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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.

A data set of airtightness test results was statistically analysed by applying probabilistic model of the distribution and using Bayesian parameter estimation techniques.

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.

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.

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.

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.

Ventilation is driven by weather conditions, occupant actions and mechanical ventilation, and so can be highly variable. This paper reports on the development of two analysis algorithms designed to facilitate investigation of ventilation in occupied homes over time.

These algorithms facilitate application of the CO₂ concentration decay tracer gas technique. The first algorithm identifies occupied periods. The second identifies periods of decaying CO₂ concentration which can be assumed to meet the assumptions required for analysis.

The algorithms were successfully applied in four occupied dwellings, giving over 100 ventilation measurements during a six-month period for three flats. The specific implementation of the decay identification algorithm had important ramifications for the ventilation rates measured, highlighting the importance of interrogating the way that appropriate periods for analysis are identified.

The analysis algorithms provide robust, reliable and repeatable identification of CO₂ decay periods appropriate for ventilation rate analysis. The algorithms were coded in Python, and these have been made available via GitHub. As well as supporting future CO₂ tracer gas experiments, the algorithms could be adapted to different purposes, including the use of other tracer gases or exploring occupant exposure to indoor air pollution.

Empirical investigations of ventilation in occupied dwellings rarely aim to investigate the variability of ventilation. This paper reports on analysis methods which can be used to address this gap in the empirical evidence.

Millions of properties have suspended timber ground floors globally, with around ten million in the UK alone. However, it is unknown what the floor void conditions are, nor the effect of insulating such floors. Upgrading floors changes the void conditions, which might increase or decrease moisture build-up and mould and fungal growth. The purpose of this paper is to provide a review of the current global evidence and present the results of in situ monitoring of 15 UK floor voids.

An extensive literature review on the moisture behaviour in both uninsulated and insulated suspended timber crawl spaces is supplemented with primary data of a monitoring campaign during different periods between 2012 and 2015. Air temperature and relative humidity sensors were placed in different floor void locations. Where possible, crawl spaces were visually inspected.

Comparison of void conditions to mould growth thresholds highlights that a large number of monitored floor voids might exceed the critical ranges for mould growth, leading to potential occupant health impacts if mould spores transfer into living spaces above. A direct comparison could not be made between insulated and uninsulated floors in the sample due to non-random sampling and because the insulated floors included historically damp floors. The study also highlighted that long-term monitoring over all seasons and high-resolution monitoring and inspection are required; conditions in one location are not representative of conditions in other locations.

This study presents the largest UK sample of monitored floors, evaluated using a review of current evidence and comparison with literature thresholds.

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.

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.

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.

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.

THE following list of contracts placed 1 y the Air Ministry during July has been extracted from the August issue of The Ministry of Labour Gazette:—

Food—national dietary standards—is a sensitive index of socio‐economic conditions generally; there are others, reflecting different aspects, but none more sensitive. A country that eats well has healthy, robust people; the housewife who cooks hearty, nourishing meals has a lusty, virile family. It is not surprising, therefore, that all governments of the world have a food policy, ranking high in its priorities and are usually prepared to sacrifice other national policies to preserve it. Before the last war, when food was much less of an instrument of government policy than now—there were not the shortages or the price vagaries—in France, any government, whatever its colour, which could not keep down the price of food so that the poor man ate his fill, never survived long; it was—to make use of the call sign of those untidy, shambling columns from our streets which seem to monopolize the television news screens—“out!” Lovers of the Old France would say that the country had been without stable government since 1870, but the explanation for the many changes in power in France in those pre‐war days could be expressed in one word—food!

The effects of dust exposure in buildings and its health and comfort consequences continue to concern occupants, particularly those who spend most of their time indoors. This study examines the influence of building opening characteristics on surface dust loading in indoor environments to determine the dust particles' impact on different opening configurations.

Indoor Harmattan dust surface loading data were collected from Maiduguri, Northeastern Nigeria, using model rooms with six different window configurations. A simple mathematical relationship was employed to assess surface dust loading characteristics in the model rooms. The study measured dust thrice between December and February for three days (72 h). The results were analyzed using descriptive statistics.

The results determined the highest average surface dust loading of 12.03 g/m2 in the room with awning windows at an indoor-to-outdoor (I/O) ratio of 0.7. In contrast, the experiment in the room with a closed window recorded the lowest average surface dust loading of 5.24 g/m2 at an I/O ratio of 0.30, which is infiltration. The outcomes further indicate that the average surface dust loading varies with the building opening type and position, as higher surface dust loadings were recorded in locations closer to the openings (doors and windows), reaffirming that the dominant source of the dust particles is outdoors. According to the study, dust incursion due to infiltration accounts for 30% of the outdoor surface loading.

Thus, Harmattan dust is a serious challenge to the health, productivity and hygiene of building occupants in the study area. The built-environment professionals must use the study's outcome to optimize building openings' designs (shape, size and form) for effective indoor dust control.