It seems to me that San Antonio has been a little behind the times when it comes to LEED projects compared to other large U.S. cities. That is why I was super excited to see a San Antonio project featured in Green Source magazine this month. The project is a new office building for the architecture firms O’Neill Conrad Oppelt (OCO) Architects and Alamo Architects. While their most notable sustainable practice was their reuse of materials, I was interested in their decision to use operable windows.

In the article their mechanical engineer explains that San Antonio’s winters are mild enough that opening the windows makes since for almost half of the year. This differs from what I’ve heard from other engineers, in particular the mechanical engineer for the current project I’m working on. His opinion was that there was only about a month out of the year when operable windows are effective and that didn’t warrant the cost of making the windows operable. So we took our building that had been designed specifically for natural ventilation and closed it up, now using the windows for just daylighting.

When discussing this week’s blog with a few co-workers they said they too thought it was a bad idea to have operable windows in San Antonio due to the high humidity. So off to the internet I went but didn’t uncover much information. My next step was to talk to our office LEED “expert”. His opinion was that if the building were small scale operable windows would be beneficial but that in the end it is the mechanical engineer’s opinion that matters. The fact is there just isn’t enough precedent of using operable windows for commercial design in San Antonio to determine if it’s good or bad. We are however starting to see their use more often and I am interested to see what the verdict will be.