Donnachadh McCarthy: The Home Ecologist

It's cheap, quick and you can keep you shash frames - this is doubleglazing, the easy way

Could we get a louder alarm siren than the recent disastrous flooding, and the forest fires consuming southern Europe, where thermometers crashed through temperatures of more than 45C? This taste of what is to come as the climate crisis worsens means a nightmare future could face our children. The Prime Minister made the link between the floods and climate change but then announced a 50 per cent cut in subsidies per train passenger, making climate-destructive car travel even more attractive.

So while they dither, the rest of us must do what we can. Double- glazing is often advocated to cut energy wasted to heat our homes. All new homes now have to have double-glazed windows. However, this does not address the millions of homes that are already built. Installing double-glazing into an average home is an expensive business and difficult to justify from a purely financial perspective. The average home uses about £700 worth of gas every year and the experts tell us that we lose up to 15 per cent of our heat through single-paned windows. So if we cut losses by a half, we save about £50 a year. As the cost for double-glazing a house starts at about £3,000, and more than £10,000 for larger homes, that means a payback period of more than 60 years!

Though summer's just (finally) arriving, it's a good idea to plan these expenditures well in advance, and the good news is that I have recently come across "retro double-glazing". Don't worry – I don't mean "retro" as in "Seventies". It simply means you replace the existing single pane of glass with a double- glazing panel while retaining the existing wooden frame. This slashes the cost and avoids the ugliness of plastic PVC window frames. I went even further when getting my two kitchen windows done: instead of getting the double-glazing company to install it, I simply ordered the units over the phone and paid an actor friend of mine to install them instead. The two windows were double-glazed for just more than £300. I was chuffed with the result, not only with the cost but the fact I had saved resources by retaining the existing good wooden frames.

There are companies that will do a very professional job of retro-fitting double-glazing for you, if you are not up to the DIY. The Sash Window Workshop was one of the companies that pioneered this method of double-glazing in the South-east. Richard Dollar, managing director of this Berkshire family-run business, says it will send a workshop van round to your home, take out the sash windows, retro-fit the double-glazing, refurbish the windows and re-install them in the existing frames for about £600 per window.

If you do not have a local company doing retro double-glazing, then you can try Express Serve, from which I bought my units and that covers the UK. I was astonished to find they had absolutely no packaging when they were delivered. When I asked where the packaging was, they said the glass is locked upright in the van and so needs zero packaging. How's that for the war on waste? So if you have insulated your loft and walls and sealed all your draughts, then get cracking on retro double-glazing in the rooms you use most often.

Donnachadh McCarthy works as an eco-auditor and is the author of 'Saving the Planet without Costing the Earth'; www.3acorns.co.uk