Zero cooling after LPD change

asked 2016-05-25 11:39:47 -0500

mikesweeney's avatar

I'm modeling a medium-size hospital facility in Philadelphia, PA, using DesignBuilder v4.7, and when I change the lighting on certain zones from 1.2 w/sf to 0.8 w/sf, the district cooling for the entire facility drops to zero and unmet cooling hours increases for nearly all zones to 100%.

When comparing IDF files, the only difference is that for any of the problematic zones, "Design lighting Level (W)" is changed. The cooling difference is stark: Changing a single 400-sf conference room from 1.2 w/sf to 0.8 w/sf while leaving the remaining 200,000 sf unchanged at 1.2 w/sf will cause the entire district facility consumption to drop from a reasonable (113,730) kBtu to (0) kBtu over a 24-hour weekday in August. This pattern holds true across the year regardless of simulation time.

I've tried pulling out the District Cooling on the air handlers and replacing with DX units, as well as replacing the District Cooling with a default Air-Cooled Chiller, but in all cases the cooling remains at zero. As far as I can tell, error logs don't seem to show anything relevant. I'd upload IDF/ERR files, but I don't have enough karma.

I’ve also tried transitioning from E+8.3 to E+8.4 to no avail, and I’ve searched through Unmet Hours as well as the general E+ ChangeLog but I haven't found anything that clues me in to what might be causing this issue. Is this a known issue? Any suggestion is greatly appreciated. Thanks!

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And you checked that the zone temperatures are above the thermostat set point temperature? If so, send me the file directly, my email address is under my profile. This sounds interesting.

rraustad's avatar rraustad  ( 2016-05-25 12:41:26 -0500 )edit