Guest guest Posted May 9, 2005 Report Share Posted May 9, 2005 The green house effect The government has set an ambitious target for reducing carbon emissions, says David Ireland, but knocking down millions of older homes and building new ones is not the way to meet it Thursday May 5, 2005 The government has set itself an ambitious target of cutting domestic carbon emissions by 60% by the middle of the century. At least 30% of the UK's total energy demand is accounted for by domestic housing, so clearly it's going to take a lot more to solve the problem than just laying a bit of loft insulation. Proposed solutions have been varied and numerous, but one in particular, to knock down " poor performing " homes down and start again, should be handled with great caution. An extreme version of this argument was offered last month by Oxford University's Environmental Change Institute. In its report, The 40% House, the institute suggested that as many as 3.2m homes should be demolished and 10m new properties built in what would be the biggest building programme for 60 years. The logic it followed to justify such a proposal you might have heard before: new homes will be built to a much higher standard of environmental efficiency than old ones, so the older, unhealthy properties should be cleared to make way for the new. But is this necessarily so? I don't think so. First, although the amount of energy people use in their homes creates an enormous amount of carbon dioxide, it's far from the only factor in domestic housing. Housebuilding itself produces huge amounts. The way to understand this is through a concept called embodied energy. Each component of a house has caused energy to be consumed in order to get it there. Most energy is consumed in production and transport. So natural materials like timber and stone will have low embodied energy. Other materials like bricks require large amounts of energy through the extracting and firing of clay. Transportation energy costs vary according to how heavy the material is and how far it's come. So stone imported from China will have caused more energy to be consumed than stone bought from a local quarry. The total embodied energy in building a house can be added up. Normally it's about 90,000kwh for a new family house. However, a typical £40,000 refurbishment of a three-bedroom semi would normally use only 15,000kwh of embodied energy. Another frequently overlooked factor is the amount of carbon dioxide given off in the chemical reaction that makes cement set. Approximately one tonne of carbon dioxide is given off for every tonne of cement used. The average new house uses 25 tonnes of concrete for foundations and floors, 4 tonnes of cement for mortar and rendering and about 1 tonne is wasted. That produces an astonishing 30 tonnes of carbon dioxide. Refurbishment, on the other hand, usually uses a tonne or two at most. That means that building a new house creates about the same amount of carbon dioxide as driving a family car around the world six times; refurbishing an old one produces about the equivalent of driving to the USA and back. A further worry is what the new houses might be like. Pressure to make housing more affordable is already leading to more prefabrication. Whilst this has many advantages, it results in houses that are less easy to adapt and therefore more prone to obsolescence. They also lend themselves less easily to recycling and future refurbishment - in other words houses with a shorter life span that will require environmentally costly replacement sooner than refurbished old houses. There are many more factors that are difficult to quantify. New build housing demands new infrastructure, new roads, shops, and car parks. They require more journeys to be undertaken to get there and back. Building, even on brownfield sites, causes loss of biodiversity, and loss of carbon absorbing plants. Of course everything we do has an environmental impact, but in the rebuild versus refurbishment argument the refurbishment option nearly always comes out on top. The argument in the report is that the environmental costs of new build housing will be outweighed in a few years by reduced domestic fuel use because of the better insulation levels. This, while clearly true, compares the new house with an unimproved old one. If the comparison is against a refurbished house incorporating good levels of insulation the advantage is far less clear. The message is obvious. Carbon dioxide emissions are going to be one of the biggest issues in housing for the next half century and we need some very big changes in our housing if we are going to meet the 2050 target. But there are other ways of approaching this than by following the recommendations set out in the ECI report. The old green mantra of reuse, recycle, reduce works here too. There are 900,000 empty homes out there doing nothing. A concerted effort to bring these into use as high quality housing is not beyond us. It's not the whole answer, but it makes more sense to me than a mass demolition and new build programme. · David Ireland is a local government adviser for the Empty Homes Agency Quote Link to comment Share on other sites More sharing options...
Guest guest Posted May 9, 2005 Report Share Posted May 9, 2005 Do y'all have " green " housing in the U.K.? Lynda - heartwerk <heartwork Sunday, May 08, 2005 11:44 PM Earthwire/ from the Guardian > The green house effect > > The government has set an ambitious target for reducing carbon > emissions, says David Ireland, but knocking down millions of older > homes and building new ones is not the way to meet it > > Thursday May 5, 2005 > > The government has set itself an ambitious target of cutting domestic > carbon emissions by 60% by the middle of the century. At least 30% of > the UK's total energy demand is accounted for by domestic housing, so > clearly it's going to take a lot more to solve the problem than just > laying a bit of loft insulation. Proposed solutions have been varied > and numerous, but one in particular, to knock down " poor performing " > homes down and start again, should be handled with great caution. > An extreme version of this argument was offered last month by Oxford > University's Environmental Change Institute. In its report, The 40% > House, the institute suggested that as many as 3.2m homes should be > demolished and 10m new properties built in what would be the biggest > building programme for 60 years. The logic it followed to justify > such a proposal you might have heard before: new homes will be built > to a much higher standard of environmental efficiency than old ones, > so the older, unhealthy properties should be cleared to make way for > the new. But is this necessarily so? I don't think so. > > First, although the amount of energy people use in their homes > creates an enormous amount of carbon dioxide, it's far from the only > factor in domestic housing. Housebuilding itself produces huge > amounts. The way to understand this is through a concept called > embodied energy. > > Each component of a house has caused energy to be consumed in order > to get it there. Most energy is consumed in production and transport. > So natural materials like timber and stone will have low embodied > energy. Other materials like bricks require large amounts of energy > through the extracting and firing of clay. Transportation energy > costs vary according to how heavy the material is and how far it's > come. So stone imported from China will have caused more energy to be > consumed than stone bought from a local quarry. > > The total embodied energy in building a house can be added up. > Normally it's about 90,000kwh for a new family house. However, a > typical £40,000 refurbishment of a three-bedroom semi would normally > use only 15,000kwh of embodied energy. > > Another frequently overlooked factor is the amount of carbon dioxide > given off in the chemical reaction that makes cement set. > Approximately one tonne of carbon dioxide is given off for every > tonne of cement used. The average new house uses 25 tonnes of > concrete for foundations and floors, 4 tonnes of cement for mortar > and rendering and about 1 tonne is wasted. That produces an > astonishing 30 tonnes of carbon dioxide. > > Refurbishment, on the other hand, usually uses a tonne or two at > most. That means that building a new house creates about the same > amount of carbon dioxide as driving a family car around the world six > times; refurbishing an old one produces about the equivalent of > driving to the USA and back. > > A further worry is what the new houses might be like. Pressure to > make housing more affordable is already leading to more > prefabrication. Whilst this has many advantages, it results in houses > that are less easy to adapt and therefore more prone to obsolescence. > They also lend themselves less easily to recycling and future > refurbishment - in other words houses with a shorter life span that > will require environmentally costly replacement sooner than > refurbished old houses. > > There are many more factors that are difficult to quantify. New build > housing demands new infrastructure, new roads, shops, and car parks. > They require more journeys to be undertaken to get there and back. > Building, even on brownfield sites, causes loss of biodiversity, and > loss of carbon absorbing plants. > > Of course everything we do has an environmental impact, but in the > rebuild versus refurbishment argument the refurbishment option nearly > always comes out on top. The argument in the report is that the > environmental costs of new build housing will be outweighed in a few > years by reduced domestic fuel use because of the better insulation > levels. This, while clearly true, compares the new house with an > unimproved old one. If the comparison is against a refurbished house > incorporating good levels of insulation the advantage is far less > clear. > > The message is obvious. Carbon dioxide emissions are going to be one > of the biggest issues in housing for the next half century and we > need some very big changes in our housing if we are going to meet the > 2050 target. But there are other ways of approaching this than by > following the recommendations set out in the ECI report. The old > green mantra of reuse, recycle, reduce works here too. > > There are 900,000 empty homes out there doing nothing. A concerted > effort to bring these into use as high quality housing is not beyond > us. It's not the whole answer, but it makes more sense to me than a > mass demolition and new build programme. > > · David Ireland is a local government adviser for the Empty Homes > Agency To send an email to - > Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You are posting as a guest. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.