Eric Mair’s Energy 101: Part 9

Dear friends,

Last month we talked about designing and planning a new building. This month I’d like to look at the materials you will be using to build it. This is where an energy consultant will be a very useful addition to your team.

In this section you need to understand the concept of “Embedded Energy” – how much energy was used in manufacturing/processing of the product and delivering it to your site? Some products have a high embedded energy because of the materials they are made from or the process through which they are produced. Cement is one of those. Others come from far away and their embedded energy component is largely due to the transport miles accumulated on the journey to your site. High embedded energy = high carbon/environmental footprint.

Before purchasing new materials consider what is available from recycled or reclaimed materials. This does not necessarily mean products will be inferior. Products like Cape Brick, which utilise recycled building rubble to produce a fine quality building material, are an essential part of a sustainable building. Reclaimed building materials can be economical and very attractive plus they have a lower carbon footprint.

Try to use local products – ‘local is lekker’ as the saying goes, but make sure the durability aspect is covered too. On the other hand “expensive” and “imported” are not necessarily guarantees of quality either! Here the important consideration is the expected useful lifetime of the product in its current form and how much maintenance it will require in its current application. In other words how long will it last and how much work will it take to keep it working/looking good? This is important too because if you buy a “natural product” that is difficult or impossible to clean for example, you won’t be able to live with it for long and it will need to be replaced. This is not sustainable, you can’t continue replacing stuff every couple of years – there just isn’t enough “stuff” to maintain the flow of products if everything needed replacement every couple of years. Try to buy the best quality you can afford with a view to making it last and be maintenance free for as long as possible.

One should also consider what will happen to the “stuff” we buy at the end of its life – how easy will it be to re-assimilate the material into the natural cycle or to recycle it into something else useful?

Some materials are easy to re-assimilate back into nature. Things like wood and wool, paper and cotton. But these are often difficult and/or expensive to maintain, so the decision becomes a balancing act of embedded energy versus energy in use. The longer the material lasts usually means it is most energy efficient. E.g. aluminium has an enormous embedded energy component but it is usually made locally (in South Africa – you should check this, it’s important), it costs next to nothing to maintain and lasts for ages. In addition to that it is wholly recyclable into more aluminium products. I’d suggest that in some cases, despite its huge embedded energy component, aluminium could be considered a sustainable building material provided it is correctly recycled at the end of its life.

Wood, provided it comes from a sustainable source (check for the Sustainable Forestry Initiative (SFI) or Forestry Stewardship Council (FSC) stamps), is widely regarded as a sustainable building material. It needs periodic maintenance but as long as this is carried out in an environmentally sound manner i.e. not with things like creosote, the product will last for a very long time and, of course, it’s easily re-assimilated back into the natural cycle at the end of its useful life.

There is a plethora of environmentally friendly or sustainable building products on the market today and more being announced all the time. Your energy consultant will help you work out which is right for your particular application.

Next month we’ll have a look at heating and cooking. Download this article here.

©Eric Mair, July 2009

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