kWh per Square Foot Calculator
A 1,500 square foot home that uses 12,000 kWh in a year has an energy use intensity of 8 kWh per square foot.
Quick answer: Divide the energy in kWh by the floor area in square feet. For example, 12,000 kWh over 1,500 sq ft is 8 kWh per sq ft, 9,000 kWh over 1,800 sq ft is 5 kWh per sq ft and 250,000 kWh over 10,000 sq ft is 25 kWh per sq ft.
The kWh per square foot formula
Energy use per square foot equals energy in kWh divided by floor area in square feet. Use a full year of energy so the seasons are included.
To get kWh per square metre, divide by 0.0929, because one square foot is 0.0929 square metres.
Take 12,000 kWh over 1,500 sq ft. 12,000 ÷ 1,500 gives 8 kWh per sq ft.
Take 9,000 kWh over 1,800 sq ft. 9,000 ÷ 1,800 gives 5 kWh per sq ft.
Energy use intensity
Energy use intensity, or EUI, is energy divided by floor area. It lets you compare a small house and a large building on the same scale.
A lower number means less energy for each square foot of space.
How to convert kWh per square foot step by step
- Add up the kWh used over a full year from your bills.
- Find the floor area in square feet.
- Divide the kWh by the square feet.
- Use the last column if you need kWh per square metre.
Example 1: 12,000 kWh over 1,500 sq ft
- Start with 12,000 kWh over 1,500 sq ft.
- 12,000 ÷ 1,500 = 8.
- The energy use intensity is 8 kWh per sq ft.
12,000 kWh over 1,500 sq ft = 8 kWh per sq ft
Example 2: 9,000 kWh over 1,800 sq ft
- Start with 9,000 kWh over 1,800 sq ft.
- 9,000 ÷ 1,800 = 5.
- The energy use intensity is 5 kWh per sq ft.
9,000 kWh over 1,800 sq ft = 5 kWh per sq ft
Example 3: 250,000 kWh over 10,000 sq ft
- Start with 250,000 kWh over 10,000 sq ft.
- 250,000 ÷ 10,000 = 25.
- The energy use intensity is 25 kWh per sq ft.
250,000 kWh over 10,000 sq ft = 25 kWh per sq ft
The comparison is fair only when both buildings use the same kind of energy and the same period.
kWh per square foot conversion table
| Energy and area | kWh per sq ft | kWh per sq m |
|---|---|---|
| 3,000 kWh over 1,000 sq ft | 3 kWh per sq ft | 32.292 kWh per sq m |
| 6,000 kWh over 1,500 sq ft | 4 kWh per sq ft | 43.056 kWh per sq m |
| 9,000 kWh over 1,500 sq ft | 6 kWh per sq ft | 64.583 kWh per sq m |
| 12,000 kWh over 1,500 sq ft | 8 kWh per sq ft | 86.111 kWh per sq m |
| 12,000 kWh over 2,400 sq ft | 5 kWh per sq ft | 53.82 kWh per sq m |
| 15,000 kWh over 2,000 sq ft | 7.5 kWh per sq ft | 80.729 kWh per sq m |
| 30,000 kWh over 2,000 sq ft | 15 kWh per sq ft | 161.46 kWh per sq m |
| 60,000 kWh over 5,000 sq ft | 12 kWh per sq ft | 129.17 kWh per sq m |
| 120,000 kWh over 10,000 sq ft | 12 kWh per sq ft | 129.17 kWh per sq m |
| 250,000 kWh over 10,000 sq ft | 25 kWh per sq ft | 269.1 kWh per sq m |
The highlighted row is the default of the calculator. The last column gives kWh per sq m.
A quick mental shortcut for kWh per square foot
Divide the yearly kWh by the square feet. 12,000 kWh over 1,500 square feet is 8.
Multiply by 10.76 to get kWh per square metre.
A commercial building benchmark
The US Energy Information Administration reports that commercial buildings used about 70,400 Btu per square foot in 2018, down from 80,000 in 2012 (EIA: Use of energy in commercial buildings in depth).
At 3,412 Btu per kWh (EIA: Energy conversion calculators), that is about 20.633 kWh per square foot, and 80,000 Btu is about 23.447 kWh.
Building types differ
EIA notes that inpatient healthcare, food sales and food service buildings are among the most energy-intensive. Warehouses and places of worship are among the least (EIA: Use of energy in commercial buildings in depth).
Compare your building with its own type, not with a different one.
Per square metre
One square metre is about 10.764 square feet. So 8 kWh per square foot is 86.111 kWh per square metre.
Use this when a report or a standard quotes metric numbers.
Use a full year
Winter heating or summer cooling can double the use in some months. A single month gives a misleading number.
Add twelve months of bills for a fair figure.
What the number leaves out
EUI does not show how many people use the space or how long. A busy shop and an empty store of the same size can differ widely.
It also mixes electricity with other fuels if you add them together, so keep the energy type the same.
Going the other way
To estimate the energy for a building, multiply the intensity by the floor area.
For 8 kWh per square foot and 1,500 square feet, the energy is 12,000 kWh.
Check your answer
Multiply your kWh per square foot by the area. You should get the original kWh.
For 5 kWh per square foot and 1,800 square feet the product is 9,000 kWh, which matches.
Quick conversion answers
| Conversion | Result |
|---|---|
| 4,500 kWh over 900 sq ft | 5 kWh per sq ft |
| 7,500 kWh over 1,200 sq ft | 6.25 kWh per sq ft |
| 10,500 kWh over 2,100 sq ft | 5 kWh per sq ft |
| 18,000 kWh over 2,500 sq ft | 7.2 kWh per sq ft |
| 90,000 kWh over 6,000 sq ft | 15 kWh per sq ft |
| 400,000 kWh over 20,000 sq ft | 20 kWh per sq ft |
Where this conversion is used
Homeowners compare their yearly kWh with similar homes.
Facility managers track a building against its past years.
Analysts compare buildings of different sizes on one scale.
Common mistakes to avoid
- Using one month of energy. Seasonal swings make a single month a poor guide.
- Using the wrong area. Check whether the number is gross floor area or only the heated area.
- Comparing different building types. A hospital and a warehouse use energy very differently.
- Mixing electricity with other fuels. Convert all fuels to one unit before adding them.
Related converters
Frequently asked questions
How do I calculate kWh per square foot?
Divide the yearly kWh by the floor area in square feet.
What is energy use intensity?
It is the energy used by a building divided by its floor area.
How do I get kWh per square metre?
Divide by 0.0929, or multiply the per square foot figure by 10.764.
What is a typical commercial building value?
EIA reported about 70,400 Btu per square foot in 2018, which is about 20.6 kWh.
Why use a full year?
Seasons change heating and cooling use, so a full year gives a fair figure.
Can I compare two different buildings?
Only if they are the same type and use the same kind of energy.
Sources
- EIA: Use of energy in commercial buildings in depth (eia.gov)
- EIA: Energy conversion calculators (eia.gov)
