Heat stress monitoring, modelling, and mitigation in a dairy cattle building in reading, UK: Impacts of current and projected heatwaves

• Integrated realistic dairy cows’ heat dissipation into building thermal modelling. • 2021 UK Heatwave: severe heat stress in milking parlour while moderate in housing. • 2080s Heatwave: indoor heat stress severity predicted to Level 4 (Emergency). • Building adaptation strategies need to be tailored to housing and milking parlours. • Advanced building adaptation strategies are critical for combating future heatwaves. Heat stress in dairy cattle buildings is a pressing challenge under global warming. While building climate resilience is as critical as improving animal thermal resilience, limited research has evaluated the effectiveness of building adaptations in specific spaces, such as cattle housing and milking parlours, particularly under extreme climate conditions. This study addresses this gap by assessing the impacts of observed and projected heatwaves on dairy housing and a milking parlour and possible mitigation solutions, through indoor heat stress measurements and dynamic livestock building thermal modelling. We advance the modelling capability by incorporating realistic sensible and latent heat dissipation from dairy cattle, accounting for body mass, daily milk production, and ambient temperatures. Measurements during the 2021 UK Heatwave revealed consistently higher indoor Temperature-Humidity Index (THI) levels compared to outdoors. The milking parlour experienced more severe heat stress (Level 3: Severe) than the housing (Level 2: Moderate) due to higher internal heat gains and poor ventilation, with notable differences between morning and afternoon milking times. Projections for the 2080s heatwave indicated that both spaces would experience heat stress day and night, with severity reaching Level 4 (Emergency) for most of the time. Under current heatwave conditions, solar reflective roof paint proved effective for the housing, while hybrid ventilation was effective for the milking parlour. However, these strategies were insufficient for future extreme heatwaves, emphasizing the need for advanced, tailored building adaptations. This study highlights the critical importance of designing climate-resilient dairy buildings to safeguard animal welfare and productivity in a warming world.