Civil Engineering Reference
In-Depth Information
The objective in this analysis was to reach energy efficient, cost-effective,
eco-friendly building design, without considering on comfort and aesthetics.
As cooling is dominating in hot climate countries, so here the main intention
was to reduce the solar heat gains and cooling demand. The application of life
cycle analysis (LCA) lets us compare the alternatives of construction materials in
order to find the environmental friendly building design.
Eco-friendly, green building is one of the best strategies for meeting the
challenge of climate change. Greenhouse gas emissions from buildings primarily
arise from their consumption of fossil-fuel-based energy, both through the direct
use of fossil fuels and through the use of electricity that has been generated from
fossil fuels. Significant greenhouse gas emissions are also generated through
construction materials, in particular insulation materials, and refrigeration and
cooling systems [UNEP].
It is fundamental to apply the life cycle vision and take into account both the
economic and environmental costs when identifying the most eco-efficient tech-
nology. Often, products that are presented as cheap in the medium term can have
high maintenance or waste management costs and highly technological products
can have very high production costs that are never recouped. Contrarily, it maybe
that when we consider the whole life cycle, materials with significant CO
2
emissions, such as concrete, can see their emissions reduced by giving them a
second life as a filler material in infrastructure, with a double effect: the reduction
of emissions compared with obtaining filler materials from quarries and the
absorption of CO
2
due to the recarbonation processes (Zabalza et al.
2011
).
The decision support system has an object group titled 'External wall' (
http://
iti.vgtu.lt/imitacijosmain/simpletable.aspx?sistemid=428
)
, which includes five
alternatives of concrete and wooden walls defined by 15 criteria—13 quantitative
and two qualitative.
The group of quantitative indicators (with their weights) included the U-value
of wall constructions (0.1), the thickness of heavyweight layer (0.05), insulation
thickness (0.05), density (0.05), estimated inertia of constructions (0.16) and price
(0.1). The application SimaPro and the aforesaid methods assessing the life cycle
of materials produced other criteria to define the alternatives: carbon footprint
(0.1) and the CED, which comprises non-renewable, fossil (0.05), non-renewable,
nuclear (0.05), non-renewable, biomass (0.05), renewable, biomass (0.03),
renewable, wind, solar, geothermal (0.03), renewable, water (0.03). The applica-
tion estimated the values of carbon footprint and CED for each structural mate-
rial—concrete, timber, thermal insulation materials, etc.—in its manufacturing
phase. The qualitative indicators for wall constructions were aesthetic properties
(0.1) and maintenance (0.05).
In this instance, the most significant indicator was the inertia of wall con-
structions with a weight of 0.16. A more massive construction is slower to react to
temperature variations, which is a highly important factor in countries with hot
climates.
Once the weights of the criteria had been considered, the system produced
results indicating 'External wall 4' as the best wall construction. The parameters of
