Measuring home appliance energy and power consumption

As anybody probably is at some time in life, I was quite surprised at the sum on one of the recently received electricity bills. I live in a multiple apartment building with a single electricity counter and with the other apartment owners, we simply split the bills into equal parts.

If you live in apartment with really low power usage (compared to the others), you may benefit from installing a counter at your own appartment, but in our case, it would probably take ages to pay off 🙂

So just to check what we are using all the electricity for I set to measure the power usage of the devices in our apartment. I used a plug in electricity counter for this task:

The devices with electrical plugs are the simplest to measure their power consumption. Simply plug them through the electricity counter.

You can measure the power and calculate the energy consumption.

Energy consumed = Power * Time

Eg. a 1kW electric heater will consume 1kWh of electric energy in 1h (when powered).

Alternatively, you can leave the electricity counter in the circuit for some time and just read the power consumption afterward. This works great for devices which switch on/off on their own eg. fridge. Just don’t forget to take a note of when you started the measurement 😉

Daily energy usage = Energy consumed during measurement / Measurement time in days

Some appliances are a bit more awkward to measure. For example, lightning and high power appliances (oven) might be connected directly to the wall with no plug in between. For these, it is easier to simply calculate the power usage from the time they are turned on and their power designation.

So here are a few measurements:

Microwave oven

Power: 1420 W, Energy consumption: 0,02 kWh/min, Daily use time: 5 min, Daily energy consumption: 0,1 kWh

Cooking oven

Power: 2500 W, Daily energy consumption: 1,25 kWh

Phillips flatscreen TV

Power: 55W (powered up), 17W (standby), Measured energy consumption: 1,31 kWh, Measurement time: 5 days, Daily energy consumption: 0,26 kWh

Water heater

Power: 2250 W, Energy consumption: 0,13 kWh to bring 1l of room temperature water to boiling, Daily energy consumption: 0,13 kWh

Dishwasher (Bosch, shortest program)

Energy consumption per washing: 1,39 kWh, Daily energy consumption: 0,79 kWh

Refridgerator (Beko)

Daily energy consumption: 0,56 kWh

Infrared heater

Power: 2000 W, Daily energy consumption: 1 kWh

Washing machine

Energy consumption per 90deg long programme 1,88kWh, Energy consumption per 40deg short programme 0,83kWh, Daily energy consumption:0,94kWh

Synthesizer (Yamaha)

Power: 1-3W, Daily energy consumption: negligible

Asus i3/i5 (4200) laptop

Power: 10-15W, Daily energy consumption: 0,36kWh

Old power adapter (transformer based)

Power: 1W, Daily energy consumption: negligible, however having multiple unloaded adapters plugged in may translate into significant energy loss.

Laser printer on standby + phone charger (normal daily charging pattern) + laptop Asus i5 4200 (powered on, minimal activity)

Average power: ca. 17,5W, Daily energy consumption: 0,42kWh

Lighting

I measured several CFL lights from Philips and Ikea brands and they mostly use what is declared on the lamp. One way to save significant amounts of electrical energy is to switch out old filament light bulbs with the newer generation CFL and LED lighting. These will give you about the same amount of light at about 5x lower energy consumption. I may write an article on light selection and the caveats of specific lighting technology in short future so stay tuned 🙂

Total installed power: 61W, Average daily usage: 6h, Daily energy consumption: 0,318kWh

So here is a table of electricity consumers in our appartment:

And also a graph for easier interpretation of results:

So in conclusion our appartment seems to use around 6,1kWh of electric energy per day, with most being consumed by the cooking oven, the infrared heater and the washing machine.