ASK me about U values. Go on, I dare you. Throw in a multiple-choice question about low-E glass while you're at it. It's a test I'm confident of getting an A+ in, because I've spent the last few weeks reading everything that's ever been written about replacement windows.
Let's rewind. It's been a month since I moved into a 100-year-old cottage, and much as I love the quaint steel-framed single-glazed windows, this summer isn't going to last forever. According to the Energy Saving Trust, double glazing halves the heat
lost through windows and installing the good ones can save you about £110 a year on heating bills.
First, a bit more about U values. This is a measure of thermal performance, and the lower the better. Single glazing comes in at a shoddy 5.5, double glazing with a low-E coating is rated 1.8 (or a bit less if it's filled with argon gas), whereas the best triple glazing comes in below 1.0 – as with most insulation issues, it's big in Scandinavia but yet to catch on here. (Low-E, in case you're wondering, is a fancy coating which reduces heat flow between the panes.)
Perhaps sensing that we consumers find all this technical talk too much, the British Fenestration Rating Council (www.bfrc.org) launched a Window Energy Rating system in 2004, complete with A-to-G-rated labels just like you find on fridges and dishwashers. If you're being eco-friendly, it's got to be an A-rating, something plenty of windows are achieving (and that does include PVC-framed ones as well as timber).
Most environmental groups hate PVC-framed windows because of the amount of energy used in manufacture (eight times that of a timber window) and because they are made using a non-sustainable source – ethylene (derived from gas or oil). Then there's the contentious issue of dioxins being given off during production, plus concerns about the windows ending up in landfill and refusing to biodegrade (recycling rates are low and an EC study in 2000 reported that 82% of PVC goes to landfill).
But since the mid-1980s, PVC windows have overtaken wood – timber accounts for only 25% of the 12 million windows sold each year in the UK. In the 1960s, in contrast, more than 95% of window frames in Britain were made of wood. Why the change? It's a one-word answer: maintenance. Why sand and paint when you can get plastic windows that last forever? That was the idea, anyway. Now that there are PVC paints and cleaners on the market, along with high-performance timber windows that have a ten-year guarantee on their finish, this argument holds less sway.
Of course, if you opt for timber, you need to make sure it's FSC-labelled, otherwise you might inadvertently be supporting illegal logging and forest destruction. And you thought you were just buying windows.
This week's awful confession is that I did get some quotes for PVC windows. What can I say, I bought into the 'no-maintenance' claim. But I'm now looking at timber as the preferred option. When I'm perched atop a ladder sanding and varnishing, I do hope the knowledge that I took the moral high ground will be a comfort. At least I'll have stopped obsessing about U values by then.
HEALTHY PLANETFAST-GROWING and sustainable, bamboo lends itself to a multitude of uses. Besides being beautiful, this bamboo optical mouse uses only a tiny bit of the plastic that normal computer mice do. (Bamboo optical mouse, £17.55, www.etree.biz)
5 Minutes to save the worldTAKE a closer look at your barbecue charcoal: 90% of it is imported from overseas, meaning air miles and the possibility that it has been manufactured using wood from tropical forests. Locally sourced, sustainable charcoal produced in traditionally coppiced woodland makes for a much greener barbie, so visit
www.bioregional.com to find a British charcoal supplier.
The full article contains 673 words and appears in Scotland On Sunday newspaper.
