|
For
Blinds and Shutters press here.
Film, a window of Opportunity
There are many examples of wasted energy in a facility
— lights left on in rooms without occupants, or inefficient HVAC
systems, for example. One source that often goes unrecognized is the
energy required to cool space heated by sunlight coming through windows.
Roughly one third of an average building’s cooling load is due to solar
heat gain through windows,. Of course, windows provide views and sunshine that can reduce
the need for artificial lighting. Even so, more daylight also means more
heat, and this requires cooling to keep occupants comfortable. One way
to reduce solar heat gain and improve the energy efficiency of a
building is window film. Solar control window film is applied to the
inside of a window where it reflects and absorbs heat. In addition to
reducing the need for cooling, window film helps create an even,
comfortable temperature throughout a building.
How Window Film Works
 |
 |
|
Solar control window film reduces heat gain by
blocking solar radiation.
When rays from the sun hit a window, some of the energy is absorbed and
some is reflected by the window, but most is transmitted through the
glass. When this energy enters a space
and is combined with the ambient heat already present in a room — due to
people, computers and reradiated heat absorbed by furniture and
carpeting — the excess heat can make an uncomfortable difference and mean
that the room needs cooling and that is when your air conditioner
switches on, Installing solar control window
film increases the amount of solar energy both reflected and absorbed by
the window. Most window films have a thin metallic coating, made up of
aluminum, stainless steel, silver or a combination of these, that
reflects and absorbs solar radiation. Of the radiation absorbed, most of
it is reradiated outward, though some is radiated into the building. The
most important performance measurement of the heat rejection ability of
solar control window film is the solar heat gain coefficient. SHGC
measures the total amount of solar energy transmitted into the room.
This includes both solar energy directly transmitted through the glass
and solar energy absorbed and radiated into the building by the film.
The heat rejection ability of window film can be as high as 80 percent.
The amount of energy reflected and absorbed varies depending on the
types and quantities of metals used in the film. A reduction in solar
heat gain can translate directly into less electricity used for cooling.
What’s more, most utilities have a separate demand charge based on the
highest monthly rate of electricity use for a year, or the peak demand.
This charge is in addition to the regular cost of electricity. By
reducing the amount of cooling needed during peak periods, demand
charges can also be reduced. Because of its ability to help save energy,
window film is recognized and encouraged as an energy-efficient
retrofit. The ability to reduce energy
costs for buildings is widely accepted by many utility companies that
offer significant incentives and rebates for installation of window
film.. Generally to qualify all south, east and west facing window must
be filmed and a contractors invoice produced..
The Full Spectrum
Although
reduction in solar heat gain and cooling costs are the primary benefits
of window film, there are other advantages as well. The near-complete
rejection of UV rays can decrease fading of furniture, drapery and
carpets and mitigate the harmful effects UV rays have on building
occupants. All quality window films reject between 95 and 99 percent of
ultraviolet energy. UV is not considered part of heat gain, but it can
be destructive, While blinds or shades can also be used to limit visible
light, window film can achieve this goal while preserving the view for
occupants and creating a more uniform look on the outside of the
building. .
Security Matters
Security and
safety window films are also making headway in the window film market.
While some security film blocks solar radiation, its primary purpose is
to prevent shards of flying glass from injuring occupants if the window
breaks. Causes of breakage can include bomb blasts, hurricanes, seismic
events, or people attempting forced entry through a window. At 4 to 14
mil , security film is significantly thicker than solar control film and
is applied differently. Security film is a recognized benefit in
hurricane-prone areas like Florida because of the round the clock
protection it provides.
|
