Fractional bin hours used in the HSPF2 in EnergyPlus are different from those in the 2023 AHRI Std 210-240

NREL / EnergyPlus

EnergyPlus™ is a whole building energy simulation program that engineers, architects, and researchers use to model both energy consumption and water use in buildings.

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Fractional bin hours used in the HSPF2 in EnergyPlus are different from those in the 2023 AHRI Std 210-240 #10664

Open Nigusse opened 2 months ago

Nigusse commented 2 months ago

Issue overview

A user identified a mismatch between the fractional bin hours used the HSPF2 calculation used in EnergyPlus and those published the 2023 AHRI Standard. The issues are described in EnergyPlus helpdesk ticket.

Details

Some additional details for this issue (if relevant):

Platform (Any)
Version of EnergyPlus (if using an intermediate build, include SHA)
helpdesk ticket number #16700.

Checklist

Add to this list or remove from it as applicable. This is a simple templated set of guidelines.

[ ] Defect file added (list location of defect file here)
[ ] Ticket added to EnergyPlus Defect Complexity (Github Project)
[ ] Pull request created (the pull request will have additional tasks related to reviewing changes that fix this defect)

Nigusse commented 2 months ago

There are two issues:

What is the source for the fractional bin hours currently used in EnergyPlus for HSPF2 calculation? They don't match the 2023 AHRI Standard 210/240 values.
The fractional bin hours published in the 2023 AHRI Std 210/240 (2020) don't sum to 1.

Nigusse commented 2 months ago

@RichSee Why does EnergyPlus use the fractional bin hours for the HSPF2 calculation not to match those in the 2023 AHRI Standard 210/240 (2020)? Did you use a different version of the standard?

Below is the 2023 AHRI Std 210/240 (2020) and the fraction for HSPF2 calculation in EnergyPlus for region VI:

Nigusse commented 2 months ago

The EnergyPlus values must have been scaled by dividing by 0.757 to get the values to sum to 1.0. This may have undesirable consequences. Instead, we should get clarification from AHRI.

Nigusse commented 2 months ago

The same values are found in Title 10, Code of Federal Regulations (CFR), Parts 429 and 430, Appendix M1, Table 20 Generalized Climatic Region Information, shown below. The fractional bin hours do not sum to 1.0 for all regions. The table below is the source for AHRI Standard 210/240.

I've included the fractional bin hours sum for each region below.