ZERO CARBON HOMES – CHANGES TO THE LONDON PLAN REQUIREMENTS Graham Suttill, 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.



One of the two main targets that needs to be met when assessing a new domestic building against Part L 2013, together with the Target Fabric Energy Efficiency (TFEE), is the Target Emission Rate (TER) for heating. A legal requirement within Part L1A, the TER sets a minimum allowable standard for a building’s energy performance using the annual CO2 emissions of a notional building similar to the proposed building.

One of the questions we are most commonly asked regarding the TER by designers and developers is “will this dwelling pass with electric or oil heating?” Most buildings are heated using gas, and unfortunately under current Building Regulations it is very difficult to get a new dwelling to pass and exceed the TER using electricity or oil due to the notional building method by which it is calculated.

The calculation methodology has two stages: first a notional building is created to the same size and shape of the actual dwelling which is to be constructed, but using reference values from appendix R of the SAP 2012 document. These values outline the building specification which needs to be met or exceeded to improve upon the TER, and include a notional heating system which is an 89.5 per cent efficient mains gas condensing boiler.

The second stage is to apply a fuel factor to the calculations to give the final TER, and the factors for the most commonplace fuels we use in SAP calculations are 1.00 for mains gas 1.17 for oil and 1.55 for grid electricity.

This shows that different fuel types will have different effects on the TER the proposed dwelling is trying to achieve. In addition, each of the fuel types have different emissions associated with them as well as primary energy factors – which represents the amount of energy needed to delivery one unit of energy.

As the table below shows, oil and electricity have a higher CO2 per kWh of fuel when burnt than mains gas. Therefore when a notional building’s TER is based upon mains gas, and for example the proposed dwelling is using electric heaters, it is clear that associated emissions to provide the electric heating will be over twice that of mains gas.

Fuel Type Emissions kg CO2 /kWh Primary energy factor
Mains Gas 0.216 1.22
Heating Oil 0.298 1.10
Grid Electricity 0.519 3.07

In conclusion, the difficulty in getting dwellings which use oil or electricity as the main heating fuel to meet the target emission rate lies with the fact that mains gas is used in the notional calculation. There are higher CO2 emissions from oil and electricity when consumed and the energy losses from transporting electricity are significantly higher than mains gas.

This does not mean that it is not possible to meet the TER using oil or electricity as the heating fuel, however significant improvements to the building fabric or the incorporation of renewable technologies will be needed to offset the higher associated emissions.



The Energy-related Products (ErP) Directive sets out a legal framework across the EU to help drive specification of more efficient products which reduce energy and resource consumption. The idea is that this will make a big contribution to meeting the EU’s ‘20-20-20’ target, namely a 20% reduction in EU greenhouse gas emissions, a 20% increase in energy efficiency, and 20% energy from renewables, which is targeted to happen by the year 2020.

The ErP Directive is not new by any means, having been implemented back in October 2009, and we are all familiar with seeing the G to A+++ rating on appliances such as refrigerators, washing machines and dishwashers. As of September 26th 2015 however the range of the Directive has been extended to encompass all residential and commercial heating products.

The ErP Directive actually comprises two separate directives: Ecodesign and Energy Labelling. The Ecodesign Directive is chiefly for manufacturers and sets out rules and mandatory requirements for the energy efficiency of products which they have to comply with in order to sell those products within the EU. The Energy Labelling Directive compliments the Ecodesign aspect with mandatory labelling requirements intended to make life easier for consumers.

The Energy Labelling Directive is intended to help communicate complicated information in a simplified format to consumers in order to allow them to make informed decisions without having any specialist knowledge of the product. All new heating products should now have an ErP energy label ranged from G to A+++ however if one or more heating products are used in combination to make a system (such as a boiler with heating controls or solar device) then an installer will be required to produce a document called a ‘fiche.’ This essentially calculates the efficiency of the combination of heating products to give an overall system efficiency/rating.

Installing more than one heating product in this way is very commonly seen currently as boilers now have separate heating controls. Most large boiler manufacturers offer the production of a fiche as a free service, however there are templates available online if a specifier wished to produce one themselves. The fiche should be left with the property owner when completed so they know how efficient their system is.

What does this mean for specifiers? Best practice would normally dictate that a specifier would always choose from latest range of products produced by a boiler manufacturer to achieve optimum energy efficiency, depending on the boiler type required. In doing this, technically they will receive an ErP compliant boiler as all new heating products available to the UK market should be ErP compliant, however the specifier should always double-check.

This blog also features as a Guest Blog on Buildingtalk, you can read it here: