With the current increased focus on conservation and green buildings, super-insulation represents the forefront of efficiency, especially for those who own an older home. Its effectiveness is being demonstrated by a Massachusetts pilot project – one of just a handful of super-insulated retrofits in the United States.
By Rolf Priesnitz
There are well insulated homes and then there are super insulated homes. Well insulated homes have varying amounts of insulation in the walls and attics. Super-insulated homes, such as Alex Cheimets’ in Arlington, Massachusetts, just outside Boston, have six inches of solid foam insulation on the roof and four inches on the exterior walls.
The 3,200 square-foot, 80-year-old building is divided into two condominiums. Cheimets says, “We needed to replace our siding and our roof soon anyway. We could simply do the minimum or we could invest now to save later – super-insulation was the better financial investment.”
To do the minimum – replacing siding and the roof – would have cost $40,000. Adding solid foam board insulation on the roof and sides cost an additional $50,000 but is expected to reduce energy use in the home by 65 to 70 percent. That will be an estimated annual savings of $2,350 to $4,000 per year. At the current heating oil cost of approximately $2.35 per gallon, it’s a 20-year payback, but a few short weeks ago the price was closer to $4 per gallon, and the price of oil is likely to rise again in the coming years, dramatically shortening the payback period.
The project is the result of an innovative public/private interface between the Massachusetts Department of Energy Resources (DOER), NStar and a group of product sponsors.
Massachusetts Energy and Environmental Affairs Secretary Ian Bowles, who chairs the Governor’s Zero Net Energy Buildings Task Force says, “Nationally, buildings account for 40 percent of all energy consumption, and one-third of all greenhouse gas emissions. This super-insulation project…promises to be a model for…innovation in the building industry.”
The scope of the insulation plan was formulated after a study of the structure’s heat-loss, developed at the request of DOER and NStar. Because this is a pilot project, both DOER and NStar are monitoring performance by tracking real-time oil usage as well as temperature and humidity at interior and exterior locations. Two neighbors with similarly constructed homes have accepted “data loggers” in their homes to act as a control group regarding temperature and humidity.
The building has been fully clad with polyisocyanurate rigid insulation. Polyiso insulation is a high R-value, closed-cell, rigid foam board insulation that allows buildings to gain LEED points. It is used to insulate the entire wall (including the framing, which accounts for at least 20 percent of the total wall area and often is uninsulated), thereby significantly reducing heat loss through both convection and conduction.
Additionally, properly insulating a structure with polyiso can decrease condensation in the walls, potentially lowering moisture-related problems. On the exterior walls, four-inches of polyiso insulation was covered with a new advanced siding system, in addition to cellulose blown into wall cavities, for a total rating of R-40.
Six inches of rigid insulation was installed on the roof deck under a new shingle roof with reflective properties, in addition to the fiberglass batts already installed in the roof rafters, for a minimum rating of R-58. In the unfinished areas of the attic, the old fiberglass was removed and replaced with water-blown Icynene foam for a minimum rating of approximately R-64. Icynene expands to 100 times its volume in seconds to fill every crack and crevice while remaining flexible so that the integrity of the seal remains intact over time. Icynene acts as a complete insulation and air barrier to minimize air leakage and seal the building envelope for optimal airtightness and can help buildings gain LEED certification. It also contributes to a healthier home because it doesn’t off-gas.
These high R-values in super-insulated retrofits like this one are higher than many zero-energy homes. They are equal to Europe’s PassiveHaus energy efficient housing construction standard.
As the work progressed on the re-insulation, it became clear that previous insulation work was not effective. “As we dug deeper into the project, it was shocking to see the bad insulation practices and how many uninsulated voids were missed by earlier generations of cellulose and fiberglass installers, and even Infrared inspectors,” says Cheimets.
The entire building envelope has been also tightened with new doors. And older single pane windows have been replaced with thermally stable fiberglass framed double-pane Low E windows.
Indoor air quality can sometimes be a problem with super-insulated retrofits and extremely tight buildings in general. Cheimets has dealt with that issue with the installation of carbon monoxide sensors on each floor and of heat recovery ventilators, which exhaust stale air and salvage the heat from that stale air to warm incoming fresh air.
Super-insulated retrofits like this one are leading the way in the energy-efficiency field, keeping families warm in winter while saving money and helping mitigate climate change.
Rolf Priesnitz is the Publisher of Natural Life Magazine, where this article was first published. He also has over fifty years worth of experience in construction.