Learning objective: Designing K-12 schools: HVAC systems
CSE, March 27, 2015
CSE: What unique HVAC requirements do K-12 school structures have that you wouldn’t encounter on other structures?
Ellis: Acoustical standards stand out as the differentiator, as system-based noise has detrimental impacts on learning, much more so than the same levels have on office production or other similar activities. Maintenance staff may not have the training to adequately support complex systems, and as such require system operation and maintenance to be as straightforward as possible; with complex systems, such as related to renewable energy systems, it may be outsourced for ongoing support.
CSE: What changes in fans, variable frequency drives, and other related equipment have you experienced?
Ellis: The biggest change in the design approach has been the introduction of de-coupling of ventilation from conditioning by the use of DOAS, and the application of VRF systems. DOAS allows for substantial energy savings in the avoidance of conditioning unnecessary ventilation air, and VRF allows for low-energy transport of heat during periods of concurrent heating and cooling. Of course, improvements in design and cost of variable frequency drives (VFDs) allows for more opportunities for implementing the energy-saving advantages associated with variable flow, both air and water, and development of inexpensive pressure independent constant air regulators allows for the mixing of constant and variable flow ventilation on the same variable air volume (VAV) DOAS, which allows for ventilation savings with highly variable occupancy classrooms with fixed makeup spaces, such as labs.