Windows 7 is build such that it helps reduce power consumption by working with the latest hardware power-management capabilities and better managing how application processes use the processor. Windows 7 includes device driver support for the latest processor power-management technologies from leading independent hardware vendors. Windows 7 comes with build in power plans, but you can create your own plan if you do not want to alter the default settings.
To create a new power plan, open the Power Options in the Control panel (All Control Panel Items-> Power Options or you can type power options in the start menu search). In the power Options, click on Create a Power Plan in the left sidebar.
Click on the next button and enter the power settings you would like to have in this plan. You need to choose the sleep and display settings.
Once you have done with the customizations, click the create button and the power plan is created. You can also change the advanced power options for this plan.
Selecting you own power plan allows you to have better control over the battery and power consumption.