Zero carbon homes - the impact on the industry

The Government has stated that all new homes be zero carbon rated by 2016. John Alker, Head of Advocacy at the UK Green Building Council, discusses the impact this has had on the house building industry.

Few green policies have had quite such an impact on a sector as the zero carbon homes policy has had in housing.

Quite a claim, not least given the very small number of zero carbon homes actually built and the fact that 2016 - the target by when all new homes are to be zero carbon - remains some way away.

But before the zero carbon target was announced, together with the associated Code for Sustainable Homes back in 2006, the mindset was all about doing what we did before just a little bit better – not a more fundamental shift towards having zero impact.

As a result, housebuilders began working with architects, forced to look at their product afresh – even taking an interest in U-values! Innovation in sustainable design took off on a scale not seen previously, as the industry recognised that homes coming to market from 2016 had to meet the future standards of regulation.

The definition of a zero carbon home

However, a not insubstantial obstacle – even for those of us who have consistently championed the zero carbon policy – has been the definition of a zero carbon home, which has been a source of endless confusion. It stemmed from the Treasury defining zero carbon for the purposes of providing stamp duty relief and in doing so excluding the use of off-site renewables that weren't connected to the development by a private wire.

This had a perverse effect, because the zero carbon definition in CLG's Technical Guidance for the Code (i.e. at Code Level 6) was belatedly amended to also exclude the use of off-site renewables in order to be consistent with the Treasury's definition – despite having previously allowed it, albeit it not in a particularly clear way.

Concerns were raised by house builders, both large and small, that this definition was unworkable. A lack of clarity over the definition in the Code, and therefore future trajectory of building regulations, threatened not only future ability to deliver the target number of homes en masse, but also created confusion amongst engineers, architects, developers and their clients in respect of those developments currently in the pipeline.

The UK Green Building Council formed a task group that reported on this issue back in May last year, recommending a more flexible interpretation of zero carbon, while remaining true to the original objectives.

It was a long time in coming, but earlier this summer CLG finally announced a change to the definition of a zero carbon home, which would reflect a more pragmatic approach. But what does this mean in practice? And where does this leave the overall policy? Has this cleared up the confusion?

Energy efficiency

CLG describes a zero carbon home as one whose net carbon dioxide emissions, taking account of emissions associated with all energy use in the home across the year, are zero. The definition of 'energy use' covers both energy uses currently regulated by the Building Regulations and other energy used in the home.

Clearly a zero carbon home must be highly energy efficient. The recent consultation quoted two standards of energy efficiency but ended up delaying a decision on exactly how this should be expressed after respondents suggested using terms such as PassivHaus didn't make sense in a UK context. Government has asked the Zero Carbon Hub to report on energy efficiency metrics and standards in order to inform what the highest practical energy efficiency level should be in all dwelling types. That decision by the Housing Minister is promised by the end of the year.

CLG has then said that the net emissions of the home, taking account of its energy efficiency and on-site energy supply (including, where relevant, connections to heat networks) will meet a minimum “carbon compliance” standard - in effect a regulatory level of carbon reduction to be achieved on-site compared to today's regulations. That level has been set at 70 per cent of regulated energy use and will be flexible enough to deal with any upcoming changes to SAP.

Allowable solutions

Any carbon not mitigated on site will be dealt with through a range of so-called "allowable solutions" – i.e. the remaining 30% of regulated energy plus all non-regulated energy use. The allowable solutions will cover carbon emitted from the home for 30 years after build. This is where things get even more complicated. Some allowable solutions have been announced, these are:

• Further carbon reductions on site beyond the regulatory standard
• Energy efficient appliances meeting a high standard which are installed as fittings within the home
• Advanced forms of building control system which reduce the level of energy use in the home
• Exports of low carbon or renewable heat from the development to other developments
• Investments in low and zero carbon community heat infrastructure.

However, we won't know until later in the year whether any other solutions will join this list, such as a way to invest in properly accredited offsite renewables.

The commitment to zero carbon

The overall commitment to the central principle of zero carbon has been maintained, which is a good thing. The majority of energy savings are to come from improvements made to the fabric of the home and through on-site or locally produced energy sources, which is also to be welcomed. Government has rightly said that of all the challenges facing the housebuilding industry, carbon reduction is not something that can be compromised on, which is refreshingly bold.

The updated definition confirms a sensible 'hierarchy' approach to carbon reductions. i.e. firstly high levels of energy efficiency in the fabric of the home; secondly a suitably ambitious level of carbon mitigation achieved on-site and thirdly, recognition that developers will need recourse to other options (the allowable solutions). Within the allowable solutions, the export of heat to nearby areas is particularly important.

The UK Green Building Council is a strong advocate of the idea of a Community Energy Fund, which we think would be the best way of delivering the most cost-effective and strategically appropriate solutions at a local level. This was not a feature of the consultation, but we think it should still be considered. Not least given our zero carbon homes solutions must also be compatible with zero carbon non-domestic building solutions – to effectively deliver a sustainable built environment, with the associated infrastructure, at a district scale.

So overall we've got the right level of ambition and government has responded in a pragmatic way to some concerns. This should provide for practical delivery and increased confidence about likely costs. However, there remains a fair amount of confusion on the ground where we don't have those 'final' answers. We certainly haven't got the absolute clarity that the industry craves – and that can't come soon enough.

Related NBS information:

Articles:

• Towards zero carbon
• Low carbon buildings – standards, assessment systems, tools

Selected links:

• Green building
• Sustainable development

Written September 2009

ViewAllArticles

BackToTop