Here's an idea

Eastleigh borough council wanted a demonstration house to show people how energy efficiency works. It chose Downland Affinity to set up the "Lighthouse", a 1930s terraced property we made more environmentally friendly.

We installed low-energy lightbulbs and bulked up its loft insulation to 200 mm. Windows were double-glazed, but using soft wood instead of PVC frames. Wall cavities were filled with argon gas, which absorbs and retains heat.

We added experimental stuff, such as solar panels on the roof to heat water, plus photovoltaic panels to power the rest. The security lights and a fountain in the garden are solar-powered.

Renovating the house cost an extra £24,000 because of these features, although a government grant covered half the price of the photovoltaic panels. The Environment Agency gave a further £3000 for water-saving measures.

Overall, we increased its SAP (energy) rating from 55 to 98 out of 120. The feature people like most is the "sunpipe", which comes down through a hole from the roof to the landing. It's shiny and reflects every bit of light from outside, brightening up the property.

It's popular: 500 visitors came in the first month. Comment forms show many introduce some of the measures themselves.

It was opened to the public on 23 October and will close on 6 December. Eastleigh will then let it to someone on its waiting list.

It was a test bed for us and we'll use some of its ideas in our new-build properties.