What’s the
best way to make historic buildings more energy efficient? There is no single alteration
or improvement to make. Instead, the best approach is to look at the building
itself and see what it needs. To assist in that, the Connecticut Trust is
offering grants of $500 to towns and cities for energy audits of their historic
buildings. The grants include follow-up consultation with one of the
Connecticut Circuit Riders to interpret the results and discuss how best to
meet the building’s energy conservation needs while preserving its historic character.
As of mid-December, six towns had applied for the grants.
The grants were
inspired by the prospect of a glut of vinyl siding and replacement windows under
government stimulus programs. Despite growing interest in sustainability, replacement
windows are often the first choice for improving energy efficiency, because
they’re easy to install, because they offer immediate and visible evidence of accomplishment,
because they’re aggressively marketed, and, unfortunately, because the public is
often unaware of other options.
Rebecca Williams, a Program Officer
for the Northeast Office of the National Trust for Historic Preservation,
discussed windows at a recent Preservation Roundtable convened by the Connecticut
Trust. Speaking to representatives of local preservation organizations, she described
the National Trust’s sustainability initiatives and then offered a detailed
discussion about windows.
To begin with, Williams pointed out,
windows are not the major source of energy leaks; they account for only about
10 percent of heat loss in winter or heat gain in summer. This was confirmed by
a recent energy audit of the Trust’s headquarters, the Eli Whitney Boarding
House, which has single-glazed reproduction windows and no storms. The audit showed
that only 11 percent of heat loss was through the windows. Much more—55
percent—is lost through the building’s uninsulated walls.
Williams
listed several reasons why retaining older wooden windows is better than
replacing them:
They’re
sustainable, because manufacturing replacement windows entails a large
energy expenditure that can take decades to recoup.
They
can be repaired, unlike replacement windows which have to be thrown out when
their seals fail.
The
old-growth wood in historic windows tends to have denser grain, which is
more durable and provides a better insulation value than new wood.
They
fit the openings in historic buildings; installing replacement windows
often entails making the openings smaller, reducing natural light and
ventilation.
Williams also suggested ways to
increase the energy efficiency of historic windows:
Be
sure that sash locks fit tightly to prevent air infiltration.
Caulk
window casings inside and outside.
Add
weather stripping.
Add
storm windows; some studies show that even a leaky wooden sash window with
a well-fitting storm window performed as well as a new vinyl replacement
window.
Use insulating
curtains or shades.
Consider
companies that retrofit historic windows with double-pane glass, such as
Bi-Glass.
Consider
using laminated glass, which provides additional insulation but has no
seal to fail and can be made in larger sheets than double-pane glass.
For more information:
Connecticut Trust energy audit grants for towns and
cities: (203) 562-6312
