Definitely do window reflective films. Cuts down on heat by 1/2 and eliminates UV by nearly 100%. I did it in my cars (even front winshield with clear UV film) and now doing the windows of the house. Even the low-e ones.
But the biggest heat reducer that I just did was to paint my asphalt shingle roof with an elastomeric roof paint. I just got the most expensive one at Lowes. It took 4 - 5 gal buckets to do 1 coat (planning on 2nd coat this weekend) and already it reduced the temperature in my house by 15 degrees. I am not exaggerating. 2 days ago, it was 105 outside and 99 inside. Unbearably hot. Yesterday, after I painted, it was 109 outside and 88 inside. That's a huge temperature differential.
I think this product works best in dry weather places like SoCal or AZ. I think people have had problems with the fact that it is waterproof and places with humidity can have issues with the air in the attic not breathing as well. But I'd think you can get around it with an electric fan vent for the roof. Anyhow, take a look at it. It'll cut down your A/C bills by a lot.
Interesting. I wonder what my wife would think about a white roof. I looked it up and that stuff is expensive, but I'm sure it would pay itself off quickly. All I have to do is stand on the roof or peak my head in the attic during the day to know that it would make a huge difference, it gets really hot up there. Thanks for the idea.
White paint makes a HUGE difference. Not only does it make the house cooler, it significantly extends the lifespan of an asphalt shingle roof. The specialized elastomeric roof paints often are designed to go over older roofs, and also prevent leaks (to some extent.) Anyway, there have been numerous scientific studies over the years, and it really does work, even with just standard white paint.*
I painted the roof white on my last house** using regular 100% acrylic exterior paint. Worked well. No doubt, the specialty paints work better - but I haven't priced them recently.
The asphalt shingle industry HATES HATES HATES if you paint your shingles, as they get a lot of their business from replacement of old, brittle shingles. Keeping the roof cooler dramatically slows the ageing of the shingles, and so your replacement times are much longer. They bullshitted their way to making it very difficult to paint asphalt shingles in Florida and still remain within code.
*Just using white paint reflects the visible spectrum and some of the UV. Some roof paints do a better job reflecting in the infrared region as well, due to pigment selection. Reflectivity can be up to 10 times better than asphalt shingles.
**When I bought this house, the roof was almost ready for replacement, in large part due to the really shitty install. One hailstorm later, and I now have white, Energy Star rated shingles, and got a 30% .gov tax credit they were offering for a couple of years. Win. The previous house also had a low-pitch roof, not visible from the street. Current house has a VERY VERY visible steep roof.