Q — I am on a limited budget, but I want to give my living room a more
open feel and get more natural light. I saw some reasonably priced bay windows
at a home show. Are they efficient and what design features should I look for?-Char
A — Adding a bay window to a large room can brighten it substantially
without the use of electric lighting and also make it seem much larger. In a
smaller area, such as a kitchen or breakfast nook, natural light enhances foods’
colors and makes them look more appetizing. It might even help get your kids
to eat their veggies.
The overall energy
efficiency of adding a bay window depends on several factors: are you replacing
an existing window, do you rely on natural ventilation sometimes during the
summer, do you use electric lights in that room during the daytime, and what
is the quality of the window?
If you are replacing
an old standard window, then almost any new bay window of the same size will
be much more energy efficient. If you are going to cut a hole in an existing
insulated wall, or enlarge an existing window opening more than double its size,
the bay window may lose more heat than the insulated wall or smaller window.
For rooms that often
require electric lights, the electricity savings from natural lighting may offset
the additional heat losses through the glass. With the bay window’s projection
outdoors beyond the wall surface, it will effectively capture gentle breezes
during the summer. This natural ventilation can lower your air-conditioning
bills and reduce the peak demand for the utility company.
Another option similar
to a bay window is a bow window. Bow windows usually consist of four or more
glass sections that simulate a more rounded appearance than typical angle bays.
Bay windows have just three sections with the side sections typically angled
at 30 or 45 degrees. Ones angled at 45 degrees provide better ventilation and
a larger sill to use for sitting, plants, etc.
Your most economical
and easiest-to-install option is a pre-assembled bay or bow window unit, as
opposed to trying to build one from scratch using three or more separate window
sections. A builder is usually required to install one from scratch.
Almost any combination
of window types is possible for a bay unit, but a large center picture window
with casements on both sides is very popular and most efficient. The clear vertical
casement glass span matches the picture window’s height. Casements provide the
best fresh air ventilation when opened and an airtight seal when closed.
Bay and bow window
frames that use vinyl or aluminum-clad wood on the exterior are attractive and
maintenance-free. The interior surface is usually either natural wood that can
be painted or stained, or special stainable vinyl. With simulated wood graining,
the stained vinyl looks authentic and is also maintenance-free.
Your choices of design
features are nearly endless. For energy efficiency, select a unit with rigid
foam insulation built into the headboard and seatboard. Some super-efficient
ones also have foam-filled frames and cavities.
The glass is the heart
of any window for efficiency, comfort, glare control, and fading resistance.
For most climates, low-emissivity (low-e) glass with argon gas in the gap is
the minimum to select. Glass with warm-edge technology (an insulating spacer
separates the glass panes) is also a good choice. This saves energy year-round
and reduces window condensation in cold climates during the winter.