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TAG keeps TSPR but approves PNNL revisions; separate proposal to remove TSPR fails
Summary
The TAG considered two competing changes to the total system performance ratio (TSPR) compliance provisions: a PNNL proposal to revise TSPR to use site energy and to update multiple inputs passed, while a separate motion to remove TSPR entirely failed. Both proposals were debated at length and included roll-call votes.
The technical advisory group addressed two competing proposals that affect how larger commercial projects demonstrate HVAC performance. The first—submitted by Pacific Northwest National Laboratory (presented by David Reddy and Lisa Rosenow)—revised the TSPR (total system performance ratio) compliance path to replace carbon-based metrics with site-energy metrics, update equipment inputs, and clarify modeling details. The TAG approved that revision by roll-call vote.
Separately, a TAG member (Ian Casey) proposed removing the TSPR provision from the prescriptive compliance path. After discussion and a roll-call vote, the motion to remove TSPR failed.
What passed: The PNNL amendment (proposal 2-10, version 2) updates TSPR in several ways, including: - Changing the compliance metric from carbon emissions to site energy. - Adding air-to-water heat-pump system support and clarifying ground-source heat-pump loop temperature inputs. - Updating rated efficiency inputs (SEER2/HSPF2 conversions, VRF and packaged equipment efficiencies) and clarifying ERV/HRV requirements for multifamily buildings so the standard reference design aligns with code minimums. TAG members said the proposal was largely cleanup and alignment work intended to make the TSPR tool consistent with the code and with I-2066 concerns. The PNNL proposal passed in a roll-call vote, 12 in favor, 2 opposed and 2 abstentions.
What failed: The competing motion to strike the TSPR requirement altogether (proposal 1-60) was advanced by a TAG member who said the prescriptive path should stand on its own and that TSPR had become a burdensome, emissions-based overlay that did not belong in the prescriptive track. That motion failed on a roll-call 4 in favor, 10 opposed and 2 abstentions.
Why it matters: TSPR is a modeling-based compliance alternative used for larger commercial buildings and can affect whether a design needs additional efficiency measures. The PNNL revisions move the model to a site-energy basis, addressing concerns about relying on carbon emissions in a code that must also comply with state law (initiative 2066) and federal EPCA requirements.
What TAG members said: Ian Casey argued that the tool'as an emissions-based requirement tied to the prescriptive path'was out of step with legal direction and should be removed. Supporters of PNNL's revision said the updates are necessary housekeeping to align the tool with current test standards, to improve modeling accuracy and to remove the emissions baseline.
Votes and next steps: The PNNL proposal will be forwarded as the TAG's recommendation for that approach. TAG members noted additional clarifications and requested staff and PNNL follow-up on items such as unit-conversion tables, ground-loop temperature assumptions, and whether PNNL staff could meet with TAG members to walk through modeling questions.
Ending: TAG members split on whether modeling-based paths belong inside the prescriptive compliance route, but they agreed on a set of technical revisions to keep the TSPR path current with testing standards and the state'level policy discussion.
