Microsoft Joulemeter: Helps Estimate Power Consumption of Your Computer

Joulemeter is a freeware software tool developed by Microsoft Research that estimates the power consumption of your computer and improves energy efficiency. It tracks computer resources, such as CPU utilization and screen brightness, and estimates power usage.

Joulemeter provides a modeling tool to measure the energy usage of virtual machines (VM), servers, desktops, laptops, and even individual software applications running on a computer. The application helps improve power provisioning costs for data centers, virtualized power budgeting, desktop energy optimizations, and mobile battery management.

The Joulemeter project focuses on the following aspects related to energy optimization:

  • Modeling — Joulemeter provides a software tool to estimate the energy usage of a virtual machine (VM), a computer, server, or software application. It also allows modeling the impact of power management of various components such as the CPU, screen, memory, and storage on total power use. Many of these power measurements are not possible in hardware since software components such as VM do not have a single wire supplying their power where a hardware power meter may be installed.
  • Optimization  We use the visibility provided by Joulemeter’s modeling techniques to improve power provisioning and consumption costs in various scenarios ranging from data centers, enterprise computing, and battery operated machines.


How to use Microsoft Joulemeter?

Download Joulemeter setup file (JoulementerSetup.msi) from the Microsoft Research website and install it. It is available only to Windows 7 users.

Laptops, notebooks or netbooks users do not need any extra hardware. Desktop computer users will need a WattsUp power meter (WattsUp Pro with USB connection) for learning an accurate power model. The software will also work without a power meter as well.

Run the application and select your setup for calibration. On the Calibration tab, select the option that best describes your setup:

  • Running on batteries: For laptops; disconnect the power cord and make sure the battery charge level is above 50%.
  • WattsUp PRO (Monitor(s) not on WattsUp): Desktop is plugged into a WattsUp PRO, but monitors are not plugged into the WattsUp.
  • WattsUp PRO (Laptop OR Monitor(s) also on WattsUp): Desktop and monitor (one or more) are plugged into a power strip that is in turn plugged into a WattsUp PRO; Or if the computer and its monitor(s) are powered by a single power outlet (such as for laptops) from a WattsUp PRO.
  • If none of these options apply, you have to do a manual calibration (see at the end of this article).


Close other open programs and click on “Perform Calibration” button. Leave the machine unused for 15 or more minutes. Joulemeter will switch to “Power Usage” after calibration is over.


Note: During calibration, the monitor may turn off and change brightness. Do not use the mouse or keyboard during calibration.

After calibration is complete, measure the power use of the computer. In the “Power Usage” tab to see the power consumption. The WattsUp meter, if used, may now be disconnected.

All power values are in Watts. Base power is computer’s power consumption when powered on but sitting idle. CPU power is the extra power used when some program(s) or the OS use the CPU. Disk power is the extra power consumed by the disk due to IO activity (disk spinning power is included in the base power). Monitor power, if shown, is the additional power consumption of the monitor and may change with brightness.

To estimate power consumption by a particular application, in the Power Usage tab, under Application Power, enter the name of the program executable, such as “myProgram.exe” and click “Start.” If the “myProgram.exe” is not yet running, Joulemeter will wait for it to be started.


Power consumption data is saved in comma separated values (CSV) format that can be opened in Microsoft Excel for easy plotting, or viewed in any text editor.

How to perform Manual Calibration in Joulemeter?

If the computing device is not a laptop or runs on battery or WattsUp based setups is unavailable, the expected range of power values can be manually entered.

  • On the Calibration tab, click the “Manual Entry” button. Select the Model type to be a laptop, desktop, or one of the values shown. Joulemeter will recommend typical values to be entered.
  • Edit the “Base power” to be the value when the computer is simply turned on but not performing much work.
  • In “Processor peak power (high frequency)” enter the power consumed at 100% CPU utilization with the processor using its highest frequency. This power value may be available in your processor’s data sheet as the Thermal Design Power (TDP) value.
  • In “Processor peak power (low-frequency)” enter the power consumed at 100% CPU utilization with the processor using its lowest P-state frequency.
  • In “Monitor power” enter the power consumption of your monitor (available from the monitor user manual). If using more than one monitor, add up the power consumption of all monitors.
  • Please consult the User Manual of the respective devices for more details.

The impact of hardware components on the battery life of your laptop allows you to tweak the power management settings. Thus you can improve battery life of your laptop. Managing and tracking PC sleep, combined with remote wakeup, allows optimizing desktop power consumption. Measuring the VM power allows developing power budgeting techniques for virtualized data centers.

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