Heating, ventilation and air conditioning (HVAC) systems are one of the largest users of energy in any commercial setting. Through the EnergyRight Solutions for Business Program, TVA offers a number of services to commercial and business customers that will help them assess their system’s efficiency and opportunities for cost savings.

chilled water systems

Many large commercial buildings have chilled-water systems, which have separate central chillers and air handlers connected by pipes and pumps. It’s important to note that focusing on the efficiency of the chiller alone will not necessarily lead to the greatest savings, for these reasons:

• Chiller efficiencies do not account for the system’s pumps and fans, and they apply only to single chillers, while most plants use multiple chillers.
• Full-load efficiency data may not be helpful because chillers rarely run at full load, and integrated part-load data is provided at too few operating points to give an accurate indication of performance.
• The best way to produce energy savings is to take an integrated approach to the operation of the entire chiller system. Improved plant operation and maintenance combined with efficiency retrofits can achieve the best energy and demand savings.

unitary systems

Unitary cooling equipment is found in about 70 percent of U.S. commercial buildings. The system may be a factory-assembled heat pump or air conditioner of the type commonly used in buildings up to three stories such as retail stores, smaller office buildings and schools. Some operating considerations for unitary systems are:

• They don’t last as long as chillers (about 15 years compared to 20-plus) and are less efficient.
• Efficiency and comfort can be maximized by comprehensive testing, adjusting, and balancing the unit and controls.
• Converting a building from a unitary to a chiller system is not usually feasible. However, replacing an old unit such as a packaged rooftop air conditioner with a new system such as an air-to-air heat pump might be advisable.
• Regular maintenance is important. See tips below.