Heating and air-conditioning systems are major targets for reducing energy use in retail stores. It’s easy to see why: Together, heating and cooling systems consume approximately 38% of the energy used in such facilities (according to the Environmental Protection Agency’s Energy Star program).
While energy use in buildings is affected by a range of other factors, including climate, optimizing the HVAC system can yield significant energy savings. The most cost-effective ways to enhance HVAC performance is through controls and system upgrades. But improved heating and cooling performance along with substantial energy savings can be achieved by implementing energy-efficiency measures. Here are a few suggestions from Energy Star:
• Consider implementing efforts to reduce heating and cooling load before selecting equipment.
• Avoid over-sizing equipment at all costs. Over-sizing equipment increases the capital cost at the time of the installation and the costs of operation of the equipment.
• Consider energy-recovery ventilation systems to reclaim waste energy from the exhaust air stream and use it to condition the incoming fresh air.
• In humid climates, consider supplemental dehumidification. By controlling humidity, you can increase occupant comfort and allow for further downsizing of equipment.
• Consider specifying economizers. Common control strategies include Energy Star qualified programmable thermostats, multiple zones and CO2 demand sensors.
• At a minimum, specify National Electrical Manufacturers Association (NEMA) premium motors on HVAC equipment, and consider specifying variable speed drives (VSD) on condenser and evaporator fans.
• In dry climates, consider evaporative coolers. These coolers use the evaporation of water to cool spaces, eliminating the need for energy intensive compressors.
• For facilities with heat-generating processes such as cooking, or on-site distributed generation equipment, consider heat recovery as a way to capture free waste heat and use it to offset facility heating and cooling costs.
Proper maintenance is critical to effective and energy-efficient HVAC operations. To improve efficiency and help ensure reliability and long life, consider the following:
• Engage a qualified HVAC firm in a maintenance contract with seasonal tune-ups. During these tune-ups, a technician should check combustion efficiency, refrigerant charge and belt tension as applicable.
• Replace air filters regularly. Accumulated dirt and dust make your fans work harder. Clean or replace filters as recommended by your system’s manufacturer.
• Clean the evaporator and condenser coils on heat pumps, air conditioners and or chillers. Dirty coils inhibit heat transfer; by keeping them clean, you save energy.
• Inspect ducts and piping for leakage or damaged insulation. Leaky ductwork is one of the biggest contributors to cooling loss in buildings. Apply duct sealer, tape and insulation as needed.
Incorporating control strategies that ensure systems are used only when necessary is a critical element in improved HVAC efficiency. Two examples:
• Multiple Zones: By dividing a facility up into multiple heating and cooling zones, a system can deliver more efficient heating and cooling by eliminating inaccuracies from a central sensor point.
• Demand or CO2 Sensors: Most heating and cooling systems draw in ventilation air by assumed occupancy, however modern technology has sidestepped this by designing systems that can actually regulate the air quality of your facility by measuring the amount of CO2 present. The result is more energy-efficient operation and better air quality.