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Our research activities in the field of high performance windows have led
us to conclude that even by using high performance insulating glass units, low
conductivity frames, and warm edge spacers, there are still untapped sources for improving
energy efficiency in the design and use of residential windows. While such high
performance windows are a dramatic improvement over conventional units, they do not reduce
conductive losses through wall framing around the window, offer guarantees against
excessive wall/window infiltration nor do they adapt to the daily and seasonal potentials
for night insulation and summer shading. To meet this need, we have been working on the
design, development, and prototyping of Integrated Window Systems (IWS) since 1993.
Integrated Window Systems are a form of panelized construction where the wall panel
includes an operable or fixed window sash, recessed night insulation, integral solar
shading, and is built in a factory setting in order to minimize thermal short circuits and
infiltration at joints. IWSs can be built in modular lengths to facilitate their
installation with conventional wood frame stick construction or other forms of panelized
construction.
Our prototype IWS uses the wall framing to anchor the window sash, thereby doing away
with the window frame. The use of supporting lumber (jack studs, headers) is also reduced.
Thin, high performance night insulation is installed in the outer inch of the cavity below
the window adjacent to the storage position of the night window insulation. When the night
insulation is deployed the window's thermal resistance doubles to approximately R12 while
the wall remains well insulated. A retractable solar shade screen, installed above the
window in space freed up by the replacement of the conventional header with a compact
engineered header, can be operated either manually or by an electric motor.
A research paper on the Integrated Window System is
available in pdf format. LBL-35417.pdf
Download a free copy of Adobe
Acrobat Reader
from Adobe.
For more information contact:
Dariush Arasteh D_Arasteh@lbl.gov, 510-486-6844
Windows and Daylighting Group, 90-3111
Lawrence Berkeley National Laboratory
Berkeley, CA 94720
FAX: 510-486-4089
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