1 Scope

This PAS speciﬁes requirements for retroﬁt of dwellings, including:

• assessment of dwellings for retroﬁt;
• identiﬁcation and evaluation of improvement options (energy efﬁciency measures, or EEMs);
• design and speciﬁcation of EEMs (whether individual measures or packages of multiple measures); and
• monitoring and evaluation of retroﬁt projects.

This PAS covers EEMs that are intended to:

• improve the insulation of the elements of the building fabric (exposed ﬂoors, walls, roofs, windows and external doors) and reduce thermal bridging;
• improve the air-tightness of the building envelope;
• establish a safe dynamic moisture equilibrium through each element of the building fabric;
• improve the resistance of the building envelope to water penetration in order to maintain the thermal properties of the building fabric and the capability of the building envelope to manage moisture in a manner suited to its construction;
• provide or upgrade ventilation to ensure good internal air quality and minimize the risk of condensation;
• minimize the risks associated with vapour or other products, for example volatile organic compounds (VOCs), released within buildings subsequent to their air-tightness being improved;
• minimize the risks associated with overheating;
• provide efﬁcient heating and cooling systems with responsive, intelligent or “smart” controls, including systems that use low or zero carbon (LZC) technologies;
• provide efﬁcient water heating systems with responsive controls, including systems that use LZC technologies;
• provide efﬁcient ﬁxed lighting with appropriate controls;
• provide efﬁcient appliances and equipment to reduce electricity use and minimize internal heat gains;
• provide locally generated renewable electric power systems that use LZC technologies;
• provide on-site energy storage to improve the usefulness of energy generated by LZC technologies; and
• provide metering and monitoring systems to promote the efﬁcient use of energy.

In addition to setting out requirements for the commissioning and handover of all of the above, this PAS also speciﬁes requirements for advising building occupants about improvement options appropriate to their homes, and the efﬁcient and appropriate use and maintenance of their retroﬁtted homes as well as for monitoring and evaluating retroﬁt projects when appropriate, and feeding back lessons learned to all parts of the supply chain, including the building occupants.

Many aspects of domestic retroﬁt are covered by existing standards. Where appropriate, those standards are referred to in this PAS, and compliance with the standards referred to is thereby a requirement of this PAS.

This PAS and the retroﬁt standards framework may be applied to all domestic retroﬁt activity and embrace work that is initiated, procured, funded and delivered in a wide variety of ways including:

• programmes of retroﬁt promoted and/or funded by national or local government schemes;
• programmes of retroﬁt initiated and/or funded by landlords, including social housing organizations, private landlords in the domestic sector and commercial property portfolio holders;
• retroﬁt of individual buildings by their owners and/or occupants, including both domestic and commercial owner-occupiers;
• retroﬁt that is integrated with and forms part of broader repairs, maintenance and improvement (RMI) activity related to individual buildings or building stocks.

This PAS and the retroﬁt standards framework may also be applied not only to retroﬁt work carried out by commercial building contractors and specialist installers of retroﬁt measures but also to work carried out by local SME builders and independent trades people working alone or in small teams.

This PAS does not apply to maintenance or repair of any element of an existing dwelling, or system installed in it, which does not involve improvement of the energy performance or ventilation of the dwelling, or a reduction of the carbon dioxide emissions associated with energy use in the dwelling. Nor does this PAS apply to “like-for-like” replacement of damaged or worn out elements or systems that do not involve improvement of the energy performance or ventilation of the dwelling, or a reduction of the carbon dioxide emissions associated with energy use in the dwelling.

NOTE Appropriate repair and maintenance of the building fabric can improve energy efﬁciency and should always be the ﬁrst step in energy efﬁciency improvements, even though it is not covered in this PAS. Otherwise an unacceptable level of risk to the future condition of the building might be introduced.

PAS 2035:2019+C2:2021

Retrofitting dwellings for improved energy efficiency. Specification and guidance

Published:

1 Jun 2019

Withdrawn:

28 Jan 2022