Heating a 20x20 foot (400 sq. ft.) room generally requires 2,000 to 4,000 watts of heating power, depending on your home's insulation. As a standard guideline, a well-insulated space requires roughly 10 watts per square foot.
A 1500-watt heater typically heats a room up to 150 square feet (as a primary heat source) or up to 250 square feet (if used as supplementary heat alongside a central system). This capacity is ideal for small to medium-sized bedrooms, home offices, or dorms.
Room Size and Heater Wattage
As a rule of thumb, a well-insulated room requires around 100 watts per square metre for adequate heating. So, for a small room of 10m², a 1000W heater would do the job nicely. For a larger room of 20m², you'd need a 2000W heater to achieve the same level of warmth.
10000-Watt Hardwired 240-Volt Electric Workshop Garage Heater Fan Forced for Ceiling Wall or Counter up to 1605 sq. ft.
10,000 Watts divided by 240 Volts equals 41.6 Amps. This unit requires a 50 Amp breaker. Wire size is determined by load, length and material of the conductor. #6 AWG copper or #4 AWG will serve up to 165 feet with an NEC maximum allowance of 3% voltage drop from the source.
Heating and cooling (HVAC) systems are the biggest energy consumers in a typical house, accounting for roughly 45−50% of your total electricity usage. Water heaters, refrigerators, and lighting round out the rest of the major draws.
It takes time for your home to warm up and cool down. If you're not sure how long it takes, try turning the heating on about 30 minutes before you need it. You should turn it off 30 minutes before you'll stop needing it.
In most homes, Heating and Cooling (HVAC) systems drive the highest energy costs, accounting for nearly 40% to 50% of your total electricity bill. Following these, the appliances that run up your bill the most include water heaters, refrigerators, and laundry machines.
If your home uses electricity for central heating, the cost is likely still cheaper than running space heaters. According to Scerbo, “Buying a space heater for every room would increase the electricity bill more than if you had just bumped up the thermostat.”
To heat a 24x24 foot (576 sq. ft.) garage, you will generally need between 30,000 and 45,000 BTUs. The exact amount depends heavily on your local climate, ceiling height, and insulation levels.
Never use extension cords for a space heater. That being said, IF you do, get a heavy duty 12ga cord in the shortest length to meet your needs. 1500 watts / 120 volts= 12.5 amps. That's a pretty high draw for any cord so get a good one such as this…
To heat a 20x20 (400 sq ft) garage, you generally need between 15,000 to 30,000 BTUs. The exact number depends heavily on your local climate, ceiling height, and insulation:
Running a 1500-watt (1.5 kW) heater for 24 hours consumes 36 kWh of electricity. Nationwide, this typically costs between $𝟑.𝟔𝟎 and $𝟖.𝟔𝟒 per day, depending on your local energy rates and how often the heater's thermostat cycles the heating element on and off.
Heating and energy expert Stephen Hankinson said that one "big energy cost saver" is to make sure you have your heating off when you're not at home. For instance, if you typically arrive home from work at around 6pm on weekdays, you could set your heating to activate just as you walk through the door.
Answer: OSHA does not require employers to provide heat or air conditioning for work spaces. OSHA does recommend temperature control in the range of 68-76°F.
For most customers, we recommend turning on your furnace when the weather is consistently below 18° Celsius, which usually happens to be around the end of September, or early October. Some homeowners try to put off turning on their furnace as long as they can to save money, which is okay if you're healthy adults.
Electric heating systems and tumble dryers tend to be the most expensive electrical items to run because they use large amounts of power over extended periods. Other high-cost appliances include electric ovens and immersion heaters. Using these efficiently and during off-peak hours can help reduce costs.
The Top Energy-Draining Appliance: Space Heating & Cooling
This includes both forced-air systems, heat pumps, furnaces, baseboards, window A/C units, and fans. Because they run for long periods and often at high wattage, they dominate the consumption profile.
Running a 500-watt device costs approximately $0.09 per hour based on the 2026 U.S. national average residential electricity rate of 17.91 cents per kWh.
The cheapest heaters to run are generally low-wattage personal heaters, such as halogen heaters or, for larger spaces, oil-filled radiators and infrared heaters that feature, or can be used with, adjustable thermostats to regulate energy consumption. Energy-efficient personal heaters like the Comfort Zone CZ35E are cost-effective choices for localized heating.
In most homes, heating and cooling systems (HVAC) consume the most electricity, making up roughly 40%−50% of your total energy bill. Water heaters are the second largest draw, followed by always-on appliances like refrigerators.
The Argument for Leaving the Heating On
This approach might seem convenient, as it avoids the discomfort of waiting for the house to warm up. However, most experts agree that it's usually cheaper to heat your home only when you need it.