Programmable Thermostat studies
stevenplane
| Posted in Energy, Heating & Insulation on
Does anyone know about any studies regarding programmable thermostats and their usage?
In particular I was trying to determine if, in a tightly constructed home (ICF in my case), it would be worth it to shut our heat pump down completely during peak electric hours, especially in the summer time.
Would the savings from the shutdown be offset by the thing kicking back on late in the day/early in the evening?
Thanks
Replies
I think it definately would. One of the benefits of thermal mass construction is the delay in the thermal loading. ICF construction is a little more complex, I think since it is insulated on both sides. Many might consider that detrimental ... but I'm not aware of any analysis/studies that support it one way or the other.
Anyway ... using your mass to provide the comfort during peak periods is a solid concept. For commercial construction (which is often much heavier than residential (thermally and literally), this is done all the time to avoid huge peak demand charges (they typically get charged for their peak demand AND their KWH consumption).
Let the house float during the day and use your cooling system in the night to recharge the mass. The efficiency of the system energy consumption goes way up because of the cooler night air. If your utility charges you more during the peak daytime hours, then you should see an even bigger savings.
If the night is cool enough, however, you should consider free cooling first ... i.e. opening doors/windows to allow the cool night air to 'free cool' the house. If you have a whole house fan, you can enhance this inexpensively by forcing some convective air movement of cool night air through the house if there is little wind to do it for you.
Free cooling may not work for you if your climate tends to be humid. You know if you can open your doors and windows at night. Out west, it works great, though.
Remember, though, while the concepts of the thermodynamics of thermal mass charging/discharging are fairly simple, the actuality can be a bit puzzling at times and it gets very commplex. Try it out for a couple of weeks or so next summer. You've got nothing/little to lose as at worst, I'm guessing that you would break even (even that should be good as you have reduced stress on your A/C system by operating it under lighter loads.
Look for others comments and contributions as well. I'm sure they can add some additional points of view.
my own non-scientific studies says there is a savings by bumping up the day time temps on the thermnostat and then having it bump back down an hour prior our normal return. That's for the airconditioning in the summer. I haven't tried shutting it off, just setting it 10 -15 degrees warmer. 100ºF days are a chellenge for it though when it' trying to drop the inside temp back down.
No savings at all for heat in the winter when the backup has to kick in to get the temps heated back up.
Good strategy for the A-C ... set up when gone ... normal when occupied. If your day temp is extreme or if your system size is on the cusp of the design load, it may struggle bringing the temp down ... particularly in the humid SE.
Heating ... sorry ... heating setback works fine (for energy savings). If you are referring to a heat pump, then that is a little different story ... although they do make heat pump setback stats that limit backup heat during the reheat cycle. Using the heat pump cycle is always better than using backup heat when you can do it.
>referring to a heat pump, then that is a little different story<
well, the OP was talking Heat Pumps
Brain fade ... comes w/ age. So beat me.
fading too
"In particular I was trying to determine if, in a tightly constructed home (ICF in my case), it would be worth it to shut our heat pump down completely during peak electric hours, especially in the summer time."
Unless you have time of day pricing it does not pay to turn if off during peak usage.
What MIGHT pay is to increase the AC times when you don't need it (not home). And reduce them when needed.
But for most people that will actually increase the peak usage.
But how much affect is hard to tell without know the thermal time constant of the house.
William the Geezer, the sequel to Billy the Kid - Shoe
If you're going to do that, get a "saver switch" installed by the PoCo and get paid for it.
I'm unfamiliar with a saver switch.
Can you enlighten me?
You have to have WHAT YOUR UTILTIY company offers in terms of different rate plans and load sharing options.They are all of the place.One local PUCO offers load sheding. Where they can turn off a compressor for a certain percent of the time during the peak loads. I don't believe that they have any discounts, but will install a free setback thermostat.Another places have time of day meter where the rates range from 2 to 30 cents per kWh and it is up to the customer to control how and when you use power.And there are others..
William the Geezer, the sequel to Billy the Kid - Shoe
It's a radio-operated switch the PoCo installs near the outside AC unit. Cuts off the AC on command, for 15 minutes at a time, during peak usage periods. Gets you a fairly good discount on your summer bill, even for folks like us that may use the AC only 3-10 days a summer.Ask if your PoCo does this.
The modern conservative is engaged in one of man's oldest exercises in moral philosophy; that is, the search for a superior moral justification for selfishness. -John Kenneth Galbraith