Articles published in 2009

Solar Collectors

We saw last month that there is a choice of two types of collector for producing solar hot water, the flat plate collector and the vacuum tube collector. When choosing a solar system, you will doubtless prefer to be able to make the choice on more substantial grounds than how pretty the brochures are. Fortunately, there are solar test centres where the performance characteristics of collectors can be measured.



Innovations in Solar Water Heating

I’m writing this article in the bleak midwinter, when sunshine is feeble and scarce. The contribution of solar to water heating in midwinter is small – about 15% of that contributed in midsummer (though a higher percentage is claimed for vacuum tube collectors). But of course, selfbuild is about the long term, and solar water heating requires consideration at any time. In carbon-saving terms, solar water heating is very effective. And in money-saving terms, as the price of energy increases, as it surely will, solar water heating will become increasingly cost effective.



Selfbuild Associations

In the early Nineties, selfbuild was just starting to make an impression on the public consciousness. The first selfbuild magazine, Build It, had come out in 1989, and in 1990 the magazine had promoted the first selfbuild exhibition of modern times, at Alexandra Palace, London. I was there selling books about selfbuild. They went like the proverbial hot cakes, showing the public’s thirst for knowledge about the subject.



More About Wood Stoves

Last month I mentioned a wood stove, the Xeoos Twinfire, for which an amazing efficiency of 90% is claimed. But the official HETAS Guide states that the gross efficiency of the Xeoos is 76%. That’s a remarkable difference, yet a similar anomaly is to be found for most stoves. For example, Aga claim an efficiency of 81% for their Little Wenlock Classic stove, yet the efficiency given in the HETAS Guide is only 74%. What’s going on? 



The Doctor Pays A Visit - To The AECB

I reported last year on the AECB’s annual conference, at which the keynote speaker was Berthold Kaufmann from the Passivhaus Institut in Germany. Normally I would not report on the annual conference again this year – I don’t want to be repetitive. But this year the keynote speaker was none other than the founder and head of the institute, Dr Wolfgang Feist, and in view of the big role that the Passive House method will soon have in house building, a report on this year’s conference does seem apposite.



Heat Pumps: The Theory

Heat pumps are becoming increasingly popular amongst selfbuilders. As we shall see below, they give lower carbon emissions and lower running costs than gas or oil boilers. Unfortunately, the capital cost for installing a heat pump system is usually higher than for installing an oil boiler with storage tank, and much higher than for installing a gas boiler with connection to a nearby gas supply. However, as new houses become more energy efficient, heat pump systems for them become smaller and more affordable. 


Solar Water Heating 

We saw last month that a flat plate collector is generally more cost effective than a vacuum tube collector. Flat plate collectors have another advantage, too – they can form part of the roof covering, replacing some tiles or slates. The advantage lies not so much in the value of the tiles or slates saved, but rather in the superior appearance. An in-roof collector looks much neater than one fitted above the roof. Most solar collectors installed so far in the UK have been retro-fitted onto existing roofs, but for the selfbuilder, the in-roof collector must surely be the better choice. 



It's Raining Inside My House!

During the cold spell at the beginning of January, I returned home one afternoon, and on entry beheld a dismal sight. The thought that came to me was “It’s raining inside my house!” Inspection showed that water was showering down from every ceiling, both upstairs and downstairs.
What to do? 



Wood and Wood Stoves

Wood is a carbon neutral fuel, and burning wood does not contribute to global warming. The amount of carbon dioxide released when wood burns equals the amount taken in from the air when the wood grew as part of a tree. Wood is also a renewable source of energy, and it can be considered as stored sunshine. It was probably humankind’s first fuel, and it looks like wood will still be in use long after the burning of fossil fuels has become taboo.



Heating with Pellets

Using carbon-neutral wood for space and water heating is a very cost-effective way of reducing the carbon footprint of a house. Last month we focussed on log burners; this month we look at pellet burners. These are fairly new to Britain but they are well established on the Continent and in North America. (Pellet burners were originally developed in the USA in the Eighties.)



Wood Heating Miscellany

When I wrote about log burners for the July edition of the magazine, I thought that ceramic stoves were too exotic to mention, that they came from another time and another place, irrelevant to a modern house in the UK. So they didn’t get a mention. However, I went on a tour of eco-renovations at the recent AECB conference, and a ceramic stove was due to be installed in one of the renovations. That prompted a re‑think on my part.



More About Heat Pumps

In assessing the viability of a heat pump system – in terms of either carbon emissions or running costs – a key factor is the Coefficient of Performance (COP). This is the ratio of the heat output to the electrical input. (Some manufacturers take into account the energy for the circulation pump, if there is one, when they quote a COP. Others don’t, and this gives a higher, better-looking figure.)