Retrotec USACE - Manual (Page 392)

K4 ENERGY & PROCESS ASSESSMENT PROTOCOL
In old urban environments, the predominant urban form is a small, closed
island. This urban form shows several characteristics having consequences on
the energy performance of the building:
Built or vegetable masks: the planted drives (caducous foliage) of ave- ■
nues limit the solar contribution in summer, particularly for the lower
fl oors; they also reduce overheating of the roadway under trees.
Joint ownership of gables, which in most cases makes it possible to
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reduce surface losses of an apartment.
Climatic variation between the street and the heart of the small urban
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island: these signifi cant variations in temperature (several degrees Cel-
sius) are observed between the two facades of the building.
In rural areas, the situation of old buildings generally tends to optimize
solar saving and to reduce thermal loss, featuring a main facade oriented to the
south, few or no openings towards the north, use of vegetation to create shad-
ing in summer, and so forth.
K.2.1 Recommendations
There is often great thermal interaction between an old building and its en-
vironment and site. There are solar shadings (buildings, trees, etc.), local cli-
matic characteristics (wind, urban microclimate, heat island, etc.) and impact
of urban morphology (adjoining buildings, etc.). Each action on environment
or site, during a global retrofi tting project of a site, may affect the energy be-
havior of an old building (shadows and solar protections, coeffi cient of refl ected
radiation, potential of cooling night ventilation).
K.3 Subsystem: Traditional Building Techniques
Older building techniques are various and depend on geographical area, local
climate, and the kind of local techniques and processes that were available at the
time of building. They provide a specifi c answer for local climatic constraints.
Some characteristics can be identifi ed:
Compact buildings reduce the thermal exchange surfaces with the out- ■
side and improve the thermal behavior in winter.
Old buildings with heavy structure have numerous heavy bearing ele-
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ments.
Walls have a strong thermal inertia distributed between facades and
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inside walls.