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Unitary System Variable for Total HVAC Power

asked 4 years ago

sashadf1's avatar

updated 4 years ago

Hi,

Using ResStock v2.2.4, OpenStudio v2.9.0, and EnergyPlus v9.2 This version of ResStock uses PAT to run simulations.

I am looking for a variable to quantify total heating or cooling delivered to a single-family detached residential building. These types of buildings typically only have one or two conditioned spaces (living zone/bedroom). The end goal is to use a heat balance model to estimate a building’s thermal mass and bulk conductivity.

I am using a single stage ASHP to deliver heating and cooling. Ideally there is one variable that represents HVAC load delivered to all conditioned zones, after it has been heated/cooled by fans, heat transfer with refrigerant loop, etc. My educated guess is that the variable is one of the following:

  1. Unitary System Total Cooling Rate
  2. Unitary System Sensible Cooling Rate
  3. Unitary System Total Heating Rate
  4. Unitary System Sensible Heating Rate

I think “Unitary System” variable is appropriate because it combines heating/cooling from all the components on the supply side of the air loop (fans, coils etc), before the conditioned air is delivered to the zone.

Is Unitary System Total Heating/Cooling Rate the best variable for what I have described? Should I consider the Sensible Rate instead, since that is what actually changes the zone temp? Am I leaving out an energy flux ([W]) if I use Unitary System Total Heating/Cooling Rate?

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@sashadf1 what simulation tool are you using? Please add a tag for the tool and mention the tool in your question so that others can provide better help.

Aaron Boranian's avatar Aaron Boranian  ( 4 years ago )

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answered 3 years ago

sashadf1's avatar

updated 3 years ago

We decided to use Unitary System Total Cooling Rate and Unitary System Total Heating Rate. If, at a certain timestep, both of these variables were non-zero, we computed a net HVAC power delivered to the building using:

Net HVAC Power = Unitary System Total Heating Rate - Unitary System Total Cooling Rate.

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Asked: 4 years ago

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Last updated: Jul 26 '21