Variable-Frequency Drive Energy Break-Even Analyzer
Find the minimum annual energy or operating savings a VFD project needs to recover its investment within a chosen time horizon. This is a threshold analysis, not a duplicate of a conventional payback calculation.
Calculate the break-even threshold
VFD break-even threshold
What the break-even threshold means
This analyzer works backward from a desired recovery period. Instead of asking how quickly a known saving repays the investment, it asks how much saving would be required to recover the investment within the user's target.
Required annual saving = Investment ÷ Target recovery period
Other annual savings are subtracted first because they reduce the amount that must come from electricity alone.
Required energy saving = Electricity portion of annual saving ÷ Electricity price
Why threshold analysis is useful
During early project screening, you may know the VFD investment and the payback target before you know whether the actual load profile can deliver sufficient energy savings. This calculation gives the project team a concrete hurdle to compare with measured data or a simulation.
Interpret the percentage carefully
The required energy reduction is calculated against the baseline annual energy you entered. A percentage above 100% means electricity savings alone cannot meet the stated target under the entered assumptions.
Limitations
- The model uses simple, non-discounted payback logic.
- Electricity price is treated as constant.
- Demand charges, escalation, financing and tax effects are excluded.
- Baseline annual energy must represent the same service level as the proposed case.
FAQs
How is this different from payback?
Payback starts with a known annual saving and calculates the recovery time. This analyzer starts with the desired recovery time and calculates the minimum saving needed.
Can annual savings exceed the investment?
Yes. That simply means the target period is less than one year under the entered assumptions.
What if the required energy saving is above baseline use?
The target is not achievable from electricity savings alone using that baseline.
Does the result prove a VFD is suitable?
No. Technical suitability and the actual speed/load relationship must be checked separately.