To 'green' the world's buildings, think retrofits

BOSTON--The cutting edge of building science these days seems to be more about expanding foam than solar power research.

Last Wednesday, I stopped by the Building Energy Conference put on by the Northeast Sustainable Energy Association (NESEA). If there was one theme that jumped out, it was energy efficiency.

Insulating and air sealing a building, with stuff like expanding foam, has always been a sensible way to lower utility bills. But weatherizing homes is increasingly seen as the first and vital step to perhaps more exciting technologies like solar and wind.

Needed: more green-tech gear like solar hot water tubes to make existing homes energy-efficient.

(Credit: Martin LaMonica/CNET)

At the morning keynote discussion, Mark Rosenbaum of building firm Energysmiths, which specializes in energy-efficiency retrofits, argued that "fixing" the millions of existing homes through efficiency will have a far bigger impact on lowering greenhouse gas emissions than any new constructions.

"The majority of the potential is in retrofits," he said. "If you're increasing the building stock one percent a year, it's not going to get you anywhere. You have to fix the existing building stock."

Installing solar panels on an efficient home will have a bigger impact than on a home that isn't well insulated or doesn't use efficient appliances, he noted.

Rosenbaum pointed to several examples of retrofit homes in the New England area that were able to reduce their energy consumption significantly--some over 50 percent. Many steps are relatively easy, such as reducing the parasitic load from appliances, while others require bigger investments and changes to behavior.

Realistically, a 70 percent improvement--a goal set in an initiative called the Thousand Home Challenge--is challenging but doable in many cases. Some super-insulated homes--well-sealed homes with insulation on the outside of the structure--with renewable energy systems like solar panels have shown that they can be net producers of energy.

At this point, there isn't a standardized way in the U.S. of reporting a building's energy performance. In Germany, the Passivhaus standard for air-tight homes that use efficient energy technologies such as ground-source heat pumps have set the benchmark around the world.

Because of the wide variety of climates, there need to be different techniques for making homes efficient, said Rosenbaum. He sees a very high demand for green technology home products and much more skilled labor in this field.

"Where are we going to find enough people who know what they're doing?" Rosenbaum said. "We need a lot of people to get trained. Otherwise, we're going to create a lot of disasters."

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