Building regulations - energy standards and associated topics - proposed changes: consultation

Part 3 – Energy, all buildings

3.1 Introduction

This section of the consultation introduces proposed changes to provisions which apply to new buildings and to new work to existing buildings. These are the provisions sought when demonstrating compliance with Standards 6.2 to 6.8 and 6.10 within section 6 (Energy).

This includes proposals for improved minimum standards for building fabric and a simplification of how these are applied across new and existing buildings.

Revisions to minimum standards for installed building services are identified, noting that, as with the 2015 review, these are aligned with changes proposed elsewhere in the UK to support consistency of application and in recognition of a UK-wide.

The review of standards for energy efficiency in the context of our wider agenda to improve compliance with building regulations is also set out, seeking to increase assurance of process from the design, specification and commissioning of buildings and reduce the potential effect these processes can have on as-built performance compared to design intent.

Note that provisions for energy performance certificates under standard 6.9 are not amended as part of this consultation. Guidance in support of EPC provision for new buildings under building regulations will be updated as part of publication of the revised Technical Handbooks in late 2021 to reflect the exit of the UK from the European Union and note any further review activity arising from implementation of our draft Heat in Buildings Strategy.

3.2 Proposals

3.2.1 Introduction of the term ‘Major Renovation’

At present, Building Regulations apply where building work is undertaken and relate to the extents of that work. This relates to both physical work to create a building or alter an existing building and to conversion of a building (specific changes in the occupation or use of a building that cause the regulations to apply).

We are proposing to introduce the term ‘major renovation’ into the regulations to provide a further means of defining a level of work to an existing building that is considered significant enough to trigger certain other activity. Be that a requirement for assessment or to seek specific additional works, which may not be part of action already intended by the building owner.

The premise of such a trigger is that the undertaking of significant construction work provide the opportunity to make other beneficial changes to the building at a lower cost than would be encountered if such works were done separately. Making such improvements more economically viable.

A similar principle is already applied for non-domestic buildings where specific ‘consequential improvements’ are sought in guidance to standards 6.3 to 6.6. where work to an existing building includes the provision of new fixed building services or alters or extends the capacity of existing fixed building services. The opportunity should be taken to review and improve the performance of fixed building systems. The approach taken is set out in Annex 6.D to the current standards.

At present, ‘major renovation’ is already defined within the legislation of other UK administrations, adopting one of the two definitions provided in the recast EU Energy Performance of Buildings Directive, 2010/31/EU as amended by 2018/844.

‘major renovation’ means the renovation of a building where:

(a) the total cost of the renovation relating to the building envelope or the technical building systems is higher than 25 % of the value of the building, excluding the value of the land upon which the building is situated; or

(b) more than 25 % of the surface of the building envelope undergoes renovation;

We propose that the term ‘major renovation’ become a defined term within Building Regulations, adopting the same definition as elsewhere in the UK to support simplicity of understanding and consistency in application. As follows:

‘major renovation’ means the renovation of a building where more than 25 % of the surface of the building envelope undergoes renovation.

Initially, we propose to introduce this to support action, as detailed within Section 7 of this consultation, on the provision of electric vehicle charging infrastructure or facilities (see section 7.5.3). Any broader application of the term as a trigger for works would be the subject of separate consultation.

Question 20 –

Do you agree with the proposed introduction of the term ‘major renovation’ as defined above as an additional means of identifying when aspects of building regulations shall be applied to an existing building?

Yes

No

Please provide a summary of the reason for your view.

3.2.2 Revision of minimum performance for building fabric – Domestic

Section 2.2.13 discusses proposals to retain the current elemental approach to setting limits on the performance of building fabric for new homes. It sets out proposed maximum area-weighted U-values for elements of fabric for the two levels of overall energy improvement proposed.

As reviews of standards continue to increase the level of fabric specification sought from work to existing buildings, it becomes more challenging to set or justify more than one set of such elemental standards. The intent is therefore to set a simple and robust set of elemental standards for all work to buildings – extensions, alterations and conversions.

We propose to apply the same recommended maximum area-weighted U-values to all work to existing dwellings, as set out in the table below.

Table 6: Proposed maximum area-weighted average U-values - new work to domestic buildings

Element	Current (2015)	Option 1 - Improved	Option 2- Advanced
Wall	0.22	0.17	0.16
Roof	0.15	0.12	0.11
Floor	0.18	0.15	0.13
Doors, windows and roof windows	1.6	1.4	1.2
Rooflights 1	1.6	1.9	1.7
Party Wall	0.2	0.0	0.0
Junctions	n/a	n/a	n/a
Infiltration	n/a	n/a	n/a

¹ U-value for rooflights is calculated on the horizontal plane

This is set out in clause 6.2.1 and 6.2.6-8 of ‘Consultation proposals - Section 6 (Energy) Domestic’.

As noted in Section 2.2.13, these values are currently being achieved in more than 50% of new construction (for ‘improved’) and 33% of new construction (for ‘advanced’). The values proposed for Option 1 are similar to those applied, since 2015, for extensions to poorer performing dwellings.

Question 21 –

Do you support the improvement in maximum U-values for elements of building fabric for Domestic buildings, as set out above?

Yes

No

Please provide a summary of the reason for your view.

We would also welcome your views on the proposed simplification achieved by setting of a single set of values for all building work to new and existing buildings.

3.2.3 Revision of minimum performance for building fabric – Non-domestic

For many non-domestic buildings, it is noted that energy demand for space heating forms a smaller part of overall energy demand than in dwellings. And that the level and disposition of that demand across energy uses will vary across building type.

As reviews of standards continue to increase the level of fabric specification sought from work to existing buildings, it becomes more challenging to set or justify more than one set of such elemental standards. The intent is therefore to set a simple and robust set of elemental standards for all work to buildings – extensions, alterations and conversions.

Accordingly, we propose a review and improvement to maximum fabric values for work to non-domestic buildings as set out below:

Table 7: Proposed maximum area-weighted average U-values - new work to non-domestic buildings

Element	Current (2015)	Option 1 (Medium)	Option 2 (High)
Walls	0.25	0.23	0.18
Floors	0.20	0.18	0.13
Roofs	0.15	0.18	0.15
Windows / roof windows	1.6	1.6	1.2
Rooflights 1	1.6	2.1	1.9
Junctions	n/a	TBC	TBC

¹ U-value for rooflights is calculated on the horizontal plane

This information is set out in clause 6.2.1 & 6.2.7-9 of ‘Consultation proposals - Section 6 (Energy) Non-domestic’.

Whilst there is less useful data to inform the definition of backstop values for non-domestic building fabric, it is noted that the values presented above can be achieved using common construction practice currently in use. The ‘Medium’ option values represent a small improvement on current values cited for extensions, noting that the backstop for roofs for the ‘medium’ option is relaxed slightly to reflect the revised notional building specification for this option. The wall value is the same as currently specified as a backstop for shell buildings where there is an expectation that fabric elements will be emphasised, to simplify subsequent fit-out.

Shell buildings

Note also that we no longer propose to set more challenging maximum U-values for shell buildings in guidance to standard 6.2. Revision of guidance on ‘shell and fit-out’ buildings under standard 6.1 (clause 6.1.8) will instead reinforce the need to for a considered specification at shell stage to optimise opportunities for compliance at fit out stage.

Question 22 –

Do you support the improvement in maximum U-values for elements of building fabric for Domestic buildings, as set out above?

Yes

No

Please provide a summary of the reason for your view.

We would also welcome your views on the proposed simplification achieved by setting of a single set of values for all building work to new and existing buildings.

3.2.4 Conversions and extensions

Conversions

There are specific changes in the use or occupation of a building which constitutes a conversion as defined in schedule 2 to regulation 4 of the Building (Scotland Regulations 2004. A conversion also occurs where a previously unoccupied part of a dwelling becomes habitable, such as extending into the attic space. Where work is defined as a conversion, current standards are applied to it, either in full, or to the extent reasonably practicable. The latter applies to standard 6.2 (building fabric).

It should be noted that the standard and guidance for conversions also apply where a defined conversion does not occur but heating is introduced to a building that was previously un-heated.

Standard 6.1 does not apply to conversions and the primary means of reducing heat demand in conversion remains the performance of the building fabric, supplemented by effective services and controls installed therein to meet that demand most effectively.

We propose that work to introduce heating to a building or part of a building and conversions are subject to the same limiting U-values for building fabric as noted in Table 6 and 7 in Section 3.2.2 and 3.2.3, subject to the application of an assessment of what is ‘reasonably practicable’.

For situations where standards can be met as far as is ‘reasonably practicable’, be this for a conversion or where avoidance of technical risk from improvement is an issue, we will seek to reinforce the need for robust assessment to determine the optimal level of specification for a given situation. A more evidence-led assessment to optimise improvement also aligns with the intent set out within our draft Heat in Buildings Strategy and the Building Standards Compliance Plan approach (see section 3.2.11) being developed for implementation.

Extensions

Standard 6.1 applies only to larger extensions to non-domestic buildings. Outwith this case, the primary driver for reducing energy demand and emissions in extensions is the performance recommended for new building fabric and, where applicable, installed building services.

The guidance on extensions under standard 6.2 indicates elemental area weighted average U-values that the extension should be built to. The weighted average U-value approach allows areas of the same building element to have a poorer average performance that the other parts of the element, however, this will require to be compensated for by improved average performance for the other parts of the element. As part of this, the maximum area of openings is defined to assist in limiting heat loss, though this can be varied if compensated for by improvement to the performance of elements.

We propose that work to extend a building shall be subject to the same limiting U-values for building fabric as noted in Table 6 and 7 in Section 3.2.2 and 3.2.3

For domestic extensions, this will remove the current approach where more challenging U-values are applied to extensions of poorer performing buildings. Again noting that, as reviews of standards continue to increase the level of fabric specification sought from work to existing buildings, it becomes more challenging to set or justify more than one set of such elemental standards.

Shell buildings

As noted in section 3.2.3, we will no longer set different maximum U-values for shell buildings.

All of the above proposals are set out in guidance to Standard 6.2 within ‘Consultation proposals - Section 6 (Energy) Domestic’ and ‘Consultation proposals - Section 6 (Energy) Non-domestic.

Question 23 –

Do you support the standardisation of values and approach for conversions, extensions and shell buildings, as set out above and in sections 3.2.2 and 3.2.3?

Yes

No

Please provide a summary of the reason for your view.

3.2.5 Presentation of information on building services

Consultation proposals are presented as highlighted changes within the current document format introduced for the 2015 review of energy standards. This is the Domestic and Non-domestic building Services Compliance Guides, two volumes which are separate but have the same status as the main Technical Handbooks.

We are aware that, as part of rationalising and improving the presentation of information, to support both designers and verifiers, proposals have been made in other UK administrations to re-integrate information back into the appropriate section of the relevant technical document, together with removal of any information that is not directly relevant to the delivered specification sought (e.g. optional good practice advice).

We would welcome your views on the future format of guidance on building services. We have identified three options:

• Retain the current format and separate documents for building services (as presented in the consultation)
• Retain the current format but include the guides as a single section within Section 6 of each Technical Handbook
• Re-integrate the current guidance into guidance under each relevant functions standard (e.g. 6.3 to 6.8)

Question 24 –

If you have a view on the preferred format for presentation of information on compliance of building services, what would be your preference?

• Retain current separate Compliance Guides
• Move Compliance Guides into Section 6 as an Annex
• Re-integrate into guidance to the relevant standard
• Other (please specify in summary box below)

Please provide a summary of the reason for your view.

3.2.6 Changes to minimum standards for building services – Domestic

As is the case with the 2015 and previous guidance on minimum standard for fixed building services, provisions set for Scotland are proposed to reflect those set elsewhere in the UK.

This recognises that products are developed and made available at a UK level and the solutions deliverable by combining individual components should reflect a consistent standard for those components across the UK administrations, supporting consistency of understanding and implementation of solutions where practicable.

The compliance guides, which applies to both new and existing buildings, provides guidance on the following aspects of building services addressed under standards 6.3 to 6.8:

• System efficiencies
• Controls
• Limiting heat loss
• Commissioning

To a large extent much of the proposed guidance on services developed for review elsewhere in the UK remains unchanged for the aspects relating to controls, commissioning and written information. However, the following changes are flagged, in summary, for the awareness of consultees. Further information, with all changes in highlighted text, is provided within ‘Consultation proposals - Domestic Building Services Compliance Guide’.

Table 8: Summary of key changes to minimum standards for fixed building services:

System/element	2015 Guidance	Proposed Guidance
Gas Central Heating Boiler	88% SEDBUK 2009	92% ErP1
Oil Central Heating Boiler (Regular)	88% SEDBUK 2009	91% ErP1
MVHR (heat recovery efficiency)	70%	73%
Warm water and hot water heat pumps	Air-to-air <12kw, SCoP of D or better Space heating (new dwellings), SCoP of 2.5 or better Space heating (existing dwellings), SCoP of 2.2 or better Domestic hot water, SCoP of 2.0 or better	No change Space heating (new dwellings), SCoP of 3.0 or better Space heating (existing dwellings), SCoP of 3.0 or better No change
Air / water cooled air conditioners	SEER 2.4/2.5	SEER 4.0
Internal Lighting	Luminous efficacy greater than 45 lamp lumens /circuit watt for 3 out of 4 fittings	All fittings to have efficacy more than 75 lamp lumens/circuit watt
External lighting	Either: Lamp capacity < 100 lamp watts per fitting, and auto control to switch off where area unoccupied and all lamps switch of in daylight Or: Lamp efficacy >45 lumens/circuit watt, and All lamps switch off in daylight	Where lamp efficacy <75 lumens/circuit watt, auto control to switch off where area unoccupied Auto controls to switch off in daylight

¹ The Eco-design Regulation 2009/125/EC introduced a new standardised calculation method to determine the seasonal efficiency of heating appliances. In 2015 this metric was adopted in the UK replacing the UK-specific SEDBUK rating other than within SAP calculations.

The following additional changes are noted:

• Replacement of fixed building services – in addition to meeting the recommended performance and specification provisions set out for a particular system, proposal that replacement of a heat generator that involves a change in fuels should not result in an increase in building emissions or an increase in overall energy demand at the building - see section 1.8 of the Guide.
• Self-regulating devices – see Section 3.2.10 of this document.
• Insulation of pipes and ducts – simplified guidance on insulation requirements, citing example and referring to BS 5422 for other cases - see section 2 (Table 5) of the Guide.
• Heat losses from storage vessels – proposed guidance to be updated with a table that confirms the maximum daily heat loss for hot water cylinders - see section 2 (Table 2) of the Guide.
• Continuous supply input and extract ventilation – proposal that ventilation systems that provide supply and extract ventilation should be fitted with a heat recovery system, summer bypass and variable speed control - see section 8 of the Guide.
• Improving system efficiency on replacement of heat source – proposal to call for additional energy efficiency measures to be introduced when a gas combination boiler is replaced - see section 2 (Table 4) of the Guide.
• Commissioning of installed systems – proposal to call for the extent of services that will be commissioned to be confirmed at design stage with confirmation of commissioning provided on completion of the building - see Section 1 (2.0) of the guide and section 6.1.5 and 6.1.6 of this document.
• System sizing – proposal for guidance to call for space heating, domestic hot water and cooling systems to be sized appropriately. In addition space heating systems to be sized to allow it to operate effectively at a low distribution temperature (55 °C or lower).
• New section on Building Automation and Control Systems (BACS) – new guidance introduced for BACS where installed in new or existing dwellings - see Section 13 of the guide.
• New section on On-site electricity generation – new guidance introduced for on-site electricity generating systems.

Question 25 –

Do you support the continued alignment of minimum provisions for fixed building services at a UK level within the Domestic Building Services Compliance Guide?

Yes

No

Please provide a summary of the reason for your view.

Are there any issues you wish to raise in relation to the amended or retained specifications set out within the draft Guide?

3.2.7 Changes to minimum standards for building services – Non-domestic

As is the case with Domestic buildings, the majority of the guidance supporting building standards 6.3 through to 6.8 is contained within the current Non-domestic Building Services Compliance Guide (NDBSCG). For the amendments to the energy standards in 2010 and 2015 the guidance provided aligned with the approach to services adopted throughout the rest of the UK. We intend to replicate this approach for the new standards.

The compliance guides, which applies to both new and existing buildings, provides guidance on the following aspects of building services:

• System efficiencies
• Controls
• Limiting heat loss
• Commissioning (though mostly addressed within standard 6.7)

To a large extent much of the proposed guidance on services remains unchanged for the aspects relating to controls, commissioning and written information. However, the following changes are flagged, in summary, for the awareness of consultees. Further information, with all changes in highlighted text, is provided within ‘Consultation proposals - Non-domestic Building Services Compliance Guide’.

• General – expanded text on heating system design and sizing; reference to low temperature distribution systems (<55 ºC).
• Heating efficiency (Section 1.7) - summary of recommended minimum energy efficiency standards - boiler seasonal efficiency values improved for most fuel types.
• Removal of the facility to define ‘effective heat generator seasonal efficiency’ via ‘heating efficiency credits’. See Section 3.2.8 of this document.
• Replacement of fixed building services – in addition to meeting the recommended performance and specification provisions set out for a particular system, proposal that replacement of a heat generator should also not result in an increase in building emissions or an increase in overall energy demand at the building.
• Self-regulating devices – see Section 3.2.10 of this document.
• Domestic hot water systems in new and existing buildings (Section 8.4) – heat source seasonal efficiency values defined/improved for most fuel types (typically 91%).
• Comfort cooling in new and existing buildings (Section 9.4) – improved SEER values cited, additional system classes added (water-to-water). Further advice on VRF systems.
• Air distribution systems in new and existing buildings (Section 10.4) – improved SFP for a number of system options; additional advice on controls; expanded advice on air leakage to include summary advice on leakage limits from DW/143(144) and clarity on test procedures.
• Proposal that ventilation systems that provide supply and extract ventilation should be fitted with a heat recovery system, where technically feasible.
• Insulation of pipes and ducts in new and existing buildings (Section 11.3) – simplified guidance on insulation requirements, citing example and referring to BS 5422 for other cases.
• Lighting in new and existing buildings (Section 12.4) – advice on lighting design and avoidance of over-illumination; revised average luminaire efficacy (95 LL/cW proposed).
• New section on Building Automation and Control Systems (BACS) – see Section 3.2.11 of this document.

Question 26 –

Do you support the continued alignment of minimum provisions for fixed building services at a UK level within the Non-domestic Building Services Compliance Guide?

Yes

No

Please provide a summary of the reason for your view.

Are there any issues you wish to raise in relation to the amended specifications set out within the draft Guide?

3.2.8 Removal of heating efficiency credits – Non-domestic

The current Non-Domestic Building Services Compliance Guide 2015 includes an option where heat generators installed in existing buildings may have a reduced seasonal efficiency provided this is compensated for through the addition of other energy efficiency measures such as additional heating controls or other system enhancements. These allowances are known as ‘heating efficiency credits’ and are referenced in sections 2.7, 3.5, 4.5, 5.5 & 8.6 of the document.

We are proposing to no longer provide this alternative approach and instead focus on the minimum efficiency of the heat generator. We consider that the level at which standards are set for heat generators can be met in full due to improvements in the energy efficiency of appliances over recent years and that such a ‘trade off’ is no longer justified. Particularly as many of the options which are cited as relevant to achieving a ‘credit’ are either also expected or recognised good practice.

We propose that there will be no published mechanism to assign heating efficiency credits for installations to existing buildings from 2022. Accordingly, references to this process are removed from the relevant sections of ‘Consultation proposals - Non-domestic Building Services Compliance Guide’.

Question 27 –

Do you agree with the proposal that the option of installing a less efficient heat generator and compensating for this using heating efficiency credits in existing buildings should be withdrawn from the Non-domestic Building Services Compliance Guide?

Yes

No

Please provide a summary of the reason for your view.

3.2.9 Limiting distribution temperature for wet heating systems

It is already recognised that lower temperature heating systems offer the benefit of improved efficiency in the operation of the heat generator, be this a combustion appliance or a heat pump. Lower temperature distribution of heat within a building also supports the delivery of heat from lower temperature external networks.

We consider that limiting distribution temperatures in wet central heating systems to be an essential element in optimising the efficiency of future low and zero carbon heat solutions, as proposed within the recent strategic consultation on a 2024 Heat Standard.

We propose that, where a wet heating system is being installed in a new building or replaced in an existing building (including both heat generator and emitters) the system should be designed and emitters sized to allow the space heating system to operate effectively and meets the heating needs of the dwelling with a mean water temperature of not more than 55 °C. Proposals are set out in relation to wet heating systems within:

• ‘Consultation proposals - Domestic Building Services Compliance Guide’ and
• ‘Consultation proposals - Non-domestic Building Services Compliance Guide’.

Question 28 –

Do you agree with the proposal to limit distribution temperatures in wet central heating systems to support effective implementation of low and zero carbon heat solutions and optimise the efficiency of heat generation and use?

Yes

No

Please provide a summary of the reason for your view.

3.2.10 Self-regulating devices

A self-regulating device is a device or system that automatically controls the output of heating (or cooling) emitters to independently control the temperature in each room or zone. Such control is usually achieved by a thermostat fitted to the emitter (e.g. thermostatic radiator valve) or within the room or zone (e.g. electronic wall thermostat linked back to the device controlling the heat generator).

The 2018 amendment of the EU Energy Performance of Building Directive sought, under Article 8(1), the presence of such devices to all emitters, where technically and economically feasible, where a heat generator (e.g. boiler or heat pump) is replaced.

At present, the provision of such control devices is sought for all emitters or rooms/zones in new buildings and where a new heating system (including emitters) or new emitters are installed in an existing building. However, there is no requirement to install self-regulating devices where only the heat generator is replaced. Though it is noted this frequently occurs as a good practice measure.

We propose to extend the provision of self-regulating devices to include installation (where absent) at the point a heat generator is replaced. Detailed proposals, including notes on feasibility and control at a room/zone level are set out in:

• Tables outlining the recommended minimum standards for control of heating systems within ‘Consultation proposals - Domestic Building Services Compliance Guide’ and
• Tables outlining recommended minimum controls package for heating systems in ‘Consultation proposals - Non-domestic Building Services Compliance Guide’.

We consider that the addition of such devices on replacement of a heat generator is an appropriate intervention point, enabling a cost-effective means of further improve the performance and controllability of a heating system.

Question 29 –

Do you agree with the proposed extension to the provision of self-regulating devices to include when replacing a heat generator?

Yes

No

Please provide a summary of the reason for your view.

Do you have any comment on issues of technical feasibility or determining when installation should be at a room/zone level?

3.2.11 Building Automation and Control Systems – Non-domestic

A Building Automation and Control System (BACS) is a centralised system used to monitor and control a building’s environment and services (i.e. heating, ventilation, air conditioning, lighting and other systems). There is currently no requirement for installing BACS in new buildings.

The 2018 amendment of the EU Energy Performance of Building Directive sought, under Articles 14(4) and 15(4) the introduction of such systems in all existing buildings by 2025. The Directive recognised that automated monitoring and control systems offered an effective alternative to inspection of building systems and can be very effective in assisting building operators reduce energy use and costs. Analysis undertaken by the UK Government in response to the Directive also suggests that BACS are a cost-effective way of saving energy in buildings.

We propose that new non-domestic buildings that have a heating system or systems for combined space heating and ventilation (with or without air-conditioning) with an effective rated output over 290 kW, should be equipped with a BACS.

The details of the specification of these systems are set out in section 14 of ‘Consultation proposals - Non-domestic Building Services Compliance Guide’. This proposes the specification of BACS as a ‘Class A’ system to EN 15232 which provides a high level of control, with the cited UK analysis suggesting it is cost-effective.

Question 30 –

Do you agree with the proposed introduction of a requirement for building automation control systems, of the type specified, in larger non-domestic buildings with systems with an effective rated output over 290kW

Yes

No

Please provide a summary of the reason for your view.

3.2.12 General comments

Question 31 –

We welcome any other comments you wish to make on the above topics and broader changes to the setting of minimum standards for all buildings.

Where practical, please with a reference to any particular issue in the context of the Domestic or Non-domestic Handbook (or both if applicable) and cite any standard or revised guidance clause relevant to the topic.