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‘Zero Carbon Homes’ Guest Blog by Graham Sutill, Sustainable Buildings Assessor, Darren Evans Assessments

As of October 1 2016, the London Plan requirements for energy statements are changing. All major developments will be required to be ‘zero carbon’ however if this cannot be achieved then a cash in lieu contribution will be sought. In addition to the ‘zero carbon’ targets, further emphasis is to be placed on district heating networks and a new requirement to follow the cooling hierarchy, which includes an in depth overheating risk analysis, will be introduced. This blog will focus on the ‘zero carbon’ element of the GLA guidance on preparing energy statements.

All major developments within the Greater London Authority (GLA) currently have to submit an energy strategy to comply with policies 5.2 to 5.9 of the London Plan. These policies cover a range of topics including but not exclusive to: sustainable design and construction, decentralised energy networks and renewable energy.

The area most developers are aware of is Policy 5.2 Minimising Carbon Dioxide Emissions, which involves following the energy hierarchy: Be Lean, Be Clean and Be Green. The Be Lean stage requires major developments to meet or exceed Part L of the building regulations through energy demand reduction methods alone. Be Clean requires the viability of district heating and combined heat and power (CHP) systems to be assessed.

The final stage, Be Green, requires a feasibility study for renewable or low/zero carbon technologies to be undertaken with a commitment to reduce CO₂ emissions through onsite generation. The current level of this commitment is to demonstrate a minimum 35% improvement over Part L of the 2013 Building Regulations.

Although the Government announced in July 2015 that it does not intend to pursue the zero carbon homes target at present, it remains in place within the London Plan and will be applied to all major residential developments received on or after October 1 2016. The “zero carbon” target requires the new developments to follow the energy hierarchy as outlined above (still meeting the 35% reduction in CO₂ at the Be Green stage) but with the remaining emissions to be off-set through a cash in lieu contribution to the relevant borough.

These funds will then be ring-fenced to secure carbon dioxide savings elsewhere. The cash in lieu payment is to be £60 per tonne of carbon dioxide for a period of 30 years based upon The Mayor’s Housing Standard’s Viability Assessment, although this figure can be decided at a borough level.

As an example, a carbon offset payment has been calculated for a previously completed project which comprised of 14 residential flats with a combined floor area of 993.50 m². The flats were designed to exceed Part L requirements using individual gas boilers for heating and hot water. Then a 15 kWp solar PV system was installed to achieve a 42% improvement over the Building Regulations standard.

After the PV at the Be Green stage, the site wide emissions stood at 10.664 tonnes CO₂/year. Assuming the offset price of £60 per tonne, this works out at £640 per year and multiplying the figure to cover the 30 years gives a total of £19,200 to be paid to the Carbon Offset Fund.

It is pleasing to see the Greater London Authority adhering to previous commitments on carbon dioxide reduction, with viability assessments indicating the “zero carbon” targets will not compromise future housing development. The target is seen as essential to ensure London is ready for the Energy Performance of Buildings Directive introduction of zero energy buildings by 2020.

Original blog post can be found here: http://www.darren-evans.co.uk/index.php/blog/