Building regulations - proposed changes to energy standards, etc: consultation analysis

3 Part 2 – Energy, new buildings

This section of the consultation covers the process of demonstrating compliance of a new building with standard 6.1 of Building Regulations via the application of the SAP or SBEM calculation methodology. It addresses the process of setting and meeting performance targets under that standard. Analysis of responses to proposed revisions applicable to both new buildings and work to existing buildings is provided within Section 4 of this report.

3.1 Introduction of an energy target for new buildings

3.1.1 Question 1

Do you support the extension of standard 6.1 to introduce an energy target in addition to the current emissions target?

In total, 114 responses were received to this question and 105 responses to the accompanying open question where respondents were asked to provide more detail to support their answer. Nine respondents provided an open response but did not answer the multiple-choice question.

Base: 114 respondents (62 no response) NB Individual respondents are listed separately at the bottom for information - as they are included in organisation responses (per Section 2.3)

3.1.2 Analysis

Overall, there is support for the introduction of an energy target in addition to the current emissions target, with 91% of respondents being in favour (Figure 3). There is substantially more support for a primary energy target (54% of all respondents), than a delivered energy target (37%).

3.1.3 A primary energy target

A recurrent theme in the consultation responses highlights the importance of adopting a fabric first approach. Several respondents suggest that a primary target might lead to more focus on fabric first and therefore reduce energy demand. Linked to this point, a few respondents specifically suggested that the overall energy needs of a building should firstly be addressed to reduce energy/heat demand.

Several respondents suggest that primary energy should be the principal metric, with CO₂ as the secondary, or prominent performance metric. The importance of CO₂ was raised by these respondents as a means to combat a risk that high carbon solutions will be installed, and that properties achieving high primary energy performance could also have high carbon emissions.

Amongst respondents in favour of a primary energy target, several expressed concerns that basing the target on SAP could present issues, for example in terms of having the right SAP software to calculate and cost accurately. A campaign response from house builders suggested that in the absence of adequate software, some members of an industry body are undertaking independent analysis with the risk of inaccuracy and assumptions made on potential impacts.

Conversely, a few respondents felt that a primary energy metric will show heat demand of a dwelling and allow for better comparison between SAP and other energy assessment schemes as well as allowing for more accurate analysis of energy demand before renewables are taken into account.

Another theme in a few responses is a perceived danger of focusing on renewables to offset or mask inefficient buildings and emissions.

Insulation was specifically mentioned by a few respondents as being a major consideration in improving building efficiency.

Other positive features of a primary energy target were identified (by at least three respondents in each case):

• The proposal corresponds with provisions in the EU Directive ‘Energy Performance of Buildings Directive’, in part because the primary energy sources use electricity, ‘which is already decarbonised’
• A primary target is more accurate in terms of overall environmental impacts because it takes account of energy loss in delivery
• The introduction of a primary target could be used to support Committee on Climate Change recommendations that new dwellings should be consistent with a space heat demand of 15-20 kWh/m²/yr

3.1.4 A delivered energy target

The responses in favour of a delivered energy target were very mixed and tended to focus on the benefits of a delivered target over a primary target.

A set of campaign responses from house builders drew attention primarily to concerns over SAP software, which they suggest makes it challenging to understand the impact of the proposals, as current analysis carries the risk of inaccuracy and assumptions made on potential impacts. These responses highlight a perceived risk that a standardised primary energy target may not fully consider individual home types.

The second most common theme amongst those who support a delivered energy target, is that such a target would provide a more accurate indication of what a dwelling requires, that is not offset by renewable sources onsite.

The third most common theme is that a delivered energy target is more straightforward because it is based on the metered energy that the building receives but, in contrast, there are many different ways of measuring primary energy.

These are the three main themes to emerge from the analysis; many other reasons were put forward as to why a delivered energy target is more appropriate than a primary target. Each of these were put forward by one respondent, so it is not possible to discern trends.

3.1.5 No support for an energy target

There are no major themes amongst the nine responses. However, two respondents each highlighted the following points:

• More definitive information is needed to make a decision on a preferred option.
• The importance of reducing carbon emissions must be considered - 1) the introduction of an energy target should not take priority over carbon emissions, and 2) carbon emissions are arguably more important to address.
• The current proposals utilising primary energy targets allow for non-renewable installations to fare better against known renewable "nearly zero" technologies, meaning renewables would not be achievable if both the CO₂ and primary energy factors are required to be lower than the existing system.

Three other points were raised:

• If primary energy targets are used, these should be updated frequently without the need for a full update of the building standards.
• The proposals risk permitting switches from an older lower carbon system (such as LPG) to a more efficient, higher carbon system, such as oil rather than replacement with a new, more efficient boiler using the lower carbon fuel.
• Embodied carbon needs to be considered.

3.2 Options for uplift in standard for new dwellings

3.2.1 Quesiton 2

What level of uplift to the 2015 standard for new dwellings do you consider should be introduced as an outcome of this review?

In total, 118 responses were received to this question and 117 responses to the accompanying open question where respondents were asked to provide more detail to support their answer.

Base: 118 respondents (58 no response) NB Individual respondents are listed separately at the bottom for information - as they are included in organisation responses (per Section 2.3)

3.2.2 Analysis

Overall, respondents support the two options presented, with 80% of respondents selecting either Option 1 or Option 2 (Figure 4). There is slightly more support for Option 2 (42%) than for Option 1 (38%).

3.2.3 Option 1: 'Improved' standard (32% emissions reduction)

The main theme in the responses in support of this option is that it is ‘adequate’ and more achievable than Option 2, although it is deemed to be a very challenging proposal. The majority of summary responses to this question then went on to explain where, in their view, Option 2 is inappropriate:

• It would lead to significant increases in design and build costs.
• It would have an adverse effect on the construction industry which is still recovering from the pandemic.
• It would be impossible to achieve as full electrification of heating and hot water will be required and should only be considered from 2024 at the earliest.
• Concerns were expressed about grid capacity: under the requirements of Option 2, boilers will no longer be a viable heating solution, meaning a move to electrical air source heat pumps and other currently unproved technologies, and placing increased pressure on the grid.
• ‘Smaller steps’ are required towards the Option 2 target.
• It would require the use of systems that are currently not in use in Scotland in any volume and that the manufacturing process is complex, requiring significant investment and machinery.
• The level of insulation required to meet Option 2 may present challenges.

Although those who selected Option 1 felt it was more achievable than Option 2, a number of challenges and considerations regarding Option 1 were identified:

• The most common theme, raised in campaign responses, is that the route will be ambitious and disruptive and potentially unviable for a range of house types. Another campaign response suggested that, using the current available SAP software tool, 32% reduction is possible via Gas Boilers but this would require maximum roof coverage of PV, flu gas heat recovery and waste water heat recovery. A campaign response highlighted concerns over the availability of power provision in the grid to achieve compliance.
• Other themes relate to the competence of installers, potential costs being considerable and that these might be passed onto consumers. Additionally, concerns were raised that the proposals only consider operational carbon and should include embodied carbon as well. A few responses also requested support/funding and collaboration from Scottish Government to help meet the target.

Positive comments regarding Option 1 point to the proposal being rightly ambitious and necessary to achieve net zero carbon emissions. A few respondents specifically mentioned alignment with the Future Home Standard and the Scottish Government’s 2045 target.

A few respondents suggested that Option 1 was a good interim step towards tighter restrictions, allowing manufacturers and installers to upskill largely because the national infrastructure and supply chain is not yet sufficiently mature to implement Option 2.

3.2.4 Option 2: 'Advanced' standard (57% emissions reduction)

The main theme amongst those in support of Option 2 is that an ‘aggressive target’ is needed in order to address climate change targets (specifically the Scottish Government’s 2045 target) and move towards low, or zero, carbon. Many respondents made this point, with a few respondents suggesting the target is comparable to Passivhaus. A common theme amongst several respondents was that setting a high target now, requiring the highest possible thermal efficiency standards, will negate the need for costly and disruptive retrofit at a later date.

A few respondents felt the target should be higher. For example, some Local Authorities which have set ambitious net zero targets (i.e., before the Scottish Government target of 2045) welcome a ‘radical approach’.

The theme of a fabric first approach was also common amongst the responses. General comments include:

• Higher levels of fabric performance help to alleviate fuel poverty (in the wake of increasing energy prices).
• A campaign response also pointed out that a fabric first approach must not be forgotten in place of renewable heating ‘which may reduce emissions, but also allows leaky buildings to waste energy’.
• Renewables installed in ‘better insulated’ dwellings will operate more efficiently and at lower cost.
• Energy demand should be reduced first along with a strong building fabric in combination with better services and efficiencies.

Although they deemed that the target is challenging, a few respondents felt it is achievable in part because products to help meet the advanced standard are already commonly available such as high-performance glass and glazing products to achieve low U-values and solar control.

A few respondents also suggested the proposal will help ‘prime the market for wider uptake of heat pumps’, saying that where a heat pump is installed it has the potential for emissions reductions to go beyond the ‘advanced’ standard.

3.2.5 Alternative solutions to Option 2 proposed:

• A need to consider mechanical ventilation with heat recovery.
• An even higher standard to meet zero carbon target.
• An emissions target followed by primary energy.

3.2.6 Other considerations raised in relation to Option 2:

• Product manufacturers (e.g., glazing) must be able to meet demand.
• More information is needed about the financial and resource implications.
• Although some rural areas developments are already moving towards this (with use of renewables due to the lack of a mains gas supply) waste water recovery in Shetland is not always possible due to the ‘perishable effect of copper pipe technology used for this’.
• The move towards air source heat pumps may mean that solar ‘may disappear from new homes as the transition to heat pumps is made’ and the benefits of solar are lost.
• Implement a transition process – plus, by implementing a 57% reduction now, ‘the step change for 2025 will not be as great’.

3.2.7 Another level of uplift

Several respondents felt that neither the ‘improved’ nor the ‘advanced’ standard go far enough. A few respondents felt the proposals were ‘too high’, with one being ‘neutral’ on the amount of uplift.

3.2.8 Concerns and alternative solutions raised in relation to another level of uplift

• Embodied carbon needs to be considered as well as operational carbon to avoid unintended consequences.
• The viability of proposals at a time of significant upheaval in industry (i.e., market uncertainty, Brexit and COVID) and concerns that early adoption of mechanical ventilation and heat pumps could create supply chain issues.
• The ‘advanced’ level provides insufficient flexibility for developers given current technology performance and achieved standards.
• The review should preclude the use of fossil fuels.
• Sea source heat pumps or district heating should be included.
• Challenges in developing commercially available SAP 10 software for assessing compliance.
• The highest possible insulation standards should be adopted to reduce the heat load and avoid further fabric upgrades being necessary.
• Client understanding of new technologies all being introduced at once needs to be managed.
• The readiness of the grid with challenges regarding infrastructure capacity for import and export across Scotland.

A small number of alternative solutions were proposed by those who suggested another level of uplift:

• A few respondents suggested that an uplift of around 20% is more realistic because a higher level is difficult to achieve across all house types.
• A few respondents suggest there are better measures such as <15kWh/m²/yr.

3.3 Options for uplift in standards for new non-domestic buildings

3.3.1 Question 3

What level of uplift to the 2015 standard for new non-domestic buildings do you consider should be introduced as an outcome of this review?

In total, 96 responses were received to this question and 91 responses to the accompanying open question where respondents were asked to provide more detail to support their answer.

Base: 96 respondents (80 no response) NB Individual respondents are listed separately at the bottom for information - as they are included in organisation responses (per Section 2.3)

3.3.2 Analysis

Overall, respondents support the two options presented, with 82% of respondents selecting either Option 1 or Option 2 (Figure 5). There is substantially more support for Option 2 (63%) than for Option 1 (20%).

3.3.3 Option 1: 'Medium' standard (16% emissions reduction)

Several respondents chose this option because it is more achievable than the higher target, although a few respondents suggest it is still challenging and ambitious.

Other respondents felt that Option 2 was too drastic a change, for various reasons.

Examples are provided below, in order of their frequency:

• A fabric first approach is necessary to ensure buildings are energy efficient as we’re already behind ‘where we need to be in decarbonising our building stock’ and it will avoid later retrofitting.
• The high standard is unachievable because of its impact on skills, infrastructure, and supply and cost of materials.
• The proposal should be considered an interim step, ahead of tighter restrictions.

3.3.4 Option 2: 'High' standard (25% emissions reduction)

Many respondents suggest that a 25% emissions reduction is an achievable target, so there is no reason why it shouldn’t be adopted. Many respondents also stated that products and technologies already exist which could be used to achieve the same, through insulation, air tightness, ventilation, and heat recovery as well as high performance glass and glazing products.

Several respondents each highlighted the following:

• By introducing a higher standard of 25% reduction in emissions, the ‘step change’ needed by 2025 will be less onerous.
• A higher target is justified when balanced against the severity of the climate emergency.
• A more robust fabric first approach is needed.
• Emissions should be reduced as much as possible, but no indication was given from these respondents whether the ‘high’ standard or another target would be more appropriate to achieve this.
• The higher target of 25% emissions reduction is in line with Local Authorities’ position on emissions reduction.

A few respondents stated that, while the ‘high’ standard goes beyond the ‘medium’, neither are ‘very good’. A greater step change is needed to mitigate climate change.

3.3.5 Caveats and observations

A range of other general comments and observations were made by those who supported Option 2:

• It is appropriate as long as it discourages use of fossil fuels.
• Owners of new or altered buildings have a responsibility and role to play in helping achieve a more sustainable future.
• The ‘higher’ standard for domestic buildings sets quite strict notional values, for example for air permeability for windows, however non-domestic buildings appear to comply with greater margins between TER/BER.
• Agreement with the ‘higher’ standard as long as the capital cost of construction (1-5%) is accurate and product manufacturers can meet demand.
• There is potentially more of an opportunity for a non-domestic building to become ‘nearly zero’ or, generally depending on processes, a net generator as opposed to a consumer.
• Commercial units should have a higher emission reduction standard given the energy consumption for non-domestic dwellings can be very high.
• On-site use and storage of renewable energy should be encouraged to minimise impacts on grid stability.

3.3.6 Another level of uplift

Fourteen responses were received to this question. The main theme – amongst nine respondents – is that the two options are too limited.

Other comments made in response to this question include:

• Fabric first should be prioritised to first reduce emissions, supplemented by renewable energy technologies.
• Concern whether there is sufficient time for the supply chain to embed the necessary changes.
• There is a wide range between Options 1 and 2, and a ‘middle ground’ is needed.

3.4 Elements forming the Domestic Notional Building Specification

3.4.1 Question 4

Do you have any comments or concerns on the values identified for the elements which make up the domestic notional building specification for either option, e.g., in terms of their viability/level of challenge?

In total, 111 responses were received to this question and 92 responses to the accompanying open question where respondents were asked to provide more detail to support their answer. Nine respondents who answered the open question did not answer the preceding closed ‘yes/no’ question.

Base: 111 respondents (65 no response) NB Individual respondents are listed separately at the bottom for information - as they are included in organisation responses (per Section 2.3)

3.4.2 Analysis

Just over two thirds (68%) of respondents stated that they had comments on the proposal (Figure 6).

Respondents generally were concerned with how the proposed values could be met in practice, and any unintended consequences of achieving them, e.g., increases in embodied carbon. Respondents suggested more time would be required to develop and test technical solutions to meet the challenges posed, and also that upskilling of the construction workforce would be necessary.

3.4.3 Insulation U-values

Several responses (including a campaign response) expressed concerns that lowering acceptable U-Values would be likely to lead to an increase in new building materials being required to support the new systems and technologies resulting in the unintended consequence of increasing embodied carbon as a result of manufacturing the new building materials, undermining the Scottish Government's aspirations for a net zero transition.

A few respondents expressed a concern that U-values of 0.13 and 0.15 would lead to cavity widths of greater than 200 mm.

A few respondents suggested alternative U-values of 0.16, 0.18 or 0.18 – 0.19. The lower U-values were identified as potentially presenting an issue with the wall build up for timber frame and that it would necessitate the use of PIR insulation, thus increasing both the embodied carbon content of the homes and the fire loading within the frame.

Lower U-values necessitating larger house footprints and increased land take was another concern expressed by a few respondents.

3.4.4 Windows and doors

A small number of specific comments were made in regard to windows and doors:

• Option 1 will be a challenge for the aluminium fenestration industry within the timescales and option 2 will require massive investment in product development. Introducing these too soon could severely restrict consumer choice.
• Option 2 U-values would be difficult to achieve for glass rooflights, likely requiring triple glazing. The weight of triple glazing was mentioned in three responses, one going on to note subsequent operational issues for the elderly and disabled.
• A lack of window products meeting the proposed specification.
• It may be difficult to meet the proposed targets considering other performance requirements such as fire rating or fire performance, as well as openable windows for free cooling.
• With respect to doors, a concern was expressed that the U-value for doors has the potential to greatly reduce the amount of door designs available on the market, leading to loss of visually interesting streetscapes.

3.4.5 Solar PV

The need for extensive modelling was expressed by several respondents (a campaign response) in part to understand the amount of roof space that would be required to install the PVs. There is a concern that small homes will not have sufficient roof space to accommodate the number of PVs required in order to meet the proposed specification.

3.4.6 Waste Water Heat Recovery (WWHR)

A few respondents expressed concern around the practical challenges of achieving the specified WWHR efficiency of 55% (proposed for gas notional dwelling) in flats. These were raised on the grounds that components may need to be housed in flats below (vertical units) and developers would be reluctant to do this.

3.4.7 Skills and competence

Several respondents (a campaign response) had concerns around the supply chain and the lack of qualified and trained installers and testers, who are needed to cope with the installation and maintenance of the new technologies. Specific points include:

• Training events for designers and installers are needed to make them aware of the requirements.
• Early engagement with industry is required.
• Checks and balances to be put in place over the installations and the competence of installers.
• Achievement of airtightness targets would be hit by skills shortages.

3.4.8 Heat pumps

A few respondents identified supply chain issues which would be caused by a wholesale shift to heat pump technology in terms installation, testing and competency.

A technical point regarding the Proposed Values for Hot Water Cylinder Declared Loss Factor was raised, with concerns that the proposed declared loss factor associated with the Hot Water Cylinder is low and quite strict, and that many heat pump specific cylinder manufacturers would find this difficult to achieve.

3.4.9 Mechanical Ventilation with Heat Recovery (MVHR)

A few respondents highlighted concerns:

• In the affordable market users switch the system off because of perceived running costs, resulting in poor ventilation and damp problems”.
• The systems are not always robust and reliable and may need to be replaced a number of times.

3.4.10 Space heating

Concerns regarding adequacy of generating capacity to achieve the switch to electrification of heat were expressed by several respondents. Other points related to a need for greater flexibility; allowing innovation to support Modern Methods of Construction; space heating demand targets should be part of the Energy Demand criteria for compliance in section 6.

3.4.11 Fabric first

Promoting a fabric first approach was identified by a few respondents as the most important and necessary step to help reduce capital and operational costs, improve energy efficiency, and reduce carbon emissions.

3.4.12 Costs

Where costs were referenced by respondents, they were generally mentioned as a challenge rather than as a barrier to achieving the specifications.

3.5 Elements forming the non-domestic Notional Building Specification

3.5.1 Question 5

Do you have any comments or concerns on the values identified for the elements which make up the non-domestic notional building specification for either option, e.g., in terms of their viability/level of challenge? - If yes, please provide your comments below:

In total, 93 responses were received to this question and 32 responses to the accompanying open question where respondents were asked to provide more detail to support their answer. Three respondents provided an open response but did not answer the preceding closed ‘yes/no’ question.

Base: 93 respondents (83 no response) NB Individual respondents are listed separately at the bottom for information - as they are included in organisation responses (per Section 2.3)

3.5.2 Analysis

Fewer than half of respondents to this question (46%) stated that they had comments to make on the proposal (Figure 7).

Technical considerations highlighted were most numerous for glazing, with some respondents expressing doubts about the achievability of the proposal in the timescales. Detailed technical responses from some organisations suggested standards could be more ambitious and gave targets for these. There was some signposting to information that respondents thought could inform the standards.

3.5.3 Glazing

A few respondents highlighted the challenges they face in achieving improved standards, such as financial implications. More specific challenges particularly relating to glazing and timescales for change were detailed by a few industry association/manufacturer respondents due to product development investment; a phased approach being needed to allow time for upskilling installers; Option 2 presenting too big a step in the time available.

A concern was expressed by a few respondents about the use of triple glazing for option 2 being difficult and costly to achieve, particularly in retail. Also, a possible unintended consequence of setting the G-value of glazing will at 0.30, in that 70% of solar gains through glazing will be lost.

3.5.4 More ambitious standards

A few respondents with no concerns about achieving the standards, went on to state that products are available in the commercial sector in Scotland to meet the higher standard. Also, with investment, the more challenging U-values could also be achieved within a reasonable time scale and that, for certain buildings, such as large industrial units, the proposed minimum level of airtightness could be strengthened much further.

A few respondents believed the Standards could go further.

A few respondents identified information that they felt should inform the Standards including: The LETI Climate Emergency Design Guide, the AECB Standard/Passivhaus Standard and Scottish Futures Trust Net Zero Carbon for Public Buildings Standard.

3.5.5 Unintended consequences

An industry association reported members’ concerns that the proposals could in effect bring the New Build Heat Standard forward from 2024. Here, concerns were raised about the capacity of electricity networks to meet the increased demands from the electrification of heat, combined with the added pressures from greater use of electric vehicles.

3.6 Change to fuel assignment of the notional building - Domestic

3.6.1 Question 6

Do you have any comments on the simplified two-specification approach to defining the domestic notional building from 2022?

In total 115 respondents answered the closed ‘yes’/’no’ question (Figure 8), with just under half (44%) stating that they have comments to make. Of the 115, 69 went on to provide comments in response to this question. Four respondents provided an open response but did not answer the preceding closed ‘yes/no’ question.

Base: 115 respondents (61 no response) NB Individual respondents are listed separately at the bottom for information - as they are included in organisation responses (per Section 2.3)

3.6.2 Support for the proposal

Various comments were received in support of the proposal including that a ‘simplified approach’ is welcomed’, it gives a degree of flexibility and that the approach should result in a progressive move away from fossil fuel heating systems. These are reported in further detail below.

Several respondents raise challenges that this approach will bring to housing in rural areas.

A few respondents pointed to the move away from fossil fuels, with the notional building specification making it more challenging to install oil or gas; and that the fabric requirements should be more onerous for new homes with gas boilers.

A campaign response suggests that the alternative approach of calculation of the total space heating demand for the building should become the default, rather than the elemental (notional building) methodology. Also, the Passivhaus Planning Package (PHPP) should be considered as an acceptable calculation methodology.

A concern was raised by a few respondents about the appropriateness of considering natural gas/oil as the alternative fuel source for non-heat pump solutions.

3.6.3 Not in support of the proposal

A few respondents were explicitly not in favour of the simplified two-specification approach. Reasons given are as follows:

• All buildings should be assessed against the same heating system (an ASHP) so that the TER is fixed and unaffected by the heating system.
• Concerns over the use of a different heat pump in a notional building (when heat pumps are specified in SAP or SBEM). This is felt to penalise a technology vital to reducing carbon emissions
• Should be based on a performance target - the notional building approach will disadvantage smaller builders.

3.6.4 Unclear or other comments

The main theme to the other comments received was that many respondents found it difficult to comment due to the issues associated with the currently available SAP software.

Other, general responses:

• Note the general reference to PV solar panels and question why there is no reference to solar thermal.
• Mandate the use of WWHR systems as part of the fabric.
• If notional building approach is retained, a fabric first approach should be adopted.
• Call for the inclusion of solar PV with air source heat pumps under the air source heat pump specification.
• High efficiency electric storage heaters can be the most suitable solution in certain circumstances.
• Further justification for the continued use of gas boilers is needed.

3.7 Changes to fuel assignment of the notional building – Non-domestic

3.7.1 Question

Do you have any comments on the simplified two-specification approach to defining the non-domestic notional building from 2022?

In total, 98 responses were received to this question. Forty-six responses were to the accompanying open question where respondents were asked to provide more detail to support their answer. Four respondents provided an open response but did not answer the preceding closed ‘yes/no’ question.

Base: 98 respondents (78 no response) NB Individual respondents are listed separately at the bottom for information - as they are included in organisation responses (per Section 2.3)

3.7.2 Analysis

Of those who responded to this question, just over a third (36%) said that they had specific comments on the simplified two-specification approach to defining the domestic non-domestic notional building from 2022 (Figure 9).

Ten respondents stated that their response is ‘as per Question 6’, meaning that their views on the proposals as they apply to domestic and non-domestic buildings are the same. These responses have therefore been included here as part of the summary below.

3.7.3 Support for the proposal

Various comments were made in support of a simplified approach and a similar approach across the domestic and non-domestic buildings was considered ‘preferable’. These are summarised below.

A campaign response stated that emphasis should be on improving the thermal performance of buildings to reduce the amount of energy required in the first instance, allowing for low carbon technologies to meet the ‘residual heat load’ and phase out gas boilers.

It was suggested in a campaign response the need to consider the fabric of non-domestic buildings that are similar to domestic buildings.

A campaign response suggested that the alternative approach of calculation of the total space heating demand for the building should become the default, and that the Passivhaus Planning Package (PHPP) should be considered as an acceptable calculation methodology.

A few respondents made comments relating to technologies: over-reliance on PV is not always suitable; a need to ensure that the carbon emissions from the property are not higher if including gas boilers; and heat pumps being the only viable option until further research is available.

3.7.4 Not in support of the proposal

A few respondents were explicitly not in favour of the simplified two-specification approach for the following reasons:

• All buildings should be assessed against the same heating system (an ASHP) so that the TER is fixed and unaffected by the heating system.
• The approach penalises a technology which will be vital in efforts to reducing carbon emissions and the impact our building have on climate change.
• Removal of a notional building specification for LPG doesn’t allow for rural off-grid businesses and new non-domestic premises being able to benefit from bio-LPG.
• Building fabric and air tightness targets should not be the same for each notional building type.

3.7.5 Unclear or other comments

The main theme in other comments – from several respondents – questions the suitability of natural gas and the decision to continue the use of gas boilers as the alternative fuel force for the non-heat pump solution.

3.7.6 Other responses

• The simplified approach will be a challenge to reduce the energy demand.
• Consideration should be given to the impact of proposals on rural and semi-rural development.
• Upskilling will be required to ensure a competent design process and that cost-effective and relevant solutions are used.
• If the notional building approach is retained a fabric first approach should be adopted.

3.8 Change to assignment of Domestic Hot Water (DHW) – Non-domestic

3.8.1 Question 8

Do you have any comments on the proposal to separate and provide a more demand-based approach to assignment of domestic hot water heating within the non-domestic notional building specification from 2022?

In total, 98 responses were received to this question and 45 responses to the accompanying open question where respondents were asked to provide more detail to support their answer. Four respondents provided an open response but did not answer the preceding closed ‘yes/no’ question.

Base: 98 respondents (78 no response) NB Individual respondents are listed separately at the bottom for information - as they are included in organisation responses (per Section 2.3)

3.8.2 Analysis

Of those who responded to this question, almost two thirds (65%) said that they had no specific comments on the proposal to separate and provide a more demand-based approach to assignment of domestic hot water heating within the non-domestic notional building specification from 2022 (Figure 10).

The vast majority of respondents expressed support for the proposal in their comments; some were unclear whether they were in favour or not.

3.8.3 Support for the proposal

The main theme amongst several respondents in favour of this proposal is that it is appropriate where there is low demand, therefore a demand-based approach seems sensible and understandable. This is because DHW use could vary across different non-domestic building types and therefore this allows for flexibility. A few respondents requested that ‘low’ and ‘high’ demand are defined.

A few respondents felt that the separation of water heating and space heating more accurately reflects the real-world situation.

The following were suggested by a few respondents:

• For building zones with high demand, the notional building should use a centralised domestic hot water system.
• Incentivising instantaneous electric water heating in situations where domestic hot water demand is low is sensible.
• Criteria need to be developed to ensure that DHW is generated in a low carbon and efficient manner.

3.8.4 Not in support of the proposal

It was suggested that calculation methods for heating and hot water demand should be used to select the relevant technology.

3.8.5 Unclear or other comments

A few respondents suggested more clarity is needed on the water consumption figures and a campaign response raised the that point system losses can be greater for DHW than for space heating and can contribute to summer overheating.

Other, general comments:

• Clarity needed on what can be done to provide domestic and non-domestic heating in the future, for a realistic price.
• As healthcare developments require a central hot water storage system, the notional building for healthcare should be based on a central hot water storage system.
• There is no specific provision for the use of solar thermal heating or solar PV.
• In modelling software, flow rates for showers and taps should be entered accurately.

3.9 Supplied heat connections

3.9.1 Question 9

Do you support the change in application of targets for supplied heat connections to new buildings, focused on delivering a consistent high level of energy performance at a building level?

In total, 97 responses were received to this question. Seventy-six responses were received to the accompanying questions which asked for a summary of the reasons for the respondent’s view. Ten respondents provided an open response but did not answer the preceding closed ‘yes/no’ question.

Base: 97 respondents (79 no response) NB Individual respondents are listed separately at the bottom for information - as they are included in organisation responses (per Section 2.3)

3.9.2 Analysis

Eighty-four per cent of respondents favoured the proposal and the remaining 17% did not support it (Figure 11).

3.9.3 Support for the proposal

Of those who supported the proposal, 60 provided additional comments. The majority stated their agreement and provided further justification for their support such as:

• Energy performance at a building level will provide more accuracy and consistency for comparison purposes.
• Allows the energy performance of new buildings to be addressed consistently, regardless of the heat source.
• Supports connection to a wide variety of existing heat networks.
• Simplifies the understanding, promotes the use of and recognises the benefits of supplying heat to a building from external networks.

A few respondents in support of the change in application of targets for supplied heat connections to new buildings gave caveats:

• SAP software must work correctly.
• Backstop should be introduced to prevent new buildings being connected to antiquated district heating schemes.
• Only support heat networks that utilise renewable sources.

Some respondents in support of the change raised concerns:

• May create complexity within the building warrant and compliance reporting process.
• The approach to HIU heat losses (6.1.6) diverges from the approach being taken in England and Wales.
• The assumption that the heat network is carbon free could act as a loophole in regulation.
• Networks are typically private and are not obliged to provide a connection.
• Connection cost levels and that these are neither competitive nor regulated.
• No competition of energy rates once connected to the heating network.
• Not possible to change supplier.
• Potential risk of heating systems being the focus of reducing emissions (fabric first approach with air-tight, well-ventilated dwellings should be the main ambition).

3.9.4 Not in support of the proposal

Several substantive comments focused on delivering a consistent high level of energy performance at a building level. Areas of concerns included:

• Proposed change may lead to complexity within the building warrant and compliance reporting process.
• Reliance on undefined regulations (Heat Networks (Scotland) Act).
• Suitability of heat networks.

3.9.5 Non-responders

Of several substantive comments received, the only common theme is the need to adopt a fabric first approach. Other areas of comment:

• Lack of opportunity to shop around for more competitive energy prices.
• Heat Distribution Networks will require considerable lead in time and investment.
• Need for monitoring of distribution losses through heat networks.
• Proposal relies on future implementation of policies (including the Heat Networks Act).
• Delivery of SAP software to become more complex.

3.10 Limited benefit from on-site generation of power

3.10.1 Question 10

Do you agree with the principle set out, that the benefit from on-site generation within the compliance calculation should be limited by a practical assessment of the extent that generated energy can be used on-site?

In total, 105 responses were received to the closed ‘yes/no’ question and 85 responses setting out the reason for their view. Twelve respondents provided an open response but did not answer the preceding closed ‘yes/no’ response; about half of these simply stated ‘no comment’.

Base: 105 respondents (71 no response) NB Individual respondents are listed separately at the bottom for information - as they are included in organisation responses (per Section 2.3)

3.10.2 Analysis

In total, just over four fifths of respondents (81%) agreed that the benefits from on-site generation within the compliance calculation should be limited by a practical assessment of the extent that generated energy can be used on site (Figure 12).

3.10.3 Support for the proposal

Of the 85 respondents in support of the proposal, 60 chose to provide further comment.

Significant supportive comments were received which include:

• Will promote improvement in the fabric performance of buildings.
• Avoids the possibility of poor fabric performance being ‘offset’ by claims of excess energy being generated.
• Accuracy and consistency are limited to the building in question and not to external factors out with the control of the designer.
• Provides a truer representation of actual usage/performance.
• Acts as an enabler for innovation.

Several respondents submitting a campaign response stated that whilst they are in general agreement with the provision, they feel it may make the process of fabric improvement more challenging. In addition, it is suggested that it also potentially creates difficulties in smaller dwelling types which utilise combi boilers for heat and water, where there is insufficient space to locate a DWH hot water cylinder.

A few concerns were raised about the outcome of the final SAP software.

3.10.4 Not in support of the proposal

Twenty respondents stated that they do not agree with the principle set out, many provided substantive further comment, as follows:

Several respondents raised concerns relating to power from PV installations. For example, because it will discourage the installation of solar PV on new buildings and may not give credit to any building that generates its own electrical supply.

Contractor Developer views vary. One considered the existing methodology fit for purpose whilst another stated that the principle proposed will make fabric improvements more challenging. A third Contractor/Developer acknowledged the complexity of the subject and suggested that SAP should recognise any benefit coming from extra electricity supplied through PV panels.

3.10.5 Non-responders

A few respondents raised concern that the use of PV will be limited as a result of the proposal.

A few respondents focused on the storage of on-site generated energy, suggesting it should be factored into the compliance methodology. They suggest that for larger applications, on-site district generation and storage models which prioritise direct energy use over grid surplus should be considered. Furthermore, it was suggested that on-site generation should also be used for mixed-use developments as well as multi-unit domestic.

A few respondents questioned whether SAP methodology is the appropriate tool for assessing how much generated energy is used onsite. In addition, they point out that SAP does not account for Electric Vehicle (EV) charging despite these now becoming a requirement.

3.10.6 Are there any particular concerns you have over this approach (per Question 10), e.g., with regards particular technologies or solutions?

In total, 85 responses were received to this question and 58 responses to the accompanying open question where respondents were asked to provide more detail to support their answer. Five respondents provided an open response but did not answer the multiple-choice question.

Base: 85 respondents (96 no response) NB Individual respondents are listed separately at the bottom for information - as they are included in organisation responses (per Section 2.3)

3.10.7 Analysis

Overall, 55% of respondents stated that they had no concerns over the approach with regards to particular technologies or solutions (Figure 13). The remaining 45% stated they had concerns and offered comments relating to same.

The dangers and disadvantages of backing a single solution were discussed and linked to the need to encourage future innovation relating to onsite generation by several respondents.

A few respondents highlighted the importance of adopting a fabric first approach to reducing energy demand in the first instance. They suggested that offsetting on-site generation against heating demand does not incentivise a fabric first approach and too much focus on onsite renewable may make urban development more difficult, potentially increasing urban sprawl and generating negative environmental impacts.

The excessive reliance on heat pumps was a focus for a few, with calls for other methods to be taken into consideration.

Concerns were also raised by a few respondents relating to the omission of the use of PV (photovoltaic) which may discourage developers from including PV in proposals.

A few respondents raised concerns over the impact the proposals are likely to have on the time required to verify proposals and in relation to compliance on site and how to achieve verification cost-effectively.

3.11 Applying standard 6.1 to buildings with low and zero emission heating

3.11.1 Question 11

Do you agree with the proposal that new buildings where heat demand is met only by 'zero direct emissions' sources should be exempt from the need for a calculation to demonstrate compliance with the Target Emissions Rate?

There were 106 responses received in total to this question and 95 responses to the following open question where respondents were asked to provide more detail to support their answer. Seven respondents provided an open response but did not answer the multiple-choice question.

Base: 106 respondents (70 no response) NB Individual respondents are listed separately at the bottom for information - as they are included in organisation responses (per Section 2.3)

3.11.2 Analysis

Overall, there is support for the proposal (61%), with the remaining 39% of respondents stating they do not support the proposal (Figure 14).

3.11.3 Support for the proposal

Those who support the proposal most commonly refer to the beneficial simplification of the design and assessment processes.

A few respondents call for further clarification around generating EPC certification on completion. Concerns were raised by a few respondents who support the proposal:

• The proposal would not cover future changes to the heating supply.
• Homes that have invested in zero emissions heat sources should also benefit from the exemption.
• If delivered energy is adopted as the energy target metric, this change could allow direct electrically heated homes to have comparatively high energy use and energy bills.
• New buildings should be designed to enable ease of retrofit to zero carbon heating.

3.11.4 Not in support of the proposal

Several respondents raised a perceived issue with downstream emissions associated with ‘zero direct emissions’ source not being counted. Several respondents felt there should be a fabric first approach to reducing energy demand in the first instance.

Several respondents refer specifically to the importance of calculating the emissions rate for the property regardless of the technology deployed and highlight that carbon intensity of heat pumps can vary depending on localised carbon emission intensity of the grid. Similarly, the carbon intensity of hydrogen can vary.

Several respondents expressed concern that the proposal may encourage the use of systems with lower up-front costs (such as direct electric heating) but with higher running costs resulting in comparatively high future energy bills. A clearer definition was felt to be needed of 'zero emissions' to ensure heat sources such as direct electric heating would need to be powered from onsite renewably generated electricity alone.

Comments relating to EPCs were made by several respondents. They highlight that EPC ratings are important for leasing buildings and raise concerns about the potential creation of a barrier to the deployment of heat networks if EPC emissions compliance is needed (i.e., for social landlords). There is a call from this group for ‘nearly zero’ technologies to be considered as part of exemption calculations.

3.11.5 Non-responders

Of those who did not answer the multiple-choice question but provided a comment, a few respondents’ comments focus on direct electrically heated homes (not generated via on-site renewably generated electricity alone) and raise concerns that the proposal could allow them to have comparatively high energy use and energy bills.

3.12 Designing for future retrofit of zero direct emissions heat solutions

3.12.1 Question 12

Do you support the need for new buildings to be designed to enable simple future adaptation to use of a zero direct emissions heat source where one is not installed on construction. And for information setting out the work necessary for such change to be provided to the building owner?

There were 106 responses received in total to this question and 88 responses to the following open question where respondents were asked to provide more detail to support their answer. A further eight respondents provided an open response but did not answer the multiple-choice question.

Base: 105 respondents (71 no response) NB Individual respondents are listed separately at the bottom for information - as they are included in organisation responses (per Section 2.3)

3.12.2 Analysis

Significant support was expressed by respondents with 81% of those who responded to the multiple-choice question (Figure 15) stating that they support the need outlined. Only 19% did not support it.

3.12.3 Support for the proposal

Of those in support of the proposal, several respondent comments focused on information for building owners and highlighted the need for this to be ‘straightforward’, ‘clear’ and ‘non-biased towards a particular technology’.

Several respondents felt there was a need for greater clarity of what constitutes ‘simple future adaptation’.

In their comments, several respondents discussed the need for adequate consideration to be given to design and planning at the outset. Failure to do so may risk the infrastructure not being at a scale where it can cope with new, additional technology. Future adaptations may also impact fabric and fire performance. These respondents also felt that the proposal would likely introduce another layer of work for developers and verifiers.

Several respondents suggested that different property types can present different levels of complexity, with smaller homes and high-rise dwellings being identified as less straightforward. It was suggested that space requirements may be too onerous in smaller properties, and, in flats, it was suggested that developers may resort to the installation of systems which would currently be very expensive to run.

A few respondents commented on the need for flexibility of design in areas where there is a skill or material shortage – something which has been brought to the fore in the post pandemic climate.

A few respondents felt the ability to quickly adapt was a key priority. A few further respondents referred specifically to hydrogen.

3.12.4 Not in support of the proposal

Of those respondents not in support of the need for new buildings to be designed to enable simple future adaptation, and for information setting out the work necessary for such change to be provided to the building owner, their comments focused on the following three key areas:

• Concern over the creation of a ‘loophole’.
• Fabric first approach.
• Consideration of external factors and future technological advances.

Several respondents shared the view that there is a risk that future installations will never take place if developers are only required to provide information setting out the work necessary regarding future adaption. A few respondents suggest the use of a zero direct emissions heat source should be made mandatory.

Several respondents pointed to the need to adopt a fabric first approach to achieve nZEB, thereby eliminating the need for future adaptation.

Several respondents felt that asking developers to account for future adaptions now, beyond that of primary pipework within the dwelling, is unrealistic as there are too many external factors to consider. In addition, advancements in new products and innovations may occur which may change the way in which we look at delivering zero direct emission heat sources.

3.12.5 Non-responders

A few of those who did not respond to the multiple-choice question but offered comments focused on the need for a fabric first approach to energy efficiency measures. They called for this to be implemented as a priority at the outset and that the design needs to accommodate for any future adaptation via an allowance plan.

A few respondents stressed that it is considerably more challenging to bring an existing building to zero direct emissions after it has been constructed than it is to achieve this during its initial construction and as such the revised standards should be designed in such a way as to minimise the need for further retrofit by setting the highest possible standards in the short term.

3.12.6 Do you have any comments on the level of information needed to support such action (as asked in Question 12) in practice and on the extent to which alterations other than at, or very close to, the heat generator can be justified?

There were 81 responses received in total to this question (Figure 16) and 48 responses to the following open question where respondents were asked to provide more detail to support their answer. Five respondents provided an open response but did not answer the multiple-choice question.

Base: 81 respondents (95 no response) NB Individual respondents are listed separately at the bottom for information - as they are included in organisation responses (per Section 2.3)

3.12.7 Analysis

Comment was provided by a total of 48 respondents. The comments vary in focus, but there are six emerging themes.

Several respondents highlight that what constitutes “simple future adaption” needs to be clarified before they go on to discuss the level of detail of the information which should be made available to homeowners. Various individual comments were made in support of this point.

A few respondents list the information which they feel should be provided in relation to heat pumps.

A few respondents highlight the considerable burden which will impact on design work, testing and verification.

The need for airtightness and airtightness testing was raised by a few respondents.

A few respondents also requested an evaluation on the impact on infrastructure should be carried out and consultation with energy providers to ensure national and localised grid networks can accommodate the required energy loadings. They suggest consultation with energy providers is also recommended to ensure localised grid networks can accommodate the required energy loadings.

A few respondents suggest that fabric first should be the focus for all new-builds in order to achieve nZEB, thereby eliminating the need for future adaptation.

3.13 Fabric performance of new dwellings - Domestic

3.13.1 Question 13

Do you support the retention of the current elemental approach to setting minimum standards for fabric performance in new dwellings, supported by the option to take an alternate approach via calculation of the total space heating demand for the dwelling (as described)?

There were 95 responses received in total to this question and 82 responses to the following open question where respondents were asked to provide more detail to support their answer. Three respondents provided an open response but did not answer the preceding closed ‘yes/no’ question.

Base: 95 respondents (81 no response) NB Individual respondents are listed separately at the bottom for information - as they are included in organisation responses (per Section 2.3)

3.13.2 Analysis

There is considerable support (91%) for the retention of the current elemental approach (Figure 17). Of these respondents, 66 provided further comments.

3.13.3 Support for the proposal

Positive comments are themed around, simplicity, flexibility, and familiarity.

Many respondents provided comments which highlight areas of concern, implication, or suggestions for further improvement.

A few respondents highlighted potential implications of the changes on design, typical construction, and provision of appropriate guidance to achieve the safe construction of these elements in line with other sections of the Scottish Building Standards (e.g., structure, fire, etc.).

A holistic and long-term approach is felt to be needed by a few respondents who suggested that total space heating demand calculations for new dwellings should achieve nZEB levels now. Linked to this, a response submitted by an industry association on behalf of their members suggests that a more effective way of defining emissions and energy efficiency targets to drive a step change in performance (whilst ensuring design flexibility and encouraging innovation) may be a space heating demand target (kWh/m²/yr).

3.13.4 Not in support of the proposal

Eight comments were received from the 10% of respondents who opposed the proposal. Each highlighted what they viewed to be perceived risks to the approach. No common themes were apparent.

3.13.5 Non-responders

A few comments were received from respondents who elected not to respond to the multiple-choice question. Two highlighted their agreement that minimum standards to drive further improvements in fabric performance are needed, and that flexibility is being retained through the alternative calculation. The third stated that if a delivered energy target is adopted and ZDE (zero direct emission) homes are exempted from an emission target, then direct electric heated homes may need a higher fabric standard.

3.13.6 In the context of the proposed approach (noted in Question 13)

Do you have any comments on the maximum U-values proposed for elements of fabric, in relation to their level of challenge and achievability at a national level?

There were 87 responses received in total to this question (Figure 18) and 63 responses to the following open question where respondents were asked to provide more detail to support their answer. Five respondents provided an open response but did not answer the multiple-choice question.

Base: 87 respondents (91 no response) NB Individual respondents are listed separately at the bottom for information - as they are included in organisation responses (per Section 2.3)

3.13.7 Analysis

Of the 55 who stated they had further comment, general statements were provided in support of the proposed approach.

Several respondents raised concerns over the availability of products, product development and potential related safety issues. Specific concerns were raised on behalf of the aluminium fenestration industry and in relation to the requirements for windows and doors and, triple glazing.

The subject of embodied carbon was raised by several respondents with three making the point that the insulation required to meet very low u-values are usually from non-renewable sources, therefore being counterproductive in terms of reducing embodied carbon.

Concerns were raised in a campaign response about achieving backstop U-Values of 0.16 and 0.17 for those involved in timber frame manufacturing. Similarly, this was a concern raised in relation to the manufacturing of windows and doors. One industry association respondent sharing the views of their members, states that whilst some feel the values proposed are ambitious but attainable, others are concerned that they are too stringent. As such, they suggest a staggered approach to tightening standards to allow industry time to adapt.

A few respondents had concerns about the increase in costs as a result of the proposal and referred to the ongoing materials shortages.

Of those who elected not to answer the multiple-choice question, several comments were received relating to aspects of glazing. For example:

• Concerns relating to the minimum allowable U-values under the ‘Advanced’ option, for doors and windows which may be difficult to achieve when also taking into consideration other performance requirements such as fire rating or fire performance, as well as openable windows for free cooling.
• The higher specification may pose a challenge for window installers who will need more time to prepare products for market that can meet the challenges set by improved U value performance while still meeting the other specifications required.
• The inclusion of triple glazing to the ‘Advanced’ option presents practical issues in handling heavy elements on site and compromises solar gains.

3.14 Increase in airtightness testing - Domestic

3.14.1 Question 14

Do you support the move to airtightness testing of all new dwellings, by registered members of an appropriate testing organisation?

There were 101 responses received in total to this question and 91 responses to the following open question where respondents were asked to provide more detail to support their answer. Three respondents provided an open response but did not answer the multiple-choice question.

Base: 101 respondents (75 no response) NB Individual respondents are listed separately at the bottom for information - as they are included in organisation responses (per Section 2.3)

3.14.2 Analysis

There is considerable support for the proposal to the move to airtightness testing of all new dwellings, by registered members of an appropriate testing organisation. Eighty-eight per cent of respondents stated they agree with the proposal (Figure 19).

3.14.3 Support for the proposal

Many respondents suggested that sample testing is not robust enough and that the standard of workmanship and site supervision on large sites cannot, or should not, be relied upon. Whilst a few respondents raised concerns in relation to cost, others suggested that 100% testing is cheap, effective and avoids confusion.

Several respondents also felt strongly that testing should be carried out by registered members of an appropriate testing organisation.

Several respondents highlighted that 100% testing will also produce accurate full market performance data.

Several respondents raised concerns and sought reassurances about the capacity of the airtightness testing industry to support the proposed change. They questioned the availability of equipment and approved assessors. A few respondents felt that early engagement with the airtightness testing industry will be critical.

3.14.4 Not in support of the proposal

Twelve respondents (12%) stated they do not agree with the proposal, eleven of whom provided a supporting comment.

All comments suggested that in certain circumstances, testing ALL new dwellings is felt to be unnecessary and excessive. Contractor/Developer respondents typically drew attention to multiplot sites and apartments where many of the same size and form are constructed and as such, a representative sample is suggested to be more appropriate. Related to this point, one respondent also drew attention to localised weather conditions which do not always permit testing to be carried out due to windspeeds which exceed the maximum permitted, potentially causing significant delays.

Several respondents expressed concerns that the air testing industry will fall significantly short in resource and capacity to cope with what will be a considerable rise in testing.

A few respondents also highlighted the cost impact for what they see as an unnecessary change.

3.14.5 Non-responders

The respondents who did not answer the multiple-choice question indicated their agreement with the proposal and its potential to raise standards. Concerns were expressed relating to weather conditions required for testing and that this may create a barrier to the achievement of the proposal.

3.15 Increase in airtightness testing – Non-domestic

3.15.1 Question 15

Do you support the move to increased airtightness testing of all new non-domestic buildings, by registered members of an appropriate testing organisation?

There were 84 responses received in total to this question (Figure 20) and 67 responses to the following open question where respondents were asked to provide more detail to support their answer. One respondent provided an open response but did not answer the multiple-choice question.

Base: 84 respondents (92 no response) NB Individual respondents are listed separately at the bottom for information - as they are included in organisation responses (per Section 2.3)

3.15.2 Analysis

The majority of respondents (93%) support the proposal to move to increased airtightness testing of all new non-domestic buildings, by registered members of an appropriate testing organisation. Just 7% of respondents rejected the proposal.

3.15.3 Support for the proposal

General comments from those in support suggest that the proposal is proportionate and that airtightness tests are felt to provide a good measure of the construction quality of a building. It was suggested that the proposal will bring consistency across the UK which will be beneficial, and more jobs will be created to cope with increased demand.

The requirement for the testing to be carried out by a registered member of an appropriate testing organisation is also supported by a few respondents, comments highlight that this will provide impartiality.

Exceptions to the requirements were raised by a few respondents. Modular buildings are the focus for one Industry Association/Manufacturer respondent who calls for relaxation of the testing for small modular buildings with a floor area of <200 m². A further respondent focused on shell and core projects which they believed are not always re-tested post-fitout when potentially the fabric of the building has changed.

3.15.4 Not in support of the proposal

Of the six respondents who stated they did not agree with the proposal, no substantive comments were received.

3.15.5 Non-responders

The open response comment provided by the respondent who elected not to answer the multiple-choice question highlights that, in their view, the proposal will ensure build quality and energy performance targets are met at completion.

3.16 Adoption of CIBSE testing methodology

3.16.1 Quesiton 16

Do you support the adoption of CIBSE TM23 as the basis for airtightness testing in Scotland?

There were 91 responses received in total to this question and 77 responses to the following open question where respondents were asked to provide more detail to support their answer. Twelve respondents provided an open response but did not answer the preceding closed ‘yes/no’ question.

Base: 91 respondents (85 no response) NB Individual respondents are listed separately at the bottom for information - as they are included in organisation responses (per Section 2.3)

3.16.2 Analysis

There is significant support for the adoption of CIBSE TM23 as the basis for airtightness testing in Scotland. Ninety-three per cent of respondents stated their support for the proposal and just 7% reject it (Figure 21).

3.16.3 Support for the proposal

Of those who agree with the adoption of CIBSE TM23 as the basis for airtightness testing in Scotland, 60 provide further comment. The main theme emerging in the comments relates to consistency across nations. Many comments highlight that CIBSE TM23 is the current standard across many parts of the UK for the testing of buildings for air leakage and that it would be practical for Scotland to adopt the same principles and standards to align with the rest of the UK.

Several respondents expressed the view that the adoption of the CIBSE guide will enhance the guidance given to airtightness testing technicians and will create a more robust testing methodology. However, there was a call for the refinement of the testing methodology document to tackle industry queries and ensure it includes all the information required for airtightness testers. Another respondent called for further versions of the guidance to incorporate input from cross-industry working groups to ensure quality and relevance.

Several respondents suggested that buildings should be tested at a range of air pressures up to 50Pa, by both pressurising and depressurising the building envelope.

3.16.4 Not in support of the proposal

Of the six respondents who stated they do not agree with the adoption of CIBSE TM23 as the basis for airtightness testing in Scotland, one provided no comment, and three felt they are not in a position to provide comment due to either insufficient information or a lack of specialist knowledge.

The other two respondents raised concern about the adoption of the CIBSE TM23 stating that the CIBSE TM23 is out of date and draw attention to the ATTMA Technical Standards TS L1, L2, L3 and now TSL4 for energy efficient (Low energy) buildings which is the named test standard in Scotland. They raised concerns about the unnecessary replacement of the standard (and associated cost to the taxpayer) when the methodology has never been questioned and no formal complaint about the independence of the standard has ever been raised (FOI request 4530647).

3.17 Adoption of option to apply ‘pulse’ test

3.17.1 Quesiton 17

Do you support the introduction of the pulse test method of airtightness testing as a further means to testing and reporting on the performance of new buildings?

There were 88 responses received in total to this question and 82 responses to the following open question where respondents were asked to provide more detail to support their answer. Fourteen respondents provided an open response but did not answer the preceding closed ‘yes/no’ question.

Base: 88 respondents (88 no response) NB Individual respondents are listed separately at the bottom for information - as they are included in organisation responses (per Section 2.3)

3.17.2 Analysis

The majority of respondents (83%) support the introduction of the pulse test method of airtightness testing as a further means to testing and reporting on the performance of new buildings (Figure 22). Seventeen per cent reject the proposal.

3.17.3 Support for the proposal

Several respondents in favour of the proposal discussed the advantages of consistency across the nations. They pointed out that this methodology has already been adopted by England and Wales, and its adoption by Scotland is seen as advantageous.

Several respondents also raised concerns around whether the apparatus will work on a timber kit, and if the vapour barrier would give incorrect readings.

Several respondents stressed that they do not feel the pulse test method should be the sole method used but as a further means to test and report on the performance of new buildings. Its use is encouraged alongside the blower door test.

Additionally, several respondents, whilst recognising the positive contribution the pulse test method will make, felt that the proposals should go further and advocate for both positive and negative pressurisation testing to properly assess the construction and ascertain where remedial action is required. Two further respondents highlighted that pulse testing cannot assist with fault finding.

Several respondents discussed how the speed, portability, and ease of operation of pulse testing will increase capacity and create a competitive market.

A few respondents stressed that they would only support the introduction of the pulse test method of airtightness testing if it is proven to be a direct equivalent of the current air tightness testing principals and call for evidence of its effectiveness.

In addition, a few respondents suggested that the pulse testing provides a cost-effective method of meeting the increase in the level of airtightness testing required.

A few respondents considered the pulse test method to be more representative of the conditions buildings are likely to experience once occupied with another stating it is less intrusive and less reliant on external weather.

A few respondents questioned if the pulse test method is sufficiently effective for low energy buildings, with one respondent noting that the pulse test method is only applicable for airtightness down to 1.5 m³/m².h and another raised concerns about its effectiveness in larger buildings.

3.17.4 Not in support of the proposal

Of the 14 comments made by respondents who stated that they did not support the introduction of the pulse test method of airtightness testing as a further means to testing and reporting on the performance of new buildings; several stated they had no comment or felt they were not in a position to comment.

A few respondents felt the introduction of the pulse test method would cause confusion in the industry by providing two sets of results one at 4 Pa and the other 50Pa.

A few other respondents raised concerns that there is currently only one supplier of pulse air testing equipment and, as such, Building Regulations should not be promoting the use of that method.

A few respondents questioned whether the pulse test has yet been proven to be consistently accurate, particularly for very airtight buildings. Similarly, a further respondent questioned its effectiveness for large scale or complex buildings.

3.17.5 Non-responders

Of the 14 comments made by the respondents who elected not to answer the multiple-choice question, the majority either stated they had no comment or, explained they did not feel qualified to provide a response. Two substantive comments were made.

• The first stated support for the introduction of the pulse test method as it is better than testing once at 50Pa.
• Conversely, the other respondent stated that they do not support the proposal as they feel it would create confusion in the industry giving results at 4 Pa rather than 50Pa.

3.17.6 (in relation to Question 17) Are there any particular benefits, risks, or limitations you would seek to identify?

There were 69 responses received in total to this question and 52 responses to the following open question where respondents were asked to provide more detail to support their answer. Sixteen respondents provided an open response but did not answer the multiple-choice question.

Base: 69 respondents (107 no response) NB Individual respondents are listed separately at the bottom for information - as they are included in organisation responses (per Section 2.3)

3.17.7 Analysis

A marginal majority of respondents (57%) state there are no particular benefits, risks, or limitations they would seek to identify (Figure 23).

The majority of those stating there were no particular benefits, risks, or limitations they would identify, provided no further comment.

Of those who stated there were particular benefits, risks, or limitations they would seek to identify, 29 provided further comment.

Benefits were specified by several respondents and include: a greater scope of choice of tests (and testers); pulse testing possible in adverse weather conditions; and that the pulse testing is easier to undertake allowing it to be completed more often throughout the construction process.

3.17.8 Risks identified by respondents

• An increased use of MVHR use as a result of the requirement for air tightness and focus on increased fabric performance.
• Developers must identify the risk(s) of using alternative test method, especially with regard to the absence of fault diagnosis.
• Ventilation & airtightness - consideration required as to how the airtightness and ventilation requirements are met (and balanced) so as to not impact to on the health and safety of occupants.
• Standards are considered in isolation - other aspects such as thermal bridging should be considered.
• Shortage of suitably trained and competent operatives.
• Lack of awareness in Scotland.

3.17.9 Limitations identified by respondents

• The capability of pulse testing to produce detailed diagnostics to identify any weak points in the building fabric.
• Accuracy and/or reliability of pulse.
• Training - current level of knowledge will need to be increased in order to deliver the net zero and higher standard in an affordable market.
• Equipment availability and/or supply.
• The effectiveness of pulse testing in a large scale or complex building requires further research.
• Maximum permeability rates need improved to Passivhaus level.
• Weight of kit and length of time to set up and charge.

3.17.10 Additional points from respondents who did not answer the multiple-choice question

Sixteen comments were received from those respondents who did not provide a response to the multiple-choice question; however, 11 stated they had no comment or that they did not feel qualified to answer the question.

The remaining five respondents highlighted what they view to be the benefits, risks, and limitations:

Benefits

• Greater consistency
• Less reliance on external factors/weather
• Speed of deployment
• Cost of deployment

Risks and/or limitations

• Introduction of further method adds complexity (and comparability of the two methods is unknown)
• Effectiveness for testing timber frame buildings
• Doesn’t support diagnosis of building defects
• Higher cost

3.18 Modular buildings – Non-domestic

3.18.1 Quesiton 18

Do you consider the amended provision provides an appropriate balance between: the requirement to improve building energy performance in new buildings; enabling the reuse of better performing modular elements; and enabling use of small units for short term use at short notice?

There were 64 responses received in total to this question and 56 responses to the following open question where respondents were asked to provide more detail to support their answer. Eighteen respondents provided an open response but did not answer the multiple-choice question.

Base: 69 respondents (107 no response) NB Individual respondents are listed separately at the bottom for information - as they are included in organisation responses (per Section 2.3)

3.18.2 Analysis

The majority of responses to the question were positive with 89% of respondents stating they do consider the amended provision provides an appropriate balance between: the requirement to improve building energy performance in new buildings; enabling the reuse of better performing modular elements; and enabling use of small units for short term use at short notice (Figure 24). Eleven per cent of respondents did not support the proposal.

3.18.3 Support for the proposal

Further comments made by several respondents focused on modular, stating that amended provision to Modular Non-Domestic Buildings does enable the continued use of existing stocks of building modules and sub-assemblies, subject to the fabric insulation meeting limiting U-values. Respondents predominantly believed the proposal strikes an appropriate balance between reuse of modules and sub-assemblies, and the need to reduce energy use.

Three respondents submitting a campaign response stated that they would welcome the Scottish Government’s views on the proposed simplification achieved by setting of a single set of values for all building work to new and existing buildings.

A few additional comments were made: consideration should be given to a restriction on the oversize of limited life modular buildings; building owners should commit to reuse and recycling at the outset (it is an important driver for a circular economy); material availability is an important limiting factor.

3.18.4 Not in support of the proposal

Seven respondents state they do not consider the amended provision provides an appropriate balance between: the requirement to improve building energy performance in new buildings; enabling the reuse of better performing modular elements; and enabling use of small units for short term use at short notice. Four respondents did not provide any comment to support their view.

3.18.5 Non-responders

Those who provided further comment without offering a response to the multiple-choice question, primarily stated they had no comment or felt they were not in a position to comment. Where comments were made, these were largely in support of the amended provision.

3.19 Further comments on setting performance targets for new buildings

3.19.1 Quesiton 19

We welcome any other comments you may wish to make on the proposed changes to the setting of performance targets for new buildings or the application of other amended provisions within Section 6 (energy) of the Technical Handbooks which apply to the delivery of new buildings.

There were 88 responses received in total to this open question where respondents were asked to provide their comments.

3.19.2 Analysis

Twenty-seven of those who provided comment in fact stated that they had ‘no comment’, 59 substantial comments were made by respondents. Points made commonly reinforce, repeat, and add emphasis to comments made in response to previous questions.

Many respondents refer to SAP and Passivhaus PHPP in their comments. Several state the need to move away from SAP as a measure of energy performance and the need to consider the use of Passivhaus PHPP (or an equivalent).

The timescales for the programme were commented on by several respondents.

Comments included:

• Clarification of what is expected to happen in 2024.
• Meeting the requirements within the timescales will be a challenge.
• A forward look would be helpful on future changes to building standards.
• The programme should be accelerated and a high as possible target set.

A few respondents suggest that the impact on and use of verifiers and certifiers should be considered.

A few respondents state that they would welcome further guidance that could be incorporated into the Technical Handbooks that will help inform designers and contractors on how to achieve net zero carbon.

A concise definition of zero direct emissions was requested by a few respondents.

3.19.3 Technical observations

• The notional specification for doors in non-domestic buildings is shown as 2.0, however, the limiting maximum U value for doors is 1.4 and 1.0.
• Allowance for not specifying an infiltration rate should be removed from the domestic handbook (6.2.4), and a design value made mandatory.
• The option to not have an air pressure test carried out if the default value of 15 was assigned should be removed (6.2.5).