Building Envelopes and their Impact on our Urban Thermal Environment
The way we design our buildings and place them in urban areas,affects our outdoor urban thermal environment through large thermal fluctuations,also described as urban heat island effect.The building envelope is the outer layer of the building that interacts most closely with the outdoor climate conditions and impacts the outdoor through diffuse and reflected radiation off its surface onto pedestrian spaces and streets.How the envelope is designed and positioned can have significant impact and should be considered during the building design process.This paper will discuss the methodology adopted to collect field test data and data analysis findings to describe the effects of different design configurations of building envelopes on pedestrian environment.Field testing was done in various sites in Hong Kong to measure radiant heat flux of sites of varying amounts of 5 main materials: exterior concrete walls,exterior windows,greenery,adjacent open space areas and visible sky.These materials were then extracted through the dissection of fish-eye photographs to isolate and determine ratio of each of the materials,referred to as view factor analysis.The four main view factors used or developed were: sky view factor,sunlit view factor,green view factor,glass view factor.These view factors were studied against the radiant fluxes to find key discoveries of the relationship between short-wave and long-wave radiation and mean radiant temperature(MRT)which is a thermal index used to understand the thermal comfort of a person from net radiant heat loss and gain.Some of the findings are summarized as the more spread apart building or lower height building envelopes may increase short wave radiation however reduce long-wave radiant heat flux meaning less trapped heat within the buildings.Glass buildings performed badly under direct sun,however under indirect sunlight conditions,performed better than opaque concrete building envelopes.
micro-climate building envelope view factor analysis
MAING Minjung
University of Hong Kong,Hong Kong SAR
国际会议
2017世界可持续建筑环境大会(the World Sustainable Built Environment Conference)
香港
英文
1054-1060
2017-06-05（万方平台首次上网日期，不代表论文的发表时间）