Thursday, December 6, 2012

ASHRAE Journal Article

In case you missed it, I have part one of a two-part article published in the November ASHRAE Journal. Part II will be in the December issue. I have been giving a talk, from which the articles are based, at ASHRAE chapters and engineer’s offices around the country for the past couple of years. The article’s premise, titled “Methods of Effective Room Air Distribution”, is that folks are responding to the request for more energy efficient systems by designing air distribution systems around alternates to overhead air delivery, which has been the design of choice for the past 30 years. Unlike overhead systems which have many years of data validation, the energy calculations for these newer systems have not been very well vetted. The result is that engineers must modify the inputs or calculations to come up with energy use values. The output, of course, is merely a guess. Hopefully it is an educated guess. This, however, is sent to the USGBC for a LEED rating.

Meanwhile, BOMA continues to report that occupants are often dissatisfied with the thermal environment we provide, even with tried and true overhead delivery systems. Now we are moving to underfloor and displacement systems. It remains to be seen if they are any better at satisfying occupants. The first part of the articles describes the “rules” for occupant comfort, including ventilation and acoustics. The second part outlines issues to be considered when designing overhead (including Chilled Beams), underfloor and displacement ventilation systems. 

Failure to comply with the “rules” (some being included in buildings and others just good practice) is likely to continue to result in unhappy occupants. And, of course, we will eventually find out if any of these designs are really more efficient than others.

Authored by: Dan Int-Hout, Chief Engineer Krueger