Friday, August 12, 2011

ASHRAE Standards

I have been asked a number of times about why Addenda A to the 62.1 2010 Standard isn’t available from ASHRAE. This addenda gives Displacement Ventilation credit to UFAD diffusers if the throw to 50 fpm is less than 4 ft, on the assumption that the ventilation will remain in the occupied space, and is based on ASHRAE sponsored research using both physical measurements and CFD calculations. The DV credit allows a reduction in ventilation (outdoor) air of 20% (divide the minimum rate by 1.2).

ASHRAE Standards that are on “continuous maintenance”, which include Standards 90.1, 55, 62.1 and several others, are modified by addenda through the ASHRAE public review process. Once an addenda is approved, it becomes a part of the Standard. This has caused a number of complaints that it was hard to stay up with what constituted the “current” standard. As a result, ASHRAE has decided to ‘bundle’ addenda into a single release, at the mid point between reprints of the standard. This is typically 18 months. So while Addenda A to 62.1 was approved (there were no comments) before the 2010 Standard was released, it will not be printed and available for probably another 6 months. The change is noted below:

Authored by: Dan Int-Hout, Chief Engineer Krueger