Civil Engineering Reference
In-Depth Information
performance certificate issue. In this case, dynamic or detailed calculation meth-
odologies would be too labour-intensive for the purpose of the energy certificate.
In fact, especially in case of old existing buildings, the accurate collection of
required input data could be difficult. To this aim, in order to simplify the evaluation,
the International Standard offers the possibility to decide at national or regional level
which kind of calculation methodology to adopt, including some simplifications and
the use of some reference catalogues with input values, suitable for local applications
and depending on the type of building and on the purpose of the assessment.
This possibility has been implemented in Italy in national guidelines which in
article 4 establish, according to some building features such as dimensions, use,
existing or new construction, the possibility of applying different methodologies to
determine the energy performance indices. For new buildings and for completely
refurbished ones, it is always required to apply assessment methods reported in
UNI/TS 11300 (part 1 and part 2), which are the most detailed ones established by
Italian laws, but also in this case, the technical standard allows us to use different
ways of calculation, such as analytical or simplified ones, and to derive parameters
respectively from tables or on the basis of more accurate evaluations.
As the new directive prescribes the development of guidelines for optimizing
the relation between cost and energy performances, the choice of the calculation
method assumes a particular importance: a kind of intervention could be wrongly
considered more efficient than another one, if the parameters or the calculation are
not univocal.
Since the existing buildings refurbishment represents a real potential of energy
saving, the influence of the method on the energy performance evaluation of a
renovated building has been analysed by means of the calculations of a refur-
bishment action for two typical constructions which characterize the Italian resi-
dential building stock of the 60'-80'.
Then a series of interventions have been simulated and compared in order to
find, starting from a low-performance construction, how it is possible to approach
the definition target of nearly zero-energy building. The analyses represent an
example of an operating procedure for the evaluation of building energy perfor-
mance in case of renewal. Moreover, for the case studies, the effectiveness of a set
of energy conservation measurements has been evaluated; in order to obtain
general reference strategies for refurbishment, further investigation have to be
developed with different construction typologies and building features. At Euro-
pean level, for evaluating the cost optimal level of refurbishment actions, member
states have to define some reference buildings according to their use, typology and
construction feature (Corgnati et al.
2013
).
On the other hand, by testing the refurbishment actions using different
assessment methods, it is possible to highlight some uncertainties in the definition
of the energy performance of the constructions and in the determination of the
energy class, which is the indicator chosen by the European Directive in order to
provide an objective parameter to evaluate the energy efficiency.
In particular, the aim of 2002/91/EC Directive, confirmed by the 2010/31/EU,
was to introduce energy certification to guarantee a future uniformity in the
