This is a free service and it is provided by http://www.onlineleaf.com/.Their standby engine is deliver a fully functional and simple way to help your website run requiring less energy to generate. It hides heavy animations, covers the window in dark colors (as these, in many cases are less energy consuming) and pauses heavily running background processes.

When your visitors are inactive, this engine launch a standby screen, with the text "Energy saving mode".

This is very easy to add to your website or blog with in few seconds.

Login to your Blogger dashboard --> Design --> Edit HTML.

You don't need to click on "Expand Widget Templates".

Scroll down to where you see the </head> tag of your template.

Now copy below code and paste it just before the </head> tag.

<script language='javascript' src='http://www.onlineleaf.com/savetheenvironment.js' type='text/javascript'/>

This standby engine uses the jQuery Javascript library, so if you are using other Javascript libraries or code, add below code instead of above code :

<script language='javascript' src='http://www.onlineleaf.com/savetheenvironment.js' type='text/javascript'/>

<script>jQuery.noConflict();</script>

Time of inactivity

Also you can easily define how long time your visitors have to be inactive, for the engine to launch the standby screen, by adding ?time=X where X should be replaced with the number of seconds you would like to define the time interval. An example could be:

<script language="javascript" type="text/javascript" src="http://www.onlineleaf.com/savetheenvironment.js?time=120"></script>

... which will set the time of inactivity to 2 minutes (120 seconds).

This can be configured to display in any of the supported languages, if you add ?lang=code, where code is one of the language short codes below.

Supported languages

ak - Akan
da - Danish
de - German
en - English
es - Spanish
fr - French
fi - Filipino
gr - Greek
hr - Croatian
id - Indonesian
jp - Japanese
it - Italian
nl - Dutch
pl - Polish
pt - Portuguese
bpt - Brazilian Portuguese
ro - Romanian
sl - Slovenian
se - Swedish
sk - Slovak
sw - Swahili
tr - Turkish
vi - Vietnamese

The following example will be using Spanish for the standby screen:

<script language="javascript" type="text/javascript" src="http://www.onlineleaf.com/savetheenvironment.js?lang=es"></script>

If you are using WordPress, just download their plugin, activate it and everything should work instantly.