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Last edited 15 Mar 2019
Zero carbon homes
The Climate Change Act was introduced in the UK in 2008, setting a target of reducing carbon emissions by 80% compared to 1990 levels by 2050, with a reduction of at least 34% by 2020. A strategy for how this was to be achieved was set out in The Carbon Plan published in December 2011.
In December 2006, the Labour government committed that from 2016 all new homes would be ‘zero carbon’ and introduced the Code for Sustainable Homes, against which the sustainability of new homes could be rated. This commitment was affirmed in the Building a Greener Future: Policy Statement in 2007 which proposed progressive tightening of the building regulations to achieve the 2016 goal, first by 25% in 2010 and then by 44% in 2013.
Whilst these were seen as bold commitments, there was scepticism about whether such ambitious targets could be met, as well as some confusion about what ‘zero carbon’ meant.
The first definition of a zero carbon home was a home achieving Level 6 of the Code for Sustainable Homes. This included emissions of both regulated energy (space heating, hot water, lighting and ventilation) as well as unregulated energy (such as appliances and cooking).
In England, the definition of a zero carbon home became one where CO2 emissions from regulated energy use were limited or mitigated by a combination of three factors (the first two of which are known as ‘carbon compliance’ standards):
- 39 kWh/m^2/year for apartments and mid-terraced houses.
- 46 kWh/m^2/year for end of terrace, semi-detached and detached houses.
- 10 kg CO2(eq)/m^2/year for detached houses.
- 11 kg CO2(eq)/m^2/year for attached houses.
- 14 kg CO2(eq)/m^2/year for low-rise apartments.
So in effect, developers would have to avoid or mitigate all regulated emissions using a combination of on-site energy efficiency measures (such as insulation and low energy heating systems), on-site zero carbon technologies (such as solar panels) and off-site measures to deal with any remaining emissions.
'Allowable solutions’ were expected to include the developer being able to make payments to an ‘allowable solutions provider' who could be a local authority provider or a private provider. There was also the possibility of creating a national carbon abatement fund, with payments made by means of an agreed fee per kg CO2 to offset emissions over a 30 year period. See CLG: Open consultation: Next steps to zero carbon homes: allowable solutions.
On 8 July 2014, the government published a response to the summary of responses to its consultation on allowable solutions. This confirmed the four approaches to allowable solutions for house builders; abatement on site, their own abatement off site, third party off-site abatement, or to payment into a price-capped fund. It also confirmed that a national design framework would be established for the scheme.
In England, the requirement for zero carbon homes was to be set out and enforced in the 2016 building regulations, specifically parts L (Conservation of Fuel and Power), F (Ventilation) and J (Heat Producing Appliances) and their approved documents.
A number of concerns were raised about these proposals:
- Typically, every year, new homes account for just 1% of the total housing stock, and at present it is considerably lower than this. This means that the proposed measures would take a long time to have a significant impact on total emissions from the UK building stock.
- Developers might find it easier to adopt ‘allowable solutions’ rather than meet the carbon compliance standards.
- The standards might not really achieve 'zero carbon', focussing on operating emissions rather than capital emissions (ie they did not take account of carbon emissions resulting from actually constructing a new home).
- It was not clear how long-term maintenance or future alterations to new buildings would be regulated.
- There was concern about the impact these measures would have on the pressing need for more new homes as the UK population increases.
- Questions remained about measures to deal with the difference between the predicted and actual energy performance of buildings which can be significant.
- Whether the time-frame for change was realistic.
The Infrastructure Bill published by the Department for Transport on 6 June 2014 proposed re-setting the zero-carbon home standard at Level 5 of the Code for Sustainable Homes, but permitting developers to build to Level 4 by using allowable solutions to achieve Level 5.
However, controversially and unexpectedly it also proposed exempting small sites from allowable solutions requirements. There was no definition of what constituted ‘small sites’, although on 17 July 2014, DLCG minister Lord Ahmad suggested it might be similar to the 10-homes exemption already proposed for Section 106 agreements (ref. Today's House of Lords debates - Thursday 17 July 2014). This was seen by some to introduce a significant loophole.
A consultation on the proposed exemption was launched on 18 November 2014 (ref. DCLG Next steps to zero carbon homes: small sites exemption). On 27 March 2015, the government published its response to the consultation, confirming that sites of 10 units or fewer or a maximum size of 1,000 sq. m of floor space would be exempt from the allowable-solutions element of the zero-carbon homes standard.
On 10 July 2015, the government published ‘Fixing the foundations: creating a more prosperous nation’ a plan for increasing Britain’s productivity.
Amongst a great number of wide-ranging changes, the report states, 'The government does not intend to proceed with the zero carbon Allowable Solutions carbon offsetting scheme, or the proposed 2016 increase in on-site energy efficiency standards, but will keep energy efficiency standards under review, recognising that existing measures to increase energy efficiency of new buildings should be allowed time to become established.'
This announcement was made with no consultation and came as a surprise to much of the industry.
Julie Hirigoyen, chief executive of the UK Green Building Council, said "It is short-sighted, unnecessary, retrograde and damaging to the house building industry, which has invested heavily in delivering energy-efficient homes".
Paul King, managing director of LendLease Europe, said, “...after almost 10 years of commitment and progress, UK house builders and developers have come a very long way. It is therefore extremely disappointing that the government has today removed a world-leading ambition for all new homes to be zero carbon from 2016.”
BSRIA Chief Executive Julia Evans said, "BSRIA is disappointed with the government’s recent announcement of the end of the UK’s zero carbon buildings policy, but the industry remains ambitious that all new homes are built to the best standard, and they adopt the most energy efficient standards possible.”
Following the announcement, the UK Green Building Council (UKGBC) organised 200 signatories to publish an open letter to the Chancellor calling on him to rethink the decision. The letter said:
"For the best part of a decade, in response to a long-established Government target, the construction and property sector has been gearing up to deliver zero carbon homes and buildings. Last Friday, we were extremely disappointed to learn that this policy is being arbitrarily scrapped, despite the fact that the necessary primary legislation only acquired Royal Assent in February this year.... Since the policy was first launched eight years ago, business has invested heavily in preparing for future standards. This sudden U-turn has undermined industry confidence in Government and will now curtail investment in British innovation and manufacturing in low carbon products and services..."
However, CIBSE technical director Hywel Davies said the decision was not a huge surprise, and the move was welcomed by the Home Builders Federation who suggested that zero-carbon standards would have cost purchasers in the order of £2,500 per home.
It is not clear where this leaves the UK in fulfilling its requirements under the Energy Performance of Buildings Directive to move towards nearly zero energy buildings. There is even less clarity about this requirement after the UK leaves the EU.
The legislation scrapping the zero carbon homes initiative was set out in the Housing and Planning Bill 2015. However, in a bizarre twist, during the Bill's report stage in the House of Lords on 25 April 2016, an amendment was approved reintroducing the requirement for zero carbon homes:
118: After Clause 143, insert the following new Clause—“Carbon compliance standard for new homes(1) The Secretary of State must within one year of the passing of this Act make regulations under section 1(1) of the Building Act 1984 (power to make building regulations) for the purpose of ensuring that all new homes in England built from 1 April 2018 achieve the carbon compliance standard.(2) For the purpose of subsection (1), “carbon compliance standard” means an improvement on the target carbon dioxide emission rate, as set out in the Building Regulations 2006, of—(a) 60% in the case of detached houses;(b) 56% in the case of attached houses; and(c) 44% in the case of flats.”
“This has a long way to go, but it demonstrates there is still Parliamentary support for zero carbon homes, to match support from progressive voices in business.
“During the 10 years prior to July 2015, the leading players spanning the housebuilding industry – developers, product manufacturers, contractors and engineers – got behind zero carbon homes, investing heavily and innovating to make it a reality. The unexpected and unwanted scrapping of the policy made a mockery of the government’s green credentials, and showed disregard for the nation’s new homes and the industry’s investment.
“Having supported the Paris climate agreement with much fanfare, cutting carbon from new homes and buildings will be vital to achieving our commitments. Re-introducing the zero carbon homes standard would be a clear next step on this journey, and would provide the certainty the industry needs to continue investing in new skills and technologies.”
 Ongoing debate
In November 2016, the House of Commons Environmental Audit Committee report on Sustainability and HM Treasury criticised the government for scrapping the zero carbon buildings standard and called for it to be reinstated.
In February 2019, a report by the Energy & Climate Intelligence Unit suggested the decision to cancel the zero carbon homes initiative had cost the UK more than £2bn in wasted energy. Ref https://eciu.net/press-releases/2019/leaky-new-build-houses-put-200-on-energy-bills
 Related articles on Designing Buildings Wiki
- Allowable solutions.
- Carbon capture and storage.
- Carbon dioxide.
- Carbon emissions.
- Carbon Plan.
- Carbon ratings for buildings.
- Climate change Act.
- Code for Sustainable Homes.
- Domestic micro-generation.
- Eco town.
- Emission rates.
- Energy Act.
- Energy performance certificate.
- Fabric first.
- Fixing the foundations: creating a more prosperous nation.
- Green building.
- Green Deal.
- Home Quality Mark.
- House of Commons Environmental Audit Committee report on Sustainability and HM Treasury.
- Nearly zero-energy building.
- Performance gap.
- PV inverter.
- Renewable energy.
- SOLCER house.
- Sustainable materials.
- The Future of Electricity in Domestic Buildings.
- Zero Bills Home.
- Zero carbon non-domestic buildings.
- Zero carbon task group.
 External references
- Zero Carbon Hub: Low Carbon Buildings and Homes, Skills and Opportunities, Phase 1 Report.
- The Zero Carbon Hub: Zero carbon homes.
- Building Regulations Part L 2013 Consultation.
- The Energy Act 2011.
- The Carbon Plan.
- The Planning Portal: Code for Sustainable Homes.
- Zero carbon compendium: Who's doing what in housing worldwide.
- CLG: Open consultation: Next steps to zero carbon homes: allowable solutions. August 2013.
- Zero Carbon Hub: Zero Carbon Strategies for Low and Zero Carbon Homes|.
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