Unseen Green: Many Energy-Saving Features Can’t Be Seen– And That’s a Good Thing

Nov 8, 2010 by

Solar sacrifice. An early solar home from the 1970s.

The energy crisis triggered by the oil embargos of the 1970s brought about an interesting revolution in residential design. Builders and architects responded to fuel shortages and high energy prices by creating a new generation of solar-heated houses.

These homes were easy to spot: Their south-facing facades were almost entirely clad in glass or clear acrylic to capture every possible Btu of solar energy. Little attention was focused on insulation or air sealing; it was all about solar gain. Unfortunately, all too many of these early houses began to develop overheating problems and glazing leaks, which later became known as “solar sacrifices.”

Today we know a lot more about how a house performs as a system, or to be more exact, as a collection of systems that interact to determine energy consumption, comfort, indoor air quality, durability, and weather resistance. The study of the house as a system is called “building science,” and it has lead to a much more effective approach to improving energy efficiency.

Unlike the solar homes of the ‘70s, today’s green homes have many energy-conserving features and renewable energy resources so well-integrated into the house that they can’t easily be seen. For example, Velux makes a solar hot water system with a roof-mounted collector that looks just like a skylight. Thanks to breakthroughs in thin-film technology, bulky roof-mounted photovoltaic arrays may give way to “buiding-integrated PV” products like PV roof shingles that provide weather protection as well as solar electricity (see photo).

Powerful roofing. The shiny roof shingles on this house are made from photovoltaic film that generates electricity from sunlight. Photo courtesy of the National Renewable Energy Laboratory.

A house that has been air-sealed to reduce energy loss doesn’t look any different than a leaky house that costs twice as much to heat and cool. Likewise, replacing an inefficient tank-type water heater with a super-efficient tankless hot water heater model won’t change a home’s appearance, but it will have a big impact on energy consumption.

One sure way to distinguish a “green” house from one that’s not is to compare utility bills and ask family members about their comfort levels. Banks, mortgage lenders and real estate agents are used to gauging a home’s value by appearance, location and size. They need to get a greener outlook and start recognizing the features that make homes more affordable to own, healthier, more comfortable and more effective at lessening our dependence on fossil fuels.

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