The task group set up by Government to deliver zero carbon homes by 2016, Zero Carbon Hub, has released formal recommendations on carbon compliance. This has some substantial implications for house building performance standards and environmental considerations.
The new Zero Carbon Hub (ZCH) recommendations
The ZCH has recommended that minimum carbon compliance emission levels are as follows:
- 10 kg CO2(eq)/m2/yr for detached homes
- 11 kg CO2(eq)/m2/yr for terraced and semi-detached homes
- 14 kg CO2(eq)/m2/yr for low rise flats.
The ZCH argues that these levels are both financially and technically feasible whilst meeting Government carbon reduction commitments.
Additionally the recommendations state that developers should be able to average their compliance across a development and that the standards should move towards actual rather than designed performance.
What is Zero-Carbon and Carbon Compliance?
The Government has committed to a target that all new homes must meet a zero carbon standard by 2016. We have known for some time that the zero carbon target would take a three stage approach to reducing carbon emissions.
Firstly, homes will need to meet high energy efficiency standards to reduce energy demand. This will be taken forward by Building Regulations, led by the Code for Sustainable Homes.
Secondly, on-site low carbon technologies may reduce emissions associated with energy use to reach an established overall maximum emissions rate. This is called carbon compliance and is the area focused on in the recent Zero Carbon Hub’s announcement.
Thirdly, developers will be able to offset the remaining emissions from new homes by investing in other carbon reduction solutions – probably off site. This use of ‘allowable solutions’ may offer more cost effective carbon reductions, though the exact nature of allowable solutions is still to be agreed.
Implications for homes and the environment
The Sustainability Consultant Richard Lupo makes some initial comments:
Together with previously reported fabric energy efficiency levels, the requirements will go some way to achieving zero carbon homes by 2016. To make the final reduction in emissions “allowable solutions” will have to be implemented, but these are yet to be defined but will more than likely mean off-site solutions.
The first thing to note is that the compliance levels are now in absolute units and not percentage improvements. We’ve reported before that percentage improvements lead to misleading pictures on how much carbon emissions have reduced. Therefore, the new absolute measures are welcome.
Also welcome is the move toward built rather than designed performance requirements based on research that found actual carbon savings fell far short of designed performance.
Are the proposed levels right?
To answer this, some understanding of how the levels were arrived at is needed. They were derived by the task group by analysis of the technical difficulty in reducing emissions once fabric energy efficiency measures have been implemented. If more than 40% of the roof space of the property (or block of flats) would need to be covered with PV this was considered technically unachievable.
The ZCH (zero carbon hub) concluded that 10 kg CO2(eq)/m2/yr was feasible for detached houses (although, based on the figures in the report, 8 kg CO2(eq)/m2/yr also looks feasible). The ZCH methodology meant that the more limited roof space on attached houses and low rise flats was insufficient to meet this level, making higher targets necessary.
So I return to the question of whether this is right. Initial working assumptions for the group were based on a 70% reduction of regulated emissions compared to 2006 building regulations. The report itself highlights that the proposed levels are far short of 70%. However Government policy, backed by science, states that we need an 80% reduction in carbon emissions against 1990 levels. Therefore comparable figures for the average home in 1990 not 2006. It would have been helpful had the ZCH made this comparison in their research.
One consideration that is continually missed from the zero carbon debate is carbon due to household appliances even though these can be approximated in proportion to home floor area.
How to prepare for zero-carbon
Four key things to consider in preparing for the zero-carbon agenda:
- Energy efficiency is gold.
- Get the design right from the start and save time, money and hassle.
- Employing an experienced team is key.
- Aim high to avoid disappointment!
We are working with house builders, landlords and designers across the country to help them prepare for zero-carbon.
2016 Zero Carbon Target: Government welcomes interim recommendations, Sustainable homes, [Online] Available at http://www.sustainablehomes.co.uk/blog/bid/51556/2016-Zero-Carbon-Target-Government-welcomes-interim-recommendations [Accessed June 2014]