Geothermal Savings Calculator Formula
Understand the math behind the geothermal savings calculator. Each variable explained with a worked example.
Formulas Used
Annual Savings
annual_savings = current_total - geo_costSavings Percentage
savings_pct = (current_total - geo_cost) / current_total * 100Geothermal Annual Cost
geo_annual_cost = geo_cost10-Year Savings
savings_10yr = (current_total - geo_cost) * 10Variables
| Variable | Description | Default |
|---|---|---|
annual_heating_cost | Current Annual Heating Cost(USD) | 2500 |
annual_cooling_cost | Current Annual Cooling Cost(USD) | 800 |
geo_efficiency | Geothermal COP(ratio) | 4 |
conventional_efficiency | Current System Efficiency(ratio) | 1 |
current_total | Derived value= annual_heating_cost + annual_cooling_cost | calculated |
geo_cost | Derived value= current_total * conventional_efficiency / geo_efficiency | calculated |
How It Works
How to Calculate Geothermal Savings
Geothermal heat pumps use stable underground temperatures to heat and cool your home much more efficiently than conventional systems.
Formula
Geothermal Cost = Current Cost * (Current Efficiency / Geothermal COP)
Savings = Current Cost - Geothermal Cost
A geothermal system with a COP of 4 delivers 4 units of heating for every 1 unit of electricity, compared to a gas furnace at about 0.95 efficiency.
Worked Example
A home spending $2,500/year heating and $800/year cooling, switching from a furnace (COP 1) to geothermal (COP 4).
- 01Current total: $2,500 + $800 = $3,300/year
- 02Geothermal cost: $3,300 * 1 / 4 = $825/year
- 03Annual savings: $3,300 - $825 = $2,475
- 04Savings percentage: $2,475 / $3,300 = 75%
Frequently Asked Questions
How much does a geothermal system cost?
Residential geothermal systems typically cost $15,000-30,000 installed. The federal tax credit covers 30%, bringing net cost to $10,500-21,000. They last 25-50 years.
What is COP in geothermal?
Coefficient of Performance (COP) measures heating efficiency. A COP of 4 means the system produces 4 units of heat per 1 unit of electricity consumed. Geothermal COPs range from 3-5.
Does geothermal work in cold climates?
Yes. Ground temperature below the frost line stays 45-75F year-round regardless of surface weather. Geothermal works well even in northern climates.
Ready to run the numbers?
Open Geothermal Savings Calculator