Friday, April 8, 2011

Ventilation Wars

The battle continues on the value of ventilation. During the most recent USGBC conference call (establishing the IE Credits for 2012), we were again confronted with push back from the energy guys. The USGBC has received several responses to the point which can be earned for increasing ventilation 30% beyond the 62.1 minimum. One comment stated “continuing this credit is proof that the USGBC isn’t serious about saving energy”. Apparently this wasn’t the only one of this type.

So we challenged the crew to show evidence of correlations between ventilation and occupant satisfaction and we now have a handful of papers all showing the relationship between ventilation and illness. The correlation is there, but the magnitude is difficult to quantify, and while illness is certainly one measure of productivity, we are looking for more data on occupant satisfaction. Since salary in a commercial building is estimated to be at east $200/sf, and energy about $2/sf, it doesn’t take much of a correlation to prove payback.

One of the challenges is the misconception that economizer mode, which is essentially 100% outside air, is likely not correlated. This is because building operators often “push the envelope” to extend economizer operation as far as possible, often at the expense of occupant comfort, in the attempt to save energy.

Increasing the amount of fresh air while maintaining comfort conditions (meaning with the air being conditioned), seems to have sufficient benefits to warrant a LEED point, but there is still a need for data better linking non-illness related factors. Stay tuned….

Authored by: Dan Int-Hout, Chief Engineer Krueger