Aircon And Power Consumption

[dagling]

Had a little discussion yesterday about the aircon and power consumption.

A buddy thought they could save a lot by having the aircon on 23 degrees and half power to the fan, versus 17 degrees.

Are there any of you who have calculated a bit on this, or is there a minimum to save as described above?

[rookball]

the difference in consumption is big between 17 and 23. easily 50%more

[candypants]

if he has got his ac on 17, it simply aint working properly

[Crossy]

Indeed ^^^, set at 17^o your A/C will probably be running continuously, a 12,000 BTU unit will be using about 2 units (8 Baht at government rates) an hour.

The rate of heat gain is roughly proportional to indoor/outdoor temperature differential.

If we assume an outdoor temp of 35^o then with an indoor temp of 17^o we have a differential of 18^o. If we adjust our indoor temp to 25^o (still comfortable) the differential will be 10^o which will reduce the heat gain by about 50% with a consequential saving of up to 50% of the energy consumption.

The above is a VERY simplistic view, but there is no doubt that the warmer you are prepared to tolerate your home the lower your A/C energy consumption will be.

EDIT The fan on the indoor unit uses a tiny proportion of the overall consumption, leave it on 'auto'.

[Naam]

A buddy thought they could save a lot by having the aircon on 23 degrees and half power to the fan, versus 17 degrees.

-your buddy's thinking does not change the laws of physics,

-anybody who sets his aircon in a hot tropical country at 17ºC should have his head examinated,

-even 23.5ºC will result in a waste of energy,

-"half power" to the fan does not save but wastes energy as the cooling efficiency drops by 5-8% (depending on the length of suction/pressure pipes),

addendum to "half power": if this setting is used temporarily to achieve a higher degree of dehumidification it is acceptable. but in this case the lowest fan speed should be selected or mode "dry" if the unit has that function.

Crossy has covered the rest.

[ZhouZhou]

Indeed ^^^, set at 17^o your A/C will probably be running continuously, a 12,000 BTU unit will be using about 2 units (8 Baht at government rates) an hour.

The rate of heat gain is roughly proportional to indoor/outdoor temperature differential.

If we assume an outdoor temp of 35^o then with an indoor temp of 17^o we have a differential of 18^o. If we adjust our indoor temp to 25^o (still comfortable) the differential will be 10^o which will reduce the heat gain by about 50% with a consequential saving of up to 50% of the energy consumption.

The above is a VERY simplistic view, but there is no doubt that the warmer you are prepared to tolerate your home the lower your A/C energy consumption will be.

EDIT The fan on the indoor unit uses a tiny proportion of the overall consumption, leave it on 'auto'.

i think it might be an exponential growth curve. for cooling the room down from -5 till -10(compared with outside temperature) will consume much more energy than just the double amount of energy needed for cooling down from 0 till -5.

special because its not an closed thermodynamic system but has all that leaks.

[Naam]

i think it might be an exponential growth curve. for cooling the room down from -5 till -10(compared with outside temperature) will consume much more energy than just the double amount of energy needed for cooling down from 0 till -5.

special because its not an closed thermodynamic system but has all that leaks.

correct!

[FunFon]

I never run mine lower than 26, usually 28 is fine.

Of course you need to have a properly sized unit and reasonably sealed room for the thermostat to even function properly.

My two A/C units pull far less than the fridge averaged over the whole month.

[Crossy]

Indeed ^^^, set at 17^o your A/C will probably be running continuously, a 12,000 BTU unit will be using about 2 units (8 Baht at government rates) an hour.

The rate of heat gain is roughly proportional to indoor/outdoor temperature differential.

If we assume an outdoor temp of 35^o then with an indoor temp of 17^o we have a differential of 18^o. If we adjust our indoor temp to 25^o (still comfortable) the differential will be 10^o which will reduce the heat gain by about 50% with a consequential saving of up to 50% of the energy consumption.

The above is a VERY simplistic view, but there is no doubt that the warmer you are prepared to tolerate your home the lower your A/C energy consumption will be.

EDIT The fan on the indoor unit uses a tiny proportion of the overall consumption, leave it on 'auto'.

i think it might be an exponential growth curve. for cooling the room down from -5 till -10(compared with outside temperature) will consume much more energy than just the double amount of energy needed for cooling down from 0 till -5.

special because its not an closed thermodynamic system but has all that leaks.

I did state that it's a VERY simplistic view the real world will be much worse consumption wise.