Why is my During Heating unmet hours measurement much higher than my During Occupied Heating unmet measurement?

asked 2024-05-03 19:18:37 -0500

Mike117
105 ●1 ●5

updated 2024-05-04 09:27:50 -0500

Aaron Boranian

13890 ●76 ●24 http://bigladdersoftware.com/

I have tried changing the following parameters:

Lighting schedule
Clothing schedule
Occupancy schedule
thermal zone design supply air temperature (increase heat)
Temperature setpoint

The During Heating measurement has remained the same throughout every change. Table below:

image description The Simple ASHRAE 55-2004 HAS +7000 UNMET hours mostly because of clothing schedules which I will change.

Is there any information that maybe necessary to help diagnose the issue? I checked the sizing parameters and they all seem to fine to me.

answered 2024-05-06 15:23:52 -0500

Craig Simmons
403 ●9 ●7

Probably has to do with the nighttime operational control of the HVAC system. Generally "Occupied" are the more important ones (for ASHRAE compliance, etc.) but it is good to be sure your unoccupied HVAC control is correct. Where you review/input that control depends on the type of HVAC system you are modeling.

Clothing schedules will not impact these unmet hours, these are purely related to dry-bulb temperature of the zone compared to the thermostat setpoint. There's a separate table for comfort metrics.

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Where can I find the table for comfort metrics?

That makes way more sense. I do not have the simulation running during the night, At night, the HVAC system is meant to turn on every 2 hours depending on zone temperatures, I care for worst case energy demand.

Mike117 ( 2024-05-06 17:29:20 -0500 )edit

It's in the eplusout.html report, called "Comfort and Setpoint Not Met Summary". However it just gives one number for time not comfortable based on "Simple ASHRAE 55-2004", probably inadequate if you're doing anything more than the most basic analysis.

There may be others in this forum that can give more specific advice. I would recommend reading the EnergyPlus "Input Output Reference". You may also find you need to move into measure writing to do something comprehensive

Craig Simmons ( 2024-05-07 08:02:22 -0500 )edit

There is this measure in the common-measures-gem (found on the BCL) https://bcl.nrel.gov/content/5ae7b6b3...

Also you'll want to figure out which reports to add for analysis and trouble-shooting. Also found in the Input Output Reference.

Craig Simmons ( 2024-05-07 08:18:26 -0500 )edit

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Why is my During Heating unmet hours measurement much higher than my During Occupied Heating unmet measurement?

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Why is my During Heating unmet hours measurement much higher than my During Occupied Heating unmet measurement?