'Deep energy retrofits' take root in homes

rch 12, 2010 6:07 AM PST
by Martin LaMonica

BOSTON--Perhaps not surprisingly, wrapping a home in an air-tight seal and adding insulation dramatically lowers utility bills. But the question is: can people afford it?

Contractors who could be considered pioneers in what is called deep energy retrofits presented results from their projects at the Northeast Sustainable Energy Association's BuildingEnergy conference here on Thursday. In general, the data from early projects in Massachusetts shows that these energy make-overs delivered big gains in efficiency--on the order of 50 percent to 70 percent.

A superinsulation project under construction in Arlington, Mass. where two layers of foam insulation are added on the outside of the home.

(Credit: Martin LaMonica/CNET) There are a number of techniques to cut building energy but the one these contractors often focus on is superinsulating, or sealing the building "envelope" and adding insulation, both inside and on the exterior of buildings.

In one multi-phase project in Western Massachusetts, the homeowners anticipate getting a 70 percent reduction in energy use by adding a layer of foam insulation on the roof and outside walls among other enhancements. Slashing energy use means lots of insulation: the roof will have an R-value, or insulating value, of 59, which is two or three times that of a typical New England home.

A superinsulation project at an 85-year-old, two-family home in Arlington, Mass. was able to reduce the amount of heating oil by about two thirds in its first year, according to homeowner Alex Cheimets. In that case, homeowners decided to seal and add insulation to the exterior of the home when they had to replace the aging shingles.

Another project where only the roof was replaced and extensive air sealing done was able to reduce cut energy usage by 44 percent based on the same average heating days, according to David Joyce, the president of Synergy Companies Construction, who worked on the project.

Although it may sound fairly straight-forward, the actual detail work of sealing a building envelope and adding insulation are very difficult, contractors report. For example, adding insulation to the exterior walls requires builders to treat windows in a very different way, taking into account sealing as well as drainage. Once homes become very air-tight, they need to have a mechanical ventilation system, such as a heat-recovery ventilator, to circulate in outdoor air.

Chasing efficiency in green homes

Another barrier to deep energy retrofits is the cost. The project in Arlington cost about $100,000, although a smaller home could be roughly half of that, according to Synergy Companies Construction. Another approach to keeping costs down is to phase the construction over many years.

In these initial cases, the building owners are obviously highly motivated to cut energy for environmental or other reasons. But that doesn't mean there isn't a return on investment. A deep energy retrofit at North Hampton Brewery is six years on a $200,000 investment, said the contractor, Sean Jeffords from Beyond Green Construction in western Massachusetts.

When on-site power generation is added, such as solar panels for electricity and hot water, it's possible for these super-efficient homes to become net-zero energy homes.

Tools needed

Deep energy retrofits are still few and far between, not only because of the cost. Massachusetts is running a pilot program where it plans to have 150 deep energy retrofits (or 300 partial retrofits) over the next three years, which will be funded in part through utilities energy-efficiency programs. The size of the rebate ranges from about $25,000 to $40,000, according to Larry Masland, an energy efficiency planner in the DER.

But even when subsidized, there remain challenges, speakers said on Thursday. Finding contractors with experience in deep energy retrofits is difficult and homeowners generally don't have access to a lot of information. Meanwhile, subcontractors such as electricians or plasterers typically don't take great care in preventing air leaks, which is vital in this sort of project.

Increasingly, general contractors can use software for modeling and blower door tests to check air tightness. Certifications and rating systems are emerging, including the HERS score, which gives an overall efficiency grade. Some contractors are also pursuing the PassiveHouse certification, a super-efficient building design system which originally took root in Germany. Other certifications are the U.S. Green Building Council's LEED for Homes rating and EnergyStar.

Photos: A Passive House in the making

Homeowners (and builders) need ways to measure the effectiveness of contractors' work and anticipated return on investment, said Jeffords. "At the end of the day, (homeowners) need tools and have a lot trust in what you do because their neighbors haven't done it," he said.

Other barriers to adoption are a lack of financing options for what are large investments and skilled workers, Jeffords added.

But when builders and homeowners focus on efficiency, the results can slash the ongoing expenses of heating and cooling a home.

Simon Hare last year began started a project to rebuild an 1850 gunshop in the Roxbury neighborhood of Boston that was so energy efficient, that it wouldn't need a heater. Having lived through much of the winter, Hare on Thursday reported that his family was able to survive the New England winter with only occasional use of an electric space heater when temperatures dip below 30 degrees. Because of the lack of drafts, his family has felt comfortable with the indoor temperature at 60 degrees, he said.

Clearly, deep energy retrofits is on the extreme end of cost and effort when it comes to making homes more energy efficient. But creating a tight seal and insulating can be done whenever there are major renovations to a home, such as replacing a roof or siding, said contractors.

In many cases, homeowners can significantly cut their utility bills--and environmental footprint--on their own by turning off unused appliances and plugging holes around their homes with caulk and expanding foam.