HVAC Tuning – Cool Savings or Hot Air

My company has been retrofitting some of its existing building HVAC systems with CO₂ sensors/fan controllers. This seems to be working out well, both with respect to improving dilution ventilation (where needed), and saving energy by throttling back the supplied air in spaces that are not accumulating CO₂.

"Will office workers ever be satisfied with the indoor temperature?"

In a word, NO.

You will never consistently make everyone happy regarding the temperature, because individuals sense temperature and comfort differently. In my experience, this is frequently very much a gender issue (refer to ASHRAE Std. 55's table of "clo" factors for various articles of clothing.)

(In Std. 62) ASHRAE even defines "acceptable air quality" as:

"air in which there are no known contaminants at harmful concentrations as determined by cognizant authorities and with which a substantial majority (80% or more) of the people exposed do not express dissatisfaction."

That means that up to 20% (1 out of 5) of the people are NOT going to be satisfied, but that is OK...

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(Just my $0.02)

I know the general norm for a re-commissioning job is at about the 10 year mark in our buildings,it seems at about that time enough on site "adjustments" have been made to have a big affect on the overall efficiency of the HVAC system. We also have enough data to have a good base line on the costs of the building's operation. after careful planning and review we then tackle the task of re-commisioning the building and updating the controls and the control phlosphy . this method has made good economic sense and we see some great results that are documented from our historic base line. look before you leap and learn to learn from the past. good luck in satisfying your people. two or three gender specific people in one office can drive us all to the edge.

One never-ending problem is most building owners seldom see the wisdom in proper maintenance or verification that the system as a whole is operating as its initial design intended. The asthetics of the buildings "win-out" over the hidden mechanicals.

Healthy buildings are expensive to build and expensive to operate. I believe building owners have a higher probability of proper commissioning if an independent company from the original installer does the set-up, it's less likely that loose ends and "not quite as designed" measurements will be covered up.

I still have some skepticism on the total benefits of "green buildings", such as R.O.I.

I find value in reading the system "show cases" in the HVAC magazines, gives good ideas for successful designs when I need to make design decisions.

A problem I run into is when we install a system designed by independent mechanical engineering companies, they often design with what is "comfortable", ( not willing to entertain new products or design concepts due to liability.)

You have to admit, cutting edge system designers stuck their necks out.

Even in a small company in a 4 season environment it can be difficult to keep the masses happy. We have 24 people and there are always at least 3 or 4 which are either too hot or too cold, some at the same time! After researching what they actually deem is 'comfortable', I realized that there was a 7-8 degree temperature spread, pretty hard to maintain in a smaller office building.

Even after putting damper/diffuser units on all vents we still had a few that would run 'heaters under their desks' while the A/C was on. Although part of the problem is the poor HVAC layout of our leased building, it is not the entire issue.

Sometimes, it is just plain maddening, other times it is simply frustrating. After much effort to appease the minority, we are considering a 'no auxillary heaters' policy. Dress for the comfort you desire and nobody else will be adversely affected. This is not to mention the insanity of wasted energy of running heaters and A/C units at the same time and the inadvertent tripping of circuit breakers. The workplace is not a spa, despite the desire by some to make it so.

Comfort, as has been pointed-out, is a matter of perception. For myself, once I accepted the fact that I would have no control over my work environment and began to (as your post suggested) dress for my own comfort, things worked out fine. I am in new construction so most of my work is either outside, or inside buildings without any functioning HVAC system. In the winter it is cold, in the summer it is hot; end of story.