Thursday, July 5, 2018

The Journey Continues

It has come to my attention that this is my 100th blog entry and that I should think about something special to say. Like all the previous ones weren’t meaningful. HA! Perhaps a bit of reflection now and then isn’t a bad thing.

I attended the Houston Annual ASHRAE meeting a couple of weeks ago. I believe this was my 83rd ASHRAE meeting, but I don’t have data going back that far, as it was before personal computers… A lot has changed since the mid 70‘s when I got involved in the science of air distribution. I had the pleasure and privilege of knowing Dr. Miller and Dr. Nevins of Kansas State who literally wrote the book “Air Distribution”. They, along with industry figures like Harold Straub of Titus and Bill Waeldner of Anemostat, were gracious enough to let me in on the secrets of converting test results into catalogues, both printed, and later, electronic. The Krueger KEC electronic catalogue was released in 1984 for the MS-DOS operating system. 

I also got to know Dr. Fanger and Dr. Gagge, who laid the foundations for our understanding of thermal comfort. I worked with those two to get a compromise on a computer algorithm combining the “two-node ET* and the PMV equations. Sadly, the ASHRAE Comfort committee (SSPC 55) is thinking about dropping the “graphical method” of compliance, in favor of computer models which either must be purchased or only run online from a university web site. There is of course, a free graphical model (the only one available) on the Krueger website. (

I also got to know the outgoing ASHRAE President, Bjarne Olesen, who was a protégé of Dr. Fanger and was who I replaced as chair of Standard 55 when he started his rise to the top at ASHRAE. The current ASHRAE President, Sheila Hayter, is the daughter of Dick Hayter, president of ASHRAE back in the 70’s. He was also at Kansas State back in the day. The involvement of Kansas State in the science of air distribution was a critical one. The ADPI predictions that are used to verify compliance to Standard 55 were developed at KSU in the late 60’s. Recently validated and updated at UT Austin through an ASHRAE research project, the ADPI predictions are valid down to minimum ventilation rates. A heating ADPI prediction is in development from the UTA data.

I went through the development cycle of DDC controls from earlier pneumatic devices in the 80’s. We had to learn that pressure independent airflow control was mandatory if multiple spaces were to be served from a single air source. It would appear that when (not if) ventilation supply is decoupled from comfort control, a pressure independent ventilation control system is also required.

Now, I am involved in the Residential Building Committee at ASHRAE. It seems we are entering the multifamily dwelling industry with about the same level of understanding of the rules for effective ventilation as we did for commercial buildings 40 years ago. I find myself doing the same training on airflow control as I did in the 80’s to a new generation of mechanical engineers who never had any training on this subject. So, job security.

And the wheels keep going round and round…..

Authored by: Dan Int-Hout, Chief Engineer Krueger