Can windcatcher's natural ventilation beat the chill? A view from heat loss and thermal discomfort

Windcatchers provide effective low-energy ventilation and summer passive cooling in temperate climates. However, their use in winter is limited due to significant ventilation heat loss and potential discomfort. Limited research has been conducted on quantifying windcatcher heat loss in cold climates, particularly through field studies. This study aims to evaluate the applicability of windcatchers in low-temperature conditions, with a focus on ventilation heat loss and thermal discomfort. Field experiments were conducted in Nottingham, UK, during an icy period. A 3D-printed prototype windcatcher and a test room were built and tested in such weather conditions. A Computational Fluid Dynamics (CFD) model validated against the field experimental data was employed to investigate the windcatcher's performance in a typical UK primary school classroom. The field experimental results indicate that the indoor airflow patterns are dynamic and continuously change with varying external wind conditions. Using static boundary conditions for ventilation analysis is inadequate, as it may lead to inaccurate predictions due to observed fluctuations and irregular airflow patterns. CFD modelling revealed significant overventilation in the classroom at external wind speeds of 3 m/s, despite being previously deemed as satisfactory, adequate, or sufficient ventilation. At wind speeds of 3 m/s or higher, the over-ventilation can cause a minimum 941.4 W heat loss, adding 4.7 kWh heating load and 1.6 pound electricity cost for a typical-sized single classroom during a 5-h occupied period. The research findings highlighted that control strategies should be introduced to reduce over-ventilation. Integrating heat recovery or thermal storage can enhance winter thermal conditions.

Automated summary

Windcatchers provide effective low-energy ventilation and summer passive cooling in temperate climates. However, their use in winter is limited due to significant ventilation heat loss and potential discomfort. This study evaluates the applicability of windcatchers in low-temperature conditions, highlighting the need for control strategies to reduce over-ventilation and the integration of heat recovery or thermal storage to enhance winter thermal conditions.