1 Scope
This PAS specifies requirements for retrofit of dwellings, including:
| a) | assessment of dwellings for retrofit; |
| b) | identification and evaluation of improvement options (energy efficiency measures, or EEMs); |
| c) | design and specification of EEMs (whether individual measures or packages of multiple measures); and |
| d) | monitoring and evaluation of retrofit projects. |
This PAS covers EEMs that are intended to:
| 1) | improve the insulation of the elements of the building fabric (external walls, roofs, floors, windows and doors) and reduce thermal bridging; |
| 2) | improve the airtightness of the building envelope; |
| 3) | establish a safe dynamic moisture equilibrium through each element of the building fabric; |
| 4) | improve the resilience of the building envelope 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; |
| 5) | reduce heat loss from ventilation with the use of high efficiency heat exchangers in a fully ducted ventilation system; |
| 6) | minimize the risks associated with vapour or other products, for example volatile organic compounds (VOCs), released within buildings subsequent to their airtightness being improved; |
| 7) | minimize the risks associated with overheating; |
| 8) | provide efficient heating and cooling systems with responsive, intelligent or “smart” controls, including systems that use low or zero carbon (LZC) technologies; |
| 9) | provide efficient water heating systems with responsive controls, including systems that use LZC technologies; |
| 10) | provide efficient fixed lighting, appliances and equipment with appropriate controls; |
| 11) | reduce electricity use and minimize internal heat gains, including systems that use LZC technologies; |
| 12) | provide on-site energy storage to improve the usefulness of energy generated by LZC technologies; and |
| 13) | reduce the impact of climate change on the building and the occupant. |
Alongside the installation of EEMs to achieve some of the intended outcomes above, this PAS also covers the installation of:
| • | ventilation to achieve good internal air quality and minimize the risk of condensation; |
| • | metering and monitoring systems to promote the efficient use of energy; and |
| • | climate change adaptations needed to improve the resilience of the building to existing and/or future risk from climate change. |
In addition to setting out requirements for the commissioning and handover of all of the above, this PAS 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.
While the PAS 2035 process includes maintenance and repair, works that consist exclusively of maintenance and repair do not necessarily need to follow the full PAS 2035 process. 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. This PAS does, however, apply to the distressed replacement of heating appliances, for which a specific process is outlined throughout.
NOTE Appropriate repair and maintenance of the building fabric can improve energy efficiency and is always 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.