Whether it’s time to replace your old heater or you simply need to add a little warmth to an area in your home, buying a new portable space heater is a great option. Keep these five things in mind as you search.

1. Type

First, choose the type of heater you want: convection, radiant, fan-forced or micathermic. Convection heaters use a heating element and a fan to provide even, full-room air heating, while radiant heaters transfer heat directly to people and objects in their immediate surroundings. Fan-forced heaters blow air across a heating element using an internal fan. Micathermic heaters combine radiant and convective heat, allowing them to heat large areas efficiently.

2. Capacity

Next, determine how large the space is that you want to heat. Typically, heating 1 square foot of space requires 10 watts of heating power, so if you want to heat a 100-square-foot space, you’ll need a 1,000-watt space heater. This is just a rule of thumb, however, and some portable heaters can cover more space depending on your indoor environment, the heating technology being used and more.

3. Efficiency

Though space heaters don’t have efficiency standards set by the U.S. Department of Energy, you can still find models made with energy savings in mind. Some space heaters include features like energy-saving modes, built-in adjustable thermostats and programmable timers to help them operate more efficiently. Choosing a heater with a wattage that is appropriate for your space can also prevent energy waste.

4. Safety features

If they’re used incorrectly or not monitored properly, space heaters can quickly become a fire hazard. Choose a model with safety features like protective grills over the heating coils and an internal switch that shuts off power if the heater is knocked over or reaches an unsafe temperature. Only buy a space heater approved by respected testing laboratories — like Underwriters Laboratory or Intertek — to ensure it meets U.S. safety standards.

5. Noise

Though many space heaters are relatively quiet, they’ll produce background noise that can still be a bother. That’s why it’s important to choose a model that adds a tolerable amount of noise. Models that don’t use fans — like radiant space heaters — will operate quietly in areas such as offices and bedrooms where little noise interruption is preferred.

Considering space heater type, capacity, efficiency, safety features and noise while you shop can help you find the best heater for that pesky chilly space in your home.