Civil Engineering Reference
In-Depth Information
demand would be reduced and it would not reduce the present demands (Asadi
et al.
2012a
). For many years to come, only measures taken in existing buildings
will have a significant effect on the total energy demand in the building stock.
Therefore, rapid enhancement of energy efficiency in existing buildings is essential
for a timely reduction in global energy use and promotion of environmental
sustainability.
During the last decade, many governments and international organizations have
put significant effort toward energy efficiency improvement in existing buildings,
as evidenced by the EU Energy Efficiency Action Plan and President Obama's
Better Buildings Initiative, among others (White House
2011
). In EU, the cor-
nerstone of the European energy policy has an explicit orientation to the conser-
vation and rational use of energy in buildings as the energy performance of
building directive (EPBD) 2002/91/EC and its recast (EPBD) 2010/31/EU indicate
(EC
2002
,
2010
). The EPBD's main objective is to promote the cost-effective
improvement of the overall energy performance of buildings. One of the best
opportunities to do so would be during building retrofit.
Existing building retrofits offer many challenges and opportunities. The main
challenge is that many uncertainties are at stake, such as climate change, services
change, human behavior change, government policy change, etc., all of which
directly affect the selection of retrofit technologies and hence the success of a retrofit
project. The subsystems in buildings are highly interdependent. Different retrofit
measures may have different impacts on distinct building subsystems due to these
interdependencies, which make the selection of retrofit technologies very complex.
Dealing with these uncertainties and system interactions is a considerable technical
challenge in any sustainable building retrofit project. Other challenges may include
financial limitations and barriers, perceived long payback periods, and interruptions
to operations of buildings. The willingness of building owners to pay for retrofits is
another challenge if there is no financial support from the government, particularly
since the issue of ''split incentives'' is often a key factor because the retrofit cost
generally falls to the building owner, whereas the benefit often flows primarily to the
tenants. On the other hand, building retrofit offers great opportunities for improved
energy efficiency, increased staff productivity, reduced maintenance costs, and
better indoor comfort. It may also help to improve a nation's energy security and
corporate social responsibility, reduce exposure to energy price volatility, create job
opportunities, and make buildings more livable (Ma et al.
2012
).
According to Ma et al. (
2012
), the overall process of a building retrofit can be
divided into five major steps (Fig.
1
). The first phase is the project setup and pre-
retrofit survey. In this phase, the building owners, or their agents, first need to
define the scope of the work and set project targets. The available resources to
frame the budget and program of work can then be determined. A pre-retrofit
survey may also be required in order to better understand building operational
problems and the main concerns of occupants.
The second phase comprises an energy audit and performance assessment (and
diagnostics). Energy auditing is used to analyze building energy data, understand
building energy use, identify areas with energy waste, and propose no-cost and
