Quantifying the domestic building fabric ‘performance gap’

Johnston, David; Miles-Shenton, D; Farmer, David

doi:10.1177/0143624415570344

Cited by 71 publications

(69 citation statements)

References 6 publications

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“…If a house could be pre-heated whilst work access was maintained, then testing across a weekend or extended weekend may be feasible, certainly to a degree of accuracy that would diagnose dwellings with significant discrepancies that may warrant further investigation. On this final point it should be noted that tests to date have been reported to be 1.6 higher than predicted [7], meaning less stringent requirements for accuracy are likely to be required to identify significantly underperforming dwellings. After all, the co-heating HTC measurement only indicates the level of heat loss, not the underlying causes.…”

Section: Discussionmentioning

confidence: 97%

“…As the number of tests performed has increased, researchers have used these measured results to try and identify trends associated with this fabric performance gap [7], although higher sample sizes and wider ranges of buildings would both extend this analysis and add greater certainty to observed patterns. At one stage the method was touted as potentially playing a larger role in verifying performance in the UK, with the 2012 building regulation consultation indicating they "...might specify a level of sample testing (e.g., whole house fabric co-heating tests or equivalent carried out post completion but pre-occupation)" [34] (p. 51).…”

Section: Co-heating Methodsmentioning

confidence: 99%

“…= 0.35 W/m 2 K, range = 0.4-2.0 W/m 2 K). Whole house heat loss coefficient measurements from co-heating tests are estimated to be on average 1.6 times higher than predicted [7]. Further, rather than representing a zero heat loss element, party wall bypasses were found to constitute an effective U-value of approximately 0.6 W/m 2 K [8], requiring revised inputs to the UK building regulations and national calculation methodology [9,10].…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Discussionmentioning

confidence: 97%

Section: Co-heating Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

2017

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“…A body of evidence has been amassed which highlights a discrepancy between the predicted and as-built thermal performance of the building fabric which threatens to reduce the desired impact of these regulatory measures (Stafford et al [3] and Johnston et al [4]). This underperformance is commonly referred to as the 'performance gap'.…”

Section: Introductionmentioning

confidence: 99%

Obtaining the heat loss coefficient of a dwelling using its heating system (integrated coheating)

Farmer

Johnston

Miles-Shenton

2016

Energy and Buildings

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This paper presents the methodology, along with some of the initial findings and observations from tests performed on two dwellings, of differing construction and form, in which a coheating test was performed using the dwelling's central heating system; this method is referred to as integrated coheating. Data obtained during the integrated coheating tests using a dwelling's heating system have been compared with data obtained during electric coheating of the same dwelling. In one instance, integrated coheating test data from one dwelling was compared to a similar adjoining control dwelling that was simultaneously subject to an electric coheating test. The results show a good agreement between the heat loss coefficients (HLC) obtained using a dwelling's own heating system and those obtained through electrical coheating. Initial analysis suggests the HLC estimate obtained from integrated coheating is likely to be more representative of how a dwelling performs in-use. The findings question the appropriateness of comparing current steady-state HLC predictions to those derived from in-use monitoring data. Integrated coheating has the potential to provide a more cost-effective and informative indication of whole house heat loss than electric coheating, as it enables in situ quantification of both fabric and heating system performance.

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“…This can be because occupants were not instructed in how to use new technology, or they are reluctant to engage with the technology (Isaksson, 2014). In some cases, the gap between predicted and measured performance can be substantial: differences of greater than 100% have been documented (Carbon Trust, 2011;Johnston, et al, 2014;Johnston, Miles-Shenton & Farmer, 2015;Stafford, Bell & Gorse, 2012;Zero Carbon Hub, 2010). …”

Section: Introductionmentioning

confidence: 99%

Reflections on retrofits: Overcoming barriers to energy efficiency among the fuel poor in the United Kingdom

Fylan

Glew

Smith

et al. 2016

Energy Research & Social Science

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To meet targets on fuel poverty, energy efficiency and carbon emissions existing homes need to be more energy efficient. We report the results of a participatory action research project to explore the challenges associated with energy efficiency retrofit programmes and ways to better implement future schemes.Six focus groups were held with 48 participants from a range of energy efficiency roles. Data were analysed thematically using the research question "What are the challenges presented by implementing energy efficiency retrofit programmes".We identified four themes in the data: Funding mechanisms; Predicting performance; Installation; and People. Challenges include funding mechanisms for retrofit programmes resulting in insufficient time to plan, publicise, implement and evaluate a scheme and insufficient flexibility to specify the most appropriate intervention for individual homes. Site workers sometimes need to adapt retrofit designs because of insufficient detail from the designer and can equate quality of installation with quality of finish. Landlords and occupier behaviour can impact on the programme's success and there is a need for greater information on benefits for landlords and for energy behaviour change interventions run alongside retrofit programmes for occupiers. There is a need for outcome evaluations of retrofit schemes with the results shared with stakeholders.

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Quantifying the domestic building fabric ‘performance gap’

Cited by 71 publications

References 6 publications

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

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

Obtaining the heat loss coefficient of a dwelling using its heating system (integrated coheating)

Reflections on retrofits: Overcoming barriers to energy efficiency among the fuel poor in the United Kingdom

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