Frequently Asked Questions
An air conditioner seems as if it cools the air, but it actually makes the space less warm by removing heat from the indoor air and transferring that heat to the outdoor air.
Heat is extracted by passing indoor air across a refrigerant coil in the indoor unit. Refrigerant lines then carry the heat to the outdoor unit, where it is released into the outside air. The cooling cycle continues until the indoor temperature reaches the thermostat setting.
A heat pump is an all-in-one heating and air conditioning system that works year-round to keep you comfortable.
During warmer months, a heat pump works as a normal air conditioner. It extracts heat from inside and transfers it to the outdoor air. In colder weather, however, the process reverses—the unit collects heat from the outdoor air and transfers it inside.
Even when the air outside feels extremely cold, the air still contains some heat. The heat pump pulls the heat from this cold outdoor air and sends it inside to warm the space. When there’s not enough heat in the outside air to meet the demand of the thermostat setting, an electric heater supplements the outdoor air to warm the space.Extremely efficient, this process produces two to three times more heat than the energy it uses.
Also, a heat pump can be an effective add-on option to use in conjunction with an existing gas furnace. With this dual-fuel option, the two systems share the heating load, but never function at the same time. Each system operates when it is most cost effective. The heat pump will be the primary heating and cooling system. However, when the temperature drops below the heat pump’s ability to operate as efficiently as the gas furnace, the gas furnace will take over until the temperature rises enough for the heat pump to operate more efficiently.
Two-stage cooling means the air conditioner or heat pump has a compressor with two levels of operation: high for hot summer days and low for milder days. Since the low setting is adequate to meet household-cooling demands 80% of the time, a two-stage unit runs for longer periods and produces more even temperatures.
Longer cooling cycles also translate to quieter, more efficient operation and enhanced humidity control. Compared to a single-stage unit, a two-stage air conditioner or heat pump can remove twice as much moisture from the air. This is important because when moisture levels are high, there’s a higher potential for mold and other pollutant problems.
“Variable speed” refers to the fan motor inside the air handler — the indoor part of an air conditioner that moves cooled or heated air throughout the ductwork. An air handler is usually a furnace or a blower coil.
Unlike conventional single-speed motors, a variable speed motor runs at a wide range of speeds to precisely control the flow of heated and cooled air throughout the space. Better airflow control has several benefits:
Variable speed motors can actually save you money on your energy bills, as they consume less electricity than standard motors.
Variable speed technology also means you will gain air conditioning efficiency or SEER.
Variable speed motors are excellent for zoning, which allows you to customize your comfort in different areas and control your energy bills.
A variable speed motor can also help clean the air. When the fan is in constant operation (indicated by the “Fan” setting on your thermostat), the motor will continue to slowly circulate air, allowing filters to capture more contaminants.
SEER (Seasonal Energy Efficiency Ratio) is a system for rating the efficiency of cooling equipment. The higher the SEER rating, the less your unit will cost to operate.
HSPF (Heating Seasonal Performance Factor) is a measurement similar to SEER, but it measures the efficiency of the heating portion of a heat pump.
Energy Efficiency Ratio (EER) This measures the cooling output of a unit divided by its total energy consumption, measured during continuous operation at a given operating condition (95 degrees or full load).
Integrated Energy Efficiency Ratio (IEER) This measure expresses cooling part-load EER efficiency for commercial unitary air conditioning and heat pump equipment on the basis of weighted operation at various load capacities.
How can I reduce my building’s energy costs?
According to the U.S. Department of Energy, as much as 50% of a commercial building’s energy is used to operate its HVAC system*. Higher-efficiency systems and advanced technology from Lennox can help businesses reduce their operational spending by creating comfortable buildings that use less energy.
Compare lifecycle costs
Controlling operational costs is much more than choosing the lowest priced equipment. Installing a system with a lower lifecycle cost can help reduce energy and maintenance costs for the life of the system.
Look for systems with higher energy-efficiency ratings to reduce monthly energy bills. Adding efficiency options such as economizers can improve efficiency even more.
Another way to reduce costs is to choose systems that are easy to install – with features such as hinged access panels – to save labor hours. Reliability features including high- and low-pressure switches that protect compressors from unnecessary wear and tear minimize maintenance expenses.
Investigate new technologies
Demand Control Ventilation
Most HVAC systems provide ventilation based on assumed occupancy, rather than how many people are actually in the room at any given time. Installing a Demand Control Ventilation (DCV) system with a carbon dioxide sensor provides an accurate reading of a room’s occupancy level. The system then controls the amount of fresh air introduced based on output from the CO2 sensor.
The result is improved energy-efficiency and indoor air quality.
When a building soaks up heat from equipment, lighting and occupants, the warmth may continue to heat the building even when the outside temperature is cool and comfortable.
That’s when it is more economical to shut off the compressors and cool using outdoor air. Integral economizers measure outdoor air’s temperature and humidity, determining if it is cool and dry enough to keep occupants comfortable. The economizer will then use the outside air for cooling rather than operating the compressors.
Building Automation Systems
Commercial control systems are available that use a single interface to control a variety of equipment and functions. These include sophisticated technologies such as remote monitoring, advanced diagnostics, system setup and alarm reset.
Equipment made by different companies can communicate with each other via BACnet® and LonTalk® protocols. BACnet or LonTalk capability can be installed on rooftop units to let them communicate with the automation system you use.
Investigate a planned replacement program
Most commercial rooftop HVAC systems have approximately a 15-year lifespan. Replacing a unit a few years earlier on a prearranged schedule—before age and wear take their toll—can dramatically reduce energy usage and help avoid lost revenue.
Installing newer, more energy-efficient equipment can reduce energy costs. While savings vary depending on system settings, maintenance, local fuel rates and other factors, today’s ENERGY STAR qualified HVAC systems offer significantly higher SEER efficiency ratings.
According to the U.S. Environmental Protection Agency (EPA), the owner of a commercial building can generate $2 to $3 of incremental asset value for every $1 invested in energy performance improvements. Many utility companies also offer rebates for higher efficiency equipment.
*Office of Energy Efficiency and the U. S. Department of Energy