More on ‘GREEN’

I’ve been pondering the issues raised by Super Spacer’s ‘Energy Efficiency’ seminar at the Ricoh Stadium, last week. Ostensibly it was all about using the available technology to raise the window efficiency and gain a higher rating. Call me a cynic, but in reality, it was about ‘marketing’ and gaining more business for all concerned than about being ‘GREEN’: More business for fabricators, suppliers, test-houses, anyone involved in handing out energy ratings – the GGF/Carbon Trust – and marketing people.

I have always been uncomfortable in the company of people who want lots of money for confirming that my products are as good as my customers claim. Having been through the test house on many occasions (and learned a lot, at considerable cost) I cannot see any real reason to repeat the process on an annual basis just to line someone else’s pocket. If the client demands it, then I suppose I’ll have to spend the money, but it puts the cost up to the client and to everyone else, and creates another mound of paper. It undoubtedly creates work and jobs for the non-productive element in society, and I suppose that it is something that we have to live with.

The light really lit up when I heard the excellent speaker on ‘Marketing’ tell the assembled throng that “....we should call our old customers and suggest they upgrade to the latest model.” in much the same way that the car dealer calls you to tell you that the new car you bought last year is now obsolete, and you should consider trading it for this year’s model.

Now, this might be good business practice, but ‘green’ it ain’t.

Glass requires a great deal of energy to manufacture. Sealed unit failure is an expensive tragedy in ‘green’ terms. Replacing sealed units in less than 25 years is not energy efficient under any circumstances.

The best way to ‘go green’ is to turn the thermostat down two degrees, put on a woolley jumper, and then make the most effective improvements to your insulation to make the house as comfortable as possible. That means loft and cavity wall insulation (if you have a cavity) the best double glazing system you can afford, replaced only when necessary, and then floor and wall insulation if practical.

Modified plantation softwood or plantation hardwood (European oak) is the only real long-term low-energy frame material with no impact on the environment. Combine it with a glazing system that will last 25 years or more, and then you can call yourself ‘green’.

For an unbiased report from the University of Wales, visit www.wvnet.co.uk/rep_abr_bangor.html

Spacia (vacuum) units

An enquiry today on The Windowman Website about these. I chased this one up early last year. After a very long silence, in the summer I received a call from a Pilkington Business Manager apologising for the delay in getting back to me about Spacia units, and we had a long discussion about them. Briefly, they were to be available this spring: The cost was likely to be very high, and sales were likely to be restricted to those conservation projects where there is little alternative and funds are available: They did not expect to sell them in great volume. This was before the economy melted down. He expected the price landed at Tilbury to be in excess of £100/m2. With the depreciation in the currency since then, I would expect, all things being equal, that this would now be closer to £150/m2. That implies a retail price in excess of £300/m2 if the whole project doesn't simply collapse. Presumably, there would be a minimum price for small units, which makes any Georgian window with separate sealed units more expensive than the price/m2 leads you to expect on first sight.
I concluded that they would be no threat to the established double glazing industry for many years to come, on cost grounds alone. I am pleased to report that while my new friend failed to sell me Spacia units, I did sell him a loft-conversion full of Accoya windows. The first time I have turned the tables on a salesman. Very satisfying.
In my view there are better ways of getting a good result without spending a fortune. The pictures alongside show how good a modern timber rising sash can be. My customers love them!

The best of everything

If you want to maximise light and thermal efficiency with privacy, you can do worse than use acid-etched glass - perhaps with a pattern in it to make it more interesting. You can find suppliers who will actually acid etch the glass before it's made into a sealed unit of whatever sort, or you can use a stick-on film that does the same thing. People who supply stick-on Fablon signs for vans will supply the stuff. I have a local supplier in Rugby whose front door is done in the stuff, and I can't tell the difference from my own front door which has the real thing. A 5mm line as a pattern acts pretty much as a secret viewer if you stick your face close to the glass, although it does work in both directions if your visitor does the same. It certainly works for me: U-value 1.3 centre pane, bright hallway and a high degree of privacy.

More on U-values

I haven't yet started to plot any results, but some early observations appear: Outside, the surface temperatures are always higher than the OAT. The insulated panel is performing best - by far - and the glass is just a tad colder than the solid wood. The glass margin is almost a degree warmer than centre pane, even with Super Spacer. Inside, the glass feels much colder to the touch than either the insulated wood panel and the solid wood rail. This may be a Thermal Capacity issue, but the effect does not change with prolonged touch. The glass always feels colder than the wood. The dawn OAT has been steadily declining for the past week (3 degrees now) so the temperature gradients are becoming significant.

Annoyed with myself today to learn that I had missed the ST advertising deadline for this week. Time then, perhaps, to revise the ad. for the following weekend. It's interesting swinging the changes and watching the changing response in the website analysis. Not enough data yet to make firm conclusions, but enough to consider some changes, perhaps.

Good news, though, on the refurb market front, with a new prospect in view for a big breakthrough. We'll see. On the one hand we have the GREEN agenda: On the other, the economy. Personally, I think the refurb market will benefit, and that brings us full circle, with the windows system designed for just that market in the first place.

The first interesting observation arrived within five minutes of the arrival of the thermometers. With a mild 10 degrees outside and a cool 18 degrees inside, the wood was one degree colder than the inside surface of the glass, but the wood was warmer to the touch. Perhaps I am seeing the difference in thermal capacity. Glass takes heat from the hand more rapidly than from the wood, and the effect of the air in the sealed unit as an insulator is not immediately apparent. I could observe no difference between solid wood and insulated wood panel. With the arctic blast expected tomorrow, and forecast to last for a few days, I should have better numbers to work on.

( PS. I didn't like the small font, so let's try this one)

More on U-values

Infra-red thermometer now ordered, hopefully it will arrive just in time for the coming cold spell forecast for this weekend. A few days of low temperatures outside should give time for temperature gradients to stabilise. Must pop down to Wilco and look for a couple of cheap thermometers to measure inside and outside air temperatures.

The more I think about this, the more I believe I might be on to something. Coated glass may well reflect energy back into the room, but if the internal surface of the glass is colder than the air in the room, (it is) the air in contact with the glass will be cooled by contact, and advect. (Opposite of convect - means cooling by contact with cold surface, and flowing downwards under its own weight. Cold air is heavier than warm, and sinks to the floor, leading to cold feet despite heating set high. It also might properly be described as a katabatic flow - cold air flowing from the hilltops and filling the valleys overnight). Is this loss properly accounted for in the calculation?

Coated glass undoubtedly reduces the energy loss through the glass, but I will still be surprised if more energy is lost directly through the adjacent wood frame which is warmer to touch than the glass.

Franchise enquiries still flowing in. Website analysis shows a growing number of visitors to the site.