Energy Saving when using backlit Cisco IP Phones
From Ciscowiki
Switch off backlight on Sunday and Saturday
A back lit Cisco IP Phone 7970 consumes approximately 15 watts. You can disable the backlight using the following command in Telephony service configuration mode when the Cisco IP Phone is registered to a Cisco Callmanager Express.
CME-CUE(config-telephony)#service phone daysDisplayNotActive 1,7
Switch off the display after a fixed Duration
If you are interested in more energy saving may use the parameter displayOnDuration as show below.
CME-CUE(config-telephony)#service phone displayOnDuration 00:10
Which make the display On for 10 minute after any activity on the IP Phone. When the backlight is switch off a phone active indicator LED switches on to indicate the IP Phone is active. Pressing and button bring the backlight display back.
Backlight configuration of IP Phone in Cisco Unified Callmanager
Similar configuration of Backlight Display can be made in Cisco IP Phones registered to Cisco Callmanager Server from the Administration page.
Logon to the Administration page, Click on Device > Phone
Search the phone in which the configuration change should be made using the Find
Click on the IP Phone to reach the Phone Configuration page. Scroll down to find the Product Specific Configuration Section. Which looks like as shown below. 
Note: This configuration is available only in Phone configuration page related to backlit Cisco IP phones like 7970, 7971 and few other.
