Environmental Engineering Reference
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were measured up to 4 C compared with the bare facade. Which means that the
thermal resistance of the greened facades increased due to the extra material
properties, air cavity, and plant tissue. Field measurements conducted by Mazzali
et al. (
2012
) in a Mediterranean climate show comparable findings with laboratory
tests and calculations conducted by Ottelé (
2011
). The facade covered with a
living wall consisting an insulation layer (external side of the wall) shows a
significant (66 %) reduction in cooling energy than a system where the insulation
material is on the internal side (more heat accumulation in the massive facade);
furthermore, they concluded that the most effective orientation of the (green)
cladding, regardless the type of wall and the latitude, was the south side.
6.5 Utilization of Green Buildings
6.5.1 Green Roofs
Realization of green roofs is becoming a good construction practice in a lot of
countries in Europe, especially in Germany, as well as in the USA (Osmundson
1999
; Köhler et al.
2012
); however, large scale implementation takes much more
time and effort. In a report published by the municipality of Rotterdam (Anonymous
2007
) a survey is given about the different types of green roofs with full financial
details. Comparison of different types was needed to stimulate large scale application
including suggestions for a system of subsidies (Anonymous
2007
).
The advantages for the built environment as stated earlier by using vegetation
on roofs are clear:
• increase of water buffering capacity (water management) instead off peak
runoff to sewage system due to delayed runoff, transpiration, and evaporation.
• improvement of air quality (deposition of particulate matter on leaves for
example).
• reduction of the heat island effect in urban areas. Energy savings (increase of
insulation capacity—keep building cool in summer and keep cold out in
winter).
• noise level reduction up to 10 dB(A).
• increase of lifetime of roofing material.
• increase of esthetic values.
• increase of ecological value and biodiversity.
In Scandinavia in the past, roofs were covered with a soil layer (sod) that was
stripped from surrounding grass meadows (Donnelly
1992
). Underneath the sod
structurally heavy timber beams were interspaced with birch bark to act as a
waterproofing layer.
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