Big Code Changes Afoot in ASHRAE 90.1-2022

Proposed changes to the ASHRAE 90.1 standard for 2022 could have a huge impact on building energy performance, according to Leonard Sciarra, AIA, of Farr Associates. “There’s a lot in version one that I feel is going to change the way that people design buildings,” said Sciarra, who chairs the building envelope subcommittee of the ASHRAE 90.1 development group. Proposed changes in the three major sections include:

• Envelope—prescriptive and performance requirements to account for and minimize thermal bridges; mandatory air-leakage testing for small buildings; the introduction of “cool walls”
• Mechanical systems—improved efficiency for variable-refrigerant-flow (VRF) systems, chillers, and service hot water systems
• Lighting—reduced lighting power density; a lower threshold for where daylight controls are required; a new section on horticultural lighing;  an expanded scope to include lighting sites that may not have a building

Additionally, when using the performance path, there is a new “envelope back-stop,” meaning the building envelope needs to account for a certain percentage of the energy savings, Sciarra explained. “It forces you to have a pretty decent envelope before you can apply your mechanical system.” This closes a loophole that allowed teams to “do a lightly insulated, high-gain envelope and make up the difference with an efficient mechanical system.”

For those projects using the prescriptive path, renewables will be required (with some exceptions—for example, if the building has insufficient solar irradiation), and for those projects using the performance path, this addition will make the baseline energy budget lower, said Sciarra.

And newly, “each of the major legs of the standard now have a standalone protocol for modeling that system alone,” Sciarra told BuildingGreen. That means envelope, lighting, and mechanical systems can be optimized independently to meet energy targets or contractual requirements without creating a full energy model.

Finally, there is a proposed system of required “energy credits” that offers efficiency options based on building type, similar to what the International Energy Conservation Code requires. For example, a hospitality project can get credits for having efficient water heating, while an office building can achieve the credits through increased economizer or energy-recovery-ventilator usage.

Overall, Sciarra said, the code is moving away from prescribing performance of specific components like windows and luminaires and striving to regulate on a system level. For example, the new protocols for system-level modeling help move the prescriptive requirements toward a larger-scale thought process.

“I think that we’re all realizing that system-level efficiency is where we’re headed because you can’t do a component-based efficient building,” Sciarra told BuildingGreen. “Efficiency is based on systems and system interactions.”