New & Notable

A version of this article appears in the September/October 2013 issue of Home Energy Magazine.

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Energy-Saving Home Networks

In 88 million homes across the United States, digital content flows through high-speed modems and routers, streaming our videos, pinging e-mail into our in-boxes—and consuming 8.3 billion kWh of electricity. All of that energy comes with a $1 billion price tag as household small networks guzzle power around the clock, even when our gadgets hibernate and we sleep. The toll to the planet comes in at 5 million metric tons of CO2, which is equal to the annual tailpipe emissions of 1.1 million vehicles.

The Natural Resources Defense Council (NRDC) and its consultant Ecova recently partnered to determine the energy use of residential small-network equipment and how much can be saved with more-efficient designs. To evaluate the power use of America's small networks, we tested 60 models from a wide range of manufacturers, in homes and in the laboratory.

We found that the most efficient models use one-third less energy than average models, and that replacing today's wasteful equipment with more-efficient models could save 2.8 billion kWh of electricity annually, (about $330 million in customer energy bills).

Fortunately, there are more-efficient options on the horizon. In addition, EPA's Energy Star program is finalizing its specifications for small-network equipment, and soon the Energy Star label will help customers choose efficient models and Internet providers that offer energy-saving network equipment in their subscription packages.

—Noah Horowitz
Noah Horowitz is director of NRDC's Center for Energy Efficiency and a senior scientist in NRDC's energy program.

NATE Adopts New Certification for Certified RESNET Home Energy Raters

North American Technician Excellence (NATE) recently announced a new certification specifically for HVAC professionals. The HVAC Performance Verification certification will soon be available for Certified RESNET Home Energy Raters. NATE is the nation's largest nonprofit certification organization for HVAC and refrigeration.

The new NATE certification could provide added credibility for raters who review load calculations and who conduct quality assurance reviews of the installation of HVAC systemsfor various programs. These programs include EPA's Energy Star Certified Homes, EPA's HVAC Quality Installation programs, and ACCA's Residential Service and Installation program.

To qualify for the new NATE HVAC Performance Verification certification, Certified RESNET Home Energy Raters must pass a NATE test. Three RESNET representatives worked with NATE in developing the test; they were Brett Dillon of IBS Advisors, Lee O'Neal of MABTEC, and Dennis Stroer of CalcsPlus.

A beta version of the test will soon be available for Certified RESNET Home Energy Raters through participating RESNET-accredited rating providers.

This new NATE HVAC Performance Verification certification offers current home raters the opportunity to expand into the existing-homes market. By adding existing-home rater services, Certified HVAC Performance Verification Raters can experience increased revenue, higher margins, and greater customer satisfaction.

New Additions to ASHRAE Handbook

Outdated internal equipment heat gain data can result in oversized systems and higher operating costs, yet it is one of the most difficult areas for engineers to define.

To assist the building environment industry in defining these loads and designing more cost-efficient systems, internal equipment heat gain and load density data have been updated in the newest edition of the ASHRAE Handbook.

The flagship of ASHRAE's Handbook series is the 2013 ASHRAE Handbook—Fundamentals. Its 39 chapters cover basic principles and data used in the HVAC and refrigeration industry. They include updated information on building materials, load calculations, energy resources and analysis, refrigerants, indoor environmental quality sustainability, controls, duct and piping system design, and more.

Specifically, the climatic design content of 2013 Fundamentals has been expanded to include data from nearly 900 more worldwide reporting stations than were cited in the 2009 edition—a 16% increase. Chapter 14, "Climatic Design Information," now contains temperature and humidity design conditions and related information for 6,443 locations in the United States, Canada, and other countries around the world. The increase in the number of reporting stations is a result of research conducted by ASHRAE Research Project 1613.

"The increased number of stations, particularly noticeable in North and Central America (+ 26%), results in a better geographical coverage and enables designers to find a station closer to the location for which a building is designed," says Didier Thevenard, chair of ASHRAE Technical Committee 4.2, Climatic Information. Each station's data now also include monthly precipitation, used in particular to determine climate zones in Standard 90.1. The method and supporting data to calculate solar irradiance during clear-sky conditions were also updated.

Other new information can be found in Chapter 2, "Thermodynamics and Refrigeration Cycles"; Chapter 5, "Two-Phase Flow"; Chapter 9, "Thermal Comfort"; Chapter 10, "Indoor Environmental Health"; Chapter 11, "Air Contaminants"; Chapter 16, "Ventilation and Infiltration"; Chapter 19, "Energy Estimating and Modeling Methods"; Chapter 21, "Duct Design"; Chapter 23, "Insulation for Mechanical Systems"; Chapter 25, "Heat, Air and Moisture Control in Building Assemblies—Fundamentals"; Chapter 26, "Heat, Air and Moisture Control in Building Assemblies—Material Properties"; Chapter 27, "Heat, Air and Moisture Control in Building Assemblies—Examples"; Chapter 29, "Refrigerants"; Chapter 30, "Thermophysical Properties of Refrigerants"; and Chapter 36, "Measurement and Instruments."

Chapters in the ASHRAE Handbook are updated based on the experience of members of ASHRAE technical committees, and on the results of ASHRAE research reported at ASHRAE conferences and published in ASHRAE special publications and in ASHRAE Transactions.

Households Living in Apartments Use 50% Less Energy

A recent study conducted by the U.S. Energy Information Administration (EIA) reports that apartments in buildings with five or more units use less energy than other types of home.

Thirty percent of new-home starts in 2012 were in apartment buildings with five or more units, the highest percentage since 1986 and up sharply from 18% in 2009 and 2010, according to the U.S. Census Bureau. About 17% of households (19 million) lived in apartment buildings with five or more units in 2009, up from 13% (11 million) in 1980, but they accounted for only 9% of home energy use in both years. Over the same period, single-family homes maintained a steady share of total households, but their share of total home energy use went up. Apartments in smaller buildings have declined as a share of both households and energy use, and mobile homes remain a small segment of the residential sector.

Households in apartment buildings with five or more units use much less energy than the average for all households, and those in newer units use even less energy than those in older ones. As recent new construction joins the housing stock and older buildings fall out, energy use per household in large apartment buildings will probably continue to decline.

Households living in apartment buildings with five or more units use about half as much energy as other types of home. Lower energy use in apartments can be partially explained by their smaller living space. In addition, apartment units are bordered by other units or common areas on one or more sides and typically have fewer windows, limiting exposure to exterior temperatures.

Since 1980, per-household energy use in the larger apartment buildings has fallen by 38%, compared with declines of 15–32% for other types of home. Energy use per household has decreased across all home types, due to efficiency improvements in major equipment and appliances, despite increases in the average size of homes and in the use of electronics. Much of this decline in home energy use is attributable to reduced consumption for space heating, as equipment has become more efficient, population has shifted to warmer climates, and many homes now have better insulation and windows. Apartments in buildings with five or more units have seen the largest change in per-household energy use for space heating, which fell by 48% between 1980 and 2009. Households in the larger apartment buildings in 1980 consumed almost as much energy for space heating (42 million Btu) as was used for all purposes in 2009 (a total of 46 million Btu for space heating, water heating, air conditioning, and appliances).

Another way to examine household energy data is to look at energy use for a single year across homes built at different times. Overall, new homes consume about as much energy as older ones, but trends differ by home type. Households living in new (2000s) single-family homes use more energy than those living in older homes. For all other types of home, the reverse is true. When homes built in the 2000s are compared to those built in the 1970s, apartments in large buildings show the greatest decrease in per-household energy consumption. Households in large apartment buildings constructed in the 2000s consume 12% less energy than those built in the 1970s. Less energy is used by households in new apartments despite having more energy-consuming devices than older apartments—more A/C equipment, more major appliances, and more consumer electronics.

These comparisons of energy use are based on the amount of energy delivered to residences; they do not include energy lost in the generation of electricity that is used by households, which is part of the total amount of primary energy required to support site-level energy use.

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