Wednesday, March 27, 2013

March Madness

Wow! It’s almost the end of March, can you believe it?! I have been to Philadelphia and Springfield Missouri ASHRAE Chapters, as well as a week in Florida with the motorcycle for bike week. We just had an all-day training session for Texas engineers yesterday at our facility (subject being “Basics of Air Distribution”). I also did a 30 minute webinar on the “Basics of Air Distribution” a couple of weeks ago, which is recorded and available on the Krueger website. I will be doing a webinar on the “Application of Dedicated Outdoor Air Systems” on April 10, and a two part webinar on the “Methods of Effective Air Distribution” in May, which was a two part ASHRAE Journal article in November and December, last year. We are certainly getting a lot of stuff in front of engineers, which is hopefully of some use.

I’ll be traveling to Montreal in Late April to chat with the NEBB (air balancers) at their national meeting. You may be assured I’ll speak to the issue of adjusting slot diffusers. I had one contractor at the training session yesterday say that they added 10 minutes to the install time for slots to allow for adjustment in coordination with the air balancers. This is excellent input, but sadly the first time I had heard of it. I asked why they did it, and was told it was in response to complaints from older projects of drafts. I’m glad someone is listening to occupant complaints. I think this is a key issue for both designers and installers: Listen to the occupants!

I was told by an engineer in North Carolina that he had been installing overhead heating at over 100°F for years and no one had complained. I have to conclude that what he meant was that no one had complained to him. In the 1000+ air distribution tests we conducted back in the late 1970’s, there was not a single test with discharge temperatures that high which met , or even came close to meeting ASHRAE Standard 55’s vertical temperature stratification limit of 5.4°F. BOMA continues to report that the number one reason for not renewing the lease in a high rise building is occupant dissatisfaction with the environment. I said it once (actually many times!) and I’ll say it again: Listen to the occupants!

Authored by: Dan Int-Hout, Chief Engineer Krueger

Tuesday, March 12, 2013

Canada in Winter

I went to Ottawa in February. I’d forgotten what winter in the cold North was all about, but it all came back in a rush.

I spoke to the Ottawa ASHRAE chapter with my latest presentation, titled “What A (Building) Load”. I’ve been working on this for a while, as my “Methods of Effective Room Air Distribution” talk is a couple of years old and was published in November and December in the ASHRAE Journal.

Having been on the project review committee of the ASHRAE research project 1515, which was a thorough study of a couple buildings in California, where occupant response, equipment operation and energy use were all mapped, I have a pretty good idea of what was in the final report, presented in Dallas last month. The building loads were all far below what most engineers design for, and required setting the minimums on the VAV boxes at 10% of maximum to keep from going into reheat every afternoon. What was most interesting is that there were minimal complaints at the low air flows, and occupants were generally satisfied at 0.2 cfm/sf. This confirms the idea that there is no minimum air speed for comfort, which has been in the ASHRAE Comfort Standard for some time.

This leads to a conclusion that using a series fan terminal with an ECM motor and varying the air flow rate to as low as possible offers a very energy efficient way to provide HVAC to a commercial office space. It can be even better if a sensible cooling coil is placed at the inlet of the unit. This concept was utilized at the Pentagon in its most recent upgrade and is being used in a number of buildings around the country.

I described this concept to a design build contractor in Ottawa, and when he realized that one could actually eliminate the air handler (using only a DOAS unit) he is going to try this on a couple of designs.

I also did some webinars a couple weeks ago on “the basics of air distribution” and maxed out our number of available connections. I guess going back to the basics is something we have to do once in a while.

Authored by: Dan Int-Hout, Chief Engineer Krueger