Home: Temperature: Thermostat
Programmable thermostat "I'm not here" feature   (+9, -4)  [vote for, against]
Save energy. Good for you and the environment.

Many homes are equipped with programmable thermostats. Basically, what these devices do, is allow you to set a temperature schedule to save energy by setting the temperature higher (for cooling) or lower (for heating) while you are at work, school, or sleeping. Most also allow you to control the temperature manually, as well.

I propose a feature that would allow a user to enter an amount of time, probably in about 15 minute intervals, that the user will be out of the house. The system will turn off for that amount of time, but start some time earlier by an amount of time calculated with
1) The time that the system takes to raise/lower the temperature by a certain amount
2) The current temperature 3) The programmed temperature

The effect would be that energy would be saved by shutting off the system while the residents are gone, but by the time they come back, the temperature would be comfortable.

To avoid damage to pipes, during the heating season, the system would not allow the temperature to drop below 50 degrees.
-- -----, Jul 26 2005

Smart Thermostats http://www.sunset.c...hermostats0601.html
[jurist, Jul 26 2005]

OSS for homes, with remote sensing. http://content.hone...k/homes/manuals.htm
Belated link for Honeywell CM series stats. [Anchovy, Jul 29 2005]

Anchovy's Link Detail http://content.hone...0(UK%20English).pdf
I think this is the pertinent item from Anchovy's link to which he meant to direct your attention. Beware, this link is a .pdf which may load slowly for you, but it gives essential details about the features, capabilities and usage of the Honeywell CM system. [jurist, Jul 29 2005]

Baked. Stats area around which both allow you to go out for a while, or stay up for a while, or tell them you're having two weeks holiday (so they come back just before you do).
-- Anchovy, Jul 26 2005

I don't see how this idea differs substantially from the many "Smart" thermostats that are already available on the market. Some thermostats handle the home/away function by being connected to the security system. It turns itself off to the seasonal default setting when you arm the system upon departure, and restores itself to the seasonal comfort level when you return as evidenced by disarming the security system. Other systems just use pattern timers. Others allow you to remote access the settings by phone or internet. Your proposed feature doesn't really seem original enough.
-- jurist, Jul 26 2005

What you describe is 'widely known to exist' in Building Automation or Management Systems (BAS or BMS) but understandably not in the Home market.
While the Home Automation Market is expanding the principle problems are twofold:
1) Cost of hardware. 2)Cost of engineering and maintenance.
Both tend to be due to the fact that the manufacturers who produce the equipment are used to dealing in a larger, commercial environment and also have developed proprietary hardware and engineering solutions which they wish to protect.
There are a number of protocols that were developed to be 'open' and were supposed to have an impact on the domestic market but they are all still expensive.
What you described in the last paragraph is an OSS (Optimum Start Stop) algorithm that is self adapting within limits. These limits also include medium temperature (i.e Chilled or Hot water), a time limit on earliest start (or run down for afternoon cooling) and occasionally boost.
-- gnomethang, Jul 26 2005

So [marked-for-deletion] widely known to exist.
-- Texticle, Jul 26 2005

Weell, not really as Jurist's link does not do OSS as such. I think that the main problem is cost fir the home market. I saw today a number of small I/O devices to control equipment that sit on a TCP/IP backbone. There is a brain in there somewhere that might have an OSS module and then you could stuff it in your house - probably for about a grand for the hardware plus cabling and your own engineering time.
I'll find a link.
-- gnomethang, Jul 26 2005

Anyone who says that this is baked is not reading the idea correctly. Their examples may be for the same purpose, but not by the same mechanism. The idea is for an automated system, rather than having to phone the system. Also, with this idea, you will come home to a house at the right temperature, rather than waiting. This saves more energy than just programming the thing to start early because it calculates exactly when to start and stop. Basically, an OSS system as [gnomethang] suggested, combined with a timer that can be set easily, rather than having to reprogram the whole thermostat.
-- -----, Jul 26 2005

I never had to 'phone' my thermostat. I had three programs in it. Program 1 was 68°, 2 was 62° and 3 was 58°. I ran program 1 from 4:40 PM to 11:00 PM, then switched to program 2 until 5:45 AM, when program 1 kicked in again. At 8:00 AM program 3 came on, lowering the temp while the house was empty... and ran until 4:40 PM again, which is 20 minutes before the first person arrived home to a warm house. This was just the weekday schedule... on weekends, I eliminated program 3 entirely. I shut it off completely during the summer, but if I had central air, I could have used it to control that as well.

All automated. Pretty much any $20 programmable thermostat can do this.

What does your system do that mine doesn't? If there's a difference, it's not that we aren't reading correctly. You're obviously not describing it well enough.
-- waugsqueke, Jul 26 2005

The system I am describing would
1) Let you program in a power-saving time on-the-fly while returning to the standard program after
2) Automatically figure out when to start the system so the temperature is already "x degrees" when it is time to be "x degrees" rather than simply starting to bring it to that temperature at that time.

The purpose is that if you are going out to a movie and are going to be back in 3 hours, you can simply enter that in when you leave. The system would shut off until just before (by a calculated amount) you are due to come home. That way, it saves energy when you leave, and when you come back, it's comfortable. The difference between [waugsqueke]'s thermostat and the one I am suggesting is that in order for [waugsqueke]'s to work, you must always leave the house and come back in at the same time for the power saving to be effective.

With this idea, you don't have to change the whole program. You can just override the program for an amount of time you specify.
-- -----, Jul 28 2005

I hate to be repetitive, but this is baked - e.g. Honeywell's CM range for homes, with optimised start and fall back temperatures, and remote sensing. They've been out for ages - I must have fitted the first one at least five years ago.
-- Anchovy, Jul 28 2005

Does this Honeywell CM allow you to set an amount of time you will be gone before it goes back to the program?
-- -----, Jul 28 2005

[Anchovy] please post a link to the data sheet or other technical information.
This is not a bad idea per se.
-- gnomethang, Jul 28 2005

As far as I know, and provided your structure is reasonably well insulated, it uses significantly less energy to maintain a steady temperature for those few hours than it is to cool and reheat.
-- bristolz, Jul 29 2005

Yup, [bris] but we are not talking about that.
The OSS algorithm works (!) because your typical building will heat in the morning and cool in the evening.
The question then is asked as to why we do both...Surely we can heat less in the morning and cool less in the afternoon?.
The OSS module attempts to do this and frankly has had very limited success because of the algorithm itself - it looks at the morning and then at the afternoon but never at the whole day.
ASHRAE have determined that a more cost effective solution is to keep the building running in a setback mode overnight or out of occupancy - e.g. half speed fans and a larger control deadband (instead of 21DegC +/- 1 we will look from 21 +/- 4 DegC).This negates the need for a morning boost and hopefully an afternoon cooling mode in the majority of conditions.
Of course, none of this is applicable to the home market! (DOH!)
-- gnomethang, Jul 29 2005

[bris], how do you figure? Unless efficiency at startup is a significant variable, I only see effects that would work toward saving energy (though not much):
1. Heat loss/gain, except through infiltration, is simply UxAxdT - the construction and geometry of your house remains the same, meaning that the higher the dT (difference between inside and outside temperature), the more heat that is lost/gained.
2. Your fan should run a little bit less.
3. Infiltration is generally a larger effect when the fan is running, and with a higher dT.
-- Worldgineer, Jul 29 2005

Connect zoning dampers to room light switches: no programming required. A remote sensor in that room then controls the damper as needed.
-- elhigh, Aug 03 2005

[world]: I didn't figure; I just read the little pamphlet that came with our gas bill.

[gnome]: We be tawkin about it now.
-- bristolz, Aug 03 2005

random, halfbakery