICHeCK
project conducted a review of 31 previous studies dealing with measured
performance, reliability of input data, quality of the works and compliance
frameworks. Additionally, 10 field studies were conducted in 9 focus countries.
These studies covered all main technology areas:
·
Transmission
characteristics and air tightness
·
Ventilation
systems
·
Summer
thermal comfort solutions
·
Renewable
systems (heat pumps, thermal solar, PV)
Five of the
field studies analysed EP compliance and EPC input data quality by site visits,
check of design documentation and new energy and EPC calculation to compare
actual and reported energy performance. One study was devoted for summer
thermal comfort compliance, including temperature measurements in Estonian
apartments, check of design documentation and temperature simulations based on
actual solutions checked by site visits. Reliability of EPC issued with
different calculation methods was studied in Spain. Last three studies worked
with transmission characteristics including quality framework for cavity wall
insulation and input data on window thermal performance in Belgium and U-values
compliance in Cyprus.
Most of the
studies raise questions related to compliance frameworks. Often compliance
frameworks stopped to schematic design/building permit and the final design,
construction phase and as-built energy performance was not controlled after the
building permit was issued. Only 4 out of 9 countries had compliance frameworks
extended to final design and construction and commissioning phases, Table 1. This means that the rest 5 countries did not have clearly defined
control mechanism and related practices how to take into account changes in
final design and production information as well as design changes during
construction. No common practice was found from commissioning procedures, which
were typically not EPBD driven and were not clearly required, but more related
to good practice.
Table 1.
Overview of time frames for energy assessment requirements for new buildings in
9 countries.
a Defined in EN/ISO 52000-1:2016
b Not based on EPC method
Sweden uses
different approach from other countries when issuing EPC. EPC in Sweden is
based on measured energy use and EPC is to be issued within 2 years after taken
in use. The measured energy use is corrected for the reference year, and should
also be corrected for normal use, but as no standard methodology is available
this is seldom done.
313 newly built
houses were studied in Sweden. Of these 100 houses had been taken in use two
years prior to this study and only 44 EPCs were available, which means that
only 44% of the buildings complied with the requirements of the EPBD. So far no
court cases of home owners lacking EPCs and the authority Boverket
have not reported and legal actions to force homeowners seem to be difficult if
houses are not sold or rented, when EPC is required and well available.
Swedish
study compared calculated and measured energy use in studied buildings. In
majority of cases the deviations were reasonable, but in some cases the
deviation was much higher than the ±10% band shown in Figure 1.
Smaller
difference than 10% is considered acceptable according to Sveby
guide. 29 houses out of 44 (66%) had a larger difference than 10%. The average
difference was 25%, max difference has 113% larger measured energy use than
calculated. Since the calculations are performed at an early stage and may not
have been updated with the latest drawings and information. It was shown that
the difference was larger for houses heated by exhaust air heat pump than for
houses heated by ground source heat pump.
Figure 1.
Comparison of measured and calculated energy use in Swedish houses.
Estonian
study was focused on summer thermal comfort. In Estonia EPBD Annex I
requirement: “1. The energy performance of a building shall be determined … and
shall reflect the … cooling energy needs
(energy needed to avoid overheating) to maintain the envisaged temperature
conditions ...” is addressed by a requirement not allowing to exceed +27°C more
than 150 Kh (Kelvin hour) in residential
buildings and +25°C more than 100 Kh in
non-residential buildings from June 1 till Aug 31, to be simulated with
standard building use and test reference year. The principle of the temperature
simulation based requirement is shown in Figure 2.
Figure 2.
Estonia limits temperature excess over 27 °C to 150 Kh
in residential buildings, to be proved by dynamic temperature simulation in critical
rooms.
This
relatively new requirement was not yet well established in practice as in many
cases no evidence of compliance was provided in the building permit design
documentation and simulations conducted for real apartments showed overheating
in 68% of studied apartment buildings, Figure 3.
Figure 3.
Assessment of overheating index in 25 buildings (based on simulated hourly mean
room temperature in degree-hours above 27°C in "worse case" dwellings
between 1st of July- 31st of August).
Estonian
study resulted in rule of thumbs how to prevent overheating. In the case of
South oriented windows an overhang (by balconies) 0.7 times window height
was enough, and for West oriented windows window-to-wall ratio times solar
factor no more than 0.2 avoided overheating.
In Cyprus,
the compliance with relatively new U-value requirements was studied. Quite
modest average U-value requirement of Umax =
1.3 was met in all buildings and deviations with design values were reasonable,
Figure 4.
Figure 4.
As built U-values comparison to design values in Cyprus.
In Romania
EPC-s of 26 residential buildings were recalculated. Compared to existing ones,
many deviations were found caused by incorrect calculations, deviations in the
assumptions and calculation of input data (net floor area, heated volume,
U-values, heat transfer area of building envelope etc.) and by the differences
caused by software tools used. As a result, 50 % of the buildings had more than
one class higher energy use for space heating and 39 % of the buildings had at
least one class higher total energy use, Figure 5.
Figure 5.
Percentage of EPC-s with more than one class deviation in Romania.
Results
reported in this article provide only small insight to QUALICHeCK
project results. Outcome of the literature review can be found from the Status
on the ground report http://qualicheck-platform.eu/about/situation-on-the-ground/
Based on these 31 studies it can be concluded:
·
Poor
ventilation is seen as a major European problem as ventilation rates and noise
typically did not comply with requirements;
·
Ductwork
air tightness is an issue in Central Europe, but was solved 30 years ago
in North Europe;
·
Building
leakage showed both good and bad examples;
·
Studies
on transmission characteristics were quite limited and mostly inconclusive;
·
Heat
pumps, solar thermal and other renewables showed good performance if certified
installers type schemes were applied;
·
Available
data on summer thermal comfort was very limited however the issue was somehow
addressed in majority of building codes.
Field
studies conducted by QUALICHeCK show:
·
In
many countries development with 5 years’ step can be seen – new requirements
and procedures 2007, 2012 etc. have been launched;
·
Systemic
changes evidently will need time, legislative changes are to be supported with
relevant compliance procedures, supervision, commissioning, performance
measurements, piloting, model solutions, guidelines, training etc.;
·
More
ambitious and sophisticated systems (such as Estonian and Swedish examples reported
here) more difficult to implement in practice – longer learning curves;
·
Compliance
frameworks are to be extended in many countries in order to be able to assess
as built performance – in about half of studied countries control mechanisms
stopped to building permit phase.
QUALICHeCK responds to the challenges related to compliance of Energy
Performance Certificate (EPC) declarations and the quality of the building
works. Find out more at http://qualicheck-platform.eu.
The QUALICHeCK
project is co-funded by the Intelligent Energy Europe Programme of the European
Union. The sole responsibility for the content of this article lies with the
author(s). It does not necessarily reflect the opinion of the European Union.
Neither the EASME nor the European Commission are responsible for any use that
may be made of the information contained therein.
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