Windmills in the back yard, rain barrels
under gutters, and concrete front lawns, it’s looking like more homeowners are
joining the sustainability movement. Sometimes these obvious efforts to do the
right thing can seem extreme. When it comes to home building or remodeling,
sustainability starts by critically thinking about how windows affect a home’s
overall climate.
Windows typically comprise 10-25% of a
home’s exterior wall area, and in a climate like ours, they can account for
35-50% of the heating and cooling needs of the home.
When you’re ready to remodel or build a new
home talk to architects and builders who understand sustainable design and
enlist them to help you create a three step balanced approach to
sustainability.
Step One: Start with Design
Principles
Step Two: Select High
Performance Windows
Step Three: Build with
Integrity
Design
Principles
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| Marvin Windows |
A good architect or designer will focus on
your thermal comfort, in our case, living in an extreme climate. A good design
reduces the need for heating and air conditioning and uses construction
materials, especially windows that help balance the thermal load. In other
words, flooring, ceilings, window sizes and framing materials, shading and
other choices interact in ways that lower thermal loads. The goal is for your
home to require less heating and cooling to maintain comfortable conditions.
Designers who understand these principles
will choose designs and products that are best suited for your home. They will orient
windows so as to optimize light and the warmth, while neutralizing the suns
overall affect on your home’s temperature. For example, sparingly place windows
on the east and west facades, and maximize the window placement on the south
side of your home. The design will provide natural ventilation by strategically
placing windows on both sides of the house to create cross-ventilation or
layouts, like ceiling level hoppers that capture cooling breezes in the summer.
High Performance
Windows
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| Marvin Windows for Ventilation |
Advances in window technology, such as
double pane and low-e coatings, substantially reduce heat loss and control heat
gain. The performance contrast between new windows and the original single
glass panes that you may have in your old home is drastic. Imagine that all
these years, all you had separating you from the Chicago winter was a single
pane of quarter-inch glass. Whether you choose wood, fiberglass, vinyl or
aluminum, modern window frame conductivity outperforms anything you’ve known
before.
Consult the standardized ratings for Solar
heat gain coefficients (SHGC) and U-values provided by the NationalFenestration Rating Council (NFRC) and Energy Star Labels, but remember that
while ratings are important, they shouldn’t be the driving factor for the
window choices. Features like thermal performance can add to condensation
problems for instance, so that interior humidity and climate also need to be
considered. Don’t rely on one value over all others; rather take the entire balanced
design into consideration when choosing new windows.
Build
Smart
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| Marvin Upper Transoms |
The success of your design and product
choices relies on building and installation techniques. High performance
windows need to be installed according to the manufacturer’s instructions so as
not to diminish the energy performance, not to mention, damage the window unit
or surrounding walls. Homeowners should expect the builder to follow key guidelines
to the highest standards.
- Meet all codes
- Properly size rough opening allowing for expansion and movement
- Install window unit level, plumb, and square
- Maintain the continuity of the weather-resistant barrier
- Insulate all voids between the window and wall with expanding foam (minimum rate)
- Maintain the integrity of air and vapor retarders
- Only apply caulks and sealants that are compatible with the substrate
The best measure of sustainability is building
something right the first time.
