Sustainable Architecture Blog: Should we retrofit or rebuild Britain’s housing stock?


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Reassessing our built environment is vital in the fight against climate change as about 45% of CO2 emissions in the UK come from energy used in our homes and buildings. It is vital that the government looks seriously at how Britain can reduce these emissions. But should we retrofit or rebuild Britain’s housing stock?

There are a host of pros and cons to both approaches, and neither is cheap in the short-term. Like most sustainable technologies, reducing the greenhouse gas emissions of a building is a long-term investment. However, the built environment accounts for over 40% of global carbon emissions so it is imperative that reducing this becomes a focus of the international agenda. With climate change looming and energy prices rising, our built environment risks being our greatest liability.

Rebuilding

As sustainable building methods become more advanced and efficient, new housing will increasingly impact less on the environment. This is why advocates of rebuilding Britain’s housing argue it is better than retrofitting as a long-term approach to reducing housing sector emissions. On the whole it is much easier to build a passivhaus from scratch than adapt existing housing. Indeed, the cost of refurbishing and maintaining existing homes can often exceed the home’s value.

Sustainable re-building requires low embodied energy and excellent insulation. A new structure that is well insulated with low embodied energy can have a negligible carbon footprint. The environmental impact of demolishing an existing building, especially one that contains little or no wood, can be severely reduced by disposing of the materials responsibly.

However, if large amounts of wood are burnt or allowed to rot carbon is released into the atmosphere (whereas, the carbon in wood can theoretically be locked up in landfill). Architects could incorporate reclaimed timber in their designs to offset these emissions, or even re-use the materials from the original building. The carbon in wood can be stored if it is well maintained.

This technique of locking up carbon within buildings is known as carbon sequestration. This can also be achieved by using buildings materials such as hemp, other biomass and reclaimed building elements.

‘Jobs, Growth and Warmer Homes’, a report by Consumer Focus in 2012, looked at how the UK government should re-invest money raised through carbon taxes and energy efficiency. Responding to these findings, The Energy Revolution argued that the UK government must invest the money by re-building houses. The fuel poverty alliance, the biggest of its type, commented that:

This report shows that in its bid to boost UK economy, the Government is not investing in the one thing which could create more jobs and growth than anything else – re-building the UK’s housing stock. Not only does this have massive economic benefits but it is the most effective way to bring down energy bills.”

Retrofitting

Rebuilding the housing sector might not be high on the government’s priorities (although targets have been set to make all new builds from 2016 carbon neutral), but eco-refurbishment certainly is. One of the UK government’s main strategies to reduce greenhouse gas emissions is to make homes more energy efficient. Their flagship policy to tackle home energy efficiency is called the Green Deal. Launched in January, this is a financial investment to make buildings more energy efficient, and is also designed to reduce fuel poverty.

Retrofitting involves the addition of new technologies and materials for the benefit of the property. For instance, improving insulation makes a building more energy efficient and therefore more sustainable. Energy efficient retrofitting is also a rapidly growing market because of the savings that can be made, and it is a much cheaper strategy in the short-term than demolishing and rebuilding properties.

But what should be Britain’s approach to be?

The UK has a tougher choice then developing nations because more of the built environment in newer countries is still to be constructed. This means developing economies can set the tone for sustainable development in a way that the UK cannot. British architects must also consider the cultural worth of historic buildings that already exist. Georgian townhouses may look impressive and have a great sense of heritage, but they can also have woefully inadequate insulation, ineffective heating and aging plumbing.

The Zero Carbon Britain (ZCB) project, a scenario for a carbon neutral United Kingdom by rapid decarbonisation, supports retrofitting the majority of the British housing stock. The researchers propose using natural materials where possible to eco-renovate buildings. Hemp shiv would be an ideal substitute for artificial insulation because it is proven to be resistant to moisture ingress. The hemp used in this insulation could also act as a carbon sink.

But this model is not possible for every home. Writing for the Guardian, Tony Hutchinson argues that:

Looking at the total cost of a refurbishment project over its lifetime (including maintenance and eventual replacement) in both cash and carbon terms the outcome can be very different. Cost and benefit modelling should be used to compare the benefits of demolition and new build with the costs of maintenance of the retrofitted building over its useful life – and the cost of further refurbishment after 30 years or complete replacement.”

So if we are hoping to build truly sustainable communities for the future, developers must look at the long-term. Where possible, Britain should rebuild its housing stock. This will take time, however, and may not be possible by ZCB’s target date of 2030.

Modern architects must be bold during this transition. Many of Britain’s houses will be too expensive to eco-renovate. If historic buildings such as Victorian and Edwardian terraces must be protected, then why not keep the facade but demolish the living spaces behind? A sustainable structure constructed in its place can be integrated with the historic face of the building. Projects like Kings Cross10 Hills Place and others demonstrate that this is achievable. Obviously there will be instances where this is not possible, but architects and eco-builders must think outside the box to find creative ways to decarbonise Britain’s buildings.