Investigating the impacts of home energy retrofit on the indoor environment through co-simulation: A UK case study
Yan Wang, Giorgos Petrou, P. Symonds, Shih-Che Hsu, James Milner, Emma Hutchinson, Michael A. Davies, Helen L. Macintyre
Abstract
A large-scale home energy efficiency (HEE) retrofit programme is required to reduce the UK building stock's carbon footprint. However, retrofits that lack adequate ventilation can deteriorate indoor air quality and result in adverse health effects. Research shows trickle vents (TrVs), recommended for installation following retrofit and presumed to remain open under the new Approved Document F (ADF) schema, are often found closed in homes. This paper quantifies the impacts of HEE retrofit and TrV use on indoor pollutant exposure and overheating risk, as one of the earliest research efforts to evaluate the potential impacts of HEE measures on the indoor environment following the latest ADF. A novel thermal-IAQ co-simulation technique using EnergyPlus and CONTAM was applied to archetypical models with different physical and environmental characteristics: a terraced house in London and a bungalow in Plymouth. The analysis considers exposures to indoor radon, formaldehyde, fine particulate matter (PM 2.5 ), nitrogen dioxide (NO 2 ), and overheating risk. Results reveal that the effect of HEE retrofit depends on pollutant type and TrV operation. Radon and formaldehyde exposures reduce post-retrofit when TrVs are continuously open but rise when kept closed. In contrast, HEE measures marginally increase PM 2.5 exposure but reduce NO 2 exposure when TrVs are open, while slightly increasing exposures to both pollutants when TrVs are closed. Furthermore, HEE retrofit without adaptation can escalate overheating risk. These findings underscore the importance of considering both HEE retrofit strategies and TrV use to mitigate indoor pollutant exposure and overheating in UK homes. • EnergyPlus-CONTAM co-simulations were used to model the indoor environment. • The effect of home energy efficiency retrofit depends on pollutant type. • The operation of trickle vents affects post-retrofit indoor air pollutant levels. • Home energy efficiency retrofit without adaptation can escalate overheating risk.