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Window Protection Film An Overview

There are many different factors associated with window protection film. The following is an article divided into seven sections, explaining in lay terms the various features, specifications and jargon surrounding window film installation and window film services.

1. Specifications

For the various window film installation options on the market we need to consider a number of specifications that determine the right fitment for the right building or vehicle. These will include factors like:

  • Percentage of infrared light.
  • Percentage of visible light.
  • Ultra violet transmission.
  • It is advisable to have an audit done by a reputable window protection film specialist company in order to determine the correct specifications for your building or vehicle.

    2. RSA Climate

    The climate in South Africa is a factor that must be acknowledged before considering window film installation.

    Our climate is quite different in that we have eight months of warm to very hot weather, where cooling is important, and four months of cool to cold weather, which is the heating season. Both extremes can affect the functioning of window protection film.

    Solar-Man products function without issue in both climates. We do, however, advise an audit be done to determine the correct window film requirements.

    3. Building Orientation

    In the southern hemisphere, our heat and light absorbing windows are facing east, west and north in comparison with east, west and south for the USA and Europe. Our north facing windows will receive more radiation and therefore will need infrared protection.

    Our dominant hot weather means that dual or triple insulation of windows in South Africa is not necessary.

    It is important to reduce heat entering through windows and overburdening the air conditioning, but also to reduce heat loss from buildings during the cold season. Solar-Man can advise on which window film services help in both respects.

    4. Solar Energy System

    The solar energy system is a major player in correct functioning of your window protection film.

    Energy, created by the sun, arrives on Earth in various wavelengths. This is called the electromagnetic spectrum.

    The electromagnetic band consists of the following:

  • Gamma rays short wavelength.
  • X-rays.
  • Ultra violet rays.
  • Visible light.
  • Infrared.
  • Radio waves longest wavelength.
  • The solar energy that results from the solar energy system can be controlled by window protection film.

    Note

    Infrared (IR) is not the total solar energy (radiant heat) that transmits through a window - visible light and ultraviolet light contributes the remaining 4%.

    When you consider the specifications for window protection film, the data on infrared rejection will be important to you. With modern spectrally selective film, that regulates specific wavelengths of the electromagnetic spectrum, it is possible to cut out infrared in part or up to the total of the IR band, removing 80 to 90% of radiant heat.

    But this will still not be the total radiant heat percentage, as visible light and UV light contribute 47% and therefore the 80 to 90% only represents 40 to 45% of heat reduction.

    This can be confusing. There is no standard (international or local) for IR measurement of window films, different suppliers will interpret performance differently and specifications will vary widely.

    To simplify selection, it is better to look at the Solar Heat Gain Coefficient (SHGC) which is a standardised performance measurement, recognised by, for example, the NFRC, and other building control standards institutions.

    5. Solar Heat Gain Coefficient

    The Solar Heat Gain Coefficient (SHGC), measures how well a product blocks heat from the sun. The SHGC is expressed as a number between 0 and 1. The lower the SHGC, the better a product is at blocking unwanted heat gain. The blocking of solar heat gain is important during the summer cooling season.

    Please note: the SHGC may be affected by factors such as climate, surface orientation and external obstructions.

    6. Emissivity

    Emissivity is the ability a product has to absorb certain types of energy (specifically infrared (IR) heat) and its ability to radiate that energy through itself and out again.

    A product with high emissivity will transfer a large percentage of IR energy from a warm room, outside to the cold air. Lower emissivity and conductivity will allow a lower rate of heat loss.

    Plain window glass has high emissivity, and will radiate heat at a high rate from the warmer to the cooler side.

    7. General Comments

    Heating or cooling problems in a domestic building can be solved easily with the retrofitting of infrared window protection film. The film controls heat transmission into the house in summer and prevents loss of heat during the colder months.

    In the business world of large buildings, it is more complicated to solve heating or cooling problems. When making retrofit investment decisions, you should have a full understanding of the impact of any action taken, to avoid false investments. For example, applying dark tinting on glass to reduce heat may result in poor visibility. More lighting will have to be installed, and that will increase heat generation inside the building, and as the air conditioner load goes up, so will the electricity bill.

    It is advisable to have a building energy audit done by a reputable window protection film specialist company. They will take all aspects into consideration before making a recommendation.

    Contact us now for window film installation, window film services and building energy audits by Solar-Man.