College, university building HVAC design
College and university campus buildings have a lot going on—classes, research, dining, and sleeping. HVAC and air quality are key aspects of these buildings.
Robert Garra, PE, CDT, Vice president, electrical engineering, Cannon Design, Buffalo, N.Y.
Randy Hassler, PE, LEED AP, Principal, McClure Engineering, St. Louis, MO
Andrew Slater, PE, Electrical engineer, HGA Architects and Engineers, Milwaukee, WI
CSE: What unique requirements do college and university HVAC systems have that you wouldn’t encounter on other structures?
Hassler: Campuses can have many different building types, or types of spaces within the buildings: offices, classrooms, laboratories, libraries, museums, data centers, clean rooms, housing, dining, performance arts, radio station, recreation complex, health care, police station, hazardous waste disposal, power plants, etc. The basic equipment (i.e., pumps, fans, air handling units, heat exchangers) that comprise the systems are similar; however, the diversity of building types requires being grounded in the fundamentals and having knowledge of the nuances of different applications.
CSE: How can automated features and remote system control benefit campus clients?
Hassler: Campus buildings, while having nominal occupancy schedules, can be occupied at all hours of the night by facility, researchers, or students. Occupancy sensors can be used to change the “mode” of the zone or system. Often people think of using occupancy sensors only for two states, occupied or unoccupied. There can be four states: normal hours—occupied or unoccupied; and after hours—occupied or unoccupied. This would be an example for an office VAV box with reheat:
- Normal hours, occupied: minimum cfm for ventilation, space temp setpoint by thermostat.
- Normal hours, unoccupied: cooling minimum cfm = 0, space temp setpoint 75 F cooling and 70 F for heating. (Strategy is to save reheat when unoccupied and keep the space within a comfortable dead band temperature range. You would not want to return from a meeting to an 85 F office and have to wait for it to cool down.)
- After hours, occupied: space temp setpoint 75 F cooling and 70 F for heating.
- After hours, unoccupied: cooling minimum cfm = 0, space temp setpoint 85 F cooling and 60 F for heating.
CSE: In general, what payback period do colleges and universities expect?
Hassler: Typically longer than other clients, 10 or more years because they own and operate their buildings for a long time. Many owners also want to consider lifecycle cost considering energy, system life, maintenance, and end-of-life replacement cost in the evaluation.