Building regulations - proposed changes to energy and environmental standards: stage 2 consultation and BRIA

2 A Scottish equivalent to the Passivhaus standard

2.1 Overview of the Scottish equivalent to the Passivhaus standard

The Scottish equivalent to the Passivhaus standard – consists of the following aspects. Please refer to sections 3 to 9 of this consultation for further information.

• Delivery programme

As part of the laying of amendment regulations in December 2024 the Scottish Government applied a coming into force date of 31 March 2028 to enable the construction sector to prepare for the changes.

As the development of the Stage 2 proposals, supporting guidance and assessment tools has taken longer than originally anticipated, the timetable set out in the Stage 1 consultation has been reviewed. Following analysis of consultation responses, we now aim to publish guidance and approved methodologies under standard 6.1 in Autumn 2027.

Consequently, to maintain a sufficient industry preparation period, we will amend the implementation date in regulations to Autumn 2029. We will also consider the most appropriate approach, including introducing the standard in full, phasing it in, or supporting voluntary adoption before compliance becomes mandatory.

• Alternative means of compliance

Responses to the July 2024 stage one consultation indicated strong support to amend standard 6.1 ‘Energy demand’ to recognise Passivhaus certification as an alternative means of compliance. This change will be progressed for implementation alongside wider review changes.

It is anticipated that such a change will require amendments to the Building (Scotland) Regulations 2004 (as amended), in particular paragraph 6.1 of Schedule 5.

• Primary compliance metric – delivered energy

Delivered energy (as opposed to primary energy) remains the main compliance metric for standard 6.1 ‘Energy demand’ as this continues to be the most relevant metric for those that occupy and manage buildings. We propose to present unregulated loads as information sitting outwith but alongside the delivered energy metric.

• Secondary compliance metric – space heating demand

Proposals introduce a space heating demand rate, as calculated through the approved methodologies, that takes into account the fabric efficiency of a new dwelling and new building.

• Level of challenge for new dwellings

Three level of challenge options for new dwellings are presented resulting in aggregate emissions reductions of between 0% and 37% against the February 2023 energy standards.

Where new dwellings are supplied from a high efficiency communal heating system it is proposed that dwellings supplied from such a source can report the net efficiency of the heat supply rather than the current default 100% efficiency.

• Method of target setting for new dwellings

It is proposed that the current notional dwelling target setting method within standard 6.1 ‘Energy demand’ is replaced with a set of target range tables. The ranges being determined by a limited number of variables including: dwelling location, dwelling archetype, dwelling orientation and dwelling heat source.

• Fabric performance for new dwellings

The maximum ‘backstop’ U-values within the guidance to standard 6.2 ‘Building insulation envelope’ are proposed to remain unchanged.

It is proposed to set a maximum upper limit of 5 m³/(h.m²) to the declared design air infiltration rate.

• Standard 6.1 compliance approved methodologies for dwellings

An interim version of a Scottish ‘wrapper’ linked to the UK Government Home Energy Model is presented as a work in progress standard 6.1 compliance tool, to be developed further before being adopted as an approved methodology prior to implementation.

It is proposed that a modified version of the Passivhaus Planning Package (PHPP) will also be developed and adopted as an approved compliance methodology.

• Level of challenge for new non-domestic buildings

Three level of challenge options for new non-domestic buildings are presented resulting in aggregate emissions reductions of between 0% and 11.5% against the February 2023 energy standards.

Where new non-domestic buildings are supplied from a high efficiency communal heating system it is proposed that buildings supplied from such a source can report the net efficiency of the heat supply rather than the current default 100% efficiency.

• Method of target setting for new non-domestic buildings

It is proposed that the current notional building target setting method within standard 6.1 ‘Energy demand’ is replaced with a set of target range tables. The bounds of the target range will be determined by a limited number of variables including: building location, building type, activity types, building heat source and building orientation.

• Fabric performance for new non-domestic buildings

The maximum ‘backstop’ U-values within standard 6.2 ‘Building insulation envelope’ are proposed to remain unchanged.

It is proposed to set a maximum upper limit of 5 m³/(h.m²) to the declared design air infiltration rate.

• Standard 6.1 compliance approved methodologies for new non-domestic buildings

An interim Scottish version of the Simplified Building Energy Model v7 is presented as a work in progress standard 6.1 compliance tool, to be developed further before being adopted as an approved methodology prior to implementation.

It is proposed that a modified version of the PHPP will also be developed and adopted as an approved compliance methodology.

• Ventilation and indoor air quality

It is proposed to continue to accept any system/solution of achieving the performance sought in standard 3.14 ‘Ventilation’. However, we will procure research outwith the stage two consultation to understand where additional guidance would be beneficial, including on the use of Mechanical Ventilation with Heat Recovery in new dwellings and non-domestic buildings. Engagement will commence at the appropriate time to be captured in confirmed guidance.

• Overheating

Scottish Government has initiated work to review and update the guidance in support of standard 3.28 ‘Overheating risk’ to identify further information that will provide greater clarity on the actions required to achieve compliance with the standard. This includes developing guidance on the potential use of PHPP as an additional option to assess and mitigate overheating risk in dwellings and some non-residential buildings.

• Compliance and assurance

We propose to introduce a ‘Building Standards Energy and Environmental Compliance Handbook’, which will provide guidance on the production of the design and construction statements as required by the Building (Procedure) (Scotland) Amendment Regulations 2024.

Consultation Question 1

With reference to the Partial Business and Regulatory Impact Assessment (BRIA) at Annex A of the consultation paper, are you able to provide any information, in confidence, that could aid in the production of the final BRIA?

Yes

No

If you have answered ‘Yes’ please contact the review team at: bsdenergystandardsreview@gov.scot

Consultation Question 2

Do you have any comments on the merits of introducing the standard on a mandatory basis through a phased implementation?

Yes

No

Please provide a summary of the reason(s) for your view.

Consultation Question 3

Do you have any comments on the merits of introducing the proposed standard initially on a voluntary basis?

Yes

No

Please provide a summary of the reason(s) for your view.