http://www.forbes.com/sites/parmyolson/2014/01/13/nest-gives...
"Nest founder and CEO Tony Fadell told Forbes last month that his company had struck deals with close to 20 utility companies, who paid Nest $30 to $50 per thermostat annually, to manage the energy usage of Nest customers who had opted into their utility’s demand-response program.
As part of the program, Nest temporarily take over the healing and cooling of a homes for a set period, perhaps a few hours, and customers are notified that an “event” is set to happen some time beforehand. When Nest does this over multiple homes in a neighborhood or county it can, Fadell claimed, lower energy costs for utilities by 50%, by re-routing peak energy being used in empty homes.
“We know how many people are home during those times,” he said “We know which homes have cooling, we can go through the data and we can say we believe we’re a five megawatt power generator or 10 megawatts in this county. That’s what we can deliver – 50-60% of the energy that was consumed in that window has been shifted away.”
The services makes Nest a middle man for utility companies, meaning that Google itself will now play a role in managing energy efficiency programs across wide swathes of home and even counties – something that Google has been keen to do for some time."
This is pretty much why I wouldn't buy a Nest. I don't need a 3rd party knowing when I'm not home.
That is, assuming you know the schedule of my automated lights and can accurately guess if I'm home or not with blackout curtains over my windows :P
Even my neighbors don't know when I'm home half the time.
I'm an odd duck.
When demand exceeds supply, brown-outs occur which means a lot of unhappy customers and, considering utilities' monopoly status, calls for investigations.
From what I can gather from tweets by participating customers, they do it because it's cool and exciting not because of the financial rewards.
[1] http://support.nest.com/article/What-is-Rush-Hour-Rewards