What temperature conserves the most energy? - Nest

[Rob]

I know that if you set your temperature range that Nest optimizes for you. I work from home so the whole ho e and away feature is completely borked. But I'm curious if there are certain ranges where efficiency is maximized. Is every degree Fahrenheit considered equal? Or could letting your house be 72/73/74 have dramatically different costs based on how insulation and physics of heat work?

This may sound like a dumb question and perhaps it is but my curiosity got the best of me.

 

[KOLIO]

I know that if you set your temperature range that Nest optimizes for you. I work from home so the whole ho e and away feature is completely borked. But I'm curious if there are certain ranges where efficiency is maximized. Is every degree Fahrenheit considered equal? Or could letting your house be 72/73/74 have dramatically different costs based on how insulation and physics of heat work?

This may sound like a dumb question and perhaps it is but my curiosity got the best of me.

People make careers out of trying to figure out what you're asking,it's not a dumb sounding question by any stretch.
For your part of the country,humidity control is key,typically more than 50% & this time of year it begins to feel a little stuffy.

If you can get a free consult from your energy provider or a free estimate from an HVAC company in your area,it may be feasible to get a dehumidifation system incorporated into your existing system.You'll be able to run at a higher temperature setting & feel just as comfortable.

For cooling,the 72-74F range is normal & a home w/decent insulation & a properly sized A/C system shouldn't struggle to keep the house at these temps,or,remove enough moisture in the air.
A well place thermostat will make a difference as well,one near exterior doors or located in direct sunlight/on a uninsulated wall may cause the system to run needlessly.

If the unit is properly sized & it runs constantly & the coil on the indoor unit ices up on occasion,you're low on refrigerant.That needs to be topped-off & fixed,most leaks leave an oil residue behind.
Keep the outside coil clean by rinsing the coil w/water on occasion & change the filters as needed.

 

[Unforgiven]

I would imagine it is relative to the ambient temperature it is trying to adjust against. It is easy to maintain 73 if it is 73 outside. If it's 0 outside then it will take a lot more energy to maintain 73 inside. That also doesn't figure in any impact from the amount and intensity of the sunlight and the materials absorbing and radiating that solar gain. Finally, AFAIK it takes a lot less energy to warm or cool dry air, so any ideal temp would have to take humidity into account.

 

[Unforgiven]

Oh sure, not only does @KOLIO ninja me, but his post just looks smarter.

 

[KOLIO]

In a nutshell, is there a sweetspot for a temperature setting in regards to ultimate energy use/savings?

Set it to where you're comfortable, a degree or two off from your comfort level, IMHO, isn't worth the trade off in the relative amount of money saved on your energy bill.
To the contrary, keeping it set at the same temperature will likely save you money vs having a home/away settings,unless you have an extremely poor insulation situation, then, it makes sense to not keep an empty home cool.

 

[KOLIO]

As for the Nest,perhaps it's a good thing, but, I think they oversell the notion of the impact it will have on your energy consumption.
You'll probably get a dividend covering the cost of the Nest, but, probably not as soon as Google would lead people to believe...

 

[Unforgiven]

To the contrary, keeping it set at the same temperature will likely save you money vs having a home/away setting

^^^that, everytime you adjust the temp up or down you are attempting to not only change the temp of the atmosphere, or the air in the room, but also all of the furniture, walls, and everything else. No matter how large or small, each item in the room will act like a heat sink.

 

[KOLIO]

^^^that, everytime to adnust the temp up or down you are attempting to not only change the temp of the atmosphere, or the air in the room, but also all of the furniture, walls, and everything else. No matter how large or small, each item in the room will act like a heat sink.

^^^^^
BINGO!

Provided the Nest algorhythms aren't too aggressive,it will save you some money over the long haul.
Otherwise,the constant tinkering is counterproductive & you'll actually use more energy.

In a somewhat relatible instance,think about what those wonderful apps known as task killers do to our phones & battery life..........

Stability (decent insulation) & humidity control are key,without both,all the high-tech in the world for energy savings is moot & possibly snake oil.

 

[shalemail]

I too am a lucky Nest user. And I agree with most of this. In fact I had this discussion with a buddy about a week ago (he just got all new heat and air installed with an old school Honeywell thermostat that is non programmable.)

He was wondering if he should upgrade the thermostat.

So I says to him With a house your size (smallish 2 bedroom 1 bath maybe 1200 sq ft) you're better finding a temp that suits you or perhaps a degree warmer - then use a fan when home.

My situation is a tad different, I have a nearly 2000 sq ft home and I do run a program for heat and air. But I only set it for a 2-3 degree difference for this exact reason. When my wife and I are gone all day no need to keep it as cool as we prefer but also refuse to drop it from say 75 to 80+ because then the system has to work overtime to get it back to comfortable. My current program is from 8am-4pm 78 from 4pm to 10pm 75 from 10pm to 8am 73 (my wife and I prefer it cool to sleep) during the winter similar applies.

Now crazy thing is, during the day I have only seen it get to 78 here over the past week of oppressive heat (mid to upper 90's) usually if I check it mid day it's around 76 in the house, it almost never warms up completely. (so a change of 3 degrees or so from the 73 overnight to 76 during the day) meaning it's only coming back a degree or so at the 4 o'clock hour to get cool for our arrival at or around 5:15-5:30.

 

[AZgl1500]

My home is ~ 2000 sq ft also, and I just recently installed the Honeywell programmable stat because my local electric utility offered to refund the total cost of the stat!!!

what a deal. There are 3 of us here at home 24/7 so it is not quite the same as for a working stiff couple, who leave home for 8+ hours a day. Even so, I have the day time temp set at 73* and then at midnight it auto changes to 72* so that we can sleep better. I am 73, the wife is 67, our daughter who lives with us ole codgers is 42 and has a home based business....

As mentioned, it is NOT cost effective to let a home's internal temp rise up to 80*+, as the a/c unit would be running full tilt for hours trying to get the "heat soak" out of the furnishings in the home. PSO tells us to not change it more than 5 degrees maximum from your normal setting for just that reason.

here are two Pix, one is via the Web, the other is a pix of the stat itself.



PSO made this offer so that in the Event of a Brown OUT, they would be able to roll off the HVAC compressors in a small area so that others could keep their electric power on. I don't mind have the HVAC turned off for a couple of hours, far better that, than to have the experience of everyone loosing power period.