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Conservation
Through Insulation
by Joe Bell for Cabin
Creek Timber Frames from their
Timber
Frame Magazine
Conservation Through
Insulationby
Joe Bell
Buildings in the
United States consume 68% of the electricity generated in the
country and 37% of the energy. If we consider our sources of energy,
the political, economic, and environmental consequences of obtaining
and using this energy, we immediately realize we have a problem. We
do not yet have an unlimited of energy. The energy needs of our
country are increasing. There are drawbacks to most energy sources.
The logical approach is to develop and refine each track in the most
benign possible way, and to be more efficient in our use of energy.
This last phase needs to be underscored, understood, and undertaken.
By becoming more energy savings , or efficient, much energy,
political expenditure, money, etc., can be conserved. How do we
become more efficient?
One building or house built
efficiently, will not answer this problem but it is a start. Each
one is built inefficiently is an addition to the overall problem. We
already have a number of tools which will cut down considerably on
the energy usage in buildings. Unfortunately, most builders,
architects, and designers choose to ignore the most important of
these. This is the use of efficient insulation. Preventing heat loss
across a material is the job of insulation. Heat loss can be by
convection, conduction, or radiation. Convection requires movement
of a gas, usually air. Conduction usually occurs through a solid
material, such as a frying pan. Radiation is the reason you feel
heat from a hot metal roof overhead in the summer.
Here is
a list of insulating materials and comments. Please see Wikipedia on
R value and qualities of various insulators.
- Fiberglass. Average. It settles
over time, losing space between fibers, allowing more conduction
and airflow or convection. Inexpensive.
- Cellulose. Settles. Can be
flammable. Inexpensive. Cold bridges.
- Icynene spray. Expensive, messy,
good, but cold bridges remain from stud construction.
- SIPS, Moderate cost. Good
insulation. No settling. Strong. Forms relatively airtight
envelope around living space with less than 1/10th the airflow
through a fiberglass stud-wall building.
- Vacuum Panels. Excellent.
Expensive. Fragile.
Years
ago, most thoughtful timber frame companies settled on insulated
panels or SIPS which significantly reduce the airflow through
building walls and roofs. The USDOE in studies at Oak Ridge National
Laboratory has shown in whole walls (including window and doors)
that equally R-rated SIPS or panel insulation compared with
fiberglass batt insulation has only 10% of the airflow through the
structure. Accurate records show that it costs half as much as to
heat, cool,and power a SIPS insulated building than a fiberglass
stud-wall building with the same R-ratings. Over a period of years,
in a fiberglass stud-wall building, these differences in air flow
along with settling of the fiberglass, consume large amounts of
wasted energy energy into a much more expensive building, and long
term costs to the owner and our country.
Here is the
key. Stud walls keep a poor insulator, wood, as a bridge every
16 or 24 inches to decrease the insulating efficiency of the wall or
roof. SIPS maintain a tight membrane.
Here is the
bottom line. One must rate an insulating system by measuring its
performance over a lifetime of a building.
Users and
manufacturers of insulated panels have known for years the
efficiency of panels and have documented these monetary savings.
Sadly, they are still a well kept secret.
A timber frame
house, 1,800 sq. ft., heated with an electric heat pump, in Western,
North Carolina has cost an a monthly average $50 to heat, cool and
power, for the past four years. |
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