What's the most important feature of an eco-building? Solar
panels? A wind turbine on the roof? Nope. It's
insulation.
High levels of insulation (together with minimal cold bridges and low
infiltration) keep buildings warm in winter and cool in summer, and so
much less energy is required for space heating and cooling.
Row houses and apartments, by sharing side walls and floors with their
neighbours, require less heating and cooling than comparable detached houses.
Making buildings more energy efficient also means making sure all the
light bulbs, appliances and boilers inside them are as energy efficient
as possible
Natural ventilation - ranging from windows that open, to wall and roof
vents driven by the wind or stack effect - should replace energy hungry air conditioning
wherever possible.
Water
Eco-buildings should conserve drinking water.
Washing machines, shower heads etc. should be as water efficient as
possible and toilets should have variable flushes.
With adequate
filtration, rainwater and greywater (water from baths, showers, hand
basins etc.) can be used in washing machines, for garden irrigation and
for flushing toilets.
Embodied Energy
Where practical, we should be using the building materials with the
lowest embodied energies - locally sourced materials and materials which
require little manufacturing.
However, this cannot be at the expense of durability.
Orientation
Maximising the southern exposures of buildings increases natural
light and cuts down on space heating during the winter.
Floors and (particularly interior) walls with a high thermal mass can
'soak up' the sun during the day, and release it into the building at
night.
But care must be taken to prevent overheating in summer.
Western exposures, which are the most difficult to shade from the sun,
should be minimised. Louvres, exterior shutters and deciduous
trees can also be used to minimise the need for cooling.
Microgeneration
Renewable microgeneration is still somewhat unproven, and many critics argue that we'd do better to invest in large scale renewables.
Indeed, poorly sited micro wind turbines can actually require more
energy to manufacture and install than they ever extract from the wind.
But recent advances in thin-film solar cells and vertical axis wind
turbines show promise for the future.
