'Bioshader for Sustainable Buildings' in proceeding of the CIB 2004 World Building Congress, 1 - 7 May 2004, Toronto, Canada (on CD). ISBN: 0-662-36716-2
External solar shading is becoming a key environmental design feature for reducing heat gain from the increasingly hotter summers. Apart from conventional shading devices such as external louvers and overhangs, vertical plant canopies, as external shading devices, are increasingly being used and often form part of the 'bioclimatic' design strategy. Live plants provide many advantages over static metallic or masonry devices including seasonal regulation of shading by deciduous climbers, air quality improvement and enhancing the aesthetic of the building. There are very few studies on the shading performance of plant canopy due to the difficulties in measuring its dynamic behaviour such as the seasonal plant cover; and the methodology representing the shading performance does not exist. Designers wanting to use this sustainable technology are hindered by the lack of performance data.
In this research I have developed theoretical thermal model and methodology for measuring the area coverage of different leaf layers; the solar transmittances of leaf layers and canopy; and the interpretation of experimental results to establish a representation of the shading effect – the Bioshading Coefficient. An experimental canopy on which Virginia Creeper was planted and monitored at the University of Brighton. New methodologies and measurement techniques were developed to obtain the plant growth and solar transmittances which are keys to establishing the Bioshading Coefficient.
The methodology I developed in this research formed the foundation towards wider and systematic investigation of thermal performance of climbing plants. Through dissemination in the CIB Sustainable Building conference I have established collaboration with Kasetsart University of Thailand and we jointly developed experimental projects to study the thermal performance of climbing plants. The dynamic Bioshading Coefficient established from this research enables integrated computer thermal modelling of the shading effect to the building. Further environmental parameters are being investigated including the thermal properties of air through canopy, which link to the work of low energy ventilation systems undertaken by M. McEvoy and R. Southall.
This research project is reported as a case study in the publication by CIRIA’s: Newton, J., D. Gedge, et al. (2007). BUILDING GREENer - Guidance on the use of green roofs, green walls and complementary features on buildings, p108 London, CIRIA.