To cut heating costs in a one-room, is an electric blanket better than the boiler?
I am from Vietnam, living in a one-room in Seoul on a D-10 visa. My city gas heating bill last winter was higher than I expected, so I want to bring it down this year. Korean friends keep telling me to use an electric blanket or a hot water mat, but I have also heard about the progressive electricity tariff and I am worried the bill could end up worse rather than better.
For a single one-room, which is actually cheaper, and is it safe to leave one on overnight?
1 Answer
For a single one-room, the electric blanket or hot water mat is generally cheaper. A boiler heats the whole volume of air and the floor, while a blanket heats only the surface your body touches. That said, do not turn the boiler off completely — the reason is at the end of this answer.
You can work out the cost yourself from the wattage printed on the product. Divide the power rating in watts by 1,000 and multiply by the hours you use it, and you have kilowatt-hours. A 100W product used eight hours a day is 0.8 kWh, or about 24 kWh over a month. In practice, blankets cycle on and off with the thermostat, so real consumption usually comes in under that figure rather than over it.
The progressive tariff is probably less of a threat than you are imagining. Residential electricity is priced in bands, with the unit rate rising as monthly usage climbs, and the band thresholds differ by season. A one-person one-room typically sits low enough in baseline usage that adding the amount above does not push you into a high band. Households vary, though, so rather than take my word for it, look at the usage figure on your last few bills and add the kWh you calculated. Current bands, unit rates and a calculator are available from KEPCO, and the phone line is 123 with no area code.
Safety matters more here than the money. Leaving one on overnight is fine if the product allows it, but with conditions attached. Never use it folded or creased — the heating wire gets damaged and heat concentrates at that point. Avoid placing it on a latex mattress or a thick topper, because the heat cannot escape and builds up underneath. Running it at maximum under layers of heavy bedding is dangerous for the same reason. Use the timer if there is one, and unplug it when you leave the apartment. When buying, check for the KC certification mark, and if you buy second-hand, spread it out flat and look for creases or kinks along the wire.
A hot water mat works differently: it circulates heated water, so there is no heating wire, but you have to top up the water periodically and the pump makes noise. If you are a light sleeper, that noise is more noticeable than people expect when they buy one.
As for why not to shut the boiler off entirely, there are two reasons. In a cold snap, water pipes can freeze and burst, which turns a heating bill into a repair bill. And with no heating at all, condensation forms on the walls and mould follows, which in a one-room shows up fast behind furniture. The practical setup is to run the boiler minimally — on an away or low-temperature setting, just enough to hold the room above freezing and keep the walls dry — and heat only the bed with the blanket. For gas billing questions, contact the regional city gas company you are contracted with.