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Revised definition of 'zero carbon' and The Green Deal

The housing sector is struggling to keep up with the ever-changing emissions standards, says Andrew Mellor

The recently revised definition of ‘zero carbon’ for new homes announced within the Budget’s Plan for Growth came as a shock to all of us who have been supporting the drive towards zero carbon performance from 2016.

Most of us were not aware the announcement would be made, never mind what the content would be. The previous definition required mitigation both of CO2 emissions associated with regulated emissions governed by the building regulations and of unregulated emissions associated with electrical appliance use. The revised definition will only consider regulated emissions, which are approximately two thirds of the combined unregulated and regulated total.

We all knew the former definition was very ambitious. Under it, many new homes would simply not have been able to meet the target due to the inability to generate electricity from renewable technologies on site, owing to lack of space or other factors, such as overshadowing.

PRP’s research for the Zero Carbon Compendium, the worldwide comparison of low carbon housing produced for the Zero Carbon Hub in 2008, showed that the UK had planned the most ambitious residential energy performance targets in the world. With this change of policy, the UK will certainly slip down the rankings in the revised 2011 edition.

As the latest definition will mitigate only two thirds of the CO2 emissions from a home (over the 2006 Building Regulations), one must ask whether the term ‘zero carbon’ should be retained, since these homes will simply not have zero emissions. I believe the term ‘zero carbon’ should be retained only for dwellings which truly are zero carbon and therefore exemplars, and not for those built to the revised definition, which should be called ‘low carbon’ homes.

The revised definition is still challenging but certainly more deliverable. Residential developers will now have to mitigate regulated emissions only, which is, perhaps, fair, as it is argued that developers cannot influence the emissions from the electrical appliances a resident uses.

But if developers are not paying to mitigate the additional one third of the total emissions, who is? Someone must, if the UK has any chance of meetings its Climate Change Act obligations, assuming, of course, that new build housing could only play a small part in meeting those requirements.

The cost will ultimately be paid for by energy consumers, funding low or zero carbon electrical energy generation on regional, district or community scales through their bills. PRP has always been an advocate of low energy homes but we believe that electrical energy, where possible, should be generated within communities or at district level.

The Green Deal, the Government’s proposed delivery mechanism for energy efficiency upgrades to existing homes, might also be extended to partially fund new homes which meet the revised zero carbon definition. In this proposal, a developer would use third party money to fund CO2 mitigation measures beyond the mandatory performance level. Residents would then pay back the third party loan plus interest through their energy bill payments.

The Green Deal loan could fund a number of mitigation measures which are not yet defined but are likely to include off-site measures such as community energy infrastructure. The Green Deal loan would be approximately £2,500 for an average semi-detached house and the new owner of a home from 2016 would effectively have that amount of debt on the energy meter from the day he or she moves in. This approach is justified by the savings in energy bills - but will new house purchasers accept it?

The revised definition offers architects more design freedom. Orientation, roof form and pitch will no longer necessarily be influenced by the need to provide large arrays of photovoltaics. We also need to be concerned with the performance of homes over time, after alterations are made, which will affect CO2 emission levels and energy bills.

This could be dealt with through awareness and skills training for those involved in home maintenance and adaptation as well as raising awareness among occupants. The Energy Performance Certification process must also become far more stringent at the point of sale or rent of the home to determine the actual performance of a home at that time.

The Conservatives promised to define zero carbon within a few weeks of getting into power, but we are still waiting for the final definition, which will be the third or fourth revision of the standard. Will there be more changes?

Now we must also wait for the forthcoming definition of ‘sustainable development’, which will establish a presumption in favour of sustainable development within planning policy, to see what impact this will have on an industry that is battling to keep up with ever-changing legislation. But the Government has, of course, promised to rationalise this mêlée!

Andrew Mellor is senior partner (environmental), PRP Architects

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