Comprehensive evaluation of energy and indoor-PM_2.5-exposure performance of residential window and roller blind control strategies

The window with a roller blind inside can have huge impacts on solar heat gains and the air exchange between indoor and outdoor environments, but its potential value in terms of improving both building energy efficiency and indoor air quality is poorly understood. This study examines cooling energy consumption and indoor PM_2.5 exposure concentrations from indoor and outdoor sources in Hong Kong dwellings under seven different window and roller blind control strategies. Dwellings with windows facing south were simulated for a selected week in April using EnergyPlus. The modelled control strategies (including conventional rule-based control and Genetic-Algorithm-based predictive control) accounted for thermal comfort and indoor and outdoor environmental conditions. A novel coupled-window-and-interior-roller-blind zone was developed in EnergyPlus and used to capture the impact of shading on ventilation performance. Results indicate that dwellings under the predictive window and roller blind control strategy used 55% less cooling energy than those with windows closed and roller blinds open, while meeting the World Health Organisation standard for PM_2.5 exposure (25 µg/m³). Comparisons between control strategies also show that shading windows (which were open) in the early morning led to an increase in cooling energy consumption, whilst opening windows at night and shading them with roller blinds in the first half of the night offered the co-benefits of cooling through increased ventilation and the ability to reduce indoor PM_2.5 exposure.