IR Blocking Polycarbonate Sheet
With interest in reducing energy bills, there has been a lot of interest in polycarbonate sheet that blocks infra-red (IR) wavelengths. The visible spectrum is in the range of 390-700nm, with UV light below the 390nm and IR light above the 700nm.
Sunlight can cause the inside of buildings and vehicles to heat up by passing through the windows. Lower wavelength light has more energy than higher energy light and causes faster heating. This means that visible light has more energy than infra red light. To reducing the heating, it is necessary to absorb or reflect the light. In the visible region there is only so much energy that you can absorb as by blocking the light you make the window darker, which is often in conflict with the purpose of the window. In addition to making the window darker, another way of reducing the heat build up is to put IR absorbers into the polycarbonate sheet to block the IR light wavelengths.
HighLine is able to offer three colors of IR blocking polycarbonate sheet, each block different amounts of visible and IR light. We currently have Grey, Light Green and Dark Green products.
Color Visible Transmission Solar Transmitted Radiation
Grey 64% 61%
Light Green 65% 53%
Dark Green 48% 34%
The grey and light green products aim to block as little visible light as possible and only have a slight tint. As a result a reasonable amount of heating still occurs in the visible region.
For greater reduction of heating there is the dark green product.
The graph below shows the transmission at the various wavelengths across the UV, visible and IR wavelengths.
It should be noted that the transmission curves for thicker material, such as 5mm or 6mm, are almost identical. Transmission curves for the thicker material, as well as samples of the material can be obtained by contacting HighLine Polycarbonate LLC.
Outside of buildings the major application for IR Blocking Polycarbonate has been for farm and forestry vehicle cabs. The polycarbonate is used to provide protection and the IR absorbers reduce the heating of the cab by the sun. With modern equipment cabs, there are a lot of electronics which also cause heating and these, combined with the sun can put a large load on the vehicle air conditioning. IR blocking polycarbonate has proved to be an effective way of reducing the air conditioning load in these vehicles.