AS Oxford Town Hall hosted the city's first climage change conference, just a stone's throw away, on Osney Island, an unassuming Victorian terraced house was already doing its bit to help the planet.

David and Barbara Hammond's East Street home may not look any different from its neighbours, but it uses just 38 per cent of the energy consumed by the average home.

The couple - he's an architect, she's an urban designer - bought the house in a run-down condition in 2000. But instead of just slotting in a new boiler and radiators, they resolved to do all they could to make it energy efficient.

A year on, they had rejected a boiler in favour of a large water thermal store tank, which is maintained at a temperature of 45C by a combination of solar power and a heat pump, and draws its heat direct from the River Thames.

Radiators were replaced by an underfloor heating system, fed by a 1.1 kilowatt solar panel system on the roof.

And by teaming this technology with good insulation, double glazing and some clever changes to the layout of the house, they not only made their home not only virtually zero carbon - carbon being the product believed to be mainly responsible for global warming - but they now channel their unused electricity back into the National Grid - so you and I can use it.

The two-storey terraced house was built in the mid 1860s, as part of the wholesale development of Osney Island in the west of Oxford.

While it faces east, it enjoys an unobstructed southern (sunny) aspect along its side. This and its close proximity to the Thames were the main inspirations for the Hammond's renovation.

Walking into the house, you find yourself in a long sun porch which is separated from the kitchen on the right by sliding doors, which can be opened up to distribute the warmth.

The open plan kitchen and living room are also warmed by underfloor heating.

And in a little cubby hole inside the back door, Mr Hammond showed me the water tank which was full of piping hot water, heated by the overhead panels, despite it being a cloudy day.

"Basically we have a pump in the river across the road which pulls the water at a rate of 35 litres per minute through a filter and a pipe which carries the water under the road and the ground floor of the house, through the heat pump, and then back into the river," he explained.

This system of water power 'on a loop' provides the house's electricity, while the solar panels sustain the heat.

But while it may all seem a little 'high tech' to some, Mr Hammond said these methods are neither new nor rocket science.

He added: "The technologies I have used have been around for decades.

"I wrote a thesis at college in the 70s on solar energy.

"And heat pump research in the 70s was based on those used in the States in the 50s.

"However, what is new is putting them together as an integrated system.

"But we have three low heat systems which actually work very well together. And what most people don't realise is that they could use one of these methods, or even two together, in their homes, quite easily."

So what's the catch? Is it costly?

"The 6kw heat pump cost £3,100, the solar conductors were around £3,000, and the underfloor heating was a bit more," he said.

"We also had to pay £600 for a Section 50 licence from Oxfordshire County Council and £1,500 for the specialist contractors to dig up the road.

"But we are probably looking at less than ten years before it all pays for itself - and even sooner if you consider how energy prices are going up.

"The way I look at it, you could go out tomorrow and spend that money on a top of the range car which would have lost half its value in a year.

"Me, I prefer to show off my solar panels! And I believe more people are moving that way too."

In the back garden, a wooden annex houses Mr Hammond's office, where a box on the wall is channelling the energy produced by the solar panels on the roof and something that looks like a digital alarm clock is pinging up a series of figures.

"The figure 2534 shows the kilowatt hours since the system was installed, while 1436 shows the kilograms of CO2 we've saved - which is over a tonne," he explained.

"The panels are powering everything in here," he added, pointing at his computer equipment, "then it gets channelled back into the house and anything else goes back into the grid."

In three years the entire system has only once required maintenance - clearing the water inlet of leaves - so no late-night calls to the plumber for the Hammonds either.

Asked whether all the hard work was worth it, Mr Hammond nods.

"Definitely. There was a lot of red tape, but I have to say that Oxford City Council, the county council and the Environment Agency were all very helpful and very interested in what we were doing too.

"I think it's great news the city council are staging this conference as I believe it is everyone's responsibility to get their carbon footprint down," he added.

"I also hope what we've done here will encourage others to make changes to their homes.

"A lot of people would be surprised at just how much they can do."