Nonresidential HVAC Controls

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.

Update 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.

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.

Guest room Controls

This submeasure will require ventilation to be shutoff to hotel and motel guest rooms within 30 minutes of all occupants leaving the room and require temperature setpoints of 60 degrees Fahrenheit for heating and 80 degrees Fahrenheit for cooling for unoccupied and unrented guest rooms.