Daylighting and cooling of atrium buildings in warm climates: Impact of the top-fenestration and wall mass area.

摘要

Sunlighting and daylighting contribute greatly to the aesthetic value of an atrium. However, today's atria are often found either overlit with extensive cooling loads, or underlit requiring increased artificial lighting loads. The increase of the top-glazing area increases the cooling loads and decreases the lighting loads. The increase of the mass in the atrium walls decreases the maximum atrium temperature and the cooling loads. Furthermore, the mass distribution and its reflectance affect the lighting levels at the atrium floor.; The purpose of this study is to investigate the simultaneous impact of the top-fenestration and the mass and reflectance of atrium walls on the cooling and daylighting performance of atria in warm climates. It attempts to determine the optimum top-fenestration for efficient daylighting and low cooling loads.; The daylighting performance was evaluated through illumination measurements in physical models in a sky simulator. The cooling performance was evaluated using the software TRNSYS 13.1. Two types of top-fenestration were tested: horizontal and vertical south-facing, each with three alternate areas. The variations of the atrium walls included materials (standard frame and heavyweight concrete) and percentage and reflectance of the solid area. Two and four-story atria were considered, each with square and linear configuration. The performance was evaluated for three warm climates.; The optimum top-fenestration for efficient daylighting was determined. The daylighting prediction algorithm was extended to include the effective reflectance of the atrium walls. The increase of mass in the atrium walls significantly decreased the atrium temperature range, the maximum atrium temperature, and the cooling loads. This impact decreased from horizontal to vertical south-facing top-glazing.; The vertical south-facing top-glazing and, to a lesser degree, the reduction of the glazed atrium cover by 50% had more cooling benefits than increasing the mass of the atrium walls by a factor of 7. The effect of mass was greater in Fresno than in Lake Charles. The need for mass increased in lower atria. The study analyzed the combined effect of the top-fenestration and mass in the atrium walls on the maximum atrium temperature, the thermal loads, and the daylight available at the atrium floor.