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

7 Ventilation and indoor air quality

7.1 Introduction

Standard 3.14 ‘Ventilation’ of the building standards requires that ventilation be provided so that the air quality inside the building is not a threat to the building or the health of the occupants.

For new homes a basic compliance guide, Annex 3.A within the Domestic Technical Handbook, was introduced in February 2023 covering the selection of systems and delivery through to commissioning. The approach applied is based on the level of fabric infiltration, and that while any system/solution for ventilation is currently accepted, the guidance that supports standard 3.14 does recommend a particular strategy based on the design infiltration level of the building fabric: mechanical supply and extract systems are recommended for very low fabric infiltration, below 3m³/(h.m²) @50Pa.

The Passivhaus standard takes a more prescriptive approach with the expectation that a mechanical ventilation with heat recovery system (MVHR) will be used to manage the delivery of thermal comfort and indoor air quality.

7.2 Proposals

It is proposed that the revised guidance will continue to accept any system/solution of achieving the performance sought in standard 3.14. However, the July 2024 stage one consultation sought views on how effective ventilation of new buildings is best achieved and on whether further guidance should be given on the application of MVHR in hew homes.

Given the strong support for the use of MVHR and the role it plays within the Passivhaus system, we will procure research outwith the stage two consultation to understand where additional guidance would be beneficial. This will consider previous research procured on the 2015 standards. Additionally, this work will consider the potential to decouple the link between fabric air infiltration and ventilation solution on the basis that such infiltration is uncontrolled and unpredictable and therefore should not be relied upon to inform a ventilation solution. Engagement will commence at the appropriate time to be captured in confirmed guidance.

Consultation Question 23

Do you agree with the proposal to accept any ventilation system/solution of achieving the performance sought in standard 3.14 ‘Ventilation’?

Yes

No

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

Consultation Question 24

Do you have any views on additional guidance for MVHR systems that would be beneficial to be included in future guidance?

Yes

No

If you answered ‘Yes’ please provide details for your response.

Consultation Question 25

Do you have any views on the proposal to decouple the link between fabric air infiltration and ventilation solution?

Yes

No

If you answered ‘Yes’ please provide details for your response, in particular thoughts on methodologies that could be implemented to determine the appropriate ventilation solution.