Even if you’ve insulated your attic and weather-stripped your windows, there might still be a room — or a person — in your house that is ­difficult to keep warm.

The most important decision when buying a space heater is to know whether you need spot heating (just bathing yourself in warmth) or something that heats a room — a drafty office or bedroom, for ­instance. Despite claims on the box, not every space heater does both jobs well.

And no matter which you choose, keep in mind that using a space heater won’t necessarily save you money. Electricity is the most expensive way to heat, so space heaters make sense only when used as a ­supplemental or occasional heat source.

Here are performance factors Consumer Reports suggests considering and some good model choices from its tests:

Best for spot heating. Testers measure the “spot’’ heating ability of a heater to directly warm up a person sitting 4½ feet away in 15 minutes. Top spot-heating picks include the Dyson AM05, $400, and the bigger Honeywell HZ-980, $190.

Best for room heating. Consumer Reports’ measure of success in room heating tests is to gauge the effectiveness of the heater to warm up a room that’s 12 feet by 17 feet with 8-foot ceilings in 15 minutes. Testers liked two models from Vornado and two from Heat Storm.

Best at doing both. Space heaters that earned top marks for both spot heating and room heating include the DeLonghi DCH1030, a bargain at only $42. (At that price, you give up some features.)

Make sure it’s safe

About 25,000 house fires and 300 deaths are attributed to space heaters each year, mostly caused when a heater is placed too close to curtains, bedding, and upholstered furniture. In addition, 6,000 people end up in the emergency room with burns from touching a heater’s hot surface.

Make sure the heater you buy carries a safety certification label from an independent testing organization, such as the UL mark from Underwriters Laboratories, the ETL ­label from Intertek, or certification from CSA International.

A smart sensor that shuts off a heater when it overheats is a must. You’ll also want a tip-over switch that does the same if the heater is knocked over.

Most space heaters do not come with a ground fault circuit interrupter plug, which prevents electric shock, so manufacturers warn that they not be used around water.

Fancy features that count

You want a space heater that’s great at its primary job, but there are other features that enhance the ease of use.

Fan with multiple speeds. Fans help distribute heat more quickly. Some models oscillate for more even heating. Slower fan speeds are less noisy.

Timer. This money-saving feature helps ensure that the heater is operating only when you need it.

Adjustable thermostat. Many space heaters have one, but others have just high-low heat settings, so the temperature is more difficult to adjust.

Remote control. Space heaters are intended to sit on the floor. A remote can help prevent having to bend over to fiddle with the controls.

Weight. Check the weight on the box if you plan to move the heater.

Warranty. Look for a model with a three- to five-year warranty.