Indoor PM2.5 exposure in London's domestic stock: Modelling current and future exposures following energy efficient refurbishment

Building Services Engineering Research and Technology

et al. 2015

Indoor temperature and air quality in dwellings are closely coupled. Differences between the indoor temperature and the temperature outside and in adjoining zones can influence airflow due to the stack effect, whilst changes in ventilation can cause changes in indoor pollution and temperature. This paper demonstrates the relationship between an indoor air pollutant, PM 2.5 , and temperature in UK domestic building archetypes using the dynamic thermal and contaminant modelling capabilities of EnergyPlus 8.0 under various UK Climate Projections 2009 (UKCP09) scenarios (current, current 'hot', 2050 High Emissions and 2050 High Emissions 'hot'), with both internal and external PM 2.5 sources. Results indicate that flats have 0.7-0.8 times as much outdoor PM 2.5 infiltrating indoors compared to detached dwellings, but 1.8-2.8 times more PM 2.5 from indoor sources. During hot periods, temperature-dependent window opening increases exposure to outdoor PM 2.5 , meaning that as temperatures rises, dwelling occupants will become exposed to relatively higher levels of outdoor PM 2.5 and lower levels of indoor PM 2.5 due to the need to increase dwelling ventilation. The practical implications for government and designers and possible policy implications of this research are discussed. Practical applications: This paper demonstrates how an increase in summertime ventilation is necessary in UK homes to reduce overheating risks due to climate change and energy-efficient building retrofits. This, in turn, will lead to a change in the profile of indoor air pollution exposure, with greater exposure to pollution from outdoor sources and reduced exposure to pollution from indoor sources. Roof insulation and trickle vents reduce overheating risk, whilst increased use of mechanical ventilation heat recovery systems in the UK is encouraged, as it offers the co-benefits of cooling through increased ventilation, energy recovery and the potential to reduce indoor pollution levels.

Section: Discussionmentioning

confidence: 99%

“…29 Due to the different size fraction of PM 2.5 from tobacco smoke, deposition for smoking was modelled at 0.10 h À1 . 30 The schedule of cooking, smoking and ventilating activities, obtained from Shrubsole et al 14 can be seen in Table 3. …”

Section: Occupancy and Pollutant Modellingmentioning

confidence: 99%

Understanding and mitigating overheating and indoor PM_2.5 risks using coupled temperature and indoor air quality models

Taylor

Mavrogianni

Building Services Engineering Research and Technology

et al. 2015

“…These values were based on a model for a single housing archetype, for which we modelled the hourly indoor concentrations over a year using a range of plausible annual average outdoor concentrations in the UK. Further details of the modelling methods are described in Shrubsole et al (2011) [3].…”

Section: Parameterizing a Health Impact Calculationmentioning

confidence: 99%

An Exposure-Mortality Relationship for Residential Indoor PM2.5 Exposure from Outdoor Sources

Milner

Armstrong

et al. 2017

Climate

A large proportion of particulate air pollution exposure in urban areas occurs due to the penetration of outdoor pollution into the residential indoor environment. Theoretical considerations suggest that quantifying health effects due to changes to indoor particulate concentrations derived from outdoor sources requires the adjustment of exposure-response coefficients based on epidemiological studies of outdoor air. Using the PM 2.5 -mortality coefficient from the American Cancer Society (ACS) cohort study as an example, we developed a theoretical model to quantify the relationship between the published coefficient and one based on personal exposure, and explored how this adjusted coefficient might be applied to changes in indoor PM 2.5 from outdoor sources. Using a probabilistic approach, our estimated average mortality coefficient for personal PM 2.5 exposure is 30-50% greater than the ACS coefficient. However, since the indoor PM 2.5 of outdoor origin accounts for only a proportion of the overall exposure, the average net adjustment required for indoor exposure is very modest. The results suggest that it is generally appropriate to apply unadjusted exposure-response functions derived from cohort studies to assess the health impact of changes in indoor particle concentrations from outdoor sources. However, it may be important to re-scale the coefficients for assessing exposures of population groups who spend a greater proportion of their time at home.

“…To demonstrate the potential of DOMVENT3D, it is used to estimate the range of infiltration rates one might expect to find in a typical UK detached house 15 12 and are applied for open, rural and urban terrain. The floor and ceiling are assumed to be completely shielded from the effects of the wind.…”

Section: Applicationsmentioning

confidence: 99%

“…2 Figure 3 suggests that this house could require additional purpose provided ventilation, which when applied with other mitigating measures 15 would help to reduce risks to the health of its occupants. This type of finding should be of interest to both engineers and policy makers.…”

Section: Applicationsmentioning

confidence: 99%

Modelling uniformly porous facades to predict dwelling infiltration rates

Jones

Lowe

Building Services Engineering Research and Technology

et al. 2013

It is important to limit dwelling infiltration to reduce energy demand and help meet national climate change commitments while concurrently providing sufficient ventilation to deliver adequate indoor air quality. DOMVENT3D is a model of infiltration and exfiltration that assumes a linear pressure distribution over any number of uniformly porous facades and integrates the airflow rate in the vertical plane to predict the theoretically correct airflow rate through them. DOMVENT3D is a new development of an existing two-dimensional model of infiltration that provides more opportunities for investigating a greater number of dwellings than was previously possible. Initial testing suggests that DOMVENT3D is mathematically robust and is suitable for modelling a wide variety of dwelling types and geometries to assist engineers and policy makers. Practical application: The modern building services engineer may be required to model airflow networks in a building to balance the conflicting needs of energy consumption reduction and occupant health. Limiting exfiltration is one method of reducing heat losses from a building and so there is a need to model it accurately. This article presents a new model of infiltration and exfiltration through a uniformly porous facade that can be incorporated within advanced complex airflow network tools or applied using a simple spreadsheet.