Thursday, August 29, 2013

ASHRAE Journal Articles

I have had 4 of the 6 promised “Engineer’s Notebook” articles published in the ASHRAE Journal. I received permission to post these on the Krueger website, which I will do as soon as they send me back the “approved” versions. We’ll update this blog entry with links as soon as they become available.

I have had a lot of very positive feedback from these articles, but today I got my first negative critique. The responder, a consultant (I assume an energy consultant) from Seattle, complained that “this kind of thinking will prevent ASHRAE from progressing the art of design”. I responded with this:

While I fully agree that oversized equipment may lead to occupant dissatisfaction, as the system attempts to operate efficiently at part load (see my most recent article in the Journal ), there are a large number of "energy efficient" buildings where occupant comfort has taken a back seat to energy savings. Following the publication of the article in question, I received a comment regarding a government building in your city, which is going for an energy award with both Underfloor Air Distribution (UFAD) and Chilled Beams. An occupant posted a picture on the internet of a temperature sensor on his desk indicating it was 90°F there. I'm sure they will have low energy use, but at what cost? Supposedly, there are umbrellas duct taped to office dividers to keep the sun off the occupants.  

I fully agree that "Energy efficiency does not make buildings uncomfortable; but the lack of good mechanical engineering design does." Sadly, so does poor understanding of how a building is supposed to operate. Innovative systems need much more building operations training than more traditional ones. Construction of innovative designs is also often compromised by poor construction. As indicated in the recently released ASHRAE UFAD Design Guide, the key to a successful UFAD system starts at the first day of construction in order to avoid issues with leakage in the end, which may be impossible to locate or remedy. 

But, the biggest issue I have with energy efficient designs is the apparent lack of validation of the energy calculations created to get owner and code acceptance (and LEED points). There are plenty of examples of buildings using far more energy than was predicted. Some schools are reporting that their expensive schools (at more than twice the cost/unit area of any prior schools in that area) are the highest energy users (again in terms of energy/unit area). I suggest that validation is lacking in many of these claims. An internet search for peer reviewed cases of proven energy savings of innovative designs will show you there isn't much out there. If these designs are so good, I'd expect the internet to be flooded with glowing reports. Sadly, that doesn't seem to be the case. Maybe all the successful building owners and designers are just bashful?

Authored by: Dan Int-Hout, Chief Engineer Krueger

Wednesday, August 21, 2013

Is it September yet?

It must be nearing quickly, as I already went to South Dakota in early August for the annual motorcycle rally. And I’m now seeing school busses on my drive to work. ASHRAE was in Denver this summer, a few issues were resolved, most notably the 40 fpm issue reported in my last blog. I have finally rolled off the USGBC’s Indoor Environmental Task Group, but can report that LEED V4 has been fully certified and will be out in the next few weeks.

We had hoped to get ASHRAE 55 2013 out in time to be referenced by the new LEED, but it will probably be in an addenda. ADPI is still the best way to prove compliance to 55 with overhead air distribution; both 55-2103 and the next ASHRAE Handbook (Applications) should be aligned to reference each other to make this proof easier to validate. I have actually been working on this, clarifying this relationship since about 1981, so I’m glad it is finally all coming together. I suspect the secret was to outlive all those who couldn’t grasp the reality of this relationship.

AHRI Standard 885 is one of two compliance paths in LEED V4 for schools. The prerequisite of 40 dBA (typically about 31 NC) for the classroom HVAC system can be substantiated by either AHRI 885 or the ASHRAE Handbooks. As there is still no reference in the ASHRAE Handbooks to the joint ASHRAE AHRI research study (RP755) conducted in the late 90’s at NRC Canada on the transmission of sound from plenum located sound sources into a room, which has been in 885 all along, I suspect AHRI 885 will be the primary documentation path. The spreadsheet associated with 885 makes both calculation and documentation quite easy. The incoming chair of TC 2.6, Sound and Vibration, has made the inclusion of the RP755 results in the Handbooks a priority, but until that happens, 885 is the best validation method.

I now have 3 of the 6 promised articles published in ASHRAE Journal. The first was on adjusting adjustable diffusers, primarily linears (which are seldom adjusted, it seems), the second was on the tradeoff between energy and comfort, and the third was on the validation of high turndown VAV systems, based on recent ASHRAE research. The next one will be on area factors for balancing diffusers and discussing why we really can’t publish them anymore, as the instrument used has become a significant variable. We will be posting them on the Krueger website when all six are out there.   

Authored by: Dan Int-Hout, Chief Engineer Krueger