Civil Engineering Reference
In-Depth Information
Working towards solutions
Reducing the energy requirements in buildings (mainly those for heating, cooling
and lighting) emphasises the role of the building envelope (opaque and transpar-
ent) as a filter between the controlled conditions indoors and the ambient outside.
The improvement of the building fabric's performances is at the basis of any cli-
mate-conscious design approach, independent of the specific context.
Solutions that allow a low or nearly zero-energy building in a cold climate (or,
for temperate climates, in winter) are quite consolidated and have already demon-
strated some economic and technical viability, including the Passivhaus buildings in
Germany and the Minergie-P buildings in Switzerland. Innovations in the next future
are likely to be concentrated on the improvement of existing products, and in particu-
lar of insulating materials. In heating-driven climates, the basic principles of very low
energy (or passive) houses are very good fabric insulation, air-tightness, exploitation
of solar radiation and internal gains and controlled ventilation with heat recovery.
Solutions relating to buildings located in warm to hot climates (aiming at summer
comfort with low or no purchased energy use) are instead less consolidated and, up
to now, have generally been defined on a case-by-case basis. Assessing the behaviour
of a building in the warm season, when windows may be open and heat flows may
change direction during the day, requires more accurate and time-consuming analyses.
Generally speaking, an efficient building in summer should be able to reduce
overheating with an efficient fabric (insulation, thermal mass and shading), elim-
inate excess heat with natural ventilation and resort to mechanical cooling only
when ambient conditions do not guarantee passive comfort inside the build-
ing. Achieving this requires close coordination by designers of technology and
mechanical systems to avoid under or over sizing the cooling system.
Climate-conscious, energy-efficient design requires the adoption of a num-
ber of coordinated strategies, with conflicting requirements potentially arising
between heating and cooling seasons. Innovation lies not just in products and com-
ponents themselves, but also in the way they are combined and coordinated.
3.1.1 Heating and Cooling
3.1.1.1 Thermal Insulation
To reduce the environmental impact on the built environment, it is essential to con-
sider further development of the efficiency of thermal insulation materials based
on the fact that:
• insulation has a great potential for reducing CO
2
emissions;
• energy conserved through insulation use outweighs the energy used in its manufac-
ture. Only when a building achieves a low energy standard does the energy embod-
ied in the insulating materials become significant (Sartori and Hestnes
2007
);
• the durability of insulation affects its performance e.g. settlement, physical deg-
radation, vapour permeability and air movement.
