That's right, an inexpensive retrofit solution to helping reduce your A/C load and electricity usage is to tint your house windows.
A window tint professional has access to many great films out there that will give you up to 80% reduction in heat gain through a window and carry a residential lifetime warranty.
You can even opt for high end films like ceramics and similar films. These will allow the majority of natural light in (up to 70% of light) and still reject over half the heat. This way you can get maximum daylight usage instead of relying on artificial light.
Just recently several window film manufacturers have gotten their products NFRC Certified! A huge step in helping provide accurate numbers for energy savings.
Check out:
Geoshield Architectural Window Film
Window Film - V KOOL USA: Your Ultimate Sun Barrier Commercial & Residential Window Film Treatme \ Residential Window Film
Nanotechnology Window Film - Huper Optik USA provides decorative, privacy, stained glass, security, hurricane, solar and safety window film technology
Global Window Films