Every purchase of window film requires some form of compromise. If you want more light to penetrate your windows, you also will get more heat-gain. If you want Maximum protection against Solar Energy coming into your home or office, you will need a dark and highly reflective film to do the job. These are the facts but many customers are misinformed that they can have Maximum heat rejection and still let in 60-70% of the light. The reason is that the sales rep, in trying to sell his spectrally selective product, discusses IR rejection as if it is the only source of heat gain. In reality IR represents 53% of the total heat-gain coming through window glass. Visible light also brings 44% of the heat as well as all of the glare issues relative to sunny windows.
Spectrally Selective films are great products when you are trying to maintain high visible light levels in a room, or very low change in the appearance of the windows when viewing from the outside, or better visibility out of the window during low-light periods. By being able to also block out 80-90% of the IR radiation, these films provide a good reduction in solar heat gain as well, but they are NOT the best films at reducing solar heat gain. If you look at the TSER, total solar energy rejection, of spectrally selective products with a visible light transmission of at least 50%, you will find that the TSER will most likely be below 60%. Very often a light, traditional film will meet the needs at a much lower cost than the Spectrally Selective films. While these IR films are great technology, they may not be the right film for you. Always closely check the data. Equally important... read the warranty and compare.
In some cases the manufacturer's further skew the information by showing only the most advantageous numbers from their data. One such company bases their claims of efficiency on just one data point when the sun is at a 60 degree angle. NFRC requires all testing to be done at a 90 degree angle, which reduces the actual energy that can be blocked.
We want you to make an informed decision when considering window tinting for your home or office.
Can you tell the difference? Probably not, but the top windows are actually darker than the lower. Clear View installed Sun Gard Optivision 35 on the lower windows and Optivision 25 on the uppers. Since the homeowner had plans to install window treatments on the lower windows they chose to use the lighter shade on these windows. But, they wanted to leave the upper windows unrestricted yet wanted to control the harsh effects of the sun. Thus, the darker shade made a great choice to keep heat gain to a minimum and protect their home furnishings. 
