Jenny Crawley, Phillip Biddulph, Jez Wingfield, Minnie Ashdown, Robert Lowe and Cliff Elwell
Compulsory airtightness testing was introduced for new dwellings in England and Wales in 2006 and in Scotland in 2010 to ensure that they are constructed according to design air…
Abstract
Purpose
Compulsory airtightness testing was introduced for new dwellings in England and Wales in 2006 and in Scotland in 2010 to ensure that they are constructed according to design air permeability targets. These targets are set to limit heat loss through air infiltration. Previous work examining the large Air Tightness Testing and Measurement Association (ATTMA) data set of UK airtightness test data suggested that, in a proportion of dwellings, the targets were being met by post-completion sealing as opposed to airtight construction, but did not quantify the prevalence of this practice. The paper aims to discuss this issue.
Design/methodology/approach
In this paper, the distribution of as-built airtightness and the proportion of dwellings undergoing post-completion sealing are estimated from the ATTMA data set covering 2015–2016. This is carried out by Bayesian statistical modelling, using the data set of recorded test results and a modelled representation of the testing process.
Findings
This analysis finds the mode of the as-built distribution of air permeability as 4.38 ± 0.01 m3/m2h. It predicts that 39 per cent of dwellings aiming for one of the five most common design targets have sealing interventions at the point of pressure testing to meet their target. The as-built distribution of the ATTMA data is compared to airtightness test data obtained from just before compulsory testing was introduced, showing an improvement in the modal air permeability of 3.6 m3/m2h since testing became mandatory.
Originality/value
This paper has investigated the available data beyond simply what is reported, to estimate what the real levels of airtightness in the UK new build stock may be.
Details
Keywords
Minnie M.A. Ashdown, Jenny Crawley, Phillip Biddulph, Jez Wingfield, Robert Lowe and Clifford A. Elwell
The purpose of this paper is to investigate the distribution of dwelling airtightness test results for a developer, between 2007 and 2011. The changes in airtightness test results…
Abstract
Purpose
The purpose of this paper is to investigate the distribution of dwelling airtightness test results for a developer, between 2007 and 2011. The changes in airtightness test results over time are discussed, and links between the airtightness test results and the construction technique are investigated.
Design/methodology/approach
A data set of airtightness test results was statistically analysed by applying probabilistic model of the distribution and using Bayesian parameter estimation techniques.
Findings
The inferred background distributions, those estimated to describe dwelling performance before secondary sealing, suggest an improvement in airtightness between 2008 and 2011, the mode decreases from 5.46±0.09 m3/m2h to 4.12±0.07 m3/m2h with a corresponding shift in practice towards a more target-driven approach. The most airtight dwellings are constructed from reinforced concrete frame, followed by “traditional” (dry lined masonry), timber frame and lightweight steel frame.
Research limitations/implications
This study is limited by the size of the available data set (901 dwellings), and by the fact that the data set contains a larger proportion of flats to houses; however, the metadata has enabled the exploration of the link between construction practices and airtightness.
Practical implications
Developers need better guidance surrounding how to meet more stringent airtightness requirements through improvements to the primary air barrier, with incentives and support to deliver changes in practice. Furthermore, if a large number of dwellings undergo secondary sealing, this may have implications for the long-term efficiency of the dwelling stock.
Originality/value
This analysis investigates two issues that have not previously been studied on a significant number of dwellings: the changes to the distribution of airtightness results over time and the link between construction methods and airtightness.
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IN this number, as is our custom at this time of the year, we turn our attention to the coming Annual Meeting of the Library Association. The choice of Leeds as a venue for the…
Abstract
IN this number, as is our custom at this time of the year, we turn our attention to the coming Annual Meeting of the Library Association. The choice of Leeds as a venue for the Conference, coming as it does after Glasgow and Birmingham, is a proof to those who need it of the earnestness which actuates the Council, and the members, of the Library Association. We note that our colleagues the accountants, surveyors and others, have a weakness for Torquay, Southport and Scarborough for their serious annual deliberations; and such a choice has one advantage: it encourages members of committees to join their officers at the meetings. There are compensations, however, as any wise man will recognise. The library movement succeeds, in so far as it is able to convince the great centres of population of its value. Meeting in them has, therefore, a primary political value, if we may use that term in this connection ; and it has a secondary professional one in that in such great towns a really complete and active application of library work can be seen.