Talk » Services » Discussing 'Cleaning window air conditioners' Keystone Energy Efficiency Alliance Copyright © 2015 The Keystone Energy Efficiency Alliance a »message agency siteLast summer, when peak temperatures -- and peak electricity load -- hit New York City, there was a call from Mayor Bloomberg for people to turn down their air conditioners to no lower than 79 degrees. One of the many problems with his plea was that he announced it on his weekly radio broadcast, which is slotted to be aired around 11 a.m. when most people are far away from their home air conditioners (not to mention that New Yorkers don’t tune in in droves for the Mayor’s radio program). For at least a fraction of New York City residents, 2012 will be different. To combat peak demand, Consolidated Edison has an expanded pilot this summer to tackle a small portion of the city’s unique energy hogs: window and wall air conditioning units. ConEd will equip 10,000 window AC units in several large apartment buildings with ThinkEco’s modlet smart plug and a smartAC thermostat, which will essentially turn the room AC unit into something that can be controlled via the internet or smart phone.

The utility will take applicants from across the city’s five boroughs, but will primarily focus on load pockets that are most strained during summer months. New York City is unique in its penetration of window AC units. In many other areas of the country, the prevalence of these units is related to income. About a third of households below the poverty line have room AC, rather than central, compared to about 15 percent of those that have an income above $100,000, according to EIA. In New York City, however, there are about six million room AC units.best 2 ton ac unit The voluntary residential demand response program, which will shed 5 megawatts during peak, is not the first for New York. wood cover for ac unitThe city already has 34 megawatts of DR from 25,000 central AC customers, about 80 percent of which are residential. ac unit heater

ConEd has about 500 megawatts total enrolled in all of its demand response programs. Residential DR is still in its infancy for most utilities. Many have pilots or old-school programs that cycle off hot water heaters or AC units with little to no control on the homeowner’s end. Oklahoma Gas & Electric, however, is moving into 150,000 homes in the coming years to cut peak demand to offset new generation. For utilities that need to offset upgrades, the cost of a little technology in select homes is far cheaper than new power plants or other significant grid investment. For the pilot in New York, applicants will be taken both from individuals who pay their bill directly and people who live in buildings where the electricity bill is rolled into their mortgage or maintenance charges, according to Adrienne Ortizo, program manager for the program, CoolNYC. The cost of the modlets and smartAC thermostats is about $200 per installation. In last year’s pilot, there was an average 26 percent savings across the 500 units during peak events.

For the program, customers will get the modlet and thermostat for free, along with a $25 gift card in exchange for allowing the utility to cycle down their AC during peak events, which there will probably be just a few of during the summer. ConEd was not specific about how high it would set the AC units, but last year’s pilot found that the AC could go to about 72 before people noticed a change in temperature. Each event will be based around the number of participants and average room temperature. The modlet is a tool used not only to reach a large swath of residential units in older cities, such as New York, Philadelphia and Boston, also to help utilities access peak reduction in some lower-income neighborhoods that have a larger number of window AC units. The problem, however, is that for demand response programs, households must also have internet, which has a lower penetration in lower-income neighborhoods. Ortizo acknowledged that having a computer and internet requirement was somewhat limiting for enrollment in CoolNYC as it expands.

The program has had about 1,300 applicants so far, according to Ortizo, and the utility is reaching out to building tenants and managers in the target buildings to fill out the program by mid-June. The technology is key to the DR program, but the website will also provide tips and suggestions for people to get the most out of their AC settings. The pilot is significantly larger than last year, but Ortizo said it was unclear how much it would scale in following years, although it will continue. Ideally, she said, it would be streamlined with the other central AC demand response program. For now, the utility is still squarely in the pilot phase when it comes to residents and DR, although a successful run this year could earn ConEd a green light from the New York Public Service Commission down the road.WEST LAFAYETTE, Ind. – Researchers are making progress in perfecting automotive and portable air-conditioning systems that use environmentally friendly carbon dioxide as a refrigerant instead of conventional, synthetic global-warming and ozone-depleting chemicals.

It was the refrigerant of choice during the early 20th century but was later replaced with manmade chemicals. Now carbon dioxide may be on the verge of a comeback, thanks to technological advances that include the manufacture of extremely thin yet strong aluminum tubing. Engineers will discuss their most recent findings from July 25 to 28, during the Gustav Lorentzen Conference on Natural Working Fluids, one of three international air-conditioning and refrigeration conferences to be held concurrently at Purdue University. Unlike the two other conferences, the biannual Gustav Lorentzen Conference, which is being held for the first time in the United States, focuses on natural refrigerants that are thought to be less harmful to the environment than synthetic chemical compounds. "The Gustav Lorentzen Conference focuses on substances like carbon dioxide, ammonia, hydrocarbons, air and water, which are all naturally occurring in the biosphere," says James Braun, an associate professor of mechanical engineering at Purdue who heads the organizing committee for all three conferences.

"Most of the existing refrigerants are manmade." Purdue engineers will present several papers detailing new findings about carbon dioxide as a refrigerant, including: • Creation of the first computer model that accurately simulates the performance of carbon-dioxide-based air conditioners. The model could be used by engineers to design air conditioners that use carbon dioxide as a refrigerant. A paper about the model will be presented on July 26 during a special session sponsored by the U.S. Army in which researchers from several universities will present new findings. • The design of a portable carbon-dioxide-based air conditioner that works as well as conventional military "environmental control units." Thousands of the units, which now use environmentally harmful refrigerants, are currently in operation. The carbon dioxide unit was designed using the new computer model. A prototype has been built by Purdue engineers and is being tested. • The development of a mathematical "correlation," a tool that will enable engineers to design heat exchangers – the radiator-like devices that release heat to the environment after it has been absorbed during cooling – for future carbon dioxide-based systems.

The mathematical correlation developed at Purdue, which will be published in a popular engineering handbook, enables engineers to determine how large a heat exchanger needs to be to provide cooling for a given area. • The development of a new method enabling engineers to predict the effects of lubricating oils on the changing pressure inside carbon dioxide-based air conditioners. Understanding the drop in pressure caused by the oil, which mixes with the refrigerant and lubricates the compressor, is vital to predicting how well an air conditioner will perform. Although carbon dioxide is a global-warming gas, conventional refrigerants called hydrofluorocarbons cause about 1,400 times more global warming than the same quantity of carbon dioxide. Meanwhile, the tiny quantities of carbon dioxide that would be released from air conditioners would be insignificant, compared to the huge amounts produced from burning fossil fuels for energy and transportation, says Eckhard Groll, an associate professor of mechanical engineering at Purdue.

Carbon dioxide is promising for systems that must be small and light-weight, such as automotive or portable air conditioners. Various factors, including the high operating pressure required for carbon-dioxide systems, enable the refrigerant to flow through small-diameter tubing, which allows engineers to design more compact air conditioners. More stringent environmental regulations now require that refrigerants removed during the maintenance and repair of air conditioners be captured with special equipment, instead of being released into the atmosphere as they have been in the past. The new "recovery" equipment is expensive and will require more training to operate, important considerations for the U.S. Army and Air Force, which together use about 40,000 portable field air conditioners. The units, which could be likened to large residential window-unit air conditioners, are hauled into the field for a variety of purposes, such as cooling troops and electronic equipment. "For every unit they buy, they will need to buy a recovery unit," Groll says.

"That's a significant cost because the recovery unit is almost as expensive as the original unit. Another problem is training. It can be done, but it's much more difficult than using carbon dioxide, where you could just open a valve and release it to the atmosphere." The recovery requirement would not apply to refrigerants made from natural gases, such as carbon dioxide, because they are environmentally benign, says Groll, who estimates that carbon dioxide systems probably will take another five to 10 years to perfect. Carbon dioxide was the refrigerant of choice a century ago, but it was later replaced by synthetic chemicals. "It was actually very heavily used as a refrigerant in human-occupied spaces, such as theaters and restaurants, and it did a great job," says Groll, who is chair of the Gustav Lorentzen Conference. But one drawback to carbon dioxide systems is that they must be operated at high pressures, up to five times as high as commonly seen in current technology.

The need to operate at high pressure posed certain engineering challenges and required the use of heavy steel tubing. During the 1930s, carbon dioxide was replaced by synthetic refrigerants, called chlorofluorocarbons, or CFCs, which worked well in low-pressure systems. But scientists later discovered that those refrigerants were damaging the Earth's stratospheric ozone layer, which filters dangerous ultraviolet radiation. CFCs have since been replaced by hydrofluorocarbons, which are not hazardous to the ozone layer but still cause global warming. However, recent advances in manufacturing and other technologies are making carbon dioxide practical again. Extremely thin yet strong aluminum tubing can now be manufactured, replacing the heavy steel tubing. Carbon dioxide offers no advantages for large air conditioners, which do not have space restrictions and can use wide-diameter tubes capable of carrying enough of the conventional refrigerants to provide proper cooling capacity.

But another natural refrigerant, ammonia, is being considered for commercial refrigeration applications, such as grocery store display cases, Groll says. Engineering those systems is complicated by the fact that ammonia is toxic, requiring a more elaborate design in which the ammonia refrigerant is isolated from human-occupied spaces. The first ammonia systems are currently being tested in Europe, and results will be presented during the Gustav Lorentzen Conference, Groll says. Groll's work is funded by the U.S. Army, Air Force and the American Society of Heating, Refrigerating and Air-Conditioning Engineers. Sources: Eckhard Groll, (765) 496-2201, groll@ecn.purdue.edu James Braun, (765) 494-9157, jbraun@ecn.purdue.edu Writer: Emil Venere, (765) 494-4709, evenere@purdue.edu Purdue News Service: (765) 494-2096; Daqing Li, a mechanical engineering graduate student at Purdue University, works on the prototype of an air conditioner that uses carbon dioxide as a refrigerant.