Compare LED displays on measured input power at the brightness and content you will actually use—not on an unexplained “average W/m²” figure. Calculate energy for each operating state, add standby and any separately metered cooling, then apply your electricity tariff. Keep the manufacturer’s maximum electrical requirements in a separate supply-design brief: average consumption is not a safe basis for sizing circuits.
For a facilities manager or DOOH operator, the useful question is not simply “Which screen uses fewer watts?” It is “Which quote will cost less to operate while delivering the same usable image?” This guide gives you a comparable measurement brief, a worked annual budget and a way to test whether a higher purchase price is justified by electricity savings alone.
What does a power figure actually tell you?
A watt is a rate of energy use. A kilowatt-hour is an amount of energy. You buy electricity in kWh; the power used to calculate it must represent the operating period being budgeted.
On a small screen, scroll the table horizontally to see every column.
| Figure in a quote | What it can answer | What is still missing |
|---|---|---|
| Maximum input power or current | What electrical requirements must the installation designer consider? | Manufacturer’s circuit, inrush and protection guidance; local design requirements |
| “Average power: 200 W/m²” | Potential starting point for an energy estimate | Content, luminance, averaging interval, operating mode and measurement boundary |
| Measured input energy: kWh over a recorded interval | How much electricity the tested system used during that interval | Whether the test represents your schedule and includes the same equipment as other bids |
| Standby or off-mode power | Energy used outside active display hours | What remains powered: screen electronics, player, network, fans or other equipment |
“Rated,” “typical” and “peak” are not interchangeable labels. Ask the supplier how each value was obtained. If only a stated maximum is available, you can calculate a deliberately conservative scenario at that load; do not present it as expected consumption.
Make two supplier measurements comparable
The most useful improvement to an energy comparison is often a better test brief, not another efficiency percentage. Give bidders the same brief and ask them to report deviations.
- Fix the visible output. State active screen area, target luminance in cd/m² (nits), white point and the display settings relevant to the test. “50% brightness” on two controllers need not produce the same luminance.
- Use the same content. Supply a representative playback loop, including bright backgrounds if your programme contains them. Record the file or version and the loop duration so the test can be repeated.
- Define the electrical boundary. Specify whether the reading covers the cabinets alone, the player/controller, integrated fans, and separate HVAC. Avoid comparing a cabinet-only figure with an entire installation.
- Record conditions and duration. Include supply conditions, ambient temperature, warm-up procedure, test length and whether automatic dimming was enabled. A measurement over one complete repeating loop is more meaningful than a single momentary reading; select a longer period if the operating pattern requires it.
- Record real energy or active power. Use suitable metering at the agreed boundary. A basic current reading multiplied by nominal voltage is not, by itself, a verified real-power measurement for an electronic load. Electrical measurement and access to live equipment belong with qualified personnel.
A supplier can provide useful evidence without every test being commissioned from an independent laboratory. What matters first is a traceable method, a defined configuration and repeatable conditions. Independent testing becomes particularly useful when the claimed saving is central to a high-value purchase or the contract requires it.
Why static versus video is the wrong shortcut
A white static price list can use more power than a dark moving video. Pixel values, brightness settings and the drive design matter—not whether the file is a JPEG or a video. Average picture level can help describe content, but two loops with the same average level can still differ in colour distribution and measured input power. Test the actual loop rather than assigning a fixed saving to “static content.”
Worked example: separate day, evening and standby
The following numbers are invented planning inputs for demonstrating the calculation, not Chipshow measurements, market averages or a quoted product specification. Assume a 20 m² screen follows the same schedule on all 365 days. The active measurements include cabinet electronics and integrated fans; a separately powered player and external HVAC are excluded.
Daily energy for one state (kWh) = area (m²) × input power density (W/m²) × hours ÷ 1,000.
On a small screen, scroll the table horizontally to see every column.
| Operating state | Example measured input | Hours per day | Calculation | Daily energy |
|---|---|---|---|---|
| Daytime programme | 250 W/m² | 8 h | 20 × 250 × 8 ÷ 1,000 | 40.00 kWh |
| Evening programme | 120 W/m² | 4 h | 20 × 120 × 4 ÷ 1,000 | 9.60 kWh |
| Defined standby state | 5 W/m² | 12 h | 20 × 5 × 12 ÷ 1,000 | 1.20 kWh |
| Total | — | 24 h | 40.00 + 9.60 + 1.20 | 50.80 kWh |
At a flat illustrative tariff of €0.25/kWh:
- Annual energy = 50.80 × 365 = 18,542 kWh.
- Annual energy charge = 18,542 × €0.25 = €4,635.50.
If a separate cooling system draws an average 0.8 kW for six hours per day, that example adds 0.8 × 6 × 365 = 1,752 kWh, or €438 at the same tariff. Add it only if it was excluded from the screen measurement. The two items together would be €5,073.50, before any other electricity charges or operating costs.
For a time-of-use tariff, multiply each period’s kWh by that period’s price before adding the totals. Use seasonal schedules where daylight hours, luminance settings or cooling differ. Demand charges, taxes and fixed charges depend on the electricity contract and are not captured by multiplying kWh by one rate.
Download the worked energy schedule and blank measurement fields.
Can a more efficient display justify a higher price?
Extend the same hypothetical example. Suppose a second offer has verified, like-for-like inputs of 220 W/m² by day and 105 W/m² in the evening, with the same 5 W/m² standby state.
Its daily energy would be:
20 × [(220 × 8) + (105 × 4) + (5 × 12)] ÷ 1,000 = 44.80 kWh.
That is 6.00 kWh/day less than the first example: 2,190 kWh/year, worth €547.50/year at €0.25/kWh. If the second offer costs €3,000 more, its simple electricity-only payback is €3,000 ÷ €547.50 = about 5.48 years.
This is a comparison method, not a promised return. At €0.15/kWh, the same difference is worth €328.50/year; at €0.35/kWh, it is worth €766.50/year. Repairs, financing, replacement parts, display availability and tariff changes can change the purchase decision. An electricity saving should not conceal a weaker service agreement or a screen that cannot meet your daytime visibility requirement.
What do common-cathode and automatic dimming claims prove?
A drive architecture can create opportunities to reduce losses, but a “common-cathode” label does not establish how much electricity the complete display will use. LED selection, voltage rails, driver operation, power supplies and output settings all affect the result. Ask for measured input power at matched visible output instead of inserting an advertised percentage into your budget.
Automatic dimming can reduce unnecessary output when ambient light falls. The benefit depends on the schedule it replaces. A timer may be adequate for some sites; a calibrated sensor and logged control schedule may suit others. Compare the actual luminance schedule and resulting consumption, not whether the controller is marketed as “AI-powered.”
A supplier request you can copy
Please provide input-power or energy measurements for the exact quoted configuration, using the attached content loop at our target daytime and evening luminance. Identify the active area, white point, controller/settings, ambient and supply conditions, warm-up and measurement duration, metering method, and all included equipment. Report the defined standby state separately. Also provide maximum electrical requirements, including relevant inrush and circuit guidance, for our installation designer. Identify any requested condition you could not reproduce.
This request makes missing evidence visible before the order. If a bidder cannot provide every measurement immediately, record the uncertainty and agree a sample-test or acceptance-test milestone rather than treating a catalogue figure as verified data.
Frequently asked questions
Does smaller pixel pitch always mean higher electricity consumption?
No. Pixel pitch changes the grid density, but it does not independently determine whole-system power at a specified luminance and content. Compare the actual offered configurations under the same output conditions; do not budget from pitch alone.
Should power factor be included in the comparison?
Record it where relevant to the electrical design and electricity contract. Power factor relates real power to apparent power; it is not a direct measure of conversion efficiency. A claimed value does not replace the real-energy measurement used for a kWh budget. Possible reactive-energy charges depend on the tariff.
Is the annual electricity bill the same as OPEX?
No. Electricity is one operating-cost line. Keep maintenance, spare parts, connectivity, content operations and service arrangements visible separately. The worked example is an energy-charge estimate, not total operating expenditure.
Turn the comparison into a usable project brief
Bring together your screen area, operating hours, content sample, brightness schedule and tariff before requesting energy comparisons. Those inputs give suppliers a concrete target and let you reject an apparently efficient quote that was tested under easier conditions.
For a Chipshow EU enquiry, include that brief with the proposed location and installation constraints, and request measurements for the exact configuration offered. This is a better basis for choosing a display than a generic “energy-saving” label.
