Optimizing glass roof design for green buildings by evaluating co-benefit of indoor daylighting and cooling load

Glass roofs have become a pivotal element in the design of green buildings, playing a crucial role in balancing daylighting and heat gain performance. This research aims to investigate the cooling load and daylight illuminance under various glass roof design parameters. Firstly, three primary design parameters were identified and parameterized: tilt angle, material and skylight-to-roof area ratio (AR). Secondly, a simulation model was developed to evaluate the photothermal performance of glass roofs under four different materials. Thirdly, a co-benefit evaluation method was introduced to quantify the impacts of the design parameters of glass roofs on daylighting and heat gain performance. The results showed that co-benefit indicators rose from 0.56% to 30.95% with the increase in transparency and heat transfer efficiency. Amongst Materials 1 to 4, co-benefit variation grew from 0.002% to 7.15%, showing that the optimal glass roofing combination varied based on design parameters. Glass Roof Material 2, with a tilt angle of 10° and a skylight-to-roof AR of 10%, was identified as the optimal option. Finally, the co-benefit evaluation method for photothermal performance was applied to a real building. Co-benefit index gradually increased from 28.16% baseline to 71.04% for Material 2. The proposed method can generate optimal values for each type of building glass roofs, providing designers with valuable design recommendations tailored to their specific needs.