Free Engineering Tool · Runs in Browser

EC vs AC Fan Energy Savings & ROI Calculator

Compare the annual electricity use, energy cost, CO₂ emissions and payback of an EC fan versus an AC fan at the same duty point. Enter the input power of your own AC fan, or auto-size a LONGWELL EC fan from airflow and static pressure. The calculator returns annual kWh saved, cost saved, percentage reduction, CO₂ avoided and a simple payback period. Vendor-neutral, runs entirely in your browser. Updated for the 2026 EC fan platform.

EC vs AC Energy Savings & ROI Tool

Air power = airflow × pressure; input power = air power ÷ wire-to-air efficiency. Based on AMCA 210/211 and ISO 5801 conventions. All assumptions are editable.

1 · Duty point

Airflow per fan (m³/h)

Total static pressure (Pa)

Number of fans

2 · Operating profile & tariff

Run schedule

Operating hours / year

Load profile Variable load increases EC advantage via speed control.

Electricity price

Currency / unit

3 · AC fan baseline (what you have today)

AC baseline source

Existing AC fan type Sets a typical wire-to-air efficiency; editable in Advanced.

4 · EC fan (the replacement)

EC fan source

▸ Advanced assumptions (efficiency, CO₂, retrofit cost)

EC wire-to-air efficiency (%) Auto-set from the sized SKU; override to match a datasheet.

AC wire-to-air efficiency (%) Follows the AC fan type unless you edit it.

Grid CO₂ factor (kg/kWh)

Retrofit / upgrade cost per fan (optional) Fan + install + controls. Leave 0 to skip payback.

Lifetime horizon (years)

How the Calculator Works

Air power is the anchor

Air power (W) = airflow (m³/s) × total static pressure (Pa). This is the useful work the fan must deliver and is the same for an EC or an AC fan at the same duty point.

Input power = air power ÷ efficiency

Electrical input power = air power ÷ wire-to-air efficiency. EC fans hold high efficiency across the load range; belt-driven AC fans lose energy to the motor, belt and slip, so they draw more power for the same air.

Annual energy & cost

Annual kWh = input power (kW) × operating hours × number of fans. Annual cost = annual kWh × electricity price. Savings is simply the AC figure minus the EC figure.

Variable load uses the fan laws

When airflow is throttled with dampers, an AC fan keeps spinning near full power, but an EC fan slows down and power falls roughly with the cube of speed. That is why throttled systems show the largest EC savings.

CO₂ and payback

CO₂ avoided = kWh saved × grid factor. Simple payback = retrofit cost ÷ annual cost saved. Both are screening numbers; a full business case also counts maintenance, downtime and control benefits.

Everything is editable

The EC and AC efficiency assumptions, grid factor and run hours are all editable so the result reflects your equipment and tariff — not a marketing default. Confirm the final figures against measured load data.

Typical Wire-to-Air Efficiency Bands (Reference)

Fan type	Drive	Typical wire-to-air η	LONGWELL platform / drop-in for
EC backward-curved plug	Direct EC	82–90%	LWBE3G · ebm-papst K3G / RadiPac, Ziehl-Abegg RH
EC axial	Direct EC	60–66%	LWAE3G · ebm-papst W3G, Ziehl-Abegg FN
EC high-pressure plug	Direct EC	83–86%	LWHV · ebm-papst K3G high-static
AC backward-curved centrifugal	Belt	55–62%	Retrofit candidate → LWBE3G
AC forward-curved (double inlet)	Belt	45–52%	Retrofit candidate → LWBE3G / LWFC
AC axial	Direct AC	45–52%	Retrofit candidate → LWAE3G

Bands are typical engineering ranges for screening. A specific fan's efficiency comes from its published PQ and power curves; LONGWELL can supply the curve for the recommended SKU.

Frequently Asked Questions

How much energy does an EC fan save versus an AC fan?

At a constant duty point, a modern EC fan typically uses on the order of 30% less electricity than a comparable AC fan, because EC motors hold high efficiency across the load range and avoid belt and slip losses. On systems that throttle airflow with dampers, EC speed control saves more because fan power falls roughly with the cube of speed. The exact figure should be confirmed against the real load profile, so this tool lets you edit both the EC and AC efficiency assumptions.

Can I use my own fan data in this calculator?

Yes. Enter the measured input power of your existing AC fan and, if you want, the input power of a specific EC fan. The calculator compares them directly at your run hours and electricity price. It is a public, vendor-neutral tool — you do not have to use LONGWELL data.

Can a LONGWELL EC fan replace my existing AC or imported EC fan?

Yes. LONGWELL can provide replacement candidates for many mainstream AC fan and imported EC fan applications, including ebm-papst and Ziehl-Abegg models. Final approval should be confirmed by duty point, voltage/control, mounting and project validation.

What payback period is realistic for an AC to EC retrofit?

Payback equals the installed retrofit cost divided by the annual energy and maintenance saving. High-hour systems running 4,000+ hours per year — AHU, CRAH, refrigeration, industrial ventilation — usually pay back fastest. This tool gives a simple screening payback; a final business case should include controls, maintenance and downtime savings.

Is the calculator result a guaranteed number?

No. It is an engineering screening estimate based on the duty point and the efficiency assumptions you enter. Final figures depend on the measured load profile, control strategy and the selected fan's published PQ and power curves, which LONGWELL can confirm for your project.