According to a new report released by the Department of Energy’s Pacific Northwest National Laboratory (PNNL), US commercial buildings could save an average of 38% on heating and cooling if they employed efficient HVAC systems. And according to the report’s authors, the most efficient of these controls are not “widely available commercially,” but the hope is that these findings can inspire manufacturers to expand production.
“The potential savings from adding advanced controls to existing packaged air conditioners with gas furnaces is enormous,” said PNNL engineer Srinivas Katipamula, who led the study.
Some of the reports highlights:
* Retrofitting packaged HVAC units with the most energy-efficient package control options results in average HVAC energy savings of about 35% for three building types (small office, standalone retail, strip mall), and 24% for supermarkets.
* For the most energy-efficient controls package considered, average HVAC cost savings are 46%, 43%, 35%, and 24%, respectively, for the small office, retail, strip mall, and supermarket buildings.
* Retrofitting packaged HVAC units with a modified (less aggressive) energy-efficient controls package option results in average HVAC energy savings of about 28% for the small office building, 32% for the standalone retail and strip mall buildings, and 24% for the supermarket.
* For the modified packaged control option, average HVAC energy cost savings are 38% for all four building types.
* The maximum controller cost will provide payback periods of no more than three years for all US locations.
Although the report also found that “individual control strategies have different degrees of impact on energy and cost savings,” ultimately in all cases retrofitted HVAC units resulted in annual savings—up to 55 trillion BTUs per year at a 30% savings rate. At that level, the report states, the energy savings are “equivalent to removing over 16 coal-powered (200 MW each) power plants.”
The report’s findings were based on computer modeling and simulation of energy usage across a wide variety of commercial buildings in different settings and climates. Katipamula and his PNNL colleagues considered four different rooftop HVAC systems, including airside economizers, supply fan speed controls, cooling capacity controls, and demand-controlled ventilation. The effects of each method were tracked using Energy Plus software, which created computer simulations of 15 climate zones in 16 cities.
Energy costs and climate impacted the total estimated savings, with final numbers ranging anywhere from a low of range of 28–48% in the Pacific Northwest to a high of 55–64% in the Los Angeles metropolitan area (http://c1cleantechnicacom.wpengine.netdna-cdn.com/files/2012/04/hvacs.jpg). Four different types of commercial buildings were included in the study, including: small offices (5,500 square feet), standalone retail facilities (25,000 square feet), strip malls (22,500 square feet) and supermarkets (45,000 square feet). The reports findings are based on 1,400 simulations that recorded potential savings in electricity use by controlling power fans, cooling compressors, and gas to produce heat.
By adding up all the simulation data, researchers were able to identify the optimal savings percentage: 67% energy saved at a small office in the San Francisco metropolitan area. Conversely, the least amount of savings would be found at a supermarket in Seattle, WA—28% energy savings by adding all four of the study’s control methods. The study also revealed that Fairbanks, AK, has the biggest monetary savings potential across all four building types, from $52,217 per year for a supermarket to $923 per year for a small office building. These savings are possible in Fairbanks, primarily because of the areas cold climate and higher energy costs.
While there are plenty of HVAC controllers available, only one company produces a product that most closely resembles the research team’s simulation. As such, the report includes information regarding potential pricing for controllers, as well as ROI estimates as a way to inform manufactures and encourage production of controllers able to replicate the report’s findings.
“Our report makes a convincing case for manufacturers to produce more advanced HVAC controllers,” said Katipamula, “and for building owners to adopt these energy saving methods.
In a statement in response to the report’s findings, US Energy Secretary Steven Chu said, “Investing in an American economy that is built to last includes taking advantage of all of America’s energy resources while working to improve efficiency. By making heating, ventilation, and air-conditioning systems in buildings more energy-efficient, American businesses can save a significant amount of money by saving energy.”
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