Whilst Yvette Cooper and her chums would have us believe that the drive towards zero-carbon homes will transform the way we design and build houses, the reality is more likely to look something like this photo. This is Barratt’s Eco Village in Chorley near Manchester and it’s probably one of the most depressing photos of the year. For it could be any Barratt estate anywhere in the past twenty years, except that it’s got a few micro wind turbines stuck up above the rooftops. Some future we have to look forward to here.
To be fair, the site has been conceived more as a test bed for zero and low carbon technologies than as an exemplar of what homes might look like. But surely the Barratt design department could have tried just a little bit harder, seeing as they knew it was going to be on view.
An article in the latest Building reports on the results of a year’s survey by the University of Manchester on the performance of five different technologies featured here at the eco-village. The results more or less confirm figures gleaned from other tests.
• Micro Wind Turbines: two different types tried: both useless, producing virtually no power at all
• Ground source heat pumps: three different ones fitted, which the manufacturers claimed would deliver a CoP (measurement of efficiency) of between 3.0 and 5.0. Average CoP achieved? Just 2.6. They work, but not as well as we are led to believe.
• Photovoltaics: three 8m2 arrays placed on three roofs. Output varied depending on orientation and angle. South facing was best (not surprisingly): a 45° one produced 1034kWh of electricity in a year. An east facing one at 60° produced 760kWh whilst another east facing one mounted at 45° produced 818kWh. These results are bang in line with expectations: no one doubts that PV arrays produce power in reasonable quantities, the problem is the cost of installing them.
• Solar thermal: comparisons were made between a 2.5m2 flat plate and a 3m2 evacuated tube, both used to heat a 180lt hot water tank. Both succeeded in doing this for the summer months: the evacuated tube could get the water to 75°C, as compared to 60°C for the flat plate collector. The researcher, Dr Tony Sung, makes an interesting point that this added performance wasn’t of any obvious value, as 60°C is plenty hot enough.
• Micro CHP: two units fitted, both Whispergens. One produced 11,000kWh of heat and 680kWh of electricity, the other 9,600kWh heat and 260kWh of electricity: the difference between them is explained by the different lifestyles of the occupants, but interesting to note that the average power:electricity ratio is 20:1, only half as good as the Carbon Trust survey results.