Wow, and I thought my energy bills were high in California. Where in the world do you live where there's room to save $300/month?
http://www.homedepot.com/p/MaxxAir-30-in-Industrial-Heavy-Du...
I've also used one like this:
http://www.homedepot.com/p/HDX-30-in-Pedestal-Fan-SFSC1-750S...
My neighbor bought a smaller one:
http://www.homedepot.com/p/MaxxAir-30-in-Industrial-Heavy-Du...
The idea is really simple. In our case these are two story homes with balconies. The fan goes on the balcony right outside the sliding glass door. You set it up to exhaust hot air from the house. Open all the windows. That will be your incoming cool air. The windows downstairs are fully open and the upstairs windows only four to six inches. Turn this on as soon as the temperature outside is significantly cooler than inside. There have been days when I've been able to get the house down to 65 degrees in a couple of hours.
I've also used the standing fan placed outside a ground level floor window blowing cold air in. Now you open the upstairs windows to push the hot air out.
So, you either pressurize your home with cool air or reduce the pressure (by sucking air out) in order to have cool air enter.
Not that hard to do. It takes all of five minutes a day to go through the open-windows-turn-on-fans dance and you save hundreds.
My next move is to automate this by integrating it into the ducting system as well as providing for a filtered cool air intake path.
The best part is that I saved the money I'll need by using this method during the last three summers. That money is going into system that should save me $1,000 to $2,000 per summer when compared to every house in my neighborhood. Nest can't even begin to compare to this performance.
My problem is that these things are being sold at my local Home Depot as some kind of magical device. This is a bedroom community of probably 100,000 to 200,000 homes. A huge number of them are two story homes of 2,000 square feet and above with three to five bedrooms. Nest is a waste of time for these people. I actually have data on this. I know six people with homes virtually equal to mine (planned community) who bought Nest to save money and could not tell you if they've saved a penny. If there's an impact it's that small.
Las summer I convinced one of those neighbors to buy a $200 fan and use it as I suggested. He immediately reported a savings of over $300 PER MONTH on his cooling bill. He saved over $1,000 last summer and expects to save over $2,000 this summer.
That's why I say it's a scam.