Does it bother you guys that hardly any commercial buildings have its AC turned off when no one's in there and/or when it's closed? I stopped at a mall's parking lot so I could text someone and the Mall's AC was on. It was dead closed at 8!!!
Air conditioner/wasting energy.
- Thread starter Popinski
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Most office buildings that I have seen do shut down the A/C at night, not sure about the malls or shopping centers though...
My moms office gets the heat/ac turned off at night. It's a small, 4 person office. In a house. Honestly it seems like it wastes more electricity/gas to turn it off. Because if it's either. A. Really cold, or B. Really hot, it will have to work harder for longer to get caught up, more so than it would need to be to maintain. Especially in a building the size of a mall.
The office building I work at do shut down air conditioning at night and weekend during summer. When I need to be there on weekend, it was hot like h***.
Originally Posted By: Popinski
Does it bother you guys that hardly any commercial buildings have its AC turned off when no one's in there and/or when it's closed? I stopped at a mall's parking lot so I could text someone and the Mall's AC was on. It was dead closed at 8!!!
Are you serious?..You need to find something else to worry about..It would take all day to cool down the mall down to a comfy 72 degrees if you shut it off at night..They probably do what the bulk of buisnesses do here in Miami and just raise the temperature to 78 degrees at night.
Nobody in Miami shuts off the a/c in their house even when they are gone for 12 hours a day..Most just raise the temperature to 78 degrees and just lower it when they get back home.
BTW I never heard of a mall closing at 8.
Does it bother you guys that hardly any commercial buildings have its AC turned off when no one's in there and/or when it's closed? I stopped at a mall's parking lot so I could text someone and the Mall's AC was on. It was dead closed at 8!!!
Are you serious?..You need to find something else to worry about..It would take all day to cool down the mall down to a comfy 72 degrees if you shut it off at night..They probably do what the bulk of buisnesses do here in Miami and just raise the temperature to 78 degrees at night.
Nobody in Miami shuts off the a/c in their house even when they are gone for 12 hours a day..Most just raise the temperature to 78 degrees and just lower it when they get back home.
BTW I never heard of a mall closing at 8.
I would guess that it is cheaper to just turn the temp up or down as needed like a setback thermostat at home does. Especially on a big building getting the temp back to a normal level after being turned off all night or weekend would take a long time and would cost more.
Originally Posted By: 65cuda
I would guess that it is cheaper to just turn the temp up or down as needed like a setback thermostat at home does. Especially on a big building getting the temp back to a normal level after being turned off all night or weekend would take a long time and would cost more.
+1; my father is an HVAC engineer and installed a commercial system in our house in the late 1970's. It cost about $2 / day to keep the house constantly air conditioned, much more to let the house get to 95F and then try to draw it back down.
On a side note, I believe many commercial buildings make ice at night when the $/KwH is less (off peak) and then uses air handlers to utilize that ice for peak (daytime) cooling.
A great savings could be realized if isolated energy situations were treated with a homogeneous approach. Our datacenter uses refrigerated air for cooling and then vents the heated air to the outside, even in the dead of winter. A separate heating system burns oil and then heats the inside of the building....
I would guess that it is cheaper to just turn the temp up or down as needed like a setback thermostat at home does. Especially on a big building getting the temp back to a normal level after being turned off all night or weekend would take a long time and would cost more.
+1; my father is an HVAC engineer and installed a commercial system in our house in the late 1970's. It cost about $2 / day to keep the house constantly air conditioned, much more to let the house get to 95F and then try to draw it back down.
On a side note, I believe many commercial buildings make ice at night when the $/KwH is less (off peak) and then uses air handlers to utilize that ice for peak (daytime) cooling.
A great savings could be realized if isolated energy situations were treated with a homogeneous approach. Our datacenter uses refrigerated air for cooling and then vents the heated air to the outside, even in the dead of winter. A separate heating system burns oil and then heats the inside of the building....
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JHZR2
Staff member
The whole supposed benefit of forced air is that there isnt much need to consdier thermal mass for fast heating or cooling. Just exchange the air a few times and then youre there... Warm or cold.
Sure, that isnt exactly the case, but it gets you on your way. Remember, what was cool during the day likely isnt going to warm up too terribly much at night when cooler.
I believe the findings have been time and time again that it is best to cycle through at least within a reasonable range, rather than staying at setpoint all the time.
I dont think there is such a thing as an AC plant working harder. Longer, perhaps. Harder? The compressor is going to do some much work until it is told to cut out. That work equates to cooling capacity.
what will be more efficient is the ability for a condensor to shed heat when the delta T is larger, i.e. it is cooler outside. Thus the ability to shed heat and move heat the fastest is when the cooling is done at the cooler parts of the day. Thus, minimizing operations when the cycle is least efficient and maximizing operations when the cycle is most efficient thermodynamically is the smartest way to go.
If you could freeze your home overnight and then not run at all during the heat of the day, I would imagine the operations would approach optimum efficiency that could be had from the cycle.
Sure, that isnt exactly the case, but it gets you on your way. Remember, what was cool during the day likely isnt going to warm up too terribly much at night when cooler.
I believe the findings have been time and time again that it is best to cycle through at least within a reasonable range, rather than staying at setpoint all the time.
I dont think there is such a thing as an AC plant working harder. Longer, perhaps. Harder? The compressor is going to do some much work until it is told to cut out. That work equates to cooling capacity.
what will be more efficient is the ability for a condensor to shed heat when the delta T is larger, i.e. it is cooler outside. Thus the ability to shed heat and move heat the fastest is when the cooling is done at the cooler parts of the day. Thus, minimizing operations when the cycle is least efficient and maximizing operations when the cycle is most efficient thermodynamically is the smartest way to go.
If you could freeze your home overnight and then not run at all during the heat of the day, I would imagine the operations would approach optimum efficiency that could be had from the cycle.
Originally Posted By: simple_gifts
On a side note, I believe many commercial buildings make ice at night when the $/KwH is less (off peak) and then uses air handlers to utilize that ice for peak (daytime) cooling.
+1 Digital Equipment Corporation had a nifty setup back in the 1970s (!) with huge pools of water (or another liquid) and compressors running off peak.
Note that malls often have special arrangements with the power company that you or I cannot get as homeowners. Even if we can't get "off peak metering" they might be able to.
Myself, I would keep an undersized AC unit running continuously during unoccupied times, just to keep the humidity in check. When a building gets "mothballed" it does okay if it has some sort of climate control, but turn it off and you get mold and other issues FAST.
On a side note, I believe many commercial buildings make ice at night when the $/KwH is less (off peak) and then uses air handlers to utilize that ice for peak (daytime) cooling.
+1 Digital Equipment Corporation had a nifty setup back in the 1970s (!) with huge pools of water (or another liquid) and compressors running off peak.
Note that malls often have special arrangements with the power company that you or I cannot get as homeowners. Even if we can't get "off peak metering" they might be able to.
Myself, I would keep an undersized AC unit running continuously during unoccupied times, just to keep the humidity in check. When a building gets "mothballed" it does okay if it has some sort of climate control, but turn it off and you get mold and other issues FAST.
Originally Posted By: RTexasF
Actually I couldn't care less.
Me either!
Actually I couldn't care less.
Me either!
Originally Posted By: Nick R
Honestly it seems like it wastes more electricity/gas to turn it off. Because if it's either. A. Really cold, or B. Really hot, it will have to work harder for longer to get caught up, more so than it would need to be to maintain. Especially in a building the size of a mall.
That's exactly why they do not "turn it off" - they simply turn the thermostat up (say, from 75 to 79......).
These days most households and businesses have "electronic" thermostats that you can set to a schedule. Willing to bet they have something set like this....
Especially a building as big as a mall, you totally shut off the AC at 8, it'll take 2-3 hours to bring the temperature back up to "comfortable" - and in the end, the A/C will be over-working itself to "catch up".....
We have a digital thermostat in our home, have it set cooler at night (75 degrees), than during the day (79 degrees) but no the system is never totally "Off".....but will say, when I'm home it only kicks in maybe once every 3 hours.....
Honestly it seems like it wastes more electricity/gas to turn it off. Because if it's either. A. Really cold, or B. Really hot, it will have to work harder for longer to get caught up, more so than it would need to be to maintain. Especially in a building the size of a mall.
That's exactly why they do not "turn it off" - they simply turn the thermostat up (say, from 75 to 79......).
These days most households and businesses have "electronic" thermostats that you can set to a schedule. Willing to bet they have something set like this....
Especially a building as big as a mall, you totally shut off the AC at 8, it'll take 2-3 hours to bring the temperature back up to "comfortable" - and in the end, the A/C will be over-working itself to "catch up".....
We have a digital thermostat in our home, have it set cooler at night (75 degrees), than during the day (79 degrees) but no the system is never totally "Off".....but will say, when I'm home it only kicks in maybe once every 3 hours.....
A local DR owns what use to be a Hechengers harware store (think a small big box store), that is vacant but used for evelts throughout the year. He told me they do not heat or cool it for these events. He stated to to heat or cool it 20 degrees either way takes 2 days and costs $3k.
As JHZR2 said, there's no such thing as an AC system "working hard" or "over-working". They are either on or off and do not exceed design values for power draw or cooling output just because of a large difference between the current and desired temperatures. It'll just have to run longer to make up the difference.
He's also right that allowing the temperature to fluctuate is more efficient than simply maintaining a low set point all the time.
jeff
He's also right that allowing the temperature to fluctuate is more efficient than simply maintaining a low set point all the time.
jeff
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