Activity Monitor Energy Tab in OS X Mavericks

The Energy tab in Activity Monitor on OS X Mavericks shows you how much power each app and process is using, both right now and over time. You open it by launching Activity Monitor (in /Applications/Utilities) and clicking the “Energy� tab. It gives you a live list of processes with their current energy impact, plus a graph of overall energy usage over the last 8 hours or 24 hours.

Why Apple Added the Energy Tab

OS X Mavericks (10.9) was released in October 2013 with a strong focus on battery life for Mac notebooks. Apple introduced several power-saving technologies under the name “App Nap,� “Timer Coalescing,� and “Compressed Memory.� The Energy tab was the visible companion to those features: it let you see which apps were actually draining your battery, instead of guessing. Before Mavericks, you could only see CPU usage, which didn’t always match power draw. An app that used little CPU but kept the hard drive spinning or the network active could still drain the battery. The Energy tab made that visible.

What Each Column Means

When you click the Energy tab, you see a table of processes. The columns are:

• App Name – the name of the process or app.
• % CPU – how much of the processor it’s using right now.
• Energy Impact – a relative score of how much power the process is using at that moment. The number is not watts; it’s a calculated estimate based on CPU usage, disk activity, network activity, and whether the app is preventing the display from sleeping. Higher numbers mean more power draw.
• Avg Energy Impact – the average Energy Impact over the last 8 hours (or since the Mac started, if less than 8 hours). This is the most useful column for finding battery hogs that are consistently active.
• App Nap – shows “Yesâ€� if the system is currently applying App Nap to that app. App Nap slows down invisible apps to save power.
• Preventing Sleep – shows “Yesâ€� if the app is keeping the Mac from sleeping (for example, a video player or a download manager).

How to Use the Energy Tab to Improve Battery Life

The Energy tab is most useful when you are on battery power and want to know what’s draining it. Here’s a practical approach:

1. Open Activity Monitor and click the Energy tab.
2. Click the “Avg Energy Impact� column header to sort by that value. The apps with the highest average are the ones that have been using the most power over time.
3. Look at the “Preventing Sleep� column. Any app that says “Yes� is keeping your Mac awake. If you don’t need it, quit it.
4. Look for apps you aren’t using that have a high Energy Impact. Quit them (select the app and click the X button in the toolbar, or press Command+Q).
5. Check the “App Nap� column. If an app is not being napped and you don’t need it, quit it. If an app is napped, that’s fine – it’s already saving power.

Note that the Energy Impact numbers are relative, not absolute. A value of 20 is not “20 watts.� It’s a composite score. You should use it to compare processes, not to measure actual power draw.

The Energy Graph

At the bottom of the Energy tab there is a graph that shows overall energy usage over time. In Mavericks, you can choose to view the last 8 hours or the last 24 hours using the buttons on the right side of the graph. The graph is a good way to see if something is causing a sudden spike in power usage – for example, if you see a spike at the same time every day, it might be a background maintenance task.

Common Problems and Misconceptions

Misconception: “Energy Impact� is the same as CPU usage. Not exactly. An app that uses a lot of CPU usually has a high Energy Impact, but an app that uses little CPU but keeps the hard drive spinning or the network adapter active can also have a high Energy Impact. The Energy Impact is a better indicator of battery drain than CPU alone.

Problem: You see “Kernel Task� with a high Energy Impact. Kernel Task is part of the operating system. A high value often means the system is doing something in the background, like indexing with Spotlight or backing up with Time Machine. You cannot quit Kernel Task. If it’s constantly high, check for background tasks.

Problem: The Energy tab doesn’t show anything. If you don’t see any processes, make sure you are not in “My Processes� view. Use the View menu and select “All Processes� to see everything.

How It Compares to Later Versions

In later versions of macOS, the Energy tab was renamed “Energy� and then became part of the “Battery� tab in newer Activity Monitor versions. In macOS Catalina (10.15) and later, the Energy tab is gone, replaced by a “Battery� tab that shows similar information but with a different layout. The core idea – showing which apps use the most power – remains the same. If you are used to Mavericks, you’ll find the newer versions slightly different but still useful.

Tips for Reducing Energy Usage

• Quit apps you aren’t using, especially web browsers with many tabs open. Each tab can keep the browser active.
• Reduce screen brightness – the display is one of the biggest battery drains.
• Turn off Bluetooth and Wi-Fi when not needed (from the menu bar).
• Use Safari instead of Chrome or Firefox if battery life is a concern – Safari is generally more energy-efficient on macOS.
• Check for apps that are “Preventing Sleepâ€� and quit them if you don’t need them to keep the Mac awake.

Frequently Asked Questions

Q: What does “Energy Impact� actually measure?
It’s a relative score computed by the system based on CPU usage, disk I/O, network activity, and whether the app is preventing the display from sleeping. It’s not a direct watt measurement, but it’s a reliable indicator of which apps are using more power than others.

Q: Can I quit an app from the Energy tab?
Yes. Select the process in the list and click the X button in the toolbar, or press Command+Q. You can also right-click and choose “Quit.�

Q: Why does the Energy tab show “App Nap: Yes� for some apps?
App Nap is a Mavericks feature that automatically slows down apps that are not visible on screen. If an app is napped, it’s already saving power. You don’t need to do anything.

Q: How do I see the energy usage of all processes, not just mine?
Use the View menu in Activity Monitor and select “All Processes.� By default, it shows “My Processes� which only includes your user’s processes.

Q: Is the Energy tab available on desktop Macs?
Yes, it appears on all Macs running Mavericks, but it’s most useful on laptops because they run on battery. On a desktop, you can still see which apps are using the most power, but it won’t affect battery life.

Q: Why does the Energy Impact number change so often?
It’s a live estimate that updates as the process’s activity changes. For example, a video player will have a higher impact while playing a video than when paused. Use the Average column for a more stable view.

Related

• Record Specific Window: How to Capture One App
• Throw in Gang Beasts? How to Grab and Toss
• Is Facebook Listening to Me? Truth & Myths