Monday, 13 October 2014

Looks good, doesn't work

The Folly of Building-Integrated Wind

That was the title of an article in Building Green back in 2009.  As author, and most prolific contributor, Alex Wilson said at the time:
The appeal of integrating wind turbines into our buildings is strong. Rooftops are elevated above ground, where it’s windier; the electricity is generated right where it’s needed; and wind energy can make a strong visual statement. Dozens of start-up wind turbine manufacturers have latched onto this idea since it fits well with a strong public sentiment to shift from fossil fuels to renewables....What’s not to like about it?
It would be fair to say that between 2009 and 2014 we have gone through a key period of rethinking what is possible in terms of the environmental impacts of buildings. Like many others, throughout most of my 40 year career in building science and architecture I held firmly to the belief that as long as we were unwilling to retreat from our expectations of late 20th century convenience and productivity, most buildings could never be energy neutral, much the less energy positive. I based this firm belief on the simple idea that the density of renewable energy available to a conventional building site in a city would never approach contemporary demands of energy consumption. Whether buildings could be neutral, and therefore sustainable, in other terms – such as the water cycle or materials extraction – I was more equivocal.

But of course, zero net energy or zero net carbon, is the outcome of the balance between demand and supply. So if supply is relatively inflexible, there is still some room to move on the demand side. And much to my surprise it turned out that technology could make a profound impact on demand, notwithstanding our apparent resistance to changing our behaviour. The biggest changes in technology contributing to the changed balance have been the advances in solid-state electronics, the development of practical LED lighting, dramatic improvements in glazing technology, and to a lesser extent in insulation. There has also been some questioning of the so-called 'system boundaries' within which a sustainable balance might be achieved.

The bottom line, however, is that even a diehard rationalist like me began to believe that zero net energy/carbon was not impossible, and that under some circumstances we could even envision 'healing buildings' – in other words buildings capable of contributing more to our energy supply, than they used to support their own operation.

Building integrated renewables are very much part of that vision. But when you think about it, there is a very small range of energy sources with which advancing technology can work. We have photovoltaics, lower grade thermal energy, and kinetic energy of the fluid in which we are all immersed – a fancy way of describing the air movement of the atmosphere, commonly known as wind. Don't get distracted by diurnal and seasonal storage capacities, night-time radiation, the role of thermal mass and phase change materials. Those do not represent incoming energy. If you want to be really radical, the most you could add would be geothermic sources, if you happened to build in one of the limited places on earth where they are available. Even photosynthesis is simply a different way of converting incoming solar radiation, as an alternative to, say, photovoltaics.

So, building integrated wind generation looms large in the hopes of some designers. But while advances in photovoltaics have significantly increased the contribution, and decreased the price of site generated electricity, building integrated wind power remains a really bad idea.

That is why anyone who missed the Building Green article in 2009, and it's succinct and evenhanded explanation of why that is so, should take the opportunity to reread it now. Wilson categorises the issues under the simple headings:
I can't do better than  he does, so go, read.  Here.

No comments: