The Building Fabric Thermal Performance of Passivhaus Dwellings—Does It Do What It Says on the Tin?

Johnston, David; Siddall, Mark

doi:10.3390/su8010097

Cited by 21 publications

(15 citation statements)

References 8 publications

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“…Surveys of a modest sample of Passive House buildings were carried out in-situ [49] and supported the conclusion of research identified earlier that the Passive House standard was robust and gave predictable savings. Research has also shown however that some Passive House dwellings have exhibited some more marginal outcomes [50] and that there is some lack of information in published sources about performance.…”

Section: Review Of Previous Researchmentioning

confidence: 67%

“…I3 thought that for architects and associated designers, the use of the PHPP [49] enabled those professionals to see and to demonstrate value in their designs, and thus provide a reason to expend money achieving it. PHPP was an aid to support the businesses of recognized low energy designers as well as to others with a passing interest trying to understand what was required.…”

Section: Financial Costs and Benefitsmentioning

confidence: 99%

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Passive House and Low Energy Buildings: Barriers and Opportunities for Future Development within UK Practice

Pitts

2017

Sustainability

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This paper describes research carried out to understand better the current and future emphases emerging from practice for the design and development of "Passive House" and low energy buildings. The paper initially discusses the extant position, particularly with regards to the UK and considers how regulation and assessment systems have changed in recent years, as well as projecting ideas forward taking account of contemporary political situations. Relevant previous research into Passive House and low energy design and construction is then reviewed. The need for greater understanding of professionals and their communication/collaboration with clients were identified as important factors impacting development. Those involved in the design and construction practice therefore have key roles in the process of enhancing energy efficiency. Five industry/practice based professional organizations were interviewed in-depth to gain insights into their experience of current low energy design, and to extrapolate the outcomes to future scenarios. The method employed used a structured interview technique with key question areas to lead the discussion. The anonymized responses discussed are grouped around key themes. Evidence suggests there has been a move towards the adoption of voluntary high level standards because of potential limitations with mandatory regulations and because of perceived additional benefits of higher quality design. This change is now more than previously, being driven by informed clients, design professionals, and the industry, with regulation taking a secondary role. New opportunities and barriers are becoming evident and these require further consideration.

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Section: Review Of Previous Researchmentioning

confidence: 67%

Section: Financial Costs and Benefitsmentioning

confidence: 99%

Passive House and Low Energy Buildings: Barriers and Opportunities for Future Development within UK Practice

Pitts

2017

Sustainability

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“…Whilst such dwellings have been successfully tested [57], they carry higher inherent risk and increased relative uncertainties-particularly from unstable internal temperatures and underestimated HTCs due to stored solar components [56]. Whilst this could mean extended testing durations are required (e.g., 6-8 weeks [37]), longer tests are unlikely to reduce any bias and shorter, highly selective periods are likely to yield improved results.…”

Section: Discussionmentioning

confidence: 99%

Assessing the Relationship between Measurement Length and Accuracy within Steady State Co-Heating Tests

2017

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Evidence of a fabric performance gap has underlined the need for measurements of in situ building performance. Steady state co-heating tests have been used since the 1980s to measure whole building heat transfer coefficients, but are often cited as impractical due to their 2-4 week test duration and limited testing season. Despite this, the required conditions for testing and test duration have never been fully assessed. Analysis of field tests show that in 12 of 16 cases, a heat loss estimate to within 10% of the result achieved across a full test period can be achieved within just 72 h. These results are supported by simulated tests upon a wider range of dwellings and across wider environmental conditions. However, systematic errors may still exist, even in cases of convergence and cases with significant uncertainties may never converge. Simulated examples of traditional dwellings and those built in line with current building regulation limits may be tested for more than half the year. However, even when simulated with reduced uncertainties, dwellings with low heat loss and high solar gains, such Passivhaus dwellings and apartments, could be successfully tested for just 22% and 12% of a year respectively, demonstrating the limitations of the co-heating method in assessing such dwellings.

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“…Another study of 7 timber dwellings reported deviations in the range of 6-21% in 6 of the cases [51]; similarly, the fabric performance gap of 3 timber and masonry was found to vary from 6 to 18% [46]. Higher HLC values than calculated have been identified also in Passivhaus constructions, although the gap is generally of a lower magnitude.…”

Section: @50mentioning

confidence: 97%

“…It is defined as air leakage rate per hour per square metre of envelope area at a test reference pressure differential across the building envelope of 50 Pa. Accordingly, it is an inherent influencer of heating and [44] 6 ✓ × ✓ Gupta R, Kapsali M. 2015 [61] 6 ✓ ×× Johnston D, Siddall M. 2016 [51] 7× × ✓ AIMC4 2014 [41] 17 [40] 44 ✓ ✓ ✓…”

Section: Methods and Datamentioning

confidence: 99%

Magnitude and extent of building fabric thermal performance gap in UK low energy housing

Gupta

Kotopouleas

2018

Applied Energy

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• Air-permeability, U-value and whole house heat loss data were statistically tested.• Building fabric thermal performance gap was widespread in low energy dwellings.• Airtightness gap was trivial in Passivhaus but significant in non-Passivhaus units.• Gap increased by 0.8 m 3 /h/m 2 for every 1 m 3 /h/m 2 decrease in design air permeability.• Building regulations should require in-situ tests to reduce fabric performance gap. ARTICLE INFO Keywords:Building fabric Low energy dwellings Passivhaus Airtightness Heat loss Thermal transmittance Co-heating test ABSTRACT This paper presents new evidence from a nationwide cross-project meta-study investigating the magnitude and extent of the difference between designed and measured thermal performance of the building fabric of 188 low energy dwellings in the UK. The dataset was drawn from the UK Government's national Building Performance Evaluation programme, and comprises 50 Passivhaus (PH) and 138 non-Passivhaus (NPH) dwellings, covering different built forms and construction systems. The difference between designed and measured values of air permeability (AP), external wall/roof thermal transmittance (U-value) and whole house heat loss were statistically analysed, along with a review of thermal imaging data to explain any discrepancies. The results showed that fabric thermal performance gap was widespread especially in terms of AP, although the magnitude of underperformance was much less in PH dwellings. While measured AP had good correlation with measured space heating energy for PH dwellings, there was no relationship between the two for NPH dwellings. The regression analysis indicated that for every 1 m 3 /h/m 2 reduction in designed air permeability, the gap increased by 0.8 m 3 /h/m 2 @50 Pa. Monte Carlo analysis showed that likelihood of AP gap was 78% in NPH dwellings designed to 5 m 3 /h/m 2 @50 Pa or lower. The study provides useful evidence for improving the fabric thermal performance of new housing through in-situ testing.

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The Building Fabric Thermal Performance of Passivhaus Dwellings—Does It Do What It Says on the Tin?

Cited by 21 publications

References 8 publications

Passive House and Low Energy Buildings: Barriers and Opportunities for Future Development within UK Practice

Passive House and Low Energy Buildings: Barriers and Opportunities for Future Development within UK Practice

Assessing the Relationship between Measurement Length and Accuracy within Steady State Co-Heating Tests

Magnitude and extent of building fabric thermal performance gap in UK low energy housing

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