Home Energy AC Pro Guide 2011 : Page 2

> PRO GUIDE SERIES BACK TO BASICS I n this compilation of Home Energy features, you will fi nd two articles aimed at helping you fi nd the correct size for the air con-ditioning unit in your home as well as an article that shows where Proctor also addresses what has become an accepted paradigm in building science: Put your efforts and your dollars into the envelope fi rst and then buy the best HVAC unit you can with the dollars that are left. This is shown in the example of identical homes in which the win-dows were fi rst improved, resulting in a huge reduction (29%) in HVAC energy consumption. Then the HVAC was downsized and this resulted in a small increase in energy use due to duct ineffi ciencies. The law of unintended consequences meets the house is a system. The bottom line for both of these articles is that proper sizing of HVAC equipment has lots of benefi ts to the occupants, the environment, and to our society, but big reductions in energy consumption are not among them. The biggest improvements in energy consumption are achieved by improving the envelopes of our structures and the design and installation of the HVAC ducts and systems themselves. Both of these articles lead us to wonder, “What is the proper re-sponse to these fi ndings?” Glad you asked. Our last article addresses “Air-Conditioning Best Practices,” and was written by Joe Kuonen and Jim Bergmann. Here, you’ll read about how the HVAC industry is at a major crossroads and how further energy improvements in our home’s comfort systems can best be achieved by going back to HVAC basics. —Douglas Garrett, CEM the HVAC industry currently stands and what best practices should be followed to make the most impact. In the fi rst article, “Smart and Cool—The Art of Air Conditioning,” John Proctor, P.E., presents the case that ACCA Manual J is the only path to properly sized units. The article, however, doesn’t make the case for rightsized equipment based on substantial energy savings (kWh) but rather on longer “on” time, providing improved comfort due to better humidity control; more effective mixing of the air; yielding even tem-peratures; and lower purchase price. Additionally, Proctor discusses why setting your air conditioner fan to “auto” is better than using the “on” option, especially in a humid climate. In the next article, “Sizing Air Conditioners,” Proctor speaks almost exclusively to energy consumption and peak demand reduction on elec-tric utility systems. The piece dispels the belief that by downsizing units there will be a large reduction in overall energy consumption (kWh). He fi nds that although the smaller units use less energy per minute, they have to run longer, which usually makes them cost just as much to operate as the larger units. Proctor explains that with rightsizing, there are big gains in occupant comfort, reduced indoor humidity and double-digit reductions in electrical grid peak demand. All of these are of critical importance to both occupants and to our utility companies, which are faced with an ever-growing peak demand. It’s the growing peak demand for electricity that forces companies to either build new and expensive power plants, which drives electric rates up, or imple-ment rolling blackouts. 2 Douglas A. Garrett , CEM, is the owner of Texas’ fi rst building science consulting business, Building Performance & Comfort (www.bldgperfor-mance.com). He conducts forensic investigations and has presented hun-dreds of seminars on applied building science, energy effi ciency, moisture management, energy codes, and air-conditioning, among other topics. Home Energy | Professional Guide 2011

BACK TO BASICS

Douglas Garrett

<br /> In this compilation of Home Energy features, you will find two articles aimed at helping you find the correct size for the air conditioning unit in your home as well as an article that shows where the HVAC industry currently stands and what best practices should be followed to make the most impact.<br /> <br /> In the first article, “Smart and Cool—The Art of Air Conditioning,” John Proctor, P.E., presents the case that ACCA Manual J is the only path to properly sized units. The article, however, doesn’t make the case for rightsized equipment based on substantial energy savings (kWh) but rather on longer “on” time, providing improved comfort due to better humidity control; more effective mixing of the air; yielding even temperatures; and lower purchase price. Additionally, Proctor discusses why setting your air conditioner fan to “auto” is better than using the “on” option, especially in a humid climate.<br /> <br /> In the next article, “Sizing Air Conditioners,” Proctor speaks almost exclusively to energy consumption and peak demand reduction on electric utility systems. The piece dispels the belief that by downsizing units there will be a large reduction in overall energy consumption (kWh). He finds that although the smaller units use less energy per minute, they have to run longer, which usually makes them cost just as much to operate as the larger units. Proctor explains that with rightsizing, there are big gains in occupant comfort, reduced indoor humidity and double-digit reductions in electrical grid peak demand. All of these are of critical importance to both occupants and to our utility companies, which are faced with an ever-growing peak demand. It’s the growing peak demand for electricity that forces companies to either build new and expensive power plants, which drives electric rates up, or implement rolling blackouts.<br /> <br /> Proctor also addresses what has become an accepted paradigm in building science: Put your efforts and your dollars into the envelope first and then buy the best HVAC unit you can with the dollars that are left. This is shown in the example of identical homes in which the windows were first improved, resulting in a huge reduction (29%) in HVAC energy consumption. Then the HVAC was downsized and this resulted in a small increase in energy use due to duct inefficiencies. The law of unintended consequences meets the house is a system.<br /> <br /> The bottom line for both of these articles is that proper sizing of HVAC equipment has lots of benefits to the occupants, the environment, and to our society, but big reductions in energy consumption are not among them. The biggest improvements in energy consumption are achieved by improving the envelopes of our structures and the design and installation of the HVAC ducts and systems themselves.<br /> <br /> Both of these articles lead us to wonder, “What is the proper response to these findings?” Glad you asked. Our last article addresses “Air-Conditioning Best Practices,” and was written by Joe Kuonen and Jim Bergmann. Here, you’ll read about how the HVAC industry is at a major crossroads and how further energy improvements in our home’s comfort systems can best be achieved by going back to HVAC basics.

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