Determining the principles for a Scottish equivalent to the Passivhaus standard - Analysis of Consultation Responses

2. Defining a Scottish equivalent to the Passivhaus standard

Section 2 of the consultation paper summarised the current building standards on energy and environmental performance, as set out within sections 3, 6 and 7 of the Building Standards Technical Handbooks, and provided an overview of the Passivhaus standard with commentary on its voluntary application. In the context of nationally applicable standards, this chapter presents respondents' views on introducing a Scottish equivalent to the Passivhaus standard, focusing on defining what 'equivalent' should or should not mean to identify the components of an equivalent standard.

Q1. Do you broadly agree with the statements on what 'equivalent' should not mean, in delivery of amended building standards to address energy and environmental performance?

Please provide information on why you agree or disagree or if you consider other actions need to be considered.

Among those answering Q1 (89% of all respondents), two thirds (65%) broadly disagreed with the statements on what 'equivalent' should not mean, while 35% agreed. Disagreement was higher among individuals than organisations at 80% and 48% respectively.

Opinions varied considerably by organisation type. While all contractor/developers, 78% of local authorities and 71% of housing providers/RSLs (Registered Social Landlords) who answered agreed, 71% of designer/consultants disagreed. Opinion was relatively evenly split among industry associations and manufacturers, with 53% of both groups agreeing and 47% disagreeing.

Almost nine tenths of all respondents commented at Q1 to explain their answer. The most common theme, reflecting the disagreement recorded at the closed question, was widespread opposition to not expecting the standard to require a similar level of prescription as the Passivhaus standard on key energy-relevant elements of building specification. However, many respondents supported the other two statements presented in the consultation paper.

Set a similar level of prescription

Many respondents disagreed with the suggestion that 'equivalent' should not necessarily mean a standard is set that requires a similar level of prescription on key energy-related elements of building specification. Respondents frequently highlighted that Passivhaus metrics had been developed over more than 30 years and should not be relaxed due to the potential for unintended consequences. Most commonly, the potential for poor building performance was raised. It was noted the Passivhaus standard is not about specific building specifications but is prescriptive on absolute energy and comfort.

While this was the most common theme, a few held the opposite view and agreed that the standard did not have to require prescription.

Agreement with the proposals

The suggestion that 'equivalent' should not necessarily mean Passivhaus is adopted for all new developments was supported by many, and several endorsed that outcomes did not necessarily mean that standards must consistently achieve built outcomes at least as good as Passivhaus. Both of these proposals were commonly supported together; though reasons were rarely provided, a preference for flexibility and pragmatism was evident.

Some also expressed agreement with the proposals to have a Scottish equivalent to the Passivhaus standard. Reasons included to allow flexibility and be less prescriptive and to give time to transition, such as in upskilling. These issues are discussed in later questions.

Use full Passivhaus, not an 'equivalent'

There were calls by several to use the full Passivhaus approach, while some advocated that the 'equivalent' should use the same or similar levels of prescription as Passivhaus. Points included that prescription was a key part of Passivhaus' success, that design could still be flexible while focused on quality performance, and that metrics developed over many years should not be diluted and risk less effective options. Some also emphasised the use of absolute metrics over specific building specifications.

Concerns over using Passivhaus

Some raised concerns over using Passivhaus, though it was not always clear whether they were referring to the Passivhaus methodology or the 'equivalent' Passivhaus approach. Views included that it would drive up costs, that it could not be delivered at scale or that it might stifle house building. The need for flexibility was emphasised by some, such as retaining the voluntary nature of Passivhaus or allowing exemptions for remote rural areas or for particular buildings.

Other themes

Some highlighted perceived risks of amending existing building standards requirements, such as concerns using only part of Passivhaus could impact its reliability, or mandating parts of a standard that are currently voluntarily applied, or commented more generally, for instance, on the need for clear metrics and standards. The Common Weal felt it would depend on which outcomes were under consideration, noting there would be cases where specific outcomes could be prioritised over energy efficiency, for instance, such as tackling embodied carbon^[4]. One industry association suggested removing the word 'necessarily' suggesting this was open to challenge.

Q2. Do you broadly agree with the statements on what 'equivalent' should require consideration of, in delivery of amended building standards to address energy and environmental performance.

Please provide information on why you agree or disagree or if you consider other actions need to be considered.

Within the consultation paper, the Scottish Government listed twelve bullet point statements on what 'equivalent' should require consideration of, setting out the rationale for the proposed approach to delivering change through the building standards system.

Among those answering Q2 (88% of all respondents), 63% broadly disagreed with the statements on what 'equivalent' should require consideration of, while 37% agreed. Four in five individuals disagreed (79%), compared to just under half of organisations (45%).

Opinions again varied considerably by organisation type, and in a similar pattern to Q1. While all professional bodies, 94% of contractor/developers, 88% of local authorities and 71% of housing providers/RSLs who answered agreed, 70% of designer/consultants disagreed. Opinion was more evenly split among industry associations (53% agreed) and manufacturers (60% agreed).

Almost all respondents left an open comment in response to this question. Most commonly, respondents disagreed with point four in the list of considerations, that 'equivalent' should require "There is an understanding of differences in outcome due to the application of our respective processes, including chosen calculation methodologies". While this was the most prevalent theme, the next most common was broad agreement with some or all the statements on what 'equivalent' should require. More specifically, many also raised concerns over how 'equivalent' would be measured.

Methods should match performance in-use

Many disagreed with the assertion that equivalent should require "There is an understanding of differences in outcome due to the application of our respective processes, including chosen calculation methodologies". Respondents felt it was important that methodologies should aim to match in-use performance and produce consistent outcomes. The need for clarity and transparency to allow occupants to understand and assess performance was highlighted.

In-use performance refers to a process that evaluates how well a building performs after it has been constructed and occupied. Using accurate calculation tools was viewed as an important way to close the performance gap, or the difference between predicted energy use at the design stage compared to the actual energy use of buildings in operation. A performance gap can result in a building not performing as intended.

Agreement with the proposals

Agreement with some, most or all of the twelve specific considerations presented in the consultation paper, or with the proposals more broadly, was given by many. The most prevalent view was agreement with all points excluding points four and five, though a few agreed with all the proposals, or gave broad support.

Comparing outcomes to Passivhaus

Point five in the consultation paper proposes that a requirement would be that "We are able to illustrate how the outcomes of our standards currently compare with those of Passivhaus certified projects". Many respondents questioned how comparable outcomes to those of Passivhaus certified projects could be demonstrated, for instance, due to Passivhaus and building standards metrics not being directly comparable.

Several suggested that the health and comfort metric of the Passivhaus standard should be included, or would need to be included, to meet this standard. Commonly respondents felt this would not be possible should standards not include the Passivhaus metrics on health and comfort.

Comments on air quality and using Mechanical Ventilation with Heat Recovery (MVHR)

Several commented regarding point 10, that "Any confirmed approach should not result in barriers to use of specific solutions or to the voluntary application of higher standards than those set under our regulations". The most prevalent view was that if the Passivhaus approach was applied, it meant some solutions to ventilation might work better than others or be ruled out, therefore the approach could result in barriers to specific solutions. Other views included that indoor air quality criteria should be considered, that the focus should be on outcomes rather than solutions, and that the market should be free to develop solutions for achieving metrics and comfort criteria.

Comments on developing the standard

A wide range of suggestions were provided on how the standard should be developed or delivered in practice. Some emphasised the need for flexibility in the approaches used, or alternatively, felt all aspects of Passivhaus should be adopted (see Q1). A few felt more clarity was needed, such as how it applied to different building types or noted the need to avoid manufacturers having to supply two product ranges, one for Passivhaus and the other for the 'equivalent' Passivhaus. A few others commented on carbon emissions (see Q14), raised concerns about using Passivhaus (see Q1), or emphasised the need for robust assurance mechanisms (see Q14).