Last week we visited a Victorian property in Hornsey, North London, which had been refurbished to reduce its energy and carbon use by 80%. The house is owned by Metropolitan Housing Association and was retrofitted by Anne Thorne Architects. Three thoughts occurred to us based on what we saw:
Time to address the tension between sustainability and conservation
We need some form of national intervention to move the bar towards what we might call “heritage-friendly sustainability”. Planning departments all over the country are refusing to allow the sort of external, rear wall insulation that we saw at the Hornsey house and much credit is due to Haringey Council for allowing this one. External insulation is easier and cheaper to install, and is more effective in terms of preventing heat loss or rainwater penetration. There needs to be some national guidance that moves us forward on these issues.
Assistance to suppliers of high performance energy efficiency kit
There are no producers of Passivhaus-certified kit in the UK. This will come but what we really need, picking up on the conservation/sustainability issue, is help for British manufacturers who try to make energy efficient kit which works for Conservation Areas.
For their Passivhaus retrofit in Princedale Road, Holland Park, Green Tomato Energy made some triple glazed windows that look exactly like Victorian sash windows from the outside, but that was very much a one off. One thing that could possibly be done would be to remove VAT from high performance energy efficiency measures (triple glazing, solid wall insulation, heat recovery ventilation).
The Passivhaus standard was developed by German engineers more than 20 years ago. It is about comfort (draught free buildings, fresh air ventilation) and energy efficiency (thick walls, triple glazing, careful use of sun and internal heat gains eg human bodies and electrical equipment). The evidence from Germany today is that people want to live and work in Passivhaus buildings because: a) they’re comfortable and b) they cost almost nothing to run. Measured outcome for Passivhaus buildings is always the same as predicted outcome and sometimes better. The reverse is the case for British low energy buildings – they almost never perform as well as predicted.
We don’t have to call it Passivhaus but we do have to use Passivhaus principles if we want to dramatically improve the energy efficiency of Britain’s buildings.