Sports, entertainment venues: HVAC systems
CSE: How do such venues vary from region to region?
Lewis: Different regions have different design conditions, and these need to be considered prior to the start of the design. For a predominately heating climate zone, it may not be the best idea to provide a VAV system unless you know that you can get good circulation of the air throughout the zone. It may be a good idea to design single-zone systems that can force the air throughout the space effectively. In warm and humid climates, you have to design with the heat and humidity in mind. In these zones it makes sense to have a way to treat the humidity the building may encounter.
McKinlay: The design of the air handling systems can vary significantly depending on the climate of a particular region. For example, an arena in the southeastern United States, where humidity is high, may need a dedicated system to pretreat outside air to provide tighter control.
CSE: What unique solutions in heating and cooling systems have you specified recently? What “unusual” HVAC systems have you offered as an option to clients?
Larwood: We’re seeing more attention being paid to high-performance building system features to reduce energy use. Due to the occupant density, sports and entertainment venues require significant amounts of outside air. With the use of air quality sensors, the use of outside air is minimized when there are extreme outdoor temperatures. Energy recovery is also a consideration—cooling the incoming outside air with the air being discharged.
Cooper: I’ve seen pool dehumidification systems, heat recovery chillers, low-temperature heating hot water systems, ventilation control systems, and locker room air transfer systems. We had a project where the domestic hot water boilers (nominally 140 F) were used as a backup source to create low-temperature heating water (nominally 125 F) for the 5 months each year that the campus turned off the steam boilers. Recognizing we had high-efficiency condensing domestic water boilers already in the project, we were able to use these boilers to provide the desired redundancy needed for the heating water system.
McKinlay: We proposed displacement ventilation under the seats for an open-air soccer stadium in the Middle East to keep spectators cool during the game.
Lewis: The trend in sports seems to be the use of VRF systems, which are somewhat unique in the fact that multiple AHUs are tied to a single condensing unit. In these systems the amount of refrigerant piped at any time is controlled by a variable frequency drive (VFD) on the compressor, which makes them very efficient under part load. When specified with the right options, these units can also have different AHUs in different modes. That is, one AHU can be in cooling while another is in heating. This increases the flexibility of the units and makes them very useful in a variety of situations.
CSE: Describe a recent HVAC challenge you encountered and how you worked to overcome it.
Lewis: The biggest challenges lately have been renovating existing arenas that don’t currently have existing air conditioning systems. In these types of situations we have been using laser scans to locate all existing pipes, conduits, and ductwork. We then add this information to the model and work with the architect and structural engineers to carve out a path for the ductwork with as little disruption to existing systems as possible. We have also designed unique return air systems where plenums are used in lieu of ductwork. This reduces the quantity of ductwork that needs to be routed through existing space and also saves money for the project.