Building sustainable housing
Buildings last a long time. Many of us live in houses built well over 100 years ago. Many public buildings – eg schools, libraries, railway stations – have also existed for many decades.
When we build today we are building for the future; so we need to think about the future we are building for.
The future is always uncertain but one of the least uncertain things is this: Our climate, nationally and globally, will be warmer. Climate change is already causing floods, droughts and heatwaves. To avoid catastrophic change we must stop using fossil fuels and to make this tolerable we must use energy much more efficiently.
In the case of buildings that means adopting much higher standards for energy efficiency and insisting that new buildings comply with them. The second point is critical. Many studies have shown that most buildings – even those claiming ‘green’ credentials – perform less well in comfort and energy efficiency than expected. This is due both poor design and poor workmanship.
The solution is to build according to Passivhaus principles since, uniquely, passivhaus defines a design process, standards and an inspection regime. The key principles of Passivhaus are:
- Insulation rather than heating.
- Design to avoid thermal bridges (which remove heat and create cold spots)
- High quality work to avoid draughts
- Mechanical ventilation
- Recovery of heat from expelled air.
The results are impressive:
- Many ‘Passivhauses’ get most of their space heating from domestic appliances and home computers.
- A Passivhaus school in Wolverhampton is heated by a single, domestic size, gas boiler.
Enfield Green Party policy, adopted in 2012, is to
- Require all new Council-funded buildings to use Passivhaus.
- Make Passivhaus-equivalent performance (especially the requirement that space heating should need no more than 15 kWh/m2 pa) a planning approval condition for all new buildings. Developers who claim to achieve this performance without fully adopting passivhaus should be required to (1) demonstrate that their plans will achieve this, (2) pay for a post-occupancy energy audit and (3) pay the buyers’ compensation for any expected excess energy use over the first 30 years of occupancy. In estimating energy performance it should not be sufficient to rely on SAP2009 calculations.
- Work with local developers and building professionals to ensure that they understand the new standards and how to achieve them. It may, in order to encourage the Greening of the local construction industry, be appropriate to subsidise some professional training.
Energy is not the only resource that is likely to become scarce. New housing should also conserve water by capturing rainwater and reusing grey water.