Energy Standards Review - Scottish Passivhaus Equivalent Working Group minutes: August 2023

Minutes from the meeting of the working group on 29 August 2023.

Attendees and apologies

  • Vikki Bell, Building Standards Division
  • Julio Bros-Williamson, The University of Edinburgh
  • Ronan Casey, Building Regulations - Northern Ireland
  • Anastasia Charalampidon, Scottish and Southern Energy Networks
  • Ryan Cossar, Scottish Futures Trust
  • Cassandra Dove, Scottish Federation of Housing Associations
  • Peter Drummond, Royal Incorporation of Architects in Scotland
  • Steven Earlie, Offsite Solutions Scotland
  • Steve Fawcett, Homes for Scotland
  • Jocelyne Fleming, Chartered Institute of Building
  • Daniel Foulds, Building Standards Division
  • Stephen Garvin, Head of Building Standards Division (co-chair)
  • Antonia Georgieva, Heat in Buildings Division
  • Stephen Good, Built Environment – Smarter Transformation (co-chair)
  • Jack Haynes, Scottish Power Energy Networks 
  • Jonathan Hines, The Passivhaus Trust
  • Caitriona Jordan, Built Environment – Smarter Transformation
  • Paul Keepins, Building Regulations - Wales
  • Lindsay Lauder, Wheatley Group
  • Bryan Leask, Rural and Islands Housing Association Forum
  • Stuart MacPherson, Chartered Institution of Building Services Engineers
  • Alan McAulay, Local Authority Building Standards Scotland
  • Michael McGurk, Scottish Property Federation
  • Sandy Robinson, Planning, Architecture and Regeneration Division
  • Steven Scott, Building Standards Division
  • Colin Sinclair, Building Research Establishment
  • John Smith, Structural Timber Association
  • Robert Toomey, Royal Institution of Chartered Surveyors 
  • Paul Tuohy, The University of Strathclyde


  • Patrick Brown, City of Edinburgh
  • Ron Fraser, Construction Scotland
  • Mike Leonard, The Building Alliance
  • Peter Tait, Federation of Master Builders
  • Mark Wilkinson, Construction Products Association

Items and actions

Welcome and ntroductions

Brief introductions were provided by new SSEN and SPEN representatives and apologies noted.

Actions from working group meeting one - Reminder to working group members to provide requested one-page summaries. Remaining actions covered by the meeting agenda.

Recap – scope of the energy standards review

Reference was made to document WG 11 (23).

Officials presented brief recap reiterating two key themes:

  • a package of measures that use reliable solutions to optimise building fabric and service performance, reduce delivered energy demand and provide a healthy indoor environment
  • the design and construction of new buildings must be supported by quality (compliance) assurance and verification processes that result in buildings which meet the high standards set

Reference was made to document WG 03 (23) - draft high-level schedule of main and secondary Working Group (WG) meetings going forward, including themed discussions – as initially presented at the first working group meeting. 

High level programme confirmed as unchanged.

Officials noted that commissioning of relevant research had temporarily been placed on hold and was to be developed following this meeting.

List of themed meetings discussed and updated. Officials to reissue document WG 03 (23) with relevant updates following today’s meeting.

Officials confirmed that a Review webpage has now been created on which working group meeting minutes and other key information will be published. 

Minutes from the first working group meeting will be uploaded to the webpage once agreed. 

Opportunities for further engagement also to be advertised via the webpage.

Members were encouraged to share the webpage, highlighting the opportunity to engage, with colleagues and wider.

Officials indicated an intent to look at how the current standards are driving design and specification since their application in February 2023. Followed by consideration of the key elements of low energy design as applied by Passivhaus. Looking towards the third working group meeting to summarise discussions and agree detail on the action needed to develop consultation proposals.

Scope of working group meeting two

Today’s meeting primarily focused on identifying the key Passivhaus elements, discussing how good and best practice currently looks in Scotland and agreeing the topics for further discussion in the range of forthcoming sub-group meetings.

Reference was made to document WG 11 (23). Members were asked to consider the information provided in this paper alongside further discussion points offered by members during this meeting.

Summary of WG01a discussions – Form and orientation

Reference was made to document WG 09 (23) issued in support of the first sub-group meeting (workshop), held online on 25 July 2023 via MS Teams, which focused on ‘Form and orientation’ as a key consideration of the Passivhaus approach.

Officials noted that form and orientation were identified as early discussion topics, with the workshop providing the opportunity to gather broader comment outwith the main working group meetings. 

Purpose of the workshop was to focus on effective action which can reduce space heating demand without the need to improve the specification of the external envelope – primarily through a smaller heat loss envelope for a given property area (form factor) or effective use of passive solar gain (orientation).

Workshop discussions included reducing the energy demand for space heating and how important this was and how best to achieve it. Also considered how action to encourage energy efficient form and orientation can be embedded into standards to optimise the benefit from improved specification.

Summary notes from the workshop will be circulated in due course.

On these topics members discussed the following: 

  • the ability of the Passivhaus Planning Package (PHPP) methodology to facilitate the ‘balancing’ of every aspect of a building, enabling optimisation of form/orientation. With complicated form requiring improved specification (e.g. insulation) to offset additional heat loss 
  • the usefulness of PHPP as both a design and certification tool, with reference to its greater accuracy/responsiveness compared to other models, and the potential to develop a Scottish Government version 
  • concerns around any Scottish Government citation of PHPP and potential implications 
  • the ability of SAP or SBEM to do basically the same as PHPP in response to a defined energy target. The issue therefore being about the way a target is defined, for example absolute (kWh/m2/yr) or relative (notional building), and how that drives design decisions on form 
  • UK Government SAP review work currently underway – BRE announces new project with BEIS to modernise home energy rating scheme in time for Future Homes Standard - BRE Group
  • performance gap identified as a critical issue. The inaccuracy of SAP considered to be contributing to this. PHPP shown to be effective in eliminating this
  • SAP/PHPP tool comparison project
  • Passivhaus Trust Position Paper - Future Homes Hub Contender Specifications for the Future Homes Standard
  • the potential benefit of setting an absolute metric to create a pivot point around which the other offsetting factors such as form, orientation, insulation values, air tightness etc could be considered. Recognition that sites often create restrictions that limit options on orientation and form
  • in terms of volume housebuilding, the benefit of standardising specification to enable cost effective delivery of homes 
  • engagement with house builders on mass housebuilding considerations, land use implications also mentioned
  • confirmation that a comparison of methodologies and implications for other policy areas will be considered within the review, which will include commissioning of supporting research
  • reiteration that the purpose/scope of the WG is to help steer a Passivhaus equivalent standard. Not just a binary discussion on Passivhaus or not – the aim is to identify a sensible implementation
  • not setting requirements for form and orientation but setting a metric which is equivalent to Passivhaus supported by a methodology to achieve this metric
  • planning considerations in relation to land use and the potential to invite further comments from planning colleagues once minutes are shared

Discussion summarised, noting indication is that formal targets to define form and orientation are not considered desirable. Members encouraged to provide ‘one-pagers’ on anything extra on the topic.

February 2023 standards

Officials noted discussions with stakeholders highlighting the need to understand where we are early on with the 2023 standards, so we have a baseline for change and also can understand where the potential opportunities for further action around elements of specification may lie.

Officials noted list of key elements and outputs for domestic and non-domestic buildings as set out in document WG 13 (23) – the elements of specification to deliver an energy efficient building. 

Officials noted intent to set out and agree a specification to gather feedback from house builders. Useful to hear members thoughts on how we can develop a similar set of data for new non-domestic buildings, recognising there are less delivered annually.

On these topics members discussed the following: 

  • Homes for Scotland looking to evidence where the 2023 standards sit and how this can be compared with a Passivhaus or equivalent standard - should be in a position to present a report on this for the next working group meeting
  • review will consider the benefit of setting absolute targets with a view to identifying where prescription in standards is beneficial and perhaps necessary
  • recognition that a good predictive modelling tool is beneficial but good design and construction also play a significant role in addressing the performance gap
  • key role played by testing and certification, during construction and at completion, in closing the performance gap
  • Building Standards Division Compliance Plan approach work
  • Scottish Futures Trust (SFT) work related to the Edinburgh Homes Demonstrator (EHD) project - includes a monitoring programme to assess the performance gap, with consideration of the actual energy performance cost and indoor air quality implications. Project offers potential point of evidence
  • as part of the evolution of the Review webpage, potential to provide links to good evidence or case studies
  • example of homes in Shetland being built in excess of the minimum building standards for years - 2023 standards still not considered to be going far enough in terms of infiltration, MVHR etc. Infiltration rate of five is considered high for Shetland with move to MVHR as standard taking place 15 years ago. On doors, as example of components, very challenging to source solutions which satisfy all functions. Weather proofing first, insulation second. Need to be conscious of what we’re trying to achieve
  • Shetland noted as a good example of response to more extreme climate conditions - necessary to keep in mind that solutions have to be based on first principles on issues such as comfort and durability. Where is prescription beneficial? 
  • example of building to the Passivhaus standard in extreme northern isles climate - able to source the right components for all functions, with better specification via Passivhaus standard delivering more robust construction through good quality components and quality assurance
  • documented examples of poor indoor air quality and environmental problems in a small minority of homes. Not necessarily a picture of how the wider new build property market is performing, however it’s important to understand extent of issues in modern buildings and how they arise – lifestyle, construction, etc
  • lack of info/evidence recognised to be an issue 
  • research work recently undertaken by Strathclyde University to evaluate the effectiveness of CO2 monitors post implementation of the 2015 standards
  • emphasis on the need for effective ventilation to be integrated as part of low energy design
  • shortcomings/issues evident. Identified lack of standards/methodologies for ventilation, MVHR being the exception
  • 40 years of Passivhaus evidence gathered to identify what works in delivering low energy and healthy internal air quality in buildings, compared to many examples of (non-Passivhaus) low energy buildings that fall short of achieving their theoretical standards 
  • does this include evidence specific to Scotland and the house building, supply chains and occupancy patterns we experience here?
  • Passivhaus track record in Scotland recognised as being more recent than some other parts of the world but Scotland's climate and supply chain not considered unique. Passivhaus is proven to work in every climate zone. Evidence from around the UK is growing
  • MVHR (designed to sufficient standards, as embedded in Passivhaus) arguably essential to achieve good indoor air quality with more airtight construction -  upskilling and training necessary to deliver at scale
  • a number of relevant webpage links were shared
  • potential to map other bits of research and groups looking at relevant topics
  • webpage links to ventilation research reports recently published and copy of Building Standards Division business plan will be shared with members
  • in regards to design and construction methodology and eliminating the performance gap, compliance recognised as being a big issue - already being looked at in the house building sector 
  • user interface also a key consideration, recognising that the Passivhaus standard is generally adopted by informed investors, which would not necessarily be the case if implemented at a national scale. Need to consider user readiness / education
  • some examples of bad experiences with MVHR in relation to damp and mould - negative unintended consequences 
  • fuel poverty focus 
  • evidence that adopting Passivhaus reduces fuel poverty and does not result in poor indoor air quality outcomes or mould. MVHR does require maintenance i.e. 1one to two filter changes per year. Regarding access concerns e.g. in social housing settings - option to site MVHR units externally, removing the need to access properties to change filters
  • social sector has been building above minimum standards for some time – potential to offer evidence
  • feedback provided in ‘one-pagers’ received to date has already fed into internal group discussions - officials will aim to summarise (identifying any emerging themes) for the next meeting to potentially inform subsequent meeting topics
  • reiteration that discussions and feedback all contributing to the direction of travel and reaching some consensus on the wide range of issues being considered. Whilst the discussion of diverse points was noted as being useful, the need to focus was also emphasised.
  • important that users are effectively informed and supported. Suggestion that it would be useful to collect user interaction data
  • evidence (more and better data) needed to understand the problems people can create in homes to inform effective regulation
  • relatively small proportion of properties built to the Passivhaus standard at present. The Passivhaus equivalent standard has to consider just transition and mass solutions which are tolerant of users
  • some evidence of MVHR systems being switched off by occupants due to a number of perceived practical or social reasons e.g. noise, cold air, expense. Emphasis of the need to consider the social element over the long-term

Good and best practice in Scotland 

Members were encouraged to offer examples of any additional good and best practice currently adopted in Scotland

Member representing Built Environment – Smarter Transformation (BE-ST) provided overview slide presentation covering:

  • role and work of BE-ST in connecting, citizens, industry, institutes and the public sector to support change and acceleration to zero carbon 
  • focus on behavioural and culture changes and supporting skills and competencies 
  • resources, including:
    • open learning academy 
    • low carbon construction bulletin
    • accelerator labs to offer practical training on Passivhaus and retrofit training rigs 
    • training courses for specific topics, including MVHR
  • ‘Z-lab’ manufacturing prototyping, including Passivhaus steel rig piloted with Morrison Construction
  • commercial Passivhaus training for all six tier one contractors
  • Passivhaus Trust endorsed courses for designers and contractors
  • project delivered on behalf of BSD, working with University of Strathclyde, to review and set out advice on route to net zero - final summary report, informed by a desktop study and the output of online and in-person workshops, due to be published shortly

Post-presentation discussion included the following points:

  • the role of BE-ST in supporting demand for upskilling where industry is considered to be now compared to where it may need to be
  • BE-ST engagement with around 2,500 people so far - all looking to upskill so difficult to use that to benchmark 
  • BE-ST looking to develop a low carbon passport for all contractors. Aim is to build on experience with tier one contractors and upskill 1,000 people per year going forward. Appetite to deliver quality is consistent amongst those BE-ST have engaged with so far. Issues are challenges around timelines. Experiences have all been positive and have driven further useful work
  • tier one work in part driven by SFT Net Zero Public Sector Buildings Standard (NZPSBS) and energy targets - Net Zero Standard
  • recent CITB local skills construction report identifying a massive shortfall in existing construction skills - new standard needs to be pitched at a level the market can deliver 
  • lack of good contractors and operatives recognised as being an issue
  • levels of capability difficult to evaluate as different skills packages needed. Post-COVID, recruitment extremely difficult across the board. Challenges getting basic operatives and attracting people into the construction sector. Some operatives there to ‘just do the job and get the wage’
  • issue not just at the workforce level but also management and supervision on site of high quality work – certification and assessment of the build itself
  • more onerous assessment/ verification processes may also require local authority verifier training/upskilling 
  • verifier skills noted as being a core element of the ongoing BSD compliance plan work, with the current consultation on building warrant fees flagging that as a consideration. Reinforcement that ultimate responsibility for getting it right sits with the applicant and their team – the designers, developers and contractors
  • testing and certification during construction and at completion highlighted as playing a key role in closing the performance gap
  • potential merit in having a skills sub-group
  • suggestion that certification of the Passivhaus equivalent standard could be done by Section 6 certifiers and that the existing Passivhaus training programme could upskill verifiers, etc.
  • accepted that local authority verifier upskilling will be required, however, in a better place now due to compliance plan journey and the creation of the building standards hub in particular. Verifier’s role is to undertake reasonable enquiry, this does not detract from the 'Relevant Person’s' duty to comply.  In regards to form and orientation, likely there will be changes in practice if a sampling approach is no longer tenable due to variation and complexity
  • general consensus that improved standards are necessary. Suggestion however, that a ‘routemap’ is required to identify and develop the necessary infrastructure in order to mitigate the risk of setting standards that are unachievable in practicality
  • need to be able to say if we are ready and if not, what can be done and what else is needed to go further
  • important to achieve balance between flexibility and design standards so we have consistent and robust solutions we can deliver e.g. industrialised/offsite solutions - industry support/investment needed
  • benefits from standardisation of product and components, in terms of performance and repeatability and cost effectiveness

Linking back to earlier presentation slides on BE-ST work, reference made to document WG 11 (23), noting its inclusion of summarised points from the pending BE-ST publication relating to current best practice in Scotland.

Brief summary of document WG 11 (23) content provided, including:

  • three main levels of Passivhaus (Classic, Plus, Premium)
  • Low Energy Building Standard
  • self-certified AECB building standard
  • the prescriptive performance targets set by Passivhaus and AECB 
  • two levels of domestic energy performance specification consulted on in 2021 – improved and advanced
  • improved specification taken forward in 2023 Standards
  • work being led by local authorities e.g. City of Edinburgh Council - Future Schools programme, Glasgow City Council – The Glasgow Standard, Midlothian Council – Net Zero Housing Design Guide, Renfrewshire Council - RenZEB
  • UK Government – Future Homes Standard - intent to engage with UKG colleagues on their review
  • LETI Net Zero Standard
  • comparison of target setting across the UK – summary table

Recognising the potential risks and benefits arising from the setting of prescriptive targets, WG was invited to express their views on where cited examples do sit in terms of deliverable best practice at a national level.

WG discussed the following points:

  • summary table three useful to illustrate context. With reference to the lessons learned from the EHD project, aim is now to standardise house typologies via South East Regional Delivery Alliance to expedite delivery of net zero ready homes. Big learning point is what can be done with the capability available, at scale and seeking to industrialise. Relevance of SFT’s NZPSBS to non-domestic discussion noted  
  • table four (EU perspective) provides useful background information - ultimately seems like we need to agree on an absolute measure of energy use and allow designers to achieve that by a mix of measures such as U values for fabric elements, air tightness, form and so on. WG generally supportive of this approach
  • further discussion on Passivhaus principles, PHPP and assurance. Suggestion of using peak load target rather than space heating demand due to better recognition of geographical variations
  • reference to experiences from Ireland in regards to how they are mapping outcomes against requirements - need to learn from what has worked elsewhere 

Any other business and meeting close

No other business raised.

Next meeting scheduled for 24 October 2023, noting three sub-group meetings planned in the intervening time.

Meeting closed.

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