Monday, May 9, 2011

Comfort & Energy Savings

I was asked to post some thoughts to my fellow presenters at the upcoming Greenbuild, in October, in Toronto, on my part where we are doing a "yes, you can have comfort and energy savings" talk. Here is what I sent them:

I've been stuck in rainy Quebec province, with limited internet access, and time, but I've been noodling the subject of the somewhat diluted 30% proposed ventilation credit (for LEED 2012)and the "same degree of ludicriness as bicycle racks" comment we got from one of the energy mavens.

I won't try to come in on naturally ventilated buildings as I suspect they represent about 1% of available spaces.

I am of course concerned about the low comfort scores LEED buildings are getting, as its hard to argue for the availability of comfort options if we can't seem to be able to achieve it anyway.

I fear that part of the problem has been the emphasis on energy at the expense, or just plain ignorance of, comfort requirements. Nonetheless, I believe there are innovative options available to both improve energy efficiency and achieve a level of comfort. I am concerned that the calculations of energy savings are greatly overplayed, and never surprised when they aren't realized.

The reality is that when folks are not comfortable they don't just "make do". They bring in heaters, and sometimes fans, to increase their comfort level. Both are huge energy wasters, as the energy they use generates heat which then goes to the chiller, costing twice the energy used by the stopgap measure.

All that aside, I'd like to focus on the potential for innovative systems to maximize ventilation when outside conditions permit, minimize it when it doesn't, and ensure that economizer isn't mis-applied (pushing the economizer envelope resulting in high humidity in the space, as was alluded to by C Dorgan in one of our recent phone calls). At the same time, the real issue, I believe, is building operations in part load conditions (which are likely 90% of the time).

System design is not an unknown science. We know how to design for effective part load operation, but seem to get lost in design load strategies. Energy costs about $2/sfy in most climates (likely less in California). Saving half the energy (probably unlikely) has a really long payback in a building that costs $10/sf extra to build. At $30/sf, the payback is 60 years. Yet building owners continue to sign up for silly stuff. I suggest we get real, and discuss opportunities to design buildings without added first cost that actually work.

Radical, huh?

Authored by: Dan Int-Hout, Chief Engineer Krueger