Energy Saving Cost Calculator

About This Calculator

This engineering calculator estimates energy reduction, operating cost savings, demand savings, maintenance savings, payback, return, and discounted project value. It is useful for lighting, motors, pumps, fans, compressed air improvements, HVAC retrofits, and other efficiency upgrades.

Enter current and proposed power demand, operating schedule, tariff information, project cost, rebate support, and financial assumptions. The page then compares baseline and improved cases, summarizes monthly and yearly savings, and visualizes the difference with an interactive graph.

Calculator

Example Data Table

Formula Used

Current kWh per day: (Current Watts × Quantity × Hours per Day) ÷ 1000

Proposed kWh per day: (Proposed Watts × Quantity × Hours per Day) ÷ 1000

Monthly Energy Saved: (Current kWh per Day − Proposed kWh per Day) × Days per Month

Monthly Energy Cost Saved: Monthly Energy Saved × Electricity Rate

Monthly Maintenance Saved: Existing Maintenance − Proposed Maintenance

Monthly Demand Savings: Demand Reduction × Demand Charge Rate

Gross Monthly Savings: Energy Cost Saved + Maintenance Saved + Demand Savings

Net Project Cost: Project Cost − Rebate Amount

Payback Period: Net Project Cost ÷ Gross Monthly Savings

Present Value of Savings: Discount each year’s savings using the selected discount rate.

Net Present Value: Present Value of Savings − Net Project Cost

How to Use This Calculator

1. Enter the present electrical load for one unit in watts.
2. Enter the upgraded load for one unit after the improvement.
3. Provide equipment quantity and operating schedule.
4. Enter the electricity tariff per kilowatt-hour.
5. Add maintenance costs for current and proposed cases.
6. Enter demand reduction and demand charge, if relevant.
7. Add project cost and any available rebate amount.
8. Set emission factor, analysis years, escalation, and discount rate.
9. Press calculate to see savings, payback, lifecycle value, and the comparison graph.
10. Use the CSV and PDF buttons to export the current result set.

Frequently Asked Questions

1. What does this calculator estimate?

It estimates baseline energy use, improved energy use, monthly and yearly cost savings, maintenance savings, demand savings, payback, return, and discounted project value for efficiency projects.

2. Can I use it for lighting upgrades?

Yes. It works well for lighting retrofits because wattage reduction, operating hours, unit count, maintenance savings, and rebate inputs are common in those projects.

3. Can this calculator handle motors or HVAC equipment?

Yes. Any retrofit with measurable power reduction and operating hours can be modeled, including motors, pumps, fans, HVAC upgrades, and process equipment improvements.

4. Why is demand charge included?

Some utility bills include a charge tied to peak demand. If your project lowers peak kilowatt demand, that reduction can create additional monthly savings.

5. What is the difference between payback and NPV?

Payback shows how long it takes savings to recover project cost. NPV measures the present worth of future savings after discounting time value.

6. Should I enter rebate money?

Yes. Rebates reduce effective project cost. A lower net cost improves payback and can significantly improve lifecycle value.

7. What emission factor should I use?

Use the factor that matches your electricity source or local reporting method. The calculator multiplies yearly saved kilowatt-hours by that factor to estimate avoided emissions.

8. What if my proposed equipment uses more energy?

The calculator will still compute the result. Savings may become negative, which helps identify poor upgrade choices before spending money.