Expert: Dan Griffin - 12/27/2007

Question
Hello Dan,
I have to analyze a commercial building for a project and have chosen a car showroom.  As I expected the occupier did not know anything about the building, so it has made it very difficult to determine the method of cladding.  As you can imagine the building has a mainly glass exterior, I was just wondering if you would have any inklings as to the cladding of this building?  For my project I have to make this more sustainable after having identified its current construction.  I will probably put into effect a triple glazed curtain walling system, I don't suppose you have any ideas about that do you?  Many thanks, hope you had a good Christmas and I wish you a happy new year!

Answer
All that exterior glass is usually called a curtain wall.  The structure of the building is held up by a steel framework that is hidden or housed inside the aluminum window frames.  I would not consider glass an example of cladding, not quite an North American term.  All of the aluminum window frame work would need to be ripped out and replaced to accommodate a difference in glass thickness.  There is a strong chance that the existing aluminum work is not thermally broken and the heat/cool transfer through the frame work is tremendous.  The R value of glass is helped slightly by double and triple glazing, but it will never be thermally efficient.

By sustainable I assume you are talking about environmental impact, "green" building, LEED points, etc.  I think you will get further by eliminating or drastically reducing the glass work to be able to create as much thermally efficient exterior wall as possible.

YOur project may lend itself better to looking at alternate building types where rigid foam board and EIFS can gain much more "R" and curb appeal faster and easier.  A standing seam roof can gain "green" points.