Efficient Buildings

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.

Passive solar and daylighting work best at low densities, but they should still be taken into account in higher density eco-cities.

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 show promise for the future.

Fit for Purpose

Although certain concessions must be made when building at a higher density, every home and workplace still needs to be a pleasant environment to live or work in.  This means windows large enough to let in sufficient daylight, ceilings high enough that you don't feel cramped, good acoustic isolation between adjoining buildings, and clever layouts to make the best use of available space.

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