Make my heater green!

March 5, 2006 9:44 PM

What's the most energy efficient way to run the heater in my office?

I am an English teacher in a school in Korea (background: in Korea they don't heat the schools whatsoever, only the individual classrooms and offices are heated). I have a swanky new English Zone with nice big office and classroom that came with a swanky new ceiling-mounted heater. The problem is that in these cold winter months, with poor insulation and no school heating, it takes up to 4 hours of 30 degree C heat pumping just to get the room remotely pleasant (it's worse for classroom than office).
I'm in my office for 8 hours and in the classroom for about 6. Subsequentally, almost right after the temp is finally nice, it's time to leave and I just turn off the heater (as I was told), giving ample time for the heat to dissipate and to start the process over again the next day.
My question: is it more efficient (in terms of wasted energy/energy consumed) to do it this way or, after it reaches comfortable temp, to lower it to, say, 19C for the ~16hours it's not in use? I wish I could give you information about the heater itself but searching the website (it's an LG Whisen) I couldn't find it, especially since it the website is in Korean. But it looks really new and nice (it's also an air-conditioner) so I assume it's not like some old lunker.
More info that might be useful: Office is about 6m x 3m, with a "normal" door that seals it pretty tight. Classroom is 10m x 7m (it has two heaters) and is connected to a hall (30m x 2m) and has two "swing"-type doors that close, but not extremely tight. Even though I'm not paying, I'm not looking for the "leave the heat on all the time! you might as well!" answer; I am curious solely from the energy consumption view. Thanks!

posted by shokod to technology (5 comments total)

1) When you leave switch it off.

2) Get a timer to switch it on for however many hours you need before you start work. If its an AC unit it should have quite fancy controls. Get one of your students to help you.

Also make sure

1) All windows are closed
2) All doors are closed

Leaving it on is also an option but not an efficient one. If electricity is not expensive then do it.
posted by Vroom_Vroom_Vroom at 11:20 PM on March 5, 2006

My home office is the only room in my house heated during the day and it is about the same size as your office. I have a small ceramic heater with a built-in thermostat and I point it under my desk at my feet. This creates a pocket of warm air that keeps me comfortable while the rest of the room warms up. I haven't seen too many portable heaters in East Asia so you might need someone to ship one over. When I lived in Japan they were the most welcome gifts that I gave and they worked fine without an adaptor.
posted by Alison at 6:53 AM on March 6, 2006

You could also try putting a kotatsu heater and a blanket under your desk. It will heat fast and at least keep your legs warm.
posted by Alison at 6:54 AM on March 6, 2006

Most heat pump units also have an "emergency" or "auxiliary" heat coil, for conditions where the outside temperature is so low that the heat transfer capability of the heat pump will not be enough to create the warmth needed. But running these resistive elements is not nearly as energy efficient as running the heat pump, since at anything above about -5 degrees C, the heat pump will be capturing at least some outside heat from the environment. So, if the walls and structure of your rooms are so poorly insulated that in the 16 hours when there is no heat in them, that they cool off very substantially, to the point where you have to run the emergency resistive heat, then yes, leaving the heat on low overnight will actually be both cheaper and more comfortable than cutting it off completely at night.
posted by paulsc at 7:50 AM on March 6, 2006

Getting to your original question:

Without getting into physics and formulas, I'm pretty sure keeping the room warm at night takes more energy than letting it reach eqilibrium with the outside, and then warming it back up in the morning -- unless the outside is VERY cold.

The only reason (otherwise empty) houses and offices are kept somewhat warm at night is prevent ruining important things that like to be well above freezing (water pipes, electronics, medicines, etc.). The most efficient way is be to heat a space only when necessary -- it may not be as comfortable (some things may have a higher heat of fusion and warm more slowly, which explains why the room is hot but the seats are still cold), but it saves $ and resources in the long run.

If the room seems to be cooling faster than you think it should, do what you can to help seal the heat in. Check the seals on the windows and doors for gaps & seal them (or re-gasket them). Close window drapes & blinds. Inquire about the insulation of walls & ceilings.
posted by catkins at 12:06 PM on March 6, 2006