Scottish Building Standards 2015 – what can be gleaned from the consultation response?
What do we know following the Scottish Government response to their January 2013 consultation on “Low Carbon Buildings – A review of energy standards and guidance within Scottish building standards” which references Section 6 Energy and closed on 15 April 2013. This blog post is about what we know now…
Scottish Ministers advised in September last year consultation proposals for energy standards within building regulations, these included proposed emissions reductions of approximately 21% for new homes and 43% for new non-domestic buildings, with implementation from October 2015.
The Scottish Government’s response to the consultation on lower carbon buildings energy standards has been published and is available at ‘Lower Carbon Buildings – A Review of Energy Standards and Guidance within Scottish Building Regulations – Consultation Report and Scottish Government Response’
The timeline for implementation announced in the consultation response is:
- July 2014 – Target setting specification confirmed for new buildings; begin Action Plan work
- August 2014 – Sign-off of final Business & Regulatory Impact Assessment; Lay SSI for amended regulations in parliament
- October 2014 – Publication of Technical Handbooks section 6 (energy) 2015 and supporting guidance; software tools supporting 2015 standards begin to become available
- December 2014 – Further supporting guidance published; update report on Action Plan discussions & outputs
- May 2015 – BSD Dissemination events begin
- October 2015 – Section 6 (energy 2015) in force; report on Action Plan discussions & outputs
So we’ll know full details in October as to what’s changed, however there are a few hints in the responses and commentaries for the various consultation questions as to what the changes may be.
- For the purposes of calculating the Target Emission Rate (TER), PV kWp contribution should be calculated based on the dwelling floor area with a revised limit of 30% of roof area
- For the purposes of calculating the Target Emission Rate (TER), it remains appropriate to retain WWHR as an element, with the number of WWHR units based on the dwelling floor area, but with a slightly reduced efficiency of 45%
Although PV and WWHR form part of the ‘notional dwelling package for target setting purposes, their use is not necessitated, the response notes that
“Designers are therefore free to use the most appropriate design choices; including solar hot water technology or a fabric first approach, provided the TER is achieved and they comply with all other provisions within the standards.”
- Efficiencies and guidance for heat pumps for target setting for the electricity package and default efficiencies for generic heat pumps used in the DER calculation will be amended
- The consultation response notes that “Improved U-values are considered to strike a balance across fabric improvement, cost and flexibility in design.”
For reference, the consulted upon proposals for new build domestic packages were for the different elements to achieve:
- Walls: 0.17W/m²K
- Floors: 0.15W/m²K
- Roofs: 0.11W/m²K
- Openings: 1.30W/m²K
The consultation response notes that the openings proposal will be relaxed to 1.40W/m²K, but otherwise doesn’t advise any change to the other proposed values, so presumably these values will form the nuclei of the fuel package target setting.
- Maximum average area weighted limiting value for floors will improve to 0.18W/m²K, in line with the target already in place for extensions since 2010.
A slight improvement to the limiting values; I can’t see anything in the response to indicate that the Scottish are considering adopting the England based TFEE and DFEE metric for fabric energy efficiency, but limiting values for Scotland were already tighter than for England, so not surprising really, considering that the Welsh also didn’t adopt this.
- The consultation response highlights that ‘reasonably practicable’ and’ greater design flexibility’ approaches are needed for extensions and conversions, so guidance will be improved, similar to that found in the new Welsh regulations, allowing compliance by either an area weighted U-value trade off just for the extension, or offsetting against improvements to the existing dwelling (following an equivalent carbon target approach using SAP presumably).
A new non-domestic CO2 emissions target for non domestic buildings will be published, together with a fully revised NCM Modelling Guide for Scotland
The consulted on fabric specification for non-domestic buildings was based on:
- Roof U-values of 0.18W/m²K for naturally ventilated and heated side lit buildings and 0.16W/m²K target for mechanically ventilated side-lit;
- Wall U-values of 0.23W/m²K for naturally ventilated and heated side lit buildings and 0.20W/m²K target for mechanically ventilated side-lit; and
- Floor U-values of 0.22W/m²K for naturally ventilated and heated side lit buildings and 0.20W/m²K target for mechanically ventilated side-lit.
It would appear that these will form the basis of the notional building for target setting (although the response is a little hard to follow).
- Backstop U-values will be maintained at the 2010 levels.
- A proxy amount of Photovoltaics based on 4.5% of floor area will form the basis of the target setting (as per consultation), but with a reduced maximum area set at 30% of available roof area.
The above covers the main points, we’ll know more in October. Watch this space and let me know your thoughts below….
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