The aspiration and challenge was to create a fully glazed façade which would provide maximum access to daylight and views out for the occupants without compromising on the energy performance. This was achieved with the design of a high-performing triple glazed façade: practical, sustainable, and beautiful.
The concept design was modelled and tested within its context using sustainable design analysis software. The results provided an understanding of the glass performance criteria and allowed us to develop a facade which is site specific and responds to orientation. The evolution of the façade design shows how the use of sustainable software can inform and benefit the design process at an early stage.
Our initial modelling studies demonstrate how the solar exposure analysis was used to inform the selection of solar control coatings and density of ceramic fritting to provide shading. The main principle behind the solar coating is to reflect most of the long-wave solar radiation (lower g value) while transmitting as much short-wave radiation (daylight) as possible (higher tL value). Therefore most of the heat remains outside, but daylight can enter. The selection of coatings responds to orientation; the north elevation has a reduced solar gain and a coating with a higher g –value, whereas the south elevation has an increased solar gain and a coating with a lower g-value.
The degree of opacity is dependent upon the percentage of fritting applied to the glass which controls the level of shading and subsequent reduction in heat gain. The level of opacity responds to orientation; the south elevation employs 50% fritted panels, the east & west 33% and the north remains clear. This reduces overheating, cooling costs and saves heating energy.
The resulting façade design uses the latest glazing technology of insulated triple glazing. The façade composition changes to reflect its position and shading effects, meeting site specific needs by varying glazing performance to allow the best possible access to views out and daylight. A total of 23 glazing types with individual solar coatings and fritting control the solar radiation and light transmission for each elevation, decreasing the use of artificial lighting.
Aesthetically the subtle differentiation in the solar coating colour and reflectivity is complimented through the choice of a grey or blue ceramic frit. This provides a degree of identity to the individual facades of the building and a clarity to the reading of the form. Importantly, the appearance of the façade reveals its environmental response to a specific site and context which could not be anywhere else.