Application of an indoor air pollution metamodel to a spatially-distributed housing stock

Jonathon Taylor; Clive Shrubsole; Phil Symonds; Ian Mackenzie; Mike Davies

doi:10.1016/j.scitotenv.2019.02.341

Application of an indoor air pollution metamodel to a spatially-distributed housing stock

Sci Total Environ. 2019 Jun 1:667:390-399. doi: 10.1016/j.scitotenv.2019.02.341. Epub 2019 Feb 25.

Authors

Jonathon Taylor¹, Clive Shrubsole², Phil Symonds², Ian Mackenzie³, Mike Davies²

Affiliations

¹ UCL Institute for Environmental Design and Engineering, Central House, 14 Upper Woburn Plc, London WC1H 0NN, UK. Electronic address: j.g.taylor@ucl.ac.uk.
² UCL Institute for Environmental Design and Engineering, Central House, 14 Upper Woburn Plc, London WC1H 0NN, UK.
³ University of Edinburgh School of GeoSciences, Crew Building, The King's Buildings, Alexander Crum Brown Road, Edinburgh EH9 3FF, UK.

Abstract

Estimates of population air pollution exposure typically rely on the outdoor component only, and rarely account for populations spending the majority of their time indoors. Housing is an important modifier of air pollution exposure due to outdoor pollution infiltrating indoors, and the removal of indoor-sourced pollution through active or passive ventilation. Here, we describe the application of an indoor air pollution modelling tool to a spatially distributed housing stock model for England and Wales, developed from Energy Performance Certificate (EPC) data and containing information for approximately 11.5 million dwellings. First, we estimate indoor/outdoor (I/O) ratios and total indoor concentrations of outdoor air pollution for PM_2.5 and NO₂ for all EPC dwellings in London. The potential to estimate concentration from both indoor and outdoor sources is then demonstrated by modelling indoor background CO levels for England and Wales pre- and post-energy efficient adaptation, including heating, cooking, and smoking as internal sources. In London, we predict a median I/O ratio of 0.60 (99% CIs; 0.53-0.73) for outdoor PM_2.5 and 0.41 (99%CIs; 0.34-0.59) for outdoor NO₂; Pearson correlation analysis indicates a greater spatial modification of PM_2.5 exposure by housing (ρ = 0.81) than NO₂ (ρ = 0.88). For the demonstrative CO model, concentrations ranged from 0.4-9.9 ppm (99%CIs)(median = 3.0 ppm) in kitchens and 0.3-25.6 ppm (median = 6.4 ppm) in living rooms. Clusters of elevated indoor concentration are found in urban areas due to higher outdoor concentrations and smaller dwellings with reduced ventilation potential, with an estimated 17.6% increase in the number of living rooms and 63% increase in the number of kitchens exceeding recommended exposure levels following retrofit without additional ventilation. The model has the potential to rapidly calculate indoor pollution exposure across large housing stocks and estimate changes to exposure under different pollution or housing policy scenarios.

Keywords: Air pollution; Building physics; I/O ratios; NO(2); PM(2.5).

Grants and funding

WT_/Wellcome Trust/United Kingdom