Building
energy efficient homes is not a new concept. For centuries different
ideas have been implemented by home builders, architects, and even
indigenous people, to achieve a house that is easy to heat in cold
weather and easy to cool in hot weather.
Until
early in the 20th century homes in this country were mostly built
with stone, brick, logs or what would now be labeled Post and Beam
Construction. Since that time most homes have been built with light
frame construction (2 x 4s). Many alternative types of construction
have been touted in recent years, such as earth shelter, underground,
super insulated, stressed skin panels, etc.; but even though these
are valid designs, they represent a small segment of the market.
The
first step in building an energy efficient home is finding the right
site, hopefully with solar orientation. Second, a designer or architect
familiar with energy efficient design techniques and products should
be chosen. Next,
find a builder that understands and implements energy efficient building
methods and uses proper installation practices. The builder should
have someone on site on a regular basis to insure employees and subcontractors
adhere to the proper building practices.
Studies
have shown that an average conventionally insulated house loses heat
in the following manner:
•
Ceilings 5%
• Walls, windows and doors 22%
• Basement walls 22%
• Basement floor 1%
• Air infiltration 35%.
A very
tight house can have less than 1/4 air exchange per hour, whereas
a poorly built house can have one or more air exchanges per hour.
A tight house is also a quiet one.
In recent
years many building officials have attempted to establish criteria
that would insure new homes were more energy efficient. They required
higher insulation values, more efficient air conditioners and furnaces,
and higher standards for windows and doors, etc. Some require calculations
for building envelope heat losses. Some other things are harder to
quantify and legislate.
Solar
gain, house design and orientation, air filtration, and many details
of construction are just as important, but not as easy to specify.
Better products help make a house more energy efficient if they are
properly installed.
Casement
windows are usually tighter than sliders or double hung windows.
Raised head trusses allow insulation to be thicker at the intersection
of the trusses and the walls; 2 x 6 walls, better insulation, products
that reduce air infiltration, heating and cooling systems that are
more efficient, and even types of lighting have an effect.
Perhaps the most important consideration in building an energy efficient
house is the attention to detail. To reduce air infiltration lots
of sealing is required. Light fixtures, switches, outlets and any
other penetrations or gaps in the walls, ceiling or floor should be
sealed. Placement of insulation should be carefully monitored. Attention
to detail by employees and subcontractors should be supervised on
a constant basis.
A house
that is exceptionally tight can have air quality problems. Attention
to outgassing characteristics of construction materials is important.
Even with good products some outgassing does occur, especially in
the first year. A positive fresh air ventilation system can help.
To sum
things up, an energy efficient house requires a good lot, well thought
out plans, proper specifications, and a contractor that pays attention
to detail.
Dick
Ludwig is a Builder, specializing in energy efficient houses.
He is the owner of Environmental Homes of Colorado, LLC and lives
with his wife Antje in Franktown, Colorado.
Dick
has a Bachelor of Science degree from Georgia Tech. and has 25 years
experience building energy efficient houses.
