Forum discussion

NC-2009 IEQp1:Minimum IAQ Performance

Time Averaged Occupancy

We have been asked to help a team with their Design Review Comments and they have received a review comment for a Dining facility whereby the reviewer noted that they could use a Time Averaged Occupancy calculation to determine the OA required. ASHRAE Section 6.2.6.2 Short Term Conditions was referenced. It appears that (Pz) Zone Population is the varying factor and it notes that it can be averaged over time (T) - can anyone please advise on how this number is calcuated for a space with a varying population?

0

You rely on LEEDuser. Can we rely on you?

LEEDuser is supported by our premium members, not by advertisers.

Go premium for $15.95  »

Wed, 05/01/2013 - 19:25

Use equation 6-9a to determine the duration of your averaging time. Calculate the average population during that time period and apply it as your Zone Population. For a dining facility, if the time period comes out to less than a typical meal duration or typical "full house" duration then you need to use the peak population. I hope that helps. Let me know if you have any other questions.

Wed, 05/01/2013 - 20:25

The question we have is how do you calculate the average population (Pz) to apply to calculation 6-9a? What are the parameteres if any in determining what is Pz?

Wed, 05/01/2013 - 20:34

You should talk to the building owner/occupant and get a feel for how many people they think will be in there at once. For a restaurant, lets assume that T = 3 hours. If the manager says that they have a staff of 25 people for 8 hours a day plus they have 100 seats then the maximum population would be 125. Now, lets say that the manager indicates that even at the highest occupancy only 80% of the seats are filled (parties of 2 or 3 at a four person table), now the max is 105. If the max only lasts 2 hours and you estimate that the half hour before and after have a 60% occupancy rate then the average would be: (2*(25+0.8*100) + 25+0.6*100)/3 = 98 people. This is all based on your own assumptions that you make for the occupancy of the facility.

Add new comment

To post a comment, you need to register for a LEEDuser Basic membership (free) or login to your existing profile.