HVAC
HVAC Energy Cost Calculator
Estimate what running a system costs across a season, from its efficiency, the load and local energy pricing.
Result
SEER is a seasonal average across a range of conditions, so hourly figures are approximate. Real consumption depends on outdoor temperature, humidity, duct losses and how well the system was installed.
Get a Free Business AuditWhat moves the number
- Run hours, which depend on the load and the climate rather than on the equipment.
- Efficiency at realistic conditions rather than the rated figure at test conditions.
- Energy price including any standing charges and seasonal rates.
Where this one goes wrong
Using the rated efficiency as though it applied year round. Ratings are measured at defined test conditions; a system running at part load in mild weather or at extremes in a heatwave performs differently.
Questions
About this calculator
Why does my estimate differ from the customer's bill?
Because the bill includes everything else in the building, and because weather, thermostat behaviour and occupancy vary. Use the estimate to compare options rather than to predict a bill.
Does a higher rated system always cost less to run?
It uses less energy for the same delivered heat or cooling, but the saving depends on run hours. In a mild climate with few run hours, the difference in running cost can be small.
What affects running cost more than the equipment?
Usually the envelope and the ductwork. A leaky duct system in an unconditioned space wastes conditioned air regardless of how efficient the equipment is.
The formula
kW = BTU/h ÷ SEER ÷ 1,000; cost = kW × hours × rate
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How to use this calculator
- System capacity (BTU/h). Enter your own figure; the page starts at 36,000.
- Efficiency (SEER or SEER2). Enter your own figure; the page starts at 16.
- Run hours per day. Enter your own figure; the page starts at 8.
- Days in the season. Enter your own figure; the page starts at 120.
- Electricity rate per kWh ($). Enter your own figure; the page starts at $0.16.
The result updates as you type, so you can try a figure, see what it does to cost per season, and change it back. Nothing you enter is sent anywhere or saved.
A worked example
These are the figures the calculator opens with. Every number in the results column below is produced by the same calculation the page runs, so you can follow it through before putting your own figures in.
What goes in
| Input | Value |
|---|---|
| System capacity (BTU/h) | 36,000 |
| Efficiency (SEER or SEER2) | 16 |
| Run hours per day | 8 |
| Days in the season | 120 |
| Electricity rate per kWh | $0.16 |
What comes out
| Result | Value |
|---|---|
| Cost per season main result | $345.60 |
| Cost per hour | $0.36 |
| Cost per month | $86.40 |
| Energy used per season | 2,160 |
Running costs about $0.36 per hour, $86.40 a month, or $345.60 across a 120-day season using 2,160 kWh.
How sensitive the answer is
Holding everything else steady and changing only electricity rate per kwh, this is what happens to cost per season. It is worth knowing which of your inputs the answer actually hinges on, and which barely move it.
| Electricity rate per kWh ($) | Cost per season |
|---|---|
| $0.08 | $172.80 |
| $0.12 | $259.20 |
| $0.16 example above | $345.60 |
| $0.24 | $518.40 |
| $0.32 | $691.20 |
Every other input is held at the example value while this one changes, which is not how a real job behaves. Treat it as a guide to which number matters most, not as five separate quotes.
What each figure means
- System capacity (BTU/h)
- A number, between 0 and 500000, starting at 36,000.
- Efficiency (SEER or SEER2)
- A number, between 0 and 40, starting at 16.
- Run hours per day
- A number, between 0 and 24, starting at 8.
- Days in the season
- A number, between 0 and 365, starting at 120.
- Electricity rate per kWh ($)
- A money amount, starting at $0.16.
What the results tell you
| Result | What it is |
|---|---|
| Cost per season | The headline result. A money figure. |
| Cost per hour | A money figure. |
| Cost per month | A money figure. |
| Energy used per season | A number. |
Before you rely on this number
Sizing, capacity and load figures here are planning estimates. A real installation depends on the manufacturer's data for the specific equipment, the duct system it is going into, and a proper load calculation for the building. Use this to sanity-check a number or price a job, not to select equipment.
Keep going
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