[BLDG-SIM] Meeting umnet hours

Hi Kevin,

Several things I look at when trying to limit the unmet hours in a building:

1. First of all, look at SS-R and SS-F reports to get a better handle on what is going on, is there simultaneous heating and cooling during the winter? If so, the tstat setpoints may be too close.

2. Do you have the economizer turned on during the winter for "free cooling" and to limit the use of mechanical cooling?This is accomplished through the OA schedule, see the help screen. Often a separate schedule is needed for each AHU. To turn the economizer on but limit the OA during unoccupied periods, use a 0.01 as the fraction. If you turn it to 0.0, you turn off the ecenomizer completely.

3. During the winter, you may be able to set the cooling setpoint slightly higher to limit the use of mechanical heating; i.e. say up to 78 or 80 instead of 75.

4. Is your OA turned off during optimal start periods or periods when you are trying to bring the spaces back to occupied temeratures?

5. If there are unmet heating hours during the summer, do you have the tstat setpoints set back to say 55F so that heating doesn't come on?

All of the above involve schedules. Keep in mind that the schedules must be identical in both the proposed and budget buildings.

I hope this helps and best of luck to you.

Dear All,

I would like some guidance concerning methodologies for systematically meeting unmet hour requirements as indicated in ASHRAE 90.1-2004 Appendix G3.1.2.2. When all building systems are believed to be correctly entered and unmet hours are out of range. I know I can make certain changes to this model to obtain less than 300 unmet hours. Is there any unspoken hierarchy of steps to input changes? Or is it all just guesswork? Is there anything that is a no-no and should not be changed? Specifically, I have a project in which the building energy management system allows cooling when the temperature is above 55°F leading to several thousand unmet hours for this heating dominated building with unusually high insulation and solar transmittance values and way oversized existing equipment. If I making cooling available year round then gone, all better. Of course there is that graph that shows how cooling in the winter is over half the cooling in used in summertime. Or should I go through each zone and systematically change occupancies, equipment wattages, outside airflows, bogus baseboard heating (anything else I can fit in here) and then do several hundred iterations of simulations until someday I may finally have under 300 unmet hours for this ? standard. Do I even need to meet this 300 hours, for LEED purposes I would have to, correct?

Yours thoughts, PLEASE?

[BLDG-SIM] Meeting umnet hours - Equest