How to choose a better envelope design? A balance between energy and daylighting performance

Abstract

Daylight has two characteristics: radiometry and photometry. Hong Kong is situated just south of the Tropic of Cancer and receives a lot of daylight which could generate more lighting energy savings but bring solar heat gain at the same time. This study appealed that the energy-efficient design should guarantee residents' luminous comfort level first. A dynamic daylight metric, average DA300 (Daylight Autonomy), was first tested to quantify occupants' luminous comfort by using statistical analysis with the data from questionnaire survey and climate-based simulation of 108 unit cases. The benchmark of Ave. DA300 is then found as 29.6 %. A new parameter EDR (Energy Daylight Rate) was also proposed to reflect the relation between daylighting performance and energy performance. Case study was conducted to optimize the green features' design and validate the utilization of EDR. The result showed the EDR could help optimize the envelope design at the early stage.