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Friday, March 27, 2015

How window films save money in Evans, Ga 30809

HOW WINDOW FILM SAVES ENERGY

HEAT GAIN AND THE BUILDING ENVELOPE

The building enevelope is the physical separator between the interior and the exterior environments of a building. These at their most basic element would be your walls, windows, roof, and doors. The many functions of the building envelope can be separated into three categories.

  • Support (to resist and transfer mechanical loads)
  • Control (the flow of matter and energy of all types)
  • Finish (to meet human desires on the inside and outside)

Of these three catagories the control function is the core of good performance. The largest whole in the building envelope is the windows, it presents one of the largest control challenges and at the same time can be an area where a sizeable amount of energy can be saved. Over 30% of a commercial building's controllable expenses are on energy. By controlling heat transfer heating and cooling demands can be reduced thus saving money on utliity expenses and maintence costs.

Energy for the sun radiates to our planet in various electromagnetic (em) wavelengths that make up what is known as the "Solar Spectrum." The Solar Spectrum can be divided into three regions Visible LightUltra Violet, and Infrared. These three regions radiate onto the building enevelope transmiting through glass windows and being absorbed by interior surfaces and bodies, it is re-radiated as heat. This re-radiated heat in turn increases the ambient temperature in the building's interior.

Solar Energy Distribution Chart

CONTROLLING HEAT GAIN WITH WINDOW FILM

Window Film acts as a filter reducing the amount of transmittance of these 3 regions of the solar spectrum through windows thus dramatically changing the proportion of energy that is absorbed by the buildings interior and occupants. Considering the fact that it requires large amounts of energy to condition hot air into cooler air, window film can reduce large loads that are placed on HVAC systems reducing energy costs up to 30% and balancing out hot spots in homes and commercial buildings.

CONTROLLING HEAT LOSS WITH WINDOW FILM

The second law of thermodynamics tells us that energy transfer is always from hot to cold. In cooler climates this means that the heat in buildings will convect through the surfaces with the least resistance back out into the cooler climate outside. The windows in the building enevelope  are typically the weakest system whereby energy is lost thus increasing heating demand resulting in higher energy consumption.

Window films can reduce heat loss by lowering emissivity and the covection of energy through the window system. When considering the fractional expense of window film versus window replacement, window films are a great way to reduce energy consumption at an affordable price.