150 / 202
KICK THE HABIT
THE CYCLE – REDUCE
150
Energy cost of various construction materials
The energy costs of building material
range from 1 to 2 800.
ALUMINIUM
141 500
STEEL
46 000
PVC
24 700
CEMENT
1 750
BRICK
1 360
SAWN
TIMBER
350
STONE
50
Energy consumed
Kilowatt hour per cubic metre
Sources: Atlas Environnement du Monde Diplomatique, 2007;
Federation of Natural Stone Industries (SN Roc); CTBA
,
L’Essentiel sur le bois, 2001.
CONCRETE
700
CO
2
emissions are not directly deducible from
energy costs. Concrete for instance is a very
CO
2
-intensive material due to the emissions from
chemical processes involved in its production,
despite the relatively low energy costs per cubic
metre.
INDIVIDUALS
It makes sense to try to get your house to do most of the work for you with-
out needing much energy at all. That may sound too good to be true, but
it is not. Germany has done a lot of work on the idea of the Passive House,
one which relies on its own intrinsic design as far as possible to meet its
energy requirements (
www.passiv.de). A house of this sort will have good
insulation, will face south, and have the best level of glazing available. It
will be airtight, will pre-heat fresh air with a ground heat-exchanger and
recover waste heat from air leaving the building, and will use renewable
energy to heat the water.
Perhaps a house like this is not an option for you, let alone one which keeps
itself warm in winter and cools in summer as well, like the ancient wind
towers of Yemen and other parts of the Middle East which are designed
to make maximum use of natural ventilation. But you do always have the
option of remembering how much energy went into building your house,
how much it needs to keep it going in the style you have adopted, and what
the scope is for saving energy – from not overfilling your kettle, to using