Technologies for Energy Efficiency

Professionals have many choices for the delivery of energy-efficient solutions to their clients, from harnessing the sun for solar hot water, to providing options for indoor air delivery and using energy-efficient windows.
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Sponsored by Heliodyne, Milgard Windows & Doors, The Modern Fan Co., Tate Access Floors
Celeste Allen Novak AIA, LEED AP

SOLAR HOT WATER

The U.S. Department of Energy (DOE) estimates that over one million solar hot water systems have been installed throughout the United States. With respect to other hot water systems this means less than one percent of all hot water comes from the sun. Ole Pilgaard conservatively predicts that this number will increase to 5 percent or more in the next 20 years. In fact, beginning in 2010, sunny states like Hawaii are beginning to mandate solar hot water heating in all new homes. The state's Governor, Linda Lingle, signed this legislation that will prohibit issuing building permits for single-family homes that do not have solar water heaters, with exceptions for homes in forested areas.3 One motivation for this legislation is energy savings; the other is to reduce Hawaii's reliance on imported fossil fuels. "It's abundantly clear that we need to take some serious action to protect Hawaii because we're so dependent on oil," said State Sen. Gary Hooser, vice chairman of the Energy and Environment Committee, adding, "I'm very pleased the governor is recognizing the importance of this bill and the huge public benefits that come out of it."4

Solar hot water heating can be installed for both residential and commercial applications saving money by offsetting the energy used to heat water. "Water heating currently represents up to 17 percent of national residential energy consumption, making it the third largest energy user in homes, behind heating and cooling, and kitchen appliances."5 The solar panel industry, now over thirty years old, has developed new "plug and play" systems that make solar hot water systems easy to install in as little as one or two days.

Components of a solar hot water heating system
A solar hot water heating system usually has three main components:
  • A collector - filled with either water or in cold climates, a glycol solution
  • A heat transfer assembly which consists of a controller, pumps, heat exchanger, and various gauges and valves
  • A solar storage tank that holds the solar heated water plumbed to a traditional hot water tank or tankless hot water system, which are used as a backup heating source

Some solar manufacturers offer single-tank solar hot water solutions for homes with limited space. In a single-tank system, an electric water heater is generally used to provide both solar storage and backup heating. Because the solar system will pull cold water from the bottom of the tank, the bottom electric element must be removed. The top electric element will only self-activate and heat the water when the solar system cannot. A single-tank system can also be achieved with the use of a tankless, on-demand water heater to provide backup heating. Most manufacturers will give a ten-year guarantee for their collectors and five years for heat transfer components. The life expectancy of a solar hot water system is well over 20 years.

Twenty-eight solar collectors line the roof of Fenway Park.

Photo courtesy of Heliodyne

 

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Originally published in GreenSource
Originally published in July 2009

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