BSI PAS 2038:2021

This PAS specifies requirements for retrofitting non-domestic buildings for improved energy efficiency. It covers all buildings except those used as private dwellings (i.e. houses, bungalows, flats or apartments). However, non-domestic buildings do include multi-residential buildings in which occupants share some communal facilities, e.g. hotels, guest houses, hostels and students’ and nurses’ accommodation.

The requirements specified in this PAS cover the:

1. safe management of the retrofit process, from inception to completion;

2. assessment of buildings for retrofit of energy efficiency and related measures;

3. identification and evaluation of improvement options (energy efficiency measures);

4. preparation of improvement plans;

5. design and specification of energy efficiency measures (whether individual measures or packages of multiple measures);

6. installation of measures;

7. testing, commissioning and handover of installed measures;

8. fine-tuning of the performance of retrofitted buildings; and

9. evaluation of retrofit projects.

This includes measures or packages of measures that are intended to:

1. improve the insulation of the building fabric (exposed floors, walls, roofs, windows and external doors), reduce thermal bridging and eliminate thermal by-pass;

2. improve the air tightness of the building envelope;

3. establish a safe and dynamic moisture equilibrium through each element of the building fabric;

4. 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;

5. minimize overheating;

6. replace building services systems that use fossil fuels with low or zero carbon (LZC) systems;

7. provide efficient heating and cooling systems with effective controls, including systems that use LZC technologies;

8. provide efficient ventilation systems with effective controls in order to maintain good internal air quality and to minimize the risk of condensation and mould growth;

9. minimize the risks associated with chemicals, e.g. volatile organic compounds (VOCs), released within buildings, which might be increased subsequent to air tightness being improved;

10. provide efficient water heating systems with effective controls, including systems that use LZC technologies;

11. provide efficient fixed lighting with effective controls as part of an efficient lighting strategy related to the use of the building and the activities accommodated;

12. provide efficient equipment to reduce electricity use and minimize internal heat gains;

13. provide locally generated renewable heat using LZC technologies;

14. provide locally generated renewable electric power using LZC technologies;

15. provide demand management (e.g. on-site energy storage) especially where on site generation by LZC technologies is also provided; and

16. provide metering and monitoring systems (e.g. smart meters) to promote the efficient use and management of energy throughout the building.

NOTE 1 Effective controls are sometimes referred to as “responsive”, “intelligent” or “smart” controls, although none of these terms is well defined; effective controls are useable and demand-responsive.

This PAS applies to the retrofit of buildings, including retrofit that is undertaken at the same time as a change of use of a building, in which the types of activity accommodated are changed. This PAS also covers Type 4 (see 0.3) retrofit projects, in which non-domestic buildings such as shops or offices are refurbished or refitted internally and the work includes any of the measures listed above.

This PAS can be applied to all non-domestic retrofit activity and embraces work that is initiated, procured, funded and delivered in a wide variety of ways, including:

1. programmes of retrofit promoted and/or funded by national or local government schemes;

2. programmes of retrofit initiated and/or funded by landlords and commercial property portfolio holders;

3. retrofit of individual buildings by their owners and/or occupants; and

4. 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 can 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 small and medium-sized enterprise (SME) builders and independent tradesmen working alone or in small teams.

This PAS is intended to support both the installation of all improvement measures at the same time or a staged approach in which improvements are implemented in stages. In either case, the recommended strategy is to reduce energy demand, improve energy efficiency and decarbonize the building services.

NOTE 2 Attention is drawn to the need to reduce the greenhouse gas emissions associated with the process of retrofitting buildings, as well as those associated with the operation of the building after retrofit. Retrofit process emissions can be taken into account when designs for retrofit projects are developed, and especially when materials, products and systems are specified. “Whole life” assessment of emissions is recommended.

This PAS is intended for use by anyone engaged in the improvement of the energy efficiency, energy performance or sustainability of non-domestic buildings, including owners and managers, tenants’ property managers, building professionals (including energy assessors and designers) contractors, builders and installers of energy efficiency measures.

This PAS does not cover or apply to:

• unheated horticultural glasshouses;

• routine maintenance or repair of any element of a building or system installed in it which does not involve improvement of the energy performance or ventilation of the building, or a reduction of the greenhouse gas emissions associated with energy use in the building; and

• “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 building, or a reduction of the greenhouse gas emissions associated with energy use in the building.

NOTE 3 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 by this PAS. However, some routine maintenance or repair work might improve energy efficiency, and thus fall within the scope of this PAS.

NOTE 4 When replacement of damaged or worn out elements of a building becomes necessary, there is an opportunity to replace them with more energy efficient elements; this would bring the replacement within the scope of this PAS. See also BEIS’ Energy Technology List (ETL) for more information, available at /2.

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