System Control Offers Increased HVAC Efficiency For Smaller Buildings
New technology has made heating, venting and air conditioning building automation systems available and affordable for small- and mid-sized buildings, which can result in considerable savings over the life of a building, according to HPAC Engineering.
In light-commercial buildings, packaged rooftops or heat pumps are controlled almost exclusively with thermostats. However, in a 2004 New Buildings Institute study, 91 percent of the packaged rooftop units tested had at least one problem that increased cooling energy consumption by 5 to 40 percent.
- Variable air volume. Constant volume bypass systems, the norm in small buildings, were not designed for efficiency. Fans always run at top speed, and efficiency drops as the temperature of the recirculated air entering a unit decreases.
- Scheduling. Proper HVAC equipment scheduling can result in large energy savings for a building. Equipment controlled by thermostats typically are not scheduled optimally and often run continuously.
- Supply-temperature reset. With system-level coordination, advanced control routines can use zone-level information to optimize rooftop unit performance.
- Pressure reset. A pressure-reset strategy can provide the minimum amount of cold air to the ductwork needed at any particular moment without starving any of the zones.
- Demand controlled ventilation. Occupancy or carbon dioxide sensors can tailor the amount of fresh air introduced into a building while maintaining good indoor air quality.
- Demand response and peak shaving. A system-level HVAC approach is the best method of implementing demand response requests from a power company because thermostats are not equipped to provide this level of control.
- Alarm and fault management. Energy management systems give customers an early indication of improper operation, which allows time to proactively address issues.
Although there are some thermostat-controlled units that offer highly efficient performance, the best way to minimize waste and lower energy costs is with a systems approach, particularly since small packaged HVAC systems with integrated controls can affordably offer most of the control functionality found in larger building automated systems.
Building automation systems have been recognized for cost-savings and energy efficiency for some time. In 2012, Telkonet installed its EcoSmart suite of energy management products at the Lewiston, Maine, Ramada Conference Center, cutting its HVAC runtime costs by 40 percent.
Photo Credit: Efficiency via Shutterstock
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