Characterising the airtightness of dwellings: Its improvement over time and relationship to construction technique

• Published in: International Journal of Building Pathology and Adaptation 2020-02, Vol.38 (1), p.89-106
• Main Authors: Ashdown, Minnie M.A., Crawley, Jenny, Biddulph, Phillip, Wingfield, Jez, Lowe, Robert, Elwell, Clifford A.
• Format: Article
• Language: English
• Subjects: 20th century; Air flow; Airtightness; Building construction; Buildings; Concrete construction; Construction; Datasets; Dwellings; Emissions; Incentives; Masonry; Parameter estimation; Permeability; Plaster; Prime ministers; Probabilistic models; Reinforced concrete; Reinforcing steels; Sealing; Steel frames; Ventilation
• ISSN: 2398-4708; 2398-4716
• DOI: 10.1108/IJBPA-02-2019-0024

PurposeThe 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/approachA data set of airtightness test results was statistically analysed by applying probabilistic model of the distribution and using Bayesian parameter estimation techniques.FindingsThe 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/implicationsThis 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 implicationsDevelopers 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/valueThis 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.