Electrical
Motor efficiency energy savings
Price fixed-output shaft work at two supplied efficiencies.
Your inputs
Complete the fields for your selected method. Zero means intentionally zero, not unknown. Currency selection labels amounts; it does not convert exchange rates.
How this calculation works
kWh saved=shaft kW*hours*(1/eta old-1/eta new). Metered alternative: energy saved = matching existing annual kWh - matching proposed annual kWh.
Same constant delivered shaft output. Efficiencies are supplied at that operating point; this does not select or size a motor. A lower proposed efficiency produces negative savings.
What information do I need?
Use records for the same job, equipment or accounting period. Only the fields for your selected entry method are required. An unknown amount is not zero.
Input definitions and where to find them
- How do you know the energy use?: Choose the information you actually have. Only the selected method is required.
- Required constant shaft output (mechanical hp): Required delivered SHAFT kW at the actual operating point: specialist supplied measurement/validated data. Used with: Measured input power and operating schedule.
- Existing motor efficiency (%): Existing efficiency at that SAME shaft work point. Used with: Measured input power and operating schedule.
- Proposed motor efficiency (%): Proposed efficiency at comparable shaft work, not a blanket peak nameplate value. Used with: Measured input power and operating schedule.
- Annual operation at stated output (hours/year): Use matching records or a clearly identified owner assumption for annual operation at stated output, in the displayed unit and the stated row/period scope. Used with: Measured input power and operating schedule.
- Electricity price per kWh (selected currency): Matching energy/volumetric tariff or bill component for electricity price per kwh, excluding fixed charges or other charges not modeled.
- Existing annual input energy at the compared output (kWh): Use an isolated record or clearly labeled estimate matching this field and period. Do not substitute an unrelated whole-site total. Used with: Metered or separately estimated kWh.
- Proposed annual input energy at the same output (kWh): Use an isolated record or clearly labeled estimate matching this field and period. Do not substitute an unrelated whole-site total. Used with: Metered or separately estimated kWh.
Use the Where to find this value controls beside the inputs for available work-it-out helpers. Estimates remain your assumptions; a helper does not verify the source figures.
Worked example
Example amounts use US dollars (USD).
Example answer: Annual electrical energy saved is 5,555.56 kWh/year for the illustrative inputs below.
Example inputs
- How do you know the energy use?: Measured input power and operating schedule
- Required constant shaft output: 13.410220895950 mechanical hp
- Existing motor efficiency: 80.00 %
- Proposed motor efficiency: 90.00 %
- Annual operation at stated output: 4,000.00 hours/year
- Electricity price per kWh: $0.15
- Annual electrical energy saved
- 5,555.56 kWh/year
- Annual electricity cost saved
- $833.33
These illustrative values are not recommended rates or industry averages. Replace every example input with your own figures.
Use the result well
Price fixed-output shaft work at two supplied efficiencies. Some modes require specialist measurements or a qualified equipment/energy estimate. If you do not have those inputs, use a directly measured alternative where offered; do not guess from unrelated bills or equipment ratings.
Keep inputs on the same scope and time basis. Calculations retain precision internally; displayed values generally round to two decimal places, with extra precision for very small values and whole-unit rounding where required. Economic comparisons describe your supplied assumptions and do not guarantee future results.
This tool provides business arithmetic. It does not approve engineering designs, establish legal or tax treatment, select equipment or certify safe operating conditions.