According to the U.S. Energy Information Administration (EIA) on average, more than half (51% in 2015) of a household’s annual energy consumption is for space heating and air conditioning. Though, seasonal heating and cooling needs vary significantly by geographic location, home size and structure, and equipment and fuels used. Nonetheless, heating and cooling your home uses more energy and costs more money than any other system in your home.
I live in climate zone 4 and made my decisions on insulation
based those factors in 2008. My brother who just bought new home (from the 1950’s)
lives in climate zone 5 in the Boston area. He is looking to add insulation to
his home. So, I am reviewing the choices
in 2021. For the insulation project, the attic and accessible areas of the
basement and crawl spaces were inspected for adequate insulation.
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| from DOE |
For my home built in 2004 with duct work for my heat pump in the attic, I followed the recommendations by the Oak Ridge National Laboratory. The attic, crawl spaces, eves, ductwork,underside of a large portion of the main level floor were insulated withcellulose (in the attic) and fiberglass batting insulation in the basement andfloor. The pipes, end caps, knee wall, sump pumps and all identified areas were sealed, the garage was insulated and an insulated garage door installed. I have a separate garage with no living space above it, I used it to test Icynene foam insulation.
My total electricity bills for the following 12 months were
27% less than I paid in the 12 months before I added the additional insulation
to the house, and the winter liquid propane usage (as measured in volume use
December through March both years) was reduced by 25%. Also, the overall
comfort in the bedroom over the garage and the master bedroom has been vastly
improved. I was very surprised at the energy savings for what was a well
insulated home. The payback on this project was under 4 years, unbelievably
good.
I used blown in cellulose for several because it was
inexpensive, but also because it is inert and I was adding insulation to a home
that already had some blown in cellulose. There was no off-gassing from urethane
based foams, no fiberglass fibers to get into the air handling system. When I
insulated my home in 2008 various foams on the market were changing due to the
removal of some foaming agents from the market. I was concerned about having a
negative impact on air quality that would be extremely difficult to remedy. Todaythe Environmental Working Group says: “spray foam containing a chemical knownas methylene diphenyl diisocyanate, or MDI, which can cause asthma and lungdamage in exposed workers. Spray foam can also contain the toxic flameretardant TCPP. If mistakes are made during installation, sprayed-on insulationfoam is difficult to remove.”
For loose-fill insulation, each manufacturer must determine
the R-value of its product at settled density and create coverage charts
showing the minimum settled thickness, minimum weight per square foot, and
coverage area per bag for various total R-values. This is because as the
installed thickness of loose-fill insulation increases, its settled density
also increases due to compression of the insulation under its own weight.
Thus, the R-value of loose-fill insulation does not change proportionately with
thickness. The manufacturers’ coverage charts specify the bags of insulation
needed per square foot of coverage area; the maximum coverage area for one bag
of insulation; the minimum weight per square foot of the installed insulation;
and the initial and settled thickness of the installed insulation needed to
achieve a particular R-value.
Spray foam comes in two types- open-cell foam or closed-cell
foam. Closed cell foam has the highest R-value of any insulation, up to R-7
per inch, but can be expensive; open-cell foam insulation values are around
R-3 to R-4 per inch of thickness. Closed cell can also serve as a moisture barrier. Spray
foam insulation should be installed by a professional, since it is tricky to do
right and almost impossible to undo. In order to spray in insulation into an attic that has some existing insulation, all the old insulation would have to be removed, or the new spray in insulation would have to be applied to the roof deck and knee walls. This can trap moisture between the roof shingles and foam mass. It could prevent mold in the attic, but allow rotting of the roof elements.
Before insulating, seal any air leaks and make roof and
other necessary repairs. If it is located in a conditioned part of the house,
also remember to insulate and air seal your attic access. Insulate and air seal
any knee walls -- vertical walls with attic space directly behind them -- in
your home as well. If the air distribution system is not within the conditioned
space but within the attic, insulating the rafters will enclose the
distribution system. Finally, the DOE advises if you live in a hot or warm
climate, consider installing a radiant barrier in your attic
to reduce summer heat gain.
- Spray foam application generates isocyanate vapors and aerosols.
- Research data indicate that inhalation exposures during spray foam insulation will typically exceed Occupational Safety and Health Administration (OSHA) occupational exposure limits and require skin, eye and respiratory protection.
- Vapors and aerosols can migrate through the building if the installation area is not properly isolated and ventilated.
- After application, vapors may linger in a building until properly ventilated and thoroughly cleaned.
These days, foam insulation is growing in popularity, especially in colder climates where higher insulation values are required by code. Available foam insulation materials include:
- Cementitious
- Phenolic
- Polyisocyanurate (polyiso)
- Polyurethane.
Polyurethane is the most commonly used right now according
to DOE. Some less common types include Icynene foam (what I used in my garage
attic) and Tripolymer foam. Icynene foam can be either sprayed or injected,
which makes it the most versatile. It also has good resistance to both air and
water intrusion. Tripolymer foam—a water-soluble foam—is injected into wall
cavities. It has excellent resistance to fire and air intrusion.
Foam insulation products and installation usually cost more
than traditional batt or blown in insulation. However, foam insulation has
higher R-values and forms an air barrier,
which can eliminate some of the other costs and tasks associated with
weatherizing a home, such as caulking, applying housewrap and vapor barrier,
and taping joints. When building a new home, this type of insulation can also
help reduce construction time and the number of specialized contractors, which
saves money for the builder so it is often used in new construction.
Liquid foam insulation materials can be sprayed,
foamed-in-place, injected, or poured. Foam-in-place insulation can be blown
into walls, on attic surfaces, or under floors to insulate and reduce air
leakage. Closed cell installations can yield a higher R-value than
traditional batt insulation for the same thickness, and can fill even the
smallest cavities, creating an effective air barrier. You can use the small
pressurized cans of foam-in-place insulation to reduce air leakage in holes and
cracks, such as window and door frames, and electrical and plumbing
penetrations. In the end the type of insulation you used is your decision.
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