Scottish Building Standards 2015 – what can be gleaned from the consultation response?

Scottish boy with the flag of Scotland

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.

Domestic Buildings

  • 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).

 

Non-Domestic Buildings

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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About

Jon Ducker is a qualified energy assessor working for Kingspan Insulation Ltd. He has an extensive knowledge of energy efficiency, renewable energy systems and sustainability in buildings with an expert knowledge of the relevant sections of buildings regulations and standards and their interactions with SAP. He provides authoritative advice regarding energy assessments for a wide range of public and private sector clients.

0 comments on “Scottish Building Standards 2015 – what can be gleaned from the consultation response?
  1. Hello,
    We are about to finally start the renovation and extension to our house in Scotland. It was build in the late 1800’s and is constructed of granite. We are doing most of the work ourselves and the trade I do need I will be project managing. I have had very conflicting information from my architect, builder and websites regarding insulation required for the wall of the existing building. I know that the new framing has to be 25mm from the wall but could you tell me the minimum thickness of kingspan that I am required to have before covering in 12.5mm standard plasterboard? Also if possible could you give me minimum insulation thickness required for the extension part of the house that we will be doing as a timber frame type construction?
    If you require further information please let me know.
    Kind Regards
    Jo

    • Dear Jo,

      Thank you for the request.

      Assuming that you are building an independent timber stud off of the existing granite wall there are a couple of options. Your could insulate purely within the stud in which case in an overall 150mm stud you will require 120mm Kooltherm K12 to achieve Scottish refurbishment regulations target U value of 0.22 W/m²K. Alternatively you can insulate between a 100mm stud with 70mm Kooltherm K12 and fix our insulated plasterboard (Kooltherm K18, 37.5mm) to the internal face of the stud.

      For the extension part of the house, based on a timber frame wall finished with timber cladding, you would require 70mm Kooltherm K12 within a 100mm stud and fix 52.5mm Kooltherm K18 to the internal face of the stud. This will achieve Column A of the extension regulations, if you are going for Column B then refer back to the above advice.

      I hope this has been of assistance,

      Kim Thayer
      Technical Advisor
      Tel: +44 (0) 1544 387382

  2. John – Consider a new build steel framed and composite roof and wall clad manufacturing building in North Wales of approx.1400 m2 and 6m to eaves and having a reinforced concrete floor slab. Heating in the main structure nominal radiant heating and in the 20% office/showroom similar wet system radiant heating.
    Please advise on Kingspan spec for under floor, wall and roof insulation.

    Regards,

    Ken

  3. I have an 1800 house in the Scottish Borders that I’m refurbishing, the single story part of my house slates are visible from the inside, I have no sarking board or lining. I was told by my architect that this is the traditional way roofs are in England. I want to insulate my roof space as I’m opening the roof to the eves. Can I insulate the roof from the inside that will be waterproof. I’d rather not remove all the slates and fit sarking board. What type of ridged insulation will I require for my roof. and walls, the walls are solid stone and rubble infill.

    Thank you

    Stephen

    • Thank you for your question Stephen.

      The good news is that you do not need to remove your slates or fit sarking board, however you will need to ensure that your roof is completely watertight and that there is no risk of rain or any other moisture penetrating. The roof construction itself would be Kingspan Kooltherm K7 Pitched Roof Board board between the rafters with Kingspan Kooltherm K18 Insulated Plasterboard under the rafters. The thickness you need will depend upon your rafter centres and depth, but for domestic refurbishment of a roof you’ll need a U-value of 0.13 W/m.K A link to a calculation is here – just amend the rafter centres to suit. You will need to ensure a clear 50mm ventilated cavity between the Kooltherm K7 and the underneath of your slates. Ventilation should be at the eaves and at the ridge ideally.

      As for your walls, as you are in Scotland, much of which is classed as a high exposure zone, we’ll need to talk to you about the condition of your wall, the building’s location, aspect etc. One of our advisors will be happy to help you on 01544 387 382.

      I hope this advice helps.

      • Thanks for the information. The rafters are 150 x 50 and I take it when you say to measure the centres you mean from the middle of each rafter to the middle of the next that measurement is 47cm. I intend to stud out the interior walls and fit kingspan between the studwork I think the u-value is 0.18 for the walls in the Scottish Borders.

  4. Hi Jon,
    I am planning on adding 100mm thermafloor to the underside of the 100mm joists in both my rooms.
    The drafts are unbearable (varnished floorboards)
    I live in a mid terrace house both rooms are 5M x 3.9M with one exposed wall in each room (3.9m)
    It has a raised timber floor with a 1.5M void with a bitumen DPC.
    There are two vent tiles on the front and back walls
    Can you please confirm that this is the correct thickness and if taping the flush joist/board would be sufficient finish (no room for battens)

    • Hi Thomas,

      You certainly sound like a man with a plan!

      We suggest using our online U-Value Calculator (or perhaps even its App version!). This will help you determine what thickness you need to comply with Building Regulations. It will also recommend a Kingspan Insulation product suitable for the job, with a link to the relevant product page on our website. If you then download the associated product literature from this page, this will advise on installation methods.

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