Cutting our energy needs

The technology to cut household energy demand by more than 80 per cent and meet 2050 greenhouse gas emission targets exists right now.

More than 60% of the energy savings in the Nelson Street house are gained through improvements made in the building fabric, through improved insulation and reduced air leakages and draughts.

The loft insulation is 42cm thick, walls are insulated to a thickness of between 8cm and 20cm and the windows are triple glazed. Special membranes have been fitted above ceilings while all holes in the outside walls have been filled. And points where beams or joists meet the walls have been made airtight, too.

The house was stripped back both outside and inside during an extensive rebuild by Leadbitter under the guidance of Ridge property and construction consultants and Low Carbon Building Group of Oxford Brookes University.

There is a highly efficient gas fired boiler for central heating with integrated controls along with low energy lighting and appliances. A solar photovoltaic system on the roof provides free and clean electricity to the house and also provides extra income through feed-in-tariffs. A solar thermal hot water system on the south-east facing roofs supplies hot water to the water cylinder.

Doors and windows are on switches so once they are opened the mechanical ventilation and heat recovery unit circulating clean air around the building shuts down.

“This home provides energy security, now, and in the future. It can generate its own electricity – not entirely but most of it. It has enough solar panels to keep it running so if there was a blackout, for example, some things in this house would always run. Always on appliances will stay on.”

Rajat Gupta, Professor of Architecture and Climate Change

‘Always on’ appliances represent what is called the ‘base load’ of a family home and Rajat has sized the solar panels to meet that base requirement.

The aim of the building project was to massively reduce demand and then make sure the house could generate enough electricity to power always-on appliances.

However, Rajat is sceptical of what he calls ‘eco bling’. “That’s when you simply put solar panels on a house which makes people think they’re green but actually they’re not. The first step is energy demand reduction.”

As well as Ridge and Leadbitter, Oxford City Council was also involved in the build project as this house is part of council’s housing stock. Oxford Brookes researchers are to spend two years monitoring the house and evaluating the impact of user behaviour on energy consumption.