Donnachadh McCarthy: My carbon-free year

Donnachadh McCarthy has turned his Victorian house into one of Britain's greenest homes. He explains how he did


The year 2007 was marked by two major events for me, one positive and the other a planetary wake-up call. The positive was that I fulfilled my dream of making my home not only carbon neutral but actually carbon negative for energy. After installing various gadgets and making some key changes to my lifestyle, my home actually reduced the amount of carbon in the atmosphere, rather than adding to it. I exported more green electricity than I imported fossil fuel (gas) over the year. And I don't live in a state-of-the-art new build but a normal Victorian terrace.

The wake-up call was the announcement in September that the summer sea ice in the Arctic had shrunk by a record 22.5 per cent. Predictions that the Arctic would have summer ice until 2070 are being urgently revised. In fact, Professor Bill McGuire of University College London believes there could be none left in 10 years.

So both events coalesced into a realisation that there is far too much CO2 already in the atmosphere and we need not only a low-carbon economy but actually a carbon-negative economy as soon as possible, which removes some of the billions of tons of CO2 the Industrial Revolution has unleashed into the atmosphere.

How did I get across the carbon-negative winning line? My dream of owning a carbon-neutral home started when I returned to the UK in 1992 after seeing the destruction of the rainforest where the Amazon's Yanomami Indians lived.

The first thing I did was take the Earth Summit pledge to turn off all heating and lighting when leaving an otherwise unoccupied room. My estimate is that well over 40 per cent of energy use can be saved by simple lifestyle changes to eliminate waste. Easy things, like reducing the number of unnecessary lamps, or only using the washing machine with a full load and at 30C.


Having decided to adopt a less wasteful lifestyle, rather than simply ensuring the house was properly insulated, I looked into whether I could install solar-electric panels on my terraced house. I had inherited 20,000 from my mother and the temptation was to pay off some of the mortgage. But the dream won over pragmatism, and in 1997 I got Sundog Energy to install a 1.2kW solar-electric system on the back roof of the house. I was able to persuade the local authority that it did not need planning permission as it did not disturb the roofline. And I decided to try and persuade London Energy to buy the excess electricity produced during the day via an export meter.

The negotiations with London Energy took about three months and I had to make the threat of going to the press before the company agreed. Thus, I became the first domestic customer that London Energy bought solar electricity from. It cost 12,000 to install the system, including 1,800 in VAT. Greenpeace used my case in its successful campaign to reduce the VAT on solar panels from 17.5 per cent to 5 per cent.

My solar-electric system has now been working for 10 years and annually produces about 1,000 kilowatt-hours of electricity; about a third of the average family consumption. It came with a display panel that lets me know how much electricity I'm producing, and consuming. Having that information has made me even more economical with electricity. All my bulbs are now energy-saving, and some are LEDs the total lighting power for the entire house comes to a minuscule 180W. I have an energy-saving fridge and washing machine, and even a low-energy iron.

The electricity I import is zero-carbon, from Good Energy. In the summer I export far more electricity to the national grid than I use, but it only produces about 10 per cent of what I need in the winter.

Wind turbine

About five years ago, I thought that installing a domestic wind-turbine would boost my energy-production in the winter, as there is more wind at that time of year. I got planning permission for London's first domestic grid-connected wind-turbine. It was installed two years ago but it has been a failure. The output has been barely enough to supply an energy-efficient light-bulb about 2 worth of electricity per year. Luckily, I was not dependent on the financial payback to service the 2,700 credit-card hit I had taken to install it. An expensive experiment but one I do not regret. You live and learn.

Solar Hot-Water

Despite the failure of the wind-turbine, I first managed to sell more green electricity than I imported four years ago, by using solar electricity and reducing the amount of energy I wasted. But I was still using gas for cooking, hot water and space-heating. Electricity only represents a third of the average home's CO2 emissions. I had to do something about my gas consumption.

The first area of gas usage that I tackled was hot water. I had a single solar panel installed on the kitchen roof by Southern Solar. It cost about 4,000, 900 of which came from grants. In summer it produces so much hot water I could invite the whole street in for a shower. Overall, it produces about 70 per cent of my total hot-water needs.

Even on sunny days in the middle of winter the water can reach 20C, requiring less top-up heat. I was lucky that my washing machine was able to take a hot feed, as if it was a cold-feed version, it would not have been able to take advantage of the free solar hot-water.

Flueless Gas-Fire

Having sorted out most of my hot water and electricity, I was still faced with the fact that I was using gas to heat the house. I had done the usual draught-proofing, installed Warmcel insulation to a depth of 30cm in the loft, sealed the floorboards and installed some double glazing. While I did not have central heating, the house was heated by an open coal-effect gas-fire and a radiant gas-fire. I was shocked to find out that coal-effect gas-fires waste up to 90 per cent of their heat up the chimney and traditional radiant gas-fires are only about 60 per cent efficient.

The coal-effect fire was banned and I replaced the radiant fire with a flueless gas-fire, which is 100 per cent efficient because of the incorporation of a catalytic converter. However, I had not read in the small print that they are only suitable for homes with central heating or wood burners. This is because they produce condensation. Consequently I had to get a dehumidifier, which I was not happy about, because of the extra electricity consumption.

Wood burner

While working on the BBC2 series It's Not Easy Being Green with Brigit and Dick Strawbridge, I was inspired to find out if wood burners are legal in central London. To my delight, I found that certain high-temperature burners are licensed for such use. My wood burner cost 800, but as the house is so old, I insisted on a metal chimney flue, so the installation cost another 2,000.

I got enough waste wood locally to keep the stove burning all last winter. Therefore, it is carbon neutral no fossil fuel is used to deliver the wood or chop it up. The stove compensates for the fact that the solar hot-water system is least effective in mid-winter, as the kettle boils easily on top of it. The flueless gas-fire is now a very handy back-up if I need a quick blast of heat.

There are small grants (sadly, slashed by up to 75 per cent by Gordon Brown's last budget) available for solar, wind, biomass central-heating and hydro systems, but none for the hugely effective wood-burner. Without doubt it was the arrival of my cosy Clearview Stove that helped me over the carbon-neutral winning line, to become one of London's first carbon-negative homes. It's sad that my excitement this year was overshadowed by the summer-ice disaster. However, the positive thing is that when I look audiences in the eye, waxing lyrical about the urgent need for a carbon-negative economy, at least I know it is possible. Wishing you a happy, peaceful and fun carbon-negative 2008.

Donnachadh McCarthy is the author of Saving the Planet Without Costing The Earth and works as an eco-auditor (

How the eco-savings add up

Gas usage
Consumption - 609 kWh
C02 footprint - 116kg

Electricity exported
Consumption - 598 kWh
CO2 footprint - 257kg

Green electricity imported
Consumption - 384 kWh
CO2 footprint - zero

Wood burner
Consumption - 6,400 kWh (est)
CO2 footprint - zero

Solar hot water
Consumption - 1,000 kWh (est)
CO2 footprint - zero

Solar electricity (produced and used on-site)
Consumption - 420 kWh.
CO2 footprint - zero

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