Measure Description
This CASE Report will further expand on economizer requirements as one submeasure and will include two additional HVAC submeasures related to HVAC controls. In total, this CASE Report will include three submeasures as described below.
Updated Economizer Requirements
During the 2019 code cycle, water-side economizer requirements were expanded to include some radiant and chilled beams systems that were previously exempted. This submeasure aims to expand on this foundational work, including further expanding the economizer requirement to cover large variable refrigerant volume (VRV) systems and heat pump systems with significant interior zones or internal loads. Unique code changes presented in this submeasure are presented below.
- Lowering the cooling capacity that ‘triggers’ the economizer requirement in code.
- Increasing the stringency/efficiency of packaged unit compressor turndown to allow packaged units to have fully-integrated economizers.
- Improving economizer design requirements for systems housing economizers to lessen negative impacts on indoor air quality.
- Enacting minimum clearances from intake/exhaust openings to the roof screens, which block the HVAC equipment from site to prevent the entrapment of exhaust.
- Requiring powered-modulated relief for packaged HVAC units with economizers to ensure that excess outdoor air introduced into the system is released.
Guest Room Controls
This measure proposes to require ventilation to be shut off to the guestroom within 5 minutes of all occupants leaving the room,andrequire temperature setpoints of at least 60°F for heating and 80°F for cooling for unrented and unoccupied guestrooms. These requirements will align Title 24Part 6with the guestroom ventilation control requirements in ASHRAE Standard 90.1 (2016)and guestroom purge requirements of 189.1 (2017).
Variable Air Volume (VAV) Minimum Airflow
This submeasure would allow terminal box minimum airflow requirements to be based on outdoor flow rate as opposed to a fixed minimum.
Dedicated Outside Air Systems (DOAS)
This measure will add prescriptive requirements to Dedicated Outside Air Systems (DOAS) when used as the primary source of ventilation in nonresidential buildings to include a minimum level of efficiency criteria and control capabilities. This measure is based on research conducted by PG&E’s Code Readiness project and code enhancements in Washington State Building Energy Code on DOAS in 2015 and 2017.
The measure will also add prescriptive requirements for exhaust air heat recovery previously presented in draft language from 2019 Title 24, Part 6 and similar to the requirements in the current version of ASHRAE 90.1.
Provide Feedback
Participate in the Utility-Sponsored Stakeholder meetings for this topic:
Dedicated Outside Air Systems and Variable Air Volume Minimum Airflow on October 15th, 2019
Air Efficiency and Guest Room Controls on November 5th, 2019
This measure description will be updated as research is developed to support the 2022 code cycle. For questions or suggestions, email info@title24stakeholders.com. Include the measure name in the subject line.
Relevant Documents
Measure proposals, supporting documents, and other outside references will be made public as they become available.
- Updated Economizer Requirements Submeasure Summary
- Guest Room Controls Submeasure Summary
- Nonresidential HVAC VAV Minimum Airflow Submeasure Summary
- Nonresidential HVAC Dedicated Outside Air Systems Submeasure Summary
- Presentation – Oct. 15 – Nonresidential HVAC Part 1 Utility-Sponsored Stakeholder Meeting
- Presentation – Nov 5th – Nonresidential HVAC and Envelope Part 2 Utility-Sponsored Stakeholder Meeting
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Use the form above to provide feedback on this measure.
Give Us Your Feedback
The Statewide CASE Team values input from all stakeholders engaged in the Title 24, Part 6 code change process. We encourage the open exchange of code change comments and concerns.