The UK Government target to make all new homes zero carbon from 2016 is one of the most stringent in the world, demanding that regulated emissions must be net zero over the course of a year. The policy forms part of Government’s wider strategy for achieving a national 80% reduction in carbon emissions by 2050.
The zero carbon homes policy was first introduced in Building a Greener Future (2007) and subsequently in the consultation paper Definition of Zero Carbon Homes and Non-domestic Buildings (2008).
Now changed in overall scope from that originally envisaged, the policy as set out today requires a home to mitigate only the emissions resulting from regulated energy use – that is the energy used to provide space heating and cooling, hot water and most lighting, as outlined in Part L1A of the Building Regulations. Emissions resulting from cooking and ‘plug-in’ appliances such as computers and televisions are not being addressed as part of this policy.
There are three core requirements which must all be met for a home to qualify as zero carbon:
- the fabric performance must, at a minimum, comply with the defined standard known as the Fabric Energy Efficiency Standard (FEES) and
- any CO2 emissions that remain after consideration of heating, cooling and ventilation, must be less than or equal to the Carbon Compliance limit established for zero carbon homes, and
- any remaining CO2 emissions (after requirements 1 and 2 have been met) must be reduced to zero.
Requirement 3 may be met by deliberately ‘over performing’ on requirements 1 and 2 so that there are no remaining emissions, or may be met by investing in Allowable Solutions.
Why has the zero carbon policy changed?
There have been two main changes to the policy since its introduction in 2007.
The first was to address points raised by the UK Green Building Council Zero Carbon Definition Task Group, who considered it not reasonable to expect zero carbon to be achieved in all cases through on-site measures alone. The Task Group recommended the introduction of a greater amount of flexibility in the use of off-site solutions and the result was the inclusion of what is commonly known today as Allowable Solutions.
The second was the announcement in the March 2011 Budget that emissions resulting from cooking and ‘plug-in’ appliances such as computers and televisions are not being addressed as part of the policy. The reason stated for this is alteration was that the so called ‘unregulated emissions’ fell beyond the influence of house builders and that these emissions would be addressed by other policies.
How does the zero carbon policy relate to the Code for Sustainable Homes?
The Code for Sustainable Homes is a nationally recognised standard for the sustainable design and construction of new homes. Homes are assessed against 9 categories, with the highest scoring homes being awarded a Level 6. Of the 9 assessment categories, energy and CO2 emissions relate most closely to the zero carbon homes policy. The main difference is that the Code for Sustainable Homes requires all CO2 emissions to be abated at plot/site level – there is no Allowable Solutions mechanism.
DCLG Consultation DEFINITION OF ZERO CARBON ... - Zero
ZCH - Defining Zero Carbon Homes report 2009