28th May 2015
Chris Jarvis was invited by the Architects’ Journal to join a round-table – chaired by the magazine’s sustainability editor, Hattie Hartman – on the subject of high-performance glazing. Following the discussion, here are a few notes on the themes and issues that were discussed.
The conversation was focused on the specification of high-performance glazing. More specifically, how fundamental changes within the industry - which include shifts in legislation and the drive for efficiency in our built environment – have resulted in the specification of glass being determined much earlier in the design process.
Glazing is no longer an adjunct that is decided upon once a concept design is complete and planning has been granted. Issues such as orientation, shading and air-tightness need to be considered in the early stages of projects along with the specification of the glass to ensure the target energy performances can be met. Rigorous energy modelling is also important to enable the right glazing option to be chosen for project, site and client.
Availability of data
One of the key challenges in the specification process is the availability of the necessary rigorous data on materials. Currently, there is a feeling across the industry that the level of detailed product information is not readily available across the board. This provokes the question of how can technology be harnessed to collate the necessary technical performance and cost data - which architects, façade engineers and contractors can use - to make the right choices earlier in the process.
A holistic approach needs to be taken to assess all of the above criteria and select the most appropriate single, double or triple glazed units to meet the performance requirements, whilst staying within budget. Triple glazing is not currently a widely used material to boost performance, mostly due to the cost of the product. However, over the next few years this is likely to change: as triple glazing products become more widely used and technology develops to decrease the weight of the product, it will become more viable for projects and client budgets.
However, the use of more advanced, highly tuned technology requires more monitoring after completion to access the efficiency of the product over the lifespan of the building. Currently, rigorous data of how glazing performs after 10 and more years does not exist; how can new products help the industry close the ‘performance gap’ and alert us to poorly performing glass that is ultimately having a major impact on the efficiency of our built environment.