Choosing glazing for a façade can seem like a trip through Alice’s Wonderland with a variety of characters all offering advice and no path being obvious.
The glazing in a façade is such an intrinsic part of the success of a building that getting it right is one of those design choices that simply cannot be left to chance. Our New Zealand experience shows that often it’s just not clear who it is that has that responsibility.
There are three main disciplines that are often looked to for glazing choice (and several others with constraints and design requirements to meet). Often the responsibility for glazing specification is passed around between the architect, the mechanical engineer and the façade engineer. Occasionally, each thinks someone else came up with the specification and its true origin is lost in the mists of time.
The façade needs to do so many interlocking things, and the attributes of the glazing influence many of them. Meeting all the needs together ensures we get it right for:
- Sunshine and Light
- Heat and Comfort
- Colour and Reflection
- Fire Protection
- Falling and Breakage
There’s a scene in ‘Alice through the Looking Glass’ where Alice states “There’s no use trying, one can’t believe impossible things.” Her companion retorts, “I daresay you haven’t had much practice. Why, sometimes I’ve believed as many as six impossible things before breakfast.”
Glazing choice can be a little like this. So many needs, and choices that are made in each case for the best of reasons but not necessarily with respect to the impacts on the others. Our list cannot become the six impossible things.
So how do we do it? The first issue as always is what is to be achieved in the building.
Basic building performance questions
What will the building be used for, and when, and by whom?
What sort of environment does that require in terms of comfort, and light, and environmental amenity?
How are the passage of heat, and air and moisture planned to be handled through the building?
Do we have a desire to limit capital or operating costs, or material resource?
Will the budget allow for flexibility between allocations for façades, HVAC, and the thermal envelope to create value in a finished building?
Armed with the answers, which provide a framework for successful construction and occupation, we can use a building performance engineering pathway involving the whole design team to piece together a solution.
Façade glazing choice, to meet all the needs, isn’t an impossible task and the impact on the success of a building of getting it right is huge. It’s one of the parts of integrated design that building performance engineering is well suited to. Are you beginning to believe that “Very few things are indeed impossible”? Welcome to the Wonderland.
Author: Ruth Williams – Principal, Buildings That Work InsideOut Ltd