The next step to ‘Zero Carbon’ buildings?


Proposed changes to the building regulations, supporting guidance and tools are out for consultation.(1) Included in this review are parts A, B, C, K, L, M, N, Access Statements, Security, Changing Places Toilets, Regulation 7 and the building control structure and process. Not too much for us to read, think about and respond to in addition to our normal workload there then!

Part L changes are proposed to reduce predicted emissions through higher performance targets and by closing the “performance gap” (2) for new buildings by stimulating improvements to existing buildings through “consequential improvements”.

For new buildings, the Government has committed to introduce a zero carbon standard (3) from 2016 for new dwellings and 2019 for all other new buildings. The proposed 2013 changes take the next step towards those zero carbon standards, by tightening the carbon dioxide (CO2) targets (DER vs TER) for all new buildings and introducing a specific energy efficiency target (FEES) for new dwellings.

I’ve always struggled with the concept of the TER vs DER. This methodology does not encourage inherently efficient design as it doesn’t assess the proposed building; rather it assesses the proposed building against the same building to a poorer standard with the same fuel. The TER vs DER methodology combined with SAP errors and the use of ‘fuel factors‘ (4) , means we can, and do, end up with some quite perverse results. I’ve seen proposed dwellings have a fuel switch to achieve greater % improvement over TER that results in increases in CO2 and running costs! (See one such example below)

There are various options on how the Fabric Energy Efficiency Standard (FEES) for Building Regulation compliance will be adopted (it is already in SAP and can be used for CfSH credits). Hopefully, the option chosen will encourage both good form factor (5) and fabric first design.

I find it surprising and disappointing that it would seem to still be acceptable to submit a Building Notice for a new dwelling. This means that although there is a requirement to submit “as-designed” SAP calculations with supporting details and a commissioning report for whole house ventilation systems no later than the day before work on site commences, there is no requirement to submit the full scheme for consideration/approval prior to starting work.

With the drive to educate and close the performance gap it is also odd that insulation is not a statutory notification stage of work. Making it so would send a clear message to both builders and building control the importance of this area of work.

For existing buildings, the focus is on the proposal to extend ‘consequential improvements’ provisions to a wider range of buildings and work. This means that when carrying out certain works to a building (extensions, loft conversions and replacement boiler/windows etc) there would be a need to undertake additional work to improve the energy efficiency of the building at the same time.

The proposal is that these changes should be phased in from October 2012, so that they are aligned with the introduction of the ‘Green Deal’. This means that building owners would have a way to meet the new requirements at no upfront cost, if they chose to take up a Green Deal offer. Other proposed measures include minor tweaks to U values for thermal elements and windows and doors to bring them closer to new build values.

Conservatories and over-glazed extensions seem to be a major loop hole in the drive to deal with energy use in existing buildings. Conservatories are in effect a cheap extension avoiding the need to comply with building regulations. Whilst there are ‘safe guards’ in place (separating doors and windows and controls on heating) these are for the most part unenforceable and counter productive. How is it better to have an electric heater in the conservatory rather than extending the gas central heating system into the new space? (Of course neither should be there - it is a conservatory not a habitable room!). Over-glazed extensions are often justified by SAP calculations either showing no trade off works are necessary or by doing upgrades to the existing house which should be done anyway and therefore no net benefit. Hopefully the effect of ‘consequential improvements’ rules will be to remove this loophole by ensuring these works are done first then the additional improvements are carried out. If the “trade off” requirement was to show no increase in energy use rather than CO2 emissions this would close the loophole where renewing an out-dated inefficient boiler (which needed replacing anyway) can be used to trade off against excessive glass.

Are we there yet with legislation, guidance and tools to ensure that new and existing buildings are low or zero carbon? Not yet. Is it a step in the right direction? Probably.


(1) Consultation doc can be found here Consultation on part L ends 27th March 2012 others in April.

(2) The performance gap has been identified as a significant problem in the drive to reduce carbon emissions from buildings. Studies in England and Ireland of housing developments designed and built under the 2006 regime showed that the majority of dwellings performed 60-120% worse than design stage predictions. It is worth noting that the contractors knew their developments were being monitored. The performance gap has been but down to a lack of knowledge and training, willful or inadvertent deviation from specification, build quality, SAP shortcomings and occupancy behaviour.

(3)Zero carbon there’s a subject for a separate blog...

(4) The ‘fuel factor’ is a way of relaxing the standards slightly for homes which have to use higher carbon fuels such as electricity because they don’t have access to the mains gas grid or a political appeasement electricity and oil companies - you choose.

(5) Form factor is the relationship between envelope and volume. A well designed building minimises envelope relative to floor area.

Twitter icon
Google icon
LinkedIn icon
Pinterest icon
Reddit icon
e-mail icon