Define terminal unit control settings
For VAV systems, the terminal unit control settings can have a significant impact on energy performance. The minimum airflow setpoint for a VAV box affects fan energy, cooling energy and reheat energy at times when a zone is experiencing low cooling loads or is in heating mode. Energy codes set limits on this setpoint: high enough to meet outdoor air ventilation requirements but as low as possible to save energy. Simulation tools may have default values that do not comply with these energy code requirements, so attention is warranted. ASHRAE Standard 90.1 and California Title 24 both call for a “dual maximum” control strategy, in which the minimum airflow setpoint is based on ventilation requirements and the airflow increases when there is a call for either cooling or heating.
| Content is available under the Creative Commons Attribution-ShareAlike License; additional terms may apply. By using this site, you agree to the Terms of Use. |