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NREL / OpenStudio-HPXML

Modeling of residential buildings in EnergyPlus using OpenStudio/HPXML.
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Water heater setpoint #642

Open shorowit opened 3 years ago

shorowit commented 3 years ago

Change our model to use a single-sided deadband instead of a centered deadband.

The argument for making this change is that it’s closer to how water heaters actually work: the maximum tank temperature they ever reach is the setpoint with no overshooting for safety reasons. It’s also a lot more like what you’d expect with using a scheduled setpoint: after making this change, if you schedule the water heater setpoint to be 125 F during certain hours, it’ll heat to 125 F, not a little over that (about 127 F) because of the deadband. Initial analysis suggests that it will result in about a 1% decrease in the consumption for gas tank water heaters.

shorowit commented 1 year ago

Switching to a one-sided deadband results in not passing the HERS Hot Water tests. Perhaps the acceptance criteria should be updated? (Note that we currently use a centered deadband when using setpoint schedules, so if you compare simulation results for a constant setpoint and an 8760 schedule using the same value, the results are a little different.)