Question-and-Answer Resource for the Building Energy Modeling Community
Get started with the Help page
Ask Your Question
1

Which fields are used in computing an unmet hour?

asked 2020-07-29 12:51:57 -0500

sashadf1 gravatar image

updated 2020-07-29 20:07:18 -0500

I know that an unmet hour is computed as 1 when the hourly setpoint and hourly zone temperature do not match up: I am trying to code my own unmet hours computation function to see why a few of my simulated buildings have ridiculously large unmet hours.

There are however multiple setpoint fields and zone temperature fields that can be compared:

image description

Which fields do I compare (ie take the difference of) to figure out if something is considered an unmet hour?

edit retag flag offensive close merge delete

1 Answer

Sort by ยป oldest newest most voted
1

answered 2020-07-29 13:44:46 -0500

This difference appears to be between Zone Thermostat Air Temperature and Zone Thermostat Cooling Setpoint Temperature or Zone Thermostat Heating Setpoint Temperature.

SetupOutputVariable("Zone Thermostat Air Temperature", OutputProcessor::Unit::C, TempTstatAir(Loop), "System", Average", Zone(Loop).Name);

deltaT = TempTstatAir(iZone) - ZoneThermostatSetPointLo(iZone);
edit flag offensive delete link more

Comments

I have reason to believe the difference might be between ZONE OPERATIVE TEMPERATURE and ZONE THERMOSTAT COOLING SETPOINT TEMPERATURE or ZONE THERMOSTAT HEATING SETPOINT TEMPERATURE.

When I take the difference between ZONE THERMOSTAT AIR TEMPERATURE and the setpoint, the unmet hours are far too low. I am using the ResStock program which gives me annual sums of unmet heating hours and unmet cooling hours. I am essentially trying to code I function myself that looks at the end_use timeseries output and computes these values manually.

The unmet hours in the resstock output are in the thousands.

sashadf1 gravatar imagesashadf1 ( 2020-07-29 13:56:26 -0500 )edit

Comparing Zone Thermostat Air Temperature to the Setpoint (using my own code) gives me unmet hours in the 10s, far too low

sashadf1 gravatar imagesashadf1 ( 2020-07-29 13:57:17 -0500 )edit

Be specific on which hours not met variable or table you are looking at and I can probably find the equation.

rraustad gravatar imagerraustad ( 2020-07-29 14:03:25 -0500 )edit

The variable is simulation_output_report.hours_cooling_setpoint_not_met in the ResStock results.csv output

The value given by my simulation, for the building in question, is 7299.66 hrs, for the entire year. The simulation uses a temperature tolerance of 1 degree Rankine.

Taking the hour-by-hour difference between ZONE THERMOSTAT COOLING SETPOINT TEMPERATURE and ZONE OPERATIVE TEMPERATURE, comparing to this tolerance of 1 degree Rankine, and averaging over all Zones in the residential building, gives me a value of 7448.75 hrs for the entire year.

sashadf1 gravatar imagesashadf1 ( 2020-07-29 14:08:19 -0500 )edit

By contrast, taking the hour-by-hour difference between ZONE THERMOSTAT COOLING SETPOINT TEMPERATURE and ZONE THERMOSTAT AIR TEMPERATURE only gives me a value of 14 hrs approximately, which doesn't agree with simulation_output_report.hours_cooling_setpoint_not_met

sashadf1 gravatar imagesashadf1 ( 2020-07-29 14:09:37 -0500 )edit

Your Answer

Please start posting anonymously - your entry will be published after you log in or create a new account.

Add Answer

 

Question Tools

1 follower

Stats

Asked: 2020-07-29 12:51:57 -0500

Seen: 167 times

Last updated: Jul 29