Civil Engineering Reference
In-Depth Information
Cost-optimal level is defined as ''the energy performance level which leads to
the lowest cost during the estimated economic lifecycle''. In order to calculate the
cost-optimal level of minimum energy performance, member states are required to
create a set of reference buildings, at national or regional level, to be used in the
calculations. Recent investigations are helpful concerning this subject (Corgnati
et al.
2013
; Hamdy et al.
2013
; Kurnitski et al.
2011
).
To complicate things, a little bit more let us considered for instance the impact
of climate change itself on the energy requirements of the buildings. Crawley
(
2008
) mentioned that ''the impact of climate change will result in a reduction in
building energy use of about 10 % for buildings in cold climates, an increase of
energy use of up to 20 % for buildings in the tropics, and a shift from heating
energy to cooling energy for buildings in temperate climates''. Depending on the
climate zone, cooling loads are likely to increase by 50 to over 90 % until the end
of the century (Roetzel and Tsangrassoulis
2012
). In addition to increased mean
temperatures, there are likely to be more frequent heat waves like for instance the
2003 European heat wave that claimed the lives of over 35,000 people (Porritt
et al.
2012
). This means that current climate conditions of each member state can
no longer be viewed as static which will complicate even more the transposition of
EPBD recast for national laws. So, Kwok and Rajkovich (
2010
) suggested miti-
gation of GHGs as well as adaptation to climate change should be added into
building energy codes and comfort standards. Recently, Ren et al. (
2011
) analysed
climate change adaptation measures for buildings and their cost-effectiveness.
Be there as it may, new buildings have limited impacts on overall energy
reduction as they represent just a tiny fraction of the existent building stock.
Popescu et al. (
2012
) mentioned that the building stock renews slowly, by only
1-2 % per year. Existing buildings constitute, therefore, the greatest opportunity
for energy-efficiency improvements (Xing et al.
2011
).
Besides, new homes use four to eight times more resources than an equivalent
refurbishment (Power 2008), which constitutes an extra argument in favour of
building refurbishment. However, Silva et al. (
2013
) mentioned that most of the
current buildings regulations present simplified methodologies that do not allow
the correct assessment of the buildings retrofit interventions.
The words refurbishment, retrofit and renovation are generally used inter-
changeably in the literature and by organizations involved in reducing the energy
use and carbon emissions of the existing housing stock (Fawcet
2011
).
Some authors (Torcellini et al.
2006
; Jensen et al.
2009
) mention that energy
building refurbishment is a two-step approach, i.e. application of energy efficiency
measures to a cost-optimal level and suppression of the remaining energy needs
through on-site renewable energy production. More recently, Dall'O et al. (
2013
)
defends a 3-step sequence to achieve a ZEB: retrofitting building materials to
reduce energy demand, installing energy-efficient equipment, and finally, installing
microgeneration technologies.
