Energy Standards Review - Scottish Passivhaus Equivalent Working Group minutes: 29 May 2025

Attendees and apologies

• Alan Hardie, Wheatley Group
• Alice Purcell, AECOM (Guest speaker)
• Alan McAulay, Scottish Building Standards Hub
• Caitriona Jordan, Built Environment – Smarter Transformation
• Ronan Casey, Building Regulations, Northern Ireland
• Cassandra Dove, Scottish Federation of Housing Associations
• Colin Sinclair, Building Research Establishment
• Daniel Hastings, Homes for Scotland
• Daniel Foulds, Scottish Government
• Fionna Kell, Homes for Scotland
• Fraser Reid, Mott MacDonald (Guest speaker)
• Ingrid Berkeley, Chartered Institution of Building Services Engineers
• Jess Fraser, Building Regulations, Northern Ireland
• John Smith, Structural Timber Association
• Jonathan Hines, The Passivhaus Trust
• Mark Wilkinson, Construction Products Association
• Michael Barton-Maynard, Scottish Government
• Michael Jarvis, Royal Incorporation of Architects in Scotland
• Mike Leonard, The Building Alliance
• Michael McGurk, Scottish Property Federation
• Paul Leask, Rural and Islands Housing Association Forum
• Rory Hughes, Scottish Federation of Housing Associations
• Ryan Cossar, Scottish Futures Trust
• Stephen Garvin, Scottish Government (co-Chair)
• Stephen Good, Built Environment - Smarter Transformation (co-Chair)
• Stephen Fawcett, Homes for Scotland
• Steven Scott, Scottish Government
• Stuart MacPherson, Chartered Institution of Building Services Engineers
• Toby Tucker, Scottish Futures Trust
• Victoria Bell, Scottish Government
• Zoe Black, Royal Incorporation of Architects Scotland

Apologies

• Julio Bros-Williamson – The University of Edinburgh
• Peter Tait – Federation of Master Builders
• Robert Toomey – Royal Institute of Chartered Surveyors

Items and actions

Welcome and introductions

The co-chair welcomed members of the group noting that the focus of the meeting will be on ongoing work to confirm the Scottish equivalent to the Passivhaus standard as well as provide updates on the research programme and presentations on the CAVLEB workstream and on the workstream to deliver domestic consultation compliance tools.

Brief introductions were provided by new and substitute members of the working group.

Confirming the Scottish equivalent to the Passivhaus standard

Reference was made to documents WG 52(25) and WG 55(25).

Officials provided a brief update on ongoing workstreams and the processes to take place in laying future regulations. The discussion focused on the series of draft proposals set out within the circulated papers with the following points noted:

• Officials confirmed that Passivhaus certification should be recognised as an alternative means of compliance with building regulations. Legal advice needs to be sought to understand how this can be simply implemented under the existing regime with further consideration given to risks of non-compliance where there is a failure to achieve fully certified Passivhaus outcomes.
  While the approach was welcomed some argued that the Passivhaus design tool, PHPP should be adopted as a defined tool for demonstrating compliance to avoid duplication in modelling or disincentivising the full Passivhaus route in light of risks of non-compliance with the approved building warrant application
• ventilation, air quality and use of MVHR remains a focus given the importance of ventilation strategies and risks identified across both natural and mechanical approaches. There is the intent to add to and improve guidance on such matters within the Technical Handbooks
• Officials intend to include PHPP outputs as a means of demonstrating compliance with Standard 3.28 Overheating within guidance for domestic and smaller non-domestic buildings in addition to the simplified and TM 59 approaches already included within the Technical Handbooks
• there must be a clear justification for introducing a new or alternative approved calculation methodology
  On HEM, there is relative confidence that this will provide an improved and more representative reporting outcome for new homes and this can be further tested against the draft SHS wrapper tool which should be available for initial testing in July.
  It is necessary to review the outcomes from comparative non-domestic (ND) modelling using HEM and SBEM, currently pending, before reaching a conclusion or confirming a position on new ND buildings. Officials indicated the intention to align with the calculation methodologies used across the rest of the UK, provided that ongoing testing continues to validate the reliability of these outputs.
  While recognising the rationale, some members highlighted their disappointment at the exclusion of PHPP as an additional calculation tool raising concern with the reliance of a tool still in development compared to one that is accepted to be robust and accurate.
  Other members considered that having two formal compliance methodologies may add confusion when attempting to work to a single metric.
  ACTION 1 – Officials will arrange a further discussion on this matter
• Officials reported that the upcoming consultation would be based on delivered energy as the basis for compliance assessment, while also supporting the reporting and presentation of unregulated energy use as valuable supplementary information. This also included continued use of the notional building approach to illustrate relative performance targets
  The benefit of absolute targets in promoting an energy efficient built form has been discussed. Officials noted that, to date, standards have not sought to prescribe approaches or how to design a building, seeking functional or performance outcomes. Noting that the stage two consultation will build a revised notional building specification into tools to illustrate revised targets but will not ‘close the door’ on this discussion and will seek views on comparative outcomes against an example of an absolute target.
  Some members reiterated concerns in relation to deviation from the working group’s consensus paper on this topic, noting that notional targets would undermine the principle of a Passivhaus equivalent standard.
  Action 2 – Officials will arrange a further discussion on this matter

Working group members were reminded that the intent of these discussions is to help inform the technical proposals for the stage two consultation. Only following consultation and approval from the Cabinet Secretary will the Scottish equivalent to the Passivhaus standard be confirmed.

Research update with presentations on the CAVLEB work and the domestic consultation tools

Officials highlighted that the development of the Scottish wrapper for HEM continues, with BRE contracted to undertake this work package. Testing is currently being undertaken on the basis of HEM engine v0.35 and the Future Homes Standard wrapper to v0.25 of HEM. Work on SBEM is running slightly later than programmed and Officials will look to present information to the working group towards the end of June. Members of the working group will be invited to join a period of testing in July to assess the functionality of the tools ahead of the stage two consultation.

Research continues on the proposed level of challenge to be set within future standards. Potential specifications for non-domestic buildings have been received and a range of options set out. Officials will look to publish research on the domestic and non-domestic level of challenge later in the summer.

Further to agreement at a previous meeting SFT provided an update presentation of the CAVLEB research. The following highlights were taken from the presentation:

• the project team are two thirds of the way through this work stream having undertaken a wide range of interviews and considered good examples of existing projects undertaken in Scotland
• key themes identified from this study included: team collaboration; quality control and assurance; upskilling supply chains; handover and post-occupancy evaluation; and third-party verification and certification
• early engagement and collaboration with contractors was viewed to be critically important in achieving a successful outcome to a project with focus given to ‘why’ rather than the ‘how’
• the second part of the research focused on mapping processes and outputs of Passivhaus, other low energy building standards, and the building standards system in Scotland. This work draws out the key stages and activities as well as the related core evidence and information requirements for compliance
• the final element of this work, the development of guidance, is currently out for tender. A draft guide will be provided to the working group ahead of the stage two consultation to allow for an update following any discussions. Work will then continue towards the end of the year to support roll out for 2026

Working group members highlighted their support for the work and noted the usefulness of the findings. Officials added that this work aligns to wider workstreams on compliance undertaken by the Scottish Government to support amendment to regulations and guidance.

Programme update

Officials noted the overview of programme timescales included in the papers and confirm that it remains the intent to launch the stage 2 consultation in early autumn.

Confirmation of onward focused engagement

Officials will take away points raised today and seek to arrange further meetings on specific areas of ongoing discussion.

Any other business and meeting close

The chair reminded the working group that we continue to face a nature and climate crisis and of the importance of the actions undertaken to deliver the best available built environment for Scotland.

Officials also noted the UK Government has announced transitional arrangements to run with both SAP 10.3 and HEM with respect to implementing the Future Homes Standard. While further detail on the arrangements are yet to be shared officials continue to engage with the UK Government on this matter and will consider whether there are any implications or benefit in allowing access to the tool.

Officials reiterated that they will arrange further engagement to present and discuss options for both calculation methodologies and absolute/relative targets as an intermediate action before progressing to develop consultation proposals in these areas.

Meeting closed