Laptop Power Consumption / Wattage - Detailed Review
Here at Reduction Revolution, we're really into energy efficiency.
So it goes without saying that we like to use energy-efficient laptops.
How do we know they're so efficient? We measure them with a plug-in power meter, of course!
In this blog post, I'll cover several different Apple laptops of varying ages so you can see how power usage has changed over time.
Dialling back to 2008 my Dell XPS laptop used to sit at around 30 watts of power consumption when running. Compared to a desktop, which may use about 100+ watts, that was already a significant improvement. But even then I knew that I could do much better. For example, I was aware that the compact 10-inch Asus Eee PC's were already down around 10 watts (or less) power consumption.
Apple Laptop Power Consumption
In my initial research (2010), it became apparent that Apple's laptops were doing pretty well. The MacBook Air, in particular, had very low power consumption. I was keen to get the Air, but in the end, I decided to get the MacBook Pro 13 inch - it even included a CD/DVD drive.
Since then, I upgraded to a newer MacBook Pro (2015). And a colleague has a newer MacBook Air (2018 / 2019). So now we can see how the energy usage of these Apple laptops has improved over time.
The following table summarises our test results. I have explained what each mode means further on in this post.
|Laptop||MacBook Pro 13in (2011)||MacBook Pro 13in (2015)||MacBook Air 13in (2018)|
|Power Adapter Only||0.03W||0.02W||0.02W|
|Plugged In & Off||0.3W||0.3W||0.05W|
|Plugged In & Sleep||1.1W||0.9W||0.3W|
|Plugged In & Idle||8-12W||6-12W||3-8W|
|Plugged In & Working||12-40W*||10-30W*||8W-25W*|
*Laptop power usage (wattage) tends to stay towards the bottom end of these ranges during typical use.
The 'Early 2011' Macbook Pro pictured above is still running fine in 2020. Its spinning-disk hard-drives were replaced with solid-state memory about five years ago. Also - this website used to be called 'negergy'.
Energy Consumed in Production vs. Operation (Lifecycle Emissions)
To Apple's credit, they publish detailed environmental reports for each of their products. The full reports can be viewed here if you scroll down to the very bottom of the page. Reviewing these reports for most Apple products reveals something very interesting:
Greenhouse emissions in production are far higher than from several years worth of usage by the customer.
Greenhouse gas emissions are primarily from energy consumption. So it leads that energy consumed during production is significant. It also shows why holding off on your next electronics purchase is so important if you're keen to reduce your environmental impact.
Apple MacBook Pro 13-inch (2011) Greenhouse Gas Emissions (production, customer use, transportation and recycling).
Interestingly, the later model 2015 MacBook Pro had much higher lifecycle emissions of 710 kg CO2e. I can only assume they manufactured it in a country with a different energy supply mix, or changed their methodology!
The latest model in our review, the MacBook Air (2018 / 2019) had total lifecycle carbon emissions of 176 kg CO2e. In other words, a 50% reduction compared to the 2011 model.
How We Tested Laptop Power Consumption
In the same reports, they show actual energy usage of the laptops in different power states. We used a Power Mate Lite to verify these readings and to extend the tests to some real-world scenarios.
Power Adapter Only (no load) - In summary, the power supplies are very efficient, and have been for many years. When your laptop is not plugged in, there is no real need to turn these off at the wall. The same is not true for other electronics, which is why we still recommend these standby power controllers for bigger energy guzzlers.
Plugged In & Off & Plugged In & Sleep - These two measurements are a more realistic representation of the laptop's standby power usage. This is because most of the time your laptop will still be plugged in when it's powered down.
Plugged In & Idle - This one depends on how exactly you do the test. My lowest readings were with the screen off, no applications open in the background, and no keyboard backlight. The highest readings were with the screen on maximum, a couple of programs open (but doing nothing), and the keyboard lighting on.
Plugged In & Working - This represents a typical range when the laptop is actually 'computing'. For example, opening up and using your web browser, using Adobe Acrobat or Photoshop, etc.
Finally, all these readings were taken with a fully charged battery. The power supply will peak much higher when also charging the battery. For its maximum possible power draw, you can be guided by the nameplate rating on the charger. This rating is a useful guide for some other household appliances, as we explain in our free electricity cost calculator.