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-insulation retrofits in the United States.
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
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
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.
|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.
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
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 are higher than many zero-energy homes and
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 the replacement of older single pane windows with thermally stable
fiberglass framed double-pane Low E windows.
Indoor air quality can sometimes be a problem with extremely
tight buildings, and 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
Photos by Alex Cheimets