4 ms·

Millions of thousands of homes today simply leave their thermostat at the same temperature all the time, failing to optimize for the large portions of the day w

Millions of thousands of homes today simply leave their thermostat at the same temperature all the time, failing to optimize for the large portions of the day when nobody is home because it's simpler (and they probably don't have a timed thermostat, or they can't figure out how to set it up.) Imagine thousands of households doing something smarter.

yitchelle 12y ago
I have noticed a trend among our friends, (not technical folks), who actually turns off their heating when they go out. It is as common as turning off their lights when they leave the room. I guess Nest is heading towards this direction, but pre-warming a house very "first-world".
- vnorby 12y ago
  Not to keep harping on the subject (see my comments above), but pre-warming or pre-cooling houses is actually a really great solution to solving our energy problems with algorithms. It's not strictly a "first world" problem. Imagine a neighborhood of 100 homes where you know all 100 people will return approximately at 6pm in the winter, and they all want 72 degrees. Taking into account the insulation of each home, if you could pre-heat the homes on a rolling schedule (say, heat 25 of them to 75 degrees at 3pm, accounting for 1 degree of heat dissipation per hour, heat another 25 to 74 degrees at 4pm, etc.), you will actually in aggregate save a lot of energy and cost because of inefficiencies in the way we deliver and generate energy during peak times. (@yitchelle - central data center)
  - yitchelle 12y ago
    That is an interest way of distributing loading of the peak heating requirements. Does Nest have a ability to interact with the other Nest in the neighborhood? Or is it all controlled from a central server?
    - ceejayoz 12y ago
      Not (yet) with other Nests that I'm aware of, but they're making deals with the power companies. Users can get discounts on their bill for allowing the power company to bump energy use down a degree or two during peak times.
  - maxerickson 12y ago
    Won't dense, affluent neighborhoods mostly be natural gas for heating?
- tomkarlo 12y ago
  Owning a house with central heating / AC that can be controlled by a Nest Thermostat via your household wifi from your smartphone while driving home in your Mercedes is a pretty "first-world" thing. Especially given that this works best for second homes like a weekend house in Tahoe where it might take a full day to warm up if you left the heat off all week.
dirktheman 12y ago
When your house is not insulated properly and you live in a cold climate, it's actually better to not turn the heat off completely. It takes more energy to warm a stone cold house than to keep it at approx. 62 degrees. A simple, programmable thermostat will make up for the purchase within the first year of service.
- asmithmd1 12y ago
  This is not true. It might seem that way because of how long it takes your house to warm up. There is no momentum or stiction with heat transfer. When the inside of your house is warmer than the outside you are losing some amount of heat to the outside proportional to the difference. Any heat you add to maintain that difference when you are not home is wasted. As long as you can tolerate a stone cold house when you return, your best efficiency is to just turn the heat off. This is assuming you have an on-off heating system, someone mentioned a throttling system is more efficient at a low flame rate so that made it better to leave the heat on low all the time. I am skeptical of that claim but don't have enough information
  - dirktheman 12y ago
    That was me, with the throttling system. It's called modulation, and is very common in Europe. While there is no momentum in heat transfer, the walls of your house store heat. If you're away long enough to allow your house to cool down it will take more fuel than it would to keep it at a reasonable temperature. Also, this is much, much more comfortable than to arrive in a stone cold house, only to open a window 30 minutes later because of the blazing heat. I'm not saying it's always better to keep a certain temperature, though. It depends on the time that you're away, the insulation of your house, the outside temperature, the efficiency of your boiler, etcetera. But, having lived in houses with ordinary thermostats and non-modulating boilers and houses with programmable thermostats and modulating boilers I can tell you this: I'm not going back to the old stuff. The indoor climate is so much better now!
  - VLM 12y ago
    It seems intuitive that heat exchanger eff increases with decreased flow rate. Also air handling is always best done as slowly as possible, because you're trying to move air, not make noise and turbulence. There doesn't seem to be any intuitive reason to think eff would be higher at low rates unless its doing something insane like varying fuel/air ratios to get a desired heat flow or some kind of slow PWM with repeated ignition losses. Real furnaces don't work like that, so... My otherwise boring furnace is variable speed and the longer its on, the faster it runs. It's really roaring after about 30 minutes. Its more than a decade old, this is pretty old COTS tech. My first zillion BTU cost me somewhat less than my last zillion BTU in any heating cycle. I live in a cold northern climate with great insulation and low heating bills and a variable speed furnace and the house is basically never empty (spouse and I work at home often enough, etc). The whole "nest" idea doesn't work financially for me although it is interesting to watch.
pauly 12y ago
Not sure this is so common in the uk. My heating is almost always off, and if it gets cold we have a timer and a thermostat, so it comes on for an hour in the morning and a couple of hours in the evening.
- koyote 12y ago
  That's how I have it working here in the UK as well and I think most people do. A couple of hours after 6pm and a couple of hours just before you wake up. All controlled from a simple timer. Yes, Nest would be a fancier solution, but I don't really see much benefit a part from the 'coolness' factor.

yitchelle 12y ago

I have noticed a trend among our friends, (not technical folks), who actually turns off their heating when they go out. It is as common as turning off their lights when they leave the room. I guess Nest is heading towards this direction, but pre-warming a house very "first-world".

vnorby 12y ago
Not to keep harping on the subject (see my comments above), but pre-warming or pre-cooling houses is actually a really great solution to solving our energy problems with algorithms. It's not strictly a "first world" problem. Imagine a neighborhood of 100 homes where you know all 100 people will return approximately at 6pm in the winter, and they all want 72 degrees. Taking into account the insulation of each home, if you could pre-heat the homes on a rolling schedule (say, heat 25 of them to 75 degrees at 3pm, accounting for 1 degree of heat dissipation per hour, heat another 25 to 74 degrees at 4pm, etc.), you will actually in aggregate save a lot of energy and cost because of inefficiencies in the way we deliver and generate energy during peak times. (@yitchelle - central data center)
- yitchelle 12y ago
  That is an interest way of distributing loading of the peak heating requirements. Does Nest have a ability to interact with the other Nest in the neighborhood? Or is it all controlled from a central server?
  - ceejayoz 12y ago
    Not (yet) with other Nests that I'm aware of, but they're making deals with the power companies. Users can get discounts on their bill for allowing the power company to bump energy use down a degree or two during peak times.
- maxerickson 12y ago
  Won't dense, affluent neighborhoods mostly be natural gas for heating?
tomkarlo 12y ago
Owning a house with central heating / AC that can be controlled by a Nest Thermostat via your household wifi from your smartphone while driving home in your Mercedes is a pretty "first-world" thing. Especially given that this works best for second homes like a weekend house in Tahoe where it might take a full day to warm up if you left the heat off all week.

dirktheman 12y ago

When your house is not insulated properly and you live in a cold climate, it's actually better to not turn the heat off completely. It takes more energy to warm a stone cold house than to keep it at approx. 62 degrees. A simple, programmable thermostat will make up for the purchase within the first year of service.

asmithmd1 12y ago
This is not true. It might seem that way because of how long it takes your house to warm up. There is no momentum or stiction with heat transfer. When the inside of your house is warmer than the outside you are losing some amount of heat to the outside proportional to the difference. Any heat you add to maintain that difference when you are not home is wasted. As long as you can tolerate a stone cold house when you return, your best efficiency is to just turn the heat off. This is assuming you have an on-off heating system, someone mentioned a throttling system is more efficient at a low flame rate so that made it better to leave the heat on low all the time. I am skeptical of that claim but don't have enough information
- dirktheman 12y ago
  That was me, with the throttling system. It's called modulation, and is very common in Europe. While there is no momentum in heat transfer, the walls of your house store heat. If you're away long enough to allow your house to cool down it will take more fuel than it would to keep it at a reasonable temperature. Also, this is much, much more comfortable than to arrive in a stone cold house, only to open a window 30 minutes later because of the blazing heat. I'm not saying it's always better to keep a certain temperature, though. It depends on the time that you're away, the insulation of your house, the outside temperature, the efficiency of your boiler, etcetera. But, having lived in houses with ordinary thermostats and non-modulating boilers and houses with programmable thermostats and modulating boilers I can tell you this: I'm not going back to the old stuff. The indoor climate is so much better now!
- VLM 12y ago
  It seems intuitive that heat exchanger eff increases with decreased flow rate. Also air handling is always best done as slowly as possible, because you're trying to move air, not make noise and turbulence. There doesn't seem to be any intuitive reason to think eff would be higher at low rates unless its doing something insane like varying fuel/air ratios to get a desired heat flow or some kind of slow PWM with repeated ignition losses. Real furnaces don't work like that, so... My otherwise boring furnace is variable speed and the longer its on, the faster it runs. It's really roaring after about 30 minutes. Its more than a decade old, this is pretty old COTS tech. My first zillion BTU cost me somewhat less than my last zillion BTU in any heating cycle. I live in a cold northern climate with great insulation and low heating bills and a variable speed furnace and the house is basically never empty (spouse and I work at home often enough, etc). The whole "nest" idea doesn't work financially for me although it is interesting to watch.

pauly 12y ago

Not sure this is so common in the uk. My heating is almost always off, and if it gets cold we have a timer and a thermostat, so it comes on for an hour in the morning and a couple of hours in the evening.

koyote 12y ago
That's how I have it working here in the UK as well and I think most people do. A couple of hours after 6pm and a couple of hours just before you wake up. All controlled from a simple timer. Yes, Nest would be a fancier solution, but I don't really see much benefit a part from the 'coolness' factor.