The Carbon Footprint of a Renovation vs New Construction
by Lloyd Alter, Toronto on 03.18.08
Thousands of houses stand empty in the Great Lakes States; in Buffalo they are demolishing 5,000 of them. It is bad enough that they are in sight of fresh water and have access to canals, railroads and highway infrastructure galore; a new British study, 'New Tricks With Old Bricks' (PDF) , says reusing and refurbishing existing and empty properties could actually save more carbon dioxide than constructing new ones.
According to the Guardian, the study found that the construction of a new house generated 50 tonnes of CO2, but the renovation of an existing house emitted only 15 tonnes. In actual use, there was little difference in the performance of the older house than in the new one, and that it could take decades for the operational savings to offset the carbon load of the initial construction. The renovated house will probably last longer too, because so much of what we build today is crap.
Bill Dunster, designer of the RuralZED, told the Guardian:
"If you are buying a flat made from chip-foam panelled walls as a low-cost housing solution, then yes, it might not last forever. We do have to stop this "dash for trash" and stop people building homes which look good but will become unlivable. We have to go back to quality." ::Guardian
This study compared the CO2 given off in building new homes and creating new homes through refurbishing old properties. The key findings are:
Reusing empty homes could make an initial saving of 35 tonnes of carbon dioxide (CO2) per property by removing the need for the energy locked into new build materials and construction.
Over a 50-year period, this means there almost no difference in the average emissions of new compared with refurbished housing.
Carbon dioxide (CO2) emissions from new homes fall into two distinct sources: “embodied” CO2 given off during the housebuilding process, and “operational” CO2 given off from normal energy use in the house once it is occupied. The new homes each gave off 50 tonnes of embodied CO2. The refurbished homes each gave off 15 tonnes.
Well-insulated new homes eventually make up for their high embodied energy costs through lower operational CO2 but it takes several decades - in most cases more than 50 years.
Embodied CO2 is not widely understood but this study shows that it accounts for 28% of CO2 emissions over the first 50 years’ lifetime of a new house.
Embodied CO2 is an investment in the environmental sustainability of a house. Refurbished old homes have lower embodied CO2 and therefore a distinct head start over new homes.
Empty homes in England provide an opportunity to create 150,000 new sustainable homes.
If the rate of VAT on repairs and renovation had been 5% instead of 17.5%, it would have cut the average cost of refurbishment by approximately £10,000 for each house.
Many house builders claim that new homes are four times more efficient than older houses. This study shows that refurbished houses can be as just efficient as new homes.
If the home being demolished is replaced with townhouses, then the space is getting increased density and efficiency of (shared) resources. This is happening along all of the arterials in Seattle. In many cases, the houses being removed are already somewhat if not entirely t(h)rashed (not always the case) being on busier streets and all. Of course, many Seattlites are getting tired of the cookie-cutter designs that maximize these lots for untis, too. But if it means less land being developed outside of the current city limits, I'm for it.
Renovating old homes is a transition strategy that is important paired with an initiative like the 2030 Challenge.
However, renovating an old house to be as inefficient as a new house is not exactly a effective use of time and resources. In order to cut the 90-100% of emissions needed, we must make all dwellings much more energy efficient. The PassivHaus standard is where we should be going, as quickly as possible.
Furthermore, there are many businesses making good profit out of building recycling. Imagine deconstructing an old house, and then using 80% of it to rebuild as a PassivHaus. Then we would be getting somewhere.
Thanks - for a potential new home owner this is very, very helpful. Still not sure which way to go though!
Material quality has definitely and gotten flimsier, but these building may persist longer than older buildings. Engineering understanding has improved greatly, as have waterproofing materials, pressure treated lumber, galvanizing and stainless steel parts, plastic insulation and piping, and so on.
Slipping construction quality that allows moisture intrusion, termite infestation, and wind damage can lead to accelerated deterioration. But building built to or better than code may have substantial longevity, despite using structural materials that our grandfathers wouldn't have used as cabinet shims.
As the linked file shows, the vast bulk of energy consumption by buildings happens during use, not in construction. So improved heating and cooling, lighting, and reducing the replacement of systems and materials will be where the bulk of savings are attainable.
By contrast, it shows that marginal increases in building mass or energy intensive materials that can deliver additional performance or longevity benefits can have outsized benefits to lifecyle energy use. The disparity is so great the doubling or quadrupling building lifespan may be insufficient to outweigh operational energy efficiency strategies. Quite a shock, really.
That said, there are real savings, and many other beneficial values, to be realized by reusing existing, older buildings while retaining as much of their existing fabric as possible.
I have to wonder how far they went with the renovation. A good designer with a head for sustainability could go pretty far with reducing the operational footprint of an existing structure, especially in a city.
Which brings me to my second point: the nearest city to me is Philadelphia, PA. In Philly there are plenty of row houses (density already achieved) being left to rot or worse—being "section-8'ed" by ringing them up to minimal living standards using the cheapest materials possible. How green is cheap wall-to-wall carpeting, cheap paint, etc? How green can a house be when the "renovators" don't care about the utility bills of their tenants? There needs to be more funding available for 'green' renovations, especially for urban homes.
Also, as far as cutting that much in emissions goes simply set that as the standard goal for renovators: get the government and banks to reward people for achieving specific goals in reduced emissions. Goverment in terms of tax breaks and grants, banks in terms of better interest rates on future loans.
I know, I know…easier said than done. Still, isn't it worth trying?
This article was helpfull in concluding the debate bewteen reno or rebuild. Thank you.