AC Advancements Increase Comfort and Lower Operating Costs
Once considered a luxury, central air conditioning is now a staple in new-home construction. According to the U.S. Census Bureau, 93.5% of new single-family homes started in 2016 had at least one system, with some larger homes employing two or more units.
While there’s no doubt AC’s cooling and antihumidity properties are essential in many parts of the country, the cost of a system goes far beyond its initial price tag. According to the U.S. Energy Information Administration (EIA), Americans spend more money cooling their homes than on any other line item on their electric bill, and this summer is no exception.
EIA’s Short-Term Energy Outlook forecasts the typical U.S. household will spend an average of $426 for electricity this summer (June–August), an increase of about 3% from the average summer expenditures in 2017. The expected increase is a result of forecast higher retail electricity prices and slightly higher projected electricity use to meet increased cooling demand.
Add to these growing costs the fact that the global climates are rising, requiring more air conditioning use than ever before. In fact, 2017 was one of top three hottest years ever recorded, and scientists warn that global temperatures are on an alarming upswing.
As the need for home cooling increases, air conditioner manufacturers have responded by developing high-efficiency equipment that uses less energy and performs better, which in turn results in improved comfort and lower utility costs—a win for today’s home buyers. When these advanced systems are paired with more efficient installation, better insulation, and enhanced building design strategies, the cost and environmental impact of cooling a home is less than ever. (Click here for a list of AC installation best practices.)
The current measure of a central air conditioner and heat pump’s efficiency is its Seasonal Energy Efficiency Ratio (SEER). As of 2015, central air conditioners are required to be at least 13 or 14 SEER, depending on regional location, and heat pumps 14 SEER. However, standards passed in December 2016 will require air conditioners to be 14 or 15 SEER, depending on region, while heat pumps will need to meet the national standard of 15 SEER for all regions. The new minimum efficiency standards, which take effect in 2023, are expected to reduce air conditioner and heat pump energy use by about 7%, which could translate into hundreds of dollars in electricity bill savings for consumers over the life of their equipment.
Thanks to technological advancements, equipment manufacturers have been able to develop cooling equipment that meets or exceeds increasingly stringent efficiency standards. Models that bear the Energy Star label, for example, use at least 8% less energy than conventional new models.
Building a Better System
Efficient air-conditioning equipment is only part of the cooling equation, notes Tony Bouza, technology manager at DOE’s Building Technologies Office. In fact, Bouza says it is critical that builders look at home cooling and comfort from a system perspective, not just as the function of one appliance. By taking a more holistic approach, builders can ensure that cooling equipment actually delivers on its promise to pass on savings to the homeowner.
“You need to first start off with the guts of the building and ensure the skeleton—the shell of the home—is done right from the beginning,” he says. “Otherwise, you will be working against the air conditioner, and you have no chance at delivering the comfort homeowners desire.”
Ductwork is also critical, says Jon Winkler, senior research engineer at the National Renewable Energy Laboratory. “I would argue the thought and design that go into the home’s ductwork is more important than the selection of equipment,” he says.
Putting ducts in a hot attic, for example, is a poor practice. “I would suggest that builders put as much of the ductwork in conditioned space as possible,” Winkler notes. Ductwork should also be sealed and insulated to reduce leaks.
Jennifer Amann, buildings program director at the American Council for an Energy-Efficient Economy, says minimizing the length of duct runs also helps save energy. “Every time you have an added turn or added branch, the harder the system has to work,” she says.
Schell Brothers, a home builder based in Rehoboth Beach, Del., has always taken a system approach when building homes, according to Carmen Marinelli, vice president of construction. This includes creating a tight building envelope so that cooling and heating systems work as efficiently as possible to both save energy and benefit homeowners. “We feel we have a responsibility to our customers to give them a high-end home with reduced operating costs,” Marinelli explains.
For the most savings, Schell uses advanced framing and insulation techniques, as well as Energy Star-rated air sealing and conditioned crawl spaces with R-10 rigid insulation and a Griffolyn vapor barrier. Schell also specifies and installs AC units with a 17 SEER rating. “When comparing a 13 SEER model, it could save 15 to 20 percent yearly of the electric costs associated to cooling,” Marinelli says.
Brandon DeYoung, executive vice president of Clovis, Calif.–based DeYoung Properties, says he, too, focuses on building an efficient foundation first and foremost. “We feel it is important to provide a solid thermal envelope so that less energy will be necessary to cool and heat the home when temperatures rise or fall, ultimately saving the homeowner money and increasing comfort,” he says.
Specifically, DeYoung utilizes 2×6 walls with continuous insulation board around the exterior, dual-pane argon gas-filled windows with triple-layer low-E film, sealed attics, a well-sealed envelope and duct, and roofing tiles that have been approved by the Cool Roof Rating Council. Once that groundwork is in place, DeYoung installs Energy Star-rated air conditioning or heat pump models as a standard practice. “Relative to HVAC systems that are less efficient, high-efficiency systems can save a significant amount of money on energy bills and more than pay off upfront cost premiums over a period time,” he says.
DeYoung says there are two important extra steps his company takes to maximize the efficiency of heating and cooling equipment. “The first is that we have our HVAC trade partner and third-party inspectors perform a multitude of diagnostic tests on our systems during the commissioning process to verify proper operation,” he says. DeYoung’s homes also utilize electronically commutated motor technology to reduce the energy consumption of their heating and cooling operation even further. This controls the unit’s speed depending on demand.
“It’s kind of like highway driving versus city driving in a car,” he says. “The system can ramp down to a lower gear for efficiency when demand is lower.”
Both Marinelli and DeYoung say their practices are not only appreciated by their customers, but also demanded. “Our home buyers are looking for cutting-edge building science and technology to save money while also helping the environment,” DeYoung says.
As consumer demand and awareness continues to grow, equipment manufacturers and builders will have no choice but to continue to push the envelope. “The standards keep getting raised in regards to efficiency and SEER in HVAC products,” Marinelli notes. “The industry is focused on energy efficiency and trying to provide products that help get homes closer to net zero.”
Hoppel of Carrier anticipates continued growth in smart controls and learning thermostats. “When you couple system efficiency with the intelligence and control of a thermostat, homeowners can make significant savings compared to even just a few years ago," Hoppel notes. She also expects ductless systems to gain more market attention.
In the coming years, Marinelli expects to see increased interest in solar or hybrid systems, as well smart technology and home automation. “I believe we will see the products that are cutting-edge today become standard,” he says.
By Lisa Bonnema
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