Question-and-Answer Resource for the Building Energy Modeling Community
 | 1 | initial version |
I'm assuming you're using IDF files made from the HPXML files from the ResStock dataset EUSS-Res 2022.1 because that has heat pump upgrades in it. The EULP 2021.1 Release is baseline (no upgrades) and assumes all baseline heat pumps are lower efficiency and single-stage.
The EUSS-Res 2022.1 release was intentionally conservative by sizing heat pumps that re-use existing ducts with cooling load priority following ACCA Manual S (up to 1.3x the cooling load for variable-speed heat pumps). This was chosen to acknowledge the fact that, unless they are modified, existing duct systems may be too small for the airflows required by larger heat pumps. There are also potential concerns about the ability of heat pumps that are oversized for cooling to provide adequate dehumidification (which is the reason ACCA Manual S limits to 1.3x cooling load; II believe ACCA is currently revising Manual S to allow more flexibility).
For EUSS-Res 2022.2 the team is planning to include some upgrades that size ducted heat pumps for the larger of the heating and cooling loads, to include a more optimistic heat pump savings profile.
EUSS-Res 2022.1 docs describing the sizing are here: https://resstock.nrel.gov/datasets
See HPXML docs for the different ASHP sizing options available in OpenStudio-HPXML: https://openstudio-hpxml.readthedocs.io/en/latest/workflow_inputs.html#hpxml-hvac-sizing-control
Re: control of supplemental heat, I think it is the latter (top up method). Descriptions of the various options available in OS-HPXML are here: https://openstudio-hpxml.readthedocs.io/en/latest/workflow_inputs.html#air-to-air-heat-pump
| | 2 | No.2 Revision |
I'm assuming you're using IDF files made from the HPXML files from the ResStock dataset EUSS-Res 2022.1 because that has heat pump upgrades in it. The EULP 2021.1 Release is baseline (no upgrades) and assumes all baseline heat pumps are lower efficiency and single-stage.
The EUSS-Res 2022.1 release was intentionally conservative by sizing heat pumps that re-use existing ducts with cooling load priority following ACCA Manual S (up to 1.3x the cooling load for variable-speed heat pumps). This was chosen to acknowledge the fact that, unless they are modified, existing duct systems may be too small for the airflows required by larger heat pumps. There are also potential concerns about the ability of heat pumps that are oversized for cooling to provide adequate dehumidification (which is the reason ACCA Manual S limits to 1.3x cooling load; II I believe ACCA is currently revising Manual S to allow more flexibility).
For EUSS-Res 2022.2 the team is planning to include some upgrades that size ducted heat pumps for the larger of the heating and cooling loads, to include a more optimistic heat pump savings profile.
EUSS-Res 2022.1 docs describing the sizing are here: https://resstock.nrel.gov/datasets
See HPXML docs for the different ASHP sizing options available in OpenStudio-HPXML: https://openstudio-hpxml.readthedocs.io/en/latest/workflow_inputs.html#hpxml-hvac-sizing-control
Re: control of supplemental heat, I think it is the latter (top up method). Descriptions of the various options available in OS-HPXML are here: https://openstudio-hpxml.readthedocs.io/en/latest/workflow_inputs.html#air-to-air-heat-pump
