Change Zone Temp Set Point in an internal closet w no OA?

[Saturninus]

Usually, yes, it saves energy to increase cooling setpoints, say from 68 to 75 degrees F.

What about if you have an internal closet with some heat producing equipment. No ventilation air is introduced. There are fan coils that cool and recirculate the air. The closet is kept cold at about 65 degrees because the controls are broken.

Are the only savings to be had due to the heat transfer through the walls and ceiling?

As I see it, once a zone is at setpoint, if the zone is adiabatic, it should be just as hard to keep it at one temperature as another.

Please tell me how I am wrong.

THanks.

 

[ChrisConley]

The zone would only be adiabatic if all of the adjacent zones are being held at the same temperature.

Otherwise you'll have a conduction heat transfer from the warm rooms to this cooler closet.

If you do have a ceiling, then you've also increased the temperature difference between the space and the room, which also increases heat gain to the space.

You'd be surprised how much difference a couple degrees can make; I bought a programmable thermostat for my house and set the temperature in the house back 2-3 deg at night and saw about a $75 per year savings.

 

[MintJulep]

Also, if the zone were adiabatic there would be no need for cooling.

Chris is right, the delta-T is probably the dominant factor. If your cooling system is DX, it probably looses some efficiency as the evaporator temp goes down.