Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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SUN REFLECTOR FOR WINDOWS
TECHNICAL FIELD
The present invention relates to a sun reflector foil for glass windows and
doors, and in particular
to a sun reflector kit for applying a sun reflector foil to windows and doors.
BACKGROUND OF THE INVENTION
Typically in northern climates there are only about two months of true summer
weather, and only
a few weeks with truly hot temperatures. Accordingly, some people consider it
a waste of
money and energy to purchase, run and maintain an air conditioning unit for
such a short period
of time. Running an air-conditioner at 21 C (typically costs more than
$200/month for an
average house. During the summer months, hydro consumption increases as much
as 25% due to
use of air conditioners. Utility companies often resort to the more polluting
power generation
such as coal plants, to meet this increased demand. Accordingly, finding
alternative solutions for
reducing uncomfortably high levels of heat can decrease peak demand for
energy, thereby
generating environmental benefits and cost savings for the home owner.
Due to heavily insulated walls, much of the heat enters a dwelling via
radiation of the sun's rays
through the windows, doors or other transparent portals, e.g. patio doors.
Single pane glass will
let in 84% of heat, while standard double pane windows allow 71% of heat to
transfer. A 4x4
window with direct sun lets in over 2000 BTU/hr of heat (equivalent to 600 kw
heater). Double
and triple pane windows with inert gas fillers minimize heat conduction, but
surprisingly even
argon filled windows allow 62% heat transfer. "Low-E" coatings for windows and
doors
attempt to minimize radiation; however, they still do not go far enough to
reflect the majority of
the suns radiation.
Window films have also been used to reflect sunlight in the past; however,
these films are
manufactured with a near permanent adhesive, which last for up to 10 years and
cannot be
removed, without destroying the film, for the other three season, when the
extra heat from the
sun is used to offset residential heating costs. Accordingly, conventional
window films are
counterproductive in northern climates with multiple seasons. Most of these
conventional films
only reflect up to 40% of the sunlight and radiant heat, and are designed to
be unnoticeable to the
naked eye, providing limited effect and no privacy at any time.
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The application process for films is also more complicated than is the case
for the current
invention, because there is a protective layer that must be peeled of, both
making the product
difficult to work with and creating waste. Furthermore, the permanent adhesive
does not allow
for multiple adjustments, resulting in failed mounting attempts, making the
products less
appealing to do-it-yourself homeowners. The films may also be hazy for 5-10
days while the
adhesive cures. Air bubbles will typically occur and disappear after the
curing process is done,
but if the air bubbles do not disappear, new product must be purchased and
applied. The films,
which are substantially thicker than the present invention and include complex
adhesives and
waste material, i.e. the film backing which is peeled off, are also more
expensive than the present
invention.
Alternatively, people cover their windows with thick aluminum foil, e.g. 6 urn
thick, which
blocks all oxygen, moisture and light, but results in a very unattractive
display, defeating the
purpose of the window.
An object of the present invention is to overcome the shortcomings of the
prior art by providing
a radiation reflecting foil for temporarily covering glass windows and doors
during the hot
summer days and months to greatly reduce the transfer of heat via the sun's
rays, while enabling
the foil to be manually applied, removed and reinstalled whenever desired.
Another object of the present invention is to provide privacy for the inside
of a home or building
during the day, when the sunlight is brighter than the inside light, while
enabling the occupants
of the home or building to observe the outside.
SUMMARY OF THE INVENTION
Accordingly, the present invention relates a heat reflector for use in
covering transparent panel to
reflect the sunlight from entering a building comprising; a polyethylene
substrate layer; a
metallized material in or on the polyethylene film layer forming a foil to
increase reflectivity to
between about 40% and about 99% of the sunlight; and a mounting element for
temporarily
mounting the foil onto a window or door and enabling manual removal and
reinstallation at any
time.
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In a preferred embodiment the foil reflects about 90% to about 99% of the
sunlight providing
privacy from outside the building looking in, while providing transparency
from inside the
building during daytime, while the sun is shining.
Another aspect of the present invention relates to the use of a heat reflector
comprising a
metallized, bi-axially-oriented polyethylene terephthalate foil sheet for
temporarily covering a
transparent panel to reflect between about 40% to about 99% of sunlight from
entering a building
and reduce heat transfer therethrough, and manual removal and reinstallation
whenever desired.
In a preferred embodiment use the foil reflects about 90% to about 99% of the
sunlight providing
privacy from outside the building looking in, while providing transparency
from inside the
building during daytime, while the sun is shining.
Another feature of the present invention provides a kit for mounting a
sunlight reflector onto a
transparent panel mounted on a building comprising: a sheet of metallized
polyethylene heat-
reflective foil for reflecting about 40% to about 99% of sunlight from
entering a building, a
cutting element for cutting the sheet of metallized polyethylene foil to fit
the transparent portal; a
mounting element for temporarily mounting the sheet onto a transparent portal,
and for enabling
manual removal and reinstallation at any time; and a squeegee for smoothing
out the sheet on the
transparent portal.
In a preferred embodiment the foil in the kit reflects about 90% to about 99%
of the sunlight
providing privacy from outside the building looking in, while providing
transparency from inside
the building during daytime, while the sun is shining.
Yet another aspect of the present invention relates to a method of preventing
the transfer of heat
through a transparent panel mounted between an inside and an outside of a
building, comprising:
cutting a sheet of metallized polyethylene foil to fit the transparent panel;
applying a temporary
adhesive material to the sheet or the transparent panel enabling manual
application, removal and
reinstallation of the sheet without damaging the sheet; mounting the sheet of
metalized
polyethylene foil onto the transparent panel; and smoothing out the sheet of
metallized
polyethylene foil on the transparent panel; wherein the metalized polyethylene
foil has a
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thickness which reflects about 40% to about 99% of the sunlight while
appearing transparent
from inside the building and opaque from outside the building during daytime.
In a preferred method the foil reflects about 90% to about 99% of the sunlight
providing privacy
from outside the building looking in, while providing transparency from inside
the building
during daytime, while the sun is shining.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be described in greater detail with reference to the
accompanying drawings
which represent preferred embodiments thereof, wherein:
Figure 1 is a cross-sectional view of the radiation reflector in accordance
with the present
invention mounted on a window; and
Figure 2 is a isometric view of a radiation reflector kit in accordance with
the present invention.
DETAILED DESCRIPTION
With reference to Figure 1, the solar reflector 1 of the present invention
includes a radiation
reflecting foil 2 that can easily be applied to transparent panels 3 mounted
on a building, such as
windows and doors, using a suitable mounting element 4, e.g. temporary
adhesive material,
during summer months, and then easily removed during the fall or on days when
the foil 2 is not
required. The term transparent panel is used interchangeably with term window
to refer to any
transparent or semi-transparent pane of glass or other material used in
windows or doors to
enable light to enter a building, home or other structure.
Ideally, the radiation reflecting foil 2 is transparent from the side without
the light source, i.e. the
inside during the day, and the outside during the night. The light from the
bright room reflected
from the foil back into the room itself is much greater than the light
transmitted from the dark
room, overwhelming the small amount of light transmitted from the dark to the
bright room;
conversely, the light reflected back into the dark side is overwhelmed by the
light transmitted
from the bright side. This allows a viewer in the dark side to observe the
bright room covertly.
An example of an inexpensive and easily acquired base or substrate material is
biaxially-oriented
polyethylene terephthalate (boPET) originally developed in the mid 1950's by
DuPont and used
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for space suits, emergency blankets and sails. Alternatives include
polypropylene, PET, nylon,
polyethylene and cast polypropylene. Typically, the substrate is approximately
10 urn to 1000
urn thick, preferably 10 urn to 100 urn thick.
BoPET is a polyester substrate made from stretched polyethylene terephthalate
(PET) and has
the following properties: high tensile strength, chemical and dimensional
stability, transparency,
reflectivity, gas and aroma barrier properties and electrical insulation. The
sun reflector 1
according to the present invention includes some form of metal material to
increase the
reflectivity of the sun reflector to from about 40% to about 99%. Ideally, a
metallized layer 6,
e.g. applied by vapor deposition onto the boPET substrate, of a thin layer of
evaporated
aluminum, gold, or other metal is provided, e.g. a thickness of between about
.0025um and about
.025um. In another embodiment, the aluminum layer 6 is between about 0.01 um
and about .025
for reflecting about 80% to about 99% of the sunlight and heat.
In the preferred embodiment in which approximately 90% to 99% of the sunlight
is reflected the
layer of aluminum 6 is of less than about .025 urn, and greater than about
.015 um (150 A to 250
A) and most preferably between about .016um and about .024um, although other
covering or
injection methods are possible. Ideally, the aluminum layer is thin enough to
be partially
transparent on the side of the foil with less light, while appearing opaque,
i.e. providing privacy,
from the side with the most light to the side with less light, e.g. people
inside of the dwelling can
see out when the sun is out during the daytime, while people outside the
dwelling cannot see in.
The resultant foil material is much less permeable to gases, e.g. 50 to 150
ccm/m2/day of oxygen,
and less than 1 to 50 g/m2/day of water vapor, but still provides for some
"breathing", and
reflects at least 90% and up to 99% of light and heat, including much of the
infrared, visible and
ultra violet spectrum, while letting a small percentage of light in to provide
limited transparency,
i.e. for aesthetics. Aluminized boPET film can also be laminated with a layer
of polyethylene 8,
which provides sealability and improves puncture resistance. The polyethylene
side 8 of such a
laminate appears dull and the PET side 2 appears shiny providing the user with
the option of
having shiny or dull appearing windows.
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A variety of companies manufacture boPET and other polyester materials under
different brand
names. In the UK, Canada and the US, the most well-known trade names are
Mylare,
Melinex and Hostaphan .
With reference to Figure 2, the present invention also relates to a kit 10 for
mounting the solar
reflector foil onto windows and doors. Each solar reflector kit 10 will
include a section of
transparent, radiation reflecting foil, preferably metallized polyester foil
1, more preferably a
metallized boPET foil, and ideally 48 gauge aluminum boBET foil, i.e. 12-13
urn thick. Each kit
can include a large section of reflector foil 1, which the homeowner will have
to cut to suite
their window requirements or each kit can include one or more sections 11 of
reflector foil pre-
10 cut into pre-determined sizes, based upon the standard windows and
doors, e.g. a standard size
(30" x 64") for standard windows, a large size (59 x 84") for larger window,
and a patio door
size (35" x 72") for patio doors.
The kit 10 may include a cutting instrument, such as scissors or a retractable
utility knife 12, for
cutting the section of reflector foil 11 to fit the windows exactly. A large
straight edge, such as
a 6" flat wooden stick 13, can be provided to facilitate the cutting of the
foil sections 11. During
cutting with the utility knife 12, the straight edge is used to hold a portion
of the foil section 11
down against a hard surface, and to provide a straight-edge guide for the
cutting instrument 12.
Once the foil section 11 are cut to fit the window, a temporary adhesive
material is applied to the
window (or the foil section 11) as a mounting element. Ideally, a mild soap or
shampoo solution,
e.g. 1 drop of dish soap per 1-2 cups of water, which may or may not be
provided in the kit 10, is
evenly applied to the entire glass portions of the window, using a sponge 14,
ideally provided in
the kit 10. Alternatively, a suitable temporary or weak adhesive layer can be
provided on a
surface or at specific areas of the foil section 11. The cut foil section 11
can then be mounted on
the window and moved around to fit perfectly. The adhesive is only temporary
and enables the
foil section 11 to be manually removed easily whenever desired, i.e. with no
additional
chemicals, power tools or machines, every day, week, month or season, without
damaging the
sheet, thereby enabling reinstallation of the sheet, as needed.
The kit 10 also includes a squeegee 16, e.g. 6 to 12 inches wide, for
straightening, smoothing and
adhering the reflector foil section 11 to the glass windowpane. Ideally, the
squeegee 16 includes
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a silicon head to reduce friction between the squeegee 16 and the reflector
foil 11 for preventing
the foil from getting scratched or tearing.
The mounting element can also include tape 17, ideally in the form of a small
roll of clear tape,
provided for anchoring the reflector foil section 11 in place, and for fixing
any scratches or tears
that may have occurred during the mounting process. The aforementioned steps
are then
repeated for each window in the house.
While window films remain on the window for all four seasons and last for up
to ten years, the
foil sheets in accordance with the present invention are mounted for ten to
twelve weeks only
and are then disposed of after the summer. The window foil can also be
temporarily removed on
cloudy days or when you want unobstructed views, and then reapplied. Most of
the films reflect
less than 40% of the radiant heat, while the preferred window foils reflect
over 90% of the
sunlight and radiant heat. The foil in accordance with a preferred embodiment
of the present
invention appears opaque from the outside during the day, thereby providing
privacy, but is also
partially transparent from the inside, enabling the home owner to see the view
outside while
controlling the climate inside, unlike typical aluminum foils that are
surprisingly used by many
throughout Canada and the United States, during heat waves.
The use of the foil of the present invention, as opposed to the prior art
films, offers the
advantages of greater ease of application, elimination of the need for special
adhesives, reduced
waste and greater ease of removal and reuse, as desired.
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