Can Glass Towers Really be Green?

John Straube, writing for Building Science, on the efficiency of all-glass buildings:

When I see a fully glazed, floor-to-ceiling commercial or institutional building, I see an energy-consuming nightmare of a building that requires lots of heating and cooling at the perimeter just to maintain comfort. The result, on a cold winter day, is that offices exposed to the sun require cooling, while those in the shade need heat. Unless the control system is highly tuned, too many of the occupants will also be uncomfortable. Although it is well accepted that “green” buildings are above all low energy consumption buildings, there is a mistaken belief, almost a myth, that buildings with large expanses of glass are somehow green.

He digs in and does a nice technical analysis of why large expanses of glazing really don’t make sense from an energy standpoint. It’s amazing how many LEED certified glass towers there are considering that even high performance glazing systems still pale in comparison to alternative options. I’ve been involved with a few glass curtain wall projects and, even though these were high performance LEED projects, we did not use a thermally broken system. Given that admittedly small sampling, it seems rare that a thermally broken system is actually specified.