[APP][Pro] Power Estimator - power that follows dimming and colour

[byackee1]

Power Estimator — power that follows the real curve, and the colour

Homey lets you give a device a power figure for on and one for off, and it scales between them with the dimmer. For a kettle or a router that is exactly right, and for a dimmed lamp it is a reasonable first guess. What that straight line cannot do is match the curve of a real LED — and it takes no notice of colour at all.

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LED power rises slowly at the bottom of the dimming range and then accelerates, so a straight line overestimates exactly where an ambiance light spends most of its life: anchored on the true measured endpoints, Homey’s line is on average 37 % off, and up to +68 % wrong at 30 % brightness. Colour is worse, because it is not in the model at all — the same colour bulb at full brightness draws between 1.6 W and 5.3 W depending on the hue you chose.

This app replaces that line with a measurement. It matches your devices against the profiles of the PowerCalc library — thousands of readings taken with a wattmeter on real hardware — and follows the state of each device to work out what it is drawing right now.

A white ambiance spot with 6.5 W typed in from the box, dimmed to 30 %, is counted at 2.2 W; the wattmeter reads 1.2 W.

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Available for testing

https://homey.app/a/com.dataweavelabs.powerestimate/test

Not yet certified — this is the test channel while I gather feedback.

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What it does

• Measured profiles, not a straight line — 744 device profiles, each one measured with a wattmeter by a contributor to the PowerCalc project. Brightness, colour temperature and hue all change the answer
• The new device replaces the old one — it takes over the controls of the original, so you switch it on, dim it and change its colour from the same tile that shows the consumption. One device to use, not two
• Manual entry as a fallback — for the devices Homey itself gives you nothing to set, because their driver declares no energy object: 21 mains-powered devices on my installation. If Homey already offers the field and a fixed value is all you need, use that instead — it is simpler than this app. Also for when a profile describes something else than the load. A smart plug’s profile is the plug, not the lamp plugged into it. Fixed value, or a curve that follows the dimmer
• Devices without a switch too — a camera, a router, a NAS never turn off and are counted as always on
• A flow diagram of the whole home — main meter → usage → room → device, as a dashboard widget. Its most useful number is the one nothing else shows you: what the meter sees and no device explains. On my installation, 428 W at the meter against 173 W identified
• A power widget for a single device
• Flow cards on the whole home — Homey already generates the per-device ones. These fire the moment estimated home power, or the unmeasured share, crosses a threshold you choose
• Sub-meters — declare that a UPS or a metered power strip feeds other devices, and what it carries stops being counted twice

The energy flow widget: main meter → usage → room → device. The hatched branch is what the meter sees and no device explains.

The power widget, for a single device.

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Requirements

• Homey Pro — reading and driving devices that belong to other apps needs an API permission Homey Cloud does not offer
• Internet on first use — profiles are downloaded on demand and cached locally. Nothing is bundled, and nothing is re-downloaded afterwards

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One thing to know before you start

Homey does not let an app change another app’s settings. After adding a device you have to tick “Exclude from Energy” on the original yourself, otherwise Energy counts it twice — once with Homey’s own estimate, once with the measured one. The app checks the real state of the source and warns you on the tile until it is done.

I would rather say this here than have you discover it in your Energy tab.

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What is not in this version

• The composite and multi_switch strategies of the PowerCalc library — 10 profiles out of 744. The other three cover 734
• No automatic detection of the lamp’s physical colour temperature range. Homey reports it as 0..1 and never exposes the real bounds, so the app assumes 153–500 mired — correct for Philips Hue, adjustable per device for anything else
• No cost calculation. Power by the Hour already does that well, and reads the devices this app creates

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Languages

• English
• French
• Dutch

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Credits

The consumption profiles come from homeassistant-powercalc, by Bram Stroker and its contributors, published under the MIT licence.

GitHub - bramstroker/homeassistant-powercalc: Home Assistant Custom component to calculate...

Every profile in it was measured with a wattmeter on a real device by someone who owned it. That library is the whole reason this app can say 4.5 W instead of guessing. Thank you for building it, and for publishing the measurements openly.

This is an independent implementation for Homey. It does not connect to, and does not require, Home Assistant.

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Feedback welcome

Running on my own Homey Pro against 30 estimated devices: 23 Philips Hue bulbs and lightstrips on measured profiles, plus a printer, a TV, cameras, a router and Zigbee bridges on manual values, reconciled against a Linky meter.

What I would like to know from you: whether the profile matching finds your devices, and how far the estimate lands from a real plug meter if you have one to compare against. Both are easy to report and both make the next version better.

Source code: GitHub - byackee/homey-powerest: Homey Pro app that estimates power and energy for devices without a meter, from the measured device profiles of the PowerCalc library · GitHub

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Support the app

Free, and built on my own time. If it makes your Energy tab tell the truth, you can support the work:

byackee Official: X | Linktree

Telling me how it behaves in your home helps just as much. Thank you

[smarthomesven]

I don’t understand why you would want an app for something Homey can already do by itself. If an app developer has not yet provided power approximations for a device, you can just ask that developer to add it. It’s just a small manifest change, the developer has to add an energy object with the approximations to the driver.compose.json. And even if they don’t provide it, you can just set it in the device settings in Homey already

[byackee1]

You are right, and on the part you describe the app adds friction rather than value. If a device already exposes Homey’s power fields and you only need a flat number, setting it in the device settings is simpler than what I built: no second device, no exclusion to tick, nothing to keep in sync. I should not have written the topic as if Homey did nothing here.

Two things pushed me to build it anyway, and I checked both against my own 94 devices before answering rather than from memory.

The field only exists if the driver declares it. energy in driver.compose.json is what makes those settings appear. On my installation, 35 devices offer them and 21 mains-powered devices do not — four cameras, the router, the NAS, two Zigbee bridges, an in-wall relay. There is nothing to set on those. Asking each developer is the right long-term answer, but it is slow and out of the user’s hands meanwhile.

The field is a single number, and lighting is where that hurts most. It cannot follow brightness or colour. A Hue LTW013 is counted at a flat 6.5 W the moment it is on; measured with a wattmeter it draws 0.9 W at 10 % and 4.5 W at full. Across the 15 profiled bulbs in my house at 70 % brightness, Homey announced 195 W where the measurements give 84 W. And 25 of the 35 devices that do have the field are lights — so the case where Homey offers a setting is also the case where a single value is least able to be right.

So your criticism lands, and the honest conclusion is that my topic claims too much. The app is not about “devices without a meter” in general — Homey covers a good part of that. It is about consumption that varies: dimmable and colour lighting above all, where no single number can be correct. I am renaming the topic accordingly, and manual entry will be presented as a fallback for the devices Homey cannot reach, not as a headline.

Thank you for pushing back — this is the feedback that makes the description honest.

[SunBeech]

@byackee1

is counted at a flat 6.5 W the moment it is on

The strange thing is that devices sometimes have one and sometimes two power consumption values that can be set. For lights, I normally have two: the ‘when on’ and ‘when off’ settings.

If the light is dimmable, Homey interpolates the power consumption between those two values. At least that is what the Insights show. So a light dimmed to 30% has an estimated power consumption of 30% of the difference between the on and off values.

If I understand correctly, this app covers the gap if the said interpolation option (settable on/off power consumption) is not available in a device.

[CasperV]

If you have this running and publised you make me happy! This energy flow diagram is what’s missing in Homey. When do you expect to have the app available in Homey?

[byackee1]

You are right,

Homey does interpolate. I set a light to 0.5 W off / 20 W on and read back what Homey reports for it at three dim levels:

dim	Homey reports
30 %	6.35 W
60 %	12.20 W
100 %	20.00 W

That is exactly off + dim × (on − off), to the hundredth. The documentation says as much in passing: it approximates “by calculating the total on-time, optionally taking into account the brightness level”.

So the sentence I wrote yesterday — that a bulb is counted at a flat 6.5 W the moment it is on — is false, and the first post said it too. I have corrected both, and the app’s description with them. Thank you for catching it.

Here is what is left once the straight line is granted.

The line is straight and the LED is not. Taking the PowerCalc measurements for a Hue white ambiance bulb and anchoring Homey’s line on the true measured endpoints — the most favourable case there is for Homey — the line is on average 37 % off across the dimming range, and up to +68 % wrong at 30 % brightness. LED power rises slowly at the bottom of the range and then accelerates, so a straight line overestimates precisely where an ambiance light spends most of its life.

Colour is not in the model at all. The same colour bulb at full brightness draws between 1.64 W and 5.29 W depending on hue and saturation — a factor of 3.2. In colour temperature, 2.57 W to 5.43 W. No pair of settings can express that.

And the figure you type comes from the box. I had 6.5 W on a spot whose measured maximum is 4.47 W. Put the three together and that spot at 30 % brightness is counted at 2.2 W where the wattmeter reads 1.2 W.

To your closing question: yes, it covers the case where the settings do not exist — 21 mains-powered devices here declare no energy object at all, so there is nothing to fill in. But that is no longer the main point. The main point is dimmable and colour lighting, where the settings do exist and a straight line still cannot be right.

[SunBeech]

Thanks for your clarification. Good to know that your app is able to provide a better more realistic estimate of the power consumption. Very interesting mechanism, the profile based approach.

[byackee1]

Hi,

the app is live ^^