In December 2022, Alex Rowley MSP proposed a Domestic Building Environmental Standards Bill, aiming to set new minimum environmental design standards for all new-build housing, with goals to improve energy efficiency and reduce fuel poverty — essentially a Scottish equivalent to the Passivhaus standard.
A dedicated Energy Standards Review Working Group, co-chaired by BE-ST and the Scottish Government’s Building Standards team, was established in June 2023 to shape the standard.
A first stage consultation ran until October 2024, laying down the legislative groundwork, defining principles, enabling amendments to the Building (Procedure) Regulations, and preparing for technical development.
I replied to the consultation with the following key themes:
- Equivalence to Passivhaus - the Scottish equivalent should truly match the Passivhaus standard and close the existing performance gaps
- Modelling tools - the modelling tools should be used as much for design as for compliance, and in this respect, PHPP is more suited to the task than the existing SAP or proposed HEM tools
- Energy metrics - I advocate for absolute/specific energy targets instead of relative benchmarks like the current Notional Building
- Airtightness and ventilation - with adaptable air tightness metrics, ventilation could be considered based on air-quality and comfort outcomes, rather than a simple threshold
- Certification - Passivhaus certification should be embedded, not just an alternate route
- Transition approach - we could consider a phased adoption of Passivhaus as a route to full integration, perhaps via an interim Section 7 sustainability level
- Implementation risks - we need to emphasise consistent quality assurance from design to construction, better documentation and communication, and designer-friendly guidance
So far, the working group reports have shown good progress towards achieving a Scottish equivalent to Passivhaus, but some questions remain on whether this will result in something which is truly equivalent, or simply a tweak to the existing regulations:
- What will the Governments future energy targets be based on?
- Will the existing Passivhaus standard and PHPP become formally recognised (beyond being an alternative route) in modelling and compliance?
- How will quality assurance evolve — will it include comfort metrics and stronger oversight from design to handover?