Wednesday, March 9, 2011

Those Who Forget the Past

A few years back, I wrote an essay for the ASHRAE Journal titled “Those Who Forget the Past” (, the punch line being “are doomed to repeat it”. Today, in responding to several technical inquiries and during my weekly conference call with the USGBC, I was reminded of that article. While it is said that wisdom comes with old age, it seems that along with it comes the realization that younger generations apparently have to go through the same painful learning experiences that us older folks did.

It is easy to say “I told you so”. Unfortunately, it gets real old, real fast. I wrote a couple of weeks ago about my dismay that some new energy design guides apparently ignore both comfort and acoustical guidelines and standards. We went through the learning experience after the unfortunate EBTR (Emergency Building Temperature Requirements) rules. These often resulted in occupants taking matters into their own hands, employing fans and heaters to remain comfortable (and productive) environments, resulting in an actual measured energy increase.

Today, I was reminded that those lessons are lost on today’s younger designers. We had a lengthy discussion of the subject of openable windows. While a potential energy saving strategy (zero energy use), one has to shut off the AC to that space to be effective as an energy strategy. The person advocating for giving a credit for having openable windows stated that an interlock with the HVAC was not necessary, as occupants surely would not leave the AC on with the window open. This person had apparently never ridden in a convertible with either the heater or AC on to maintain comfort.

In fact, data in buildings with an interlock have found that after the first few weeks, occupants would no longer open the windows, as it was much more comfortable, quiet, and less drafty with the windows closed. The discussion will continue, but the conclusion is obvious to those willing to look at the available data. Openable windows are more of a gimmick than an energy solution.

I also spent some time giving advice on overhead heating strategies, also covered in an ASHRAE Journal article, which is available on our site ( The engineer I was speaking to thought it was more of an art than a science. In fact, of course, there is plenty of science available to help with the design.

We are beginning to record our engineering webinars so that folks can download or stream them on demand. The first of these is available here :

Those of us who have been there need to be able to pass our experiences along to those entering this industry so that we don’t repeat our mistakes.

Authored by: Dan Int-Hout, Chief Engineer Krueger