Civil Engineering Reference
In-Depth Information
efficiency of the heating system as well as in building materials. The reference
house had an energy demand for heating of 353 MJ/(m
2
y). The other houses
showed values of energy consumption between 122 and 187 MJ/(m
2
y), typical for
low-energy houses. The houses only differed slightly in their sizes and layouts.
The study showed that the adoption of high-efficiency design solutions (higher
insulation, high-efficiency plants, low-energy materials, etc.) sensibly decreased
the global energy demands with respect to a common reference building. Worse
performances of the examined buildings were generally to be related to inadequate
insulation or to the use of electricity for the building heating.
An Italian case study (Blengini and Di Carlo
2010
) compared a standard house
and a low-energy house, clearly showing the different role of embodied energy in
relative terms. The primary energy used for construction and maintenance
increased by 20 % when taking the step from the standard house to a low-energy
house. The analysis was performed by collecting and estimating data from each
phase of the building, including the design phase, production of construction
materials and components, energy and water supply, construction and installation
of plants, use, maintenance and management of the building end-life. The results
showed that the use phase involved the most significant energy consumption,
accounting for 75 % of the total primary energy demand. The construction phase
required 19 % of the total energy demand, while the maintenance and end of life
phases accounted for 6 % of the total primary energy demand. A more detailed
analysis of the use phase showed that the electricity consumption was dominant,
followed by the use of LPG for house heating, hot water demand and cooking. A
large part of the consumptions were related to the use of household appliances and
other electrical equipment.
All the above case studies show that the embodied energy has decreased
slightly over time, indicating that the construction of buildings and technical
systems in general has become more effective over time. However, the relative
share of embodied energy in the life-cycle energy assessment is increasing and the
most relevant efforts that should be made are to choose insulation materials with
low embodied energy instead of increasing the amount of insulation and to
increase the share of renewable energy use.
Scientific literature shows few studies specifically focused on building refur-
bishment actions. The EU Project 'BRiTA in PuBs' (Bringing Retrofit Innovation
to Application in Public Buildings was aimed at: (1) increasing the market pen-
etration of innovative and effective retrofit solutions; (2) improving energy effi-
ciency of public buildings; and (3) promoting renewable energy technologies in
public buildings all over Europe.
The following sections summarise the results of energy and environmental
assessment of a set of retrofit actions implemented in the framework of the above-
mentioned project (Ardente et al.
2011
). In detail, following a life-cycle approach,
the authors present a balance between energy and environmental benefits and
drawbacks concerning exemplary building retrofit actions, such as the introduction
of insulation and windows with high thermal efficiency, installation of renewable
