Power consumption of Home Routers

I wanted to explore a bit about the power consumptions of CPEs in Belgian ISPs. This blogpost is not to be considered research-grade, it’s more a hobbyist’s peak into the power consumption of the equipment.

My main questions were: is there a significative power consumption difference between ISPs (inside consumer’s homes). And more importantly: is there a “hidden” cost behind some ISP. And finally, does the network usage impact the power consumption.

I switched ISPs 3 times in a row, and I give here a graph (taken from Home Assistant which is recording the measures from a TP-Link P110 plug) and a CSV file for the same period.


Before switching to Orange, I captured the consumption of Voo(Cable/Docsis) for a week. The amplifier and modem ensemble consumes around 20.2 watts (note the Y axis, this graph is actually a straight line).


I stayed at Orange (Cable/DOCSIS) for about 6 months. The consumption includes the mandatory amplifier and the modem in bridge mode. Note that the amplifier is the same as Voo. The Wi-Fi is deactivated. It seems some update from Orange impacted the consumption, which is now around 16.8 Watts. It is a 3 Watts improvement over Voo, which, for a year represents 26kWh, so roughly 10€ in electricity.

I have no explanation for the increase in power at the end of October (another update?). Similarly there are a few spikes in September, it could be false positives I would not make conclusions based on that. This is not related to the traffic pattern, because day-to-day it’s the same power consumption. I tried to launch a speedtest and observe the instantaneous consumption and I couldn’t spot any difference.

Proximus Fiber

I then switched to Fiber with Proximus, as soon as I could. The connection is much faster: 500Mbps symmetrical.

The equipment is divided in two part : the ONT which “converts” the fiber to Ethernet, and then the modem that includes a switch, WiFi and telephony.

You observe 3 steps here. At the beginning I had the Modem in router mode, with Wifi activated at 8.5Watts. That’s what most people would have.

Then, the second step at 7Watts is with the Modem in Bridge mode, without WiFi. In bridge mode the modem directly give a public IP address to a single equipment connected to it. Typical for people with their own routers.

But one can go further. What I have used since February is directly the ONT at a spectacular 2,75Watts. I don’t need the modem because I don’t have fixed telephony, and don’t use WiFi in my garage. I have my own access points and want my home router anyway to handle my own ICT (I have some websites handle at home, home automation, etc).


First, the network usage does not impact the device’s power consumption. It is not surprising. All those modems are gigabit-capable or even more. The Orange allowance of my subscription is 150 Mbps, Voo was around the same. Hence, the modem is residing in its idle zone. With Proximus the ONT “rises” to 3 Watts during a speedtest instead of 2,75. It’s marginal.

The second question was the hidden cost. Proximus Fiber equipment drives as low as 8,5 Watts. That’s a 8,3 Watt reduction from Orange. That’s 73 kWh/year, at the Belgian average of 0,35€/kWh it’s roughly 25€ per year It’s not nothing, but it’s not high compared to the price of the subscription itself. If you have no use for the modem, then you gain 14Watts or 123kWh/year. That’s a more consequent 43€ saved.

73kWh is also 2% of the power consumption of the average Belgian household. Again, not nothing, but probably not the most urgent thing to do for the planet. It’s already much more than stupid “advices” like unplugging transformers of charging a smartphone on solar panels.