The Green House

You need more than a bat box in the drive to make your home truly sustainable

The claims of religion and the proofs of science; the benefits of healthcare and the value of art; the smell of lavender and a blackbird's song: in each of these conjunctions, meaningful comparison is remarkably difficult because the two sides of the argument are incommensurable.

I am rather fond of this word, which packs in the rhythmic range of an entire poem: a sharp, rocky prologue followed by a descending wave that is rapidly lost in the sand. It describes so much contemporary debate, a fruitless talking past one another with no basis for real engagement; clashes of values dressed up as disputes about fact.

This problem gets everywhere. Within the world of green building (and, more generally, green politics), conflicts often arise because different green actions have seriously incommensurable outcomes. For example, do you want to promote biodiversity, reduce environmental pollution, save the rainforest, contain climate change, minimise waste, live in a healthy home or protect the landscape? Which matters more and why?

If this problem was limited to a Richard Dawkins vs the Pope shouting match, I would be content. In practice, more damage is done by disregarding these differences, resulting in quick and dirty trade-offs between them. An environmental consultant recently told me that he had pulled out of a "sustainable" building project when the client sacrificed half his roof insulation for the sake of an interesting design but still felt comfortable with his green credentials because of the bat boxes he had commissioned for the car park.

More sophisticated trade-offs have long been part of environmental assessment methods, such as EcoHomes (www.breeam.org/ ecohomes.html), that give one overall rating for a house against a wide range of environmental impacts. Although this is necessary for a holistic view, I increasingly feel that one impact should no longer be tradable: climate change. We have to radically reduce carbon emissions in all new and existing homes if we are to meet this not-quite-runaway global threat. If we fail, everything else - rivers, air quality, landscape and bats - can go whistle.

Unfortunately, our dear leaders have decided to do exactly the opposite. John Prescott's draft Code for Sustainable Building makes it possible for a house to get a "sustainable" star even if its energy performance is no better than building regulations. This is worse than useless, as the WWF indicated by pulling out of the steering group. If this all seems a bit academic, you should stop and consider your own eco-priorities. It's not unusual to feel bewildered by the range of green lifestyle options out there, and it's easy to be distracted by sexy bits of kit. If you can do it all, great. If not, decisions are easier to make if you clarify which outcomes matter to you most.

Everyone has different priorities, so feel free to ignore my insulation-first rant. I will completely understand if bat preservation is top of your list - as long as central heating is not required to sustain your Transylvanian lifestyle.

w.anderson@independent.co.uk

GREAT BUY

Kingspan phenolic board insulation is made from petrochemicals but it keeps the heat in like nothing else ( www.kingspan.co.uk).

GREAT WEBSITE

Some of the most useful information on the Energy Saving Trust's website ( www.est.org.uk) takes a bit of finding. Check out the online best-practice publications by using the "housing and buildings" link.