Word Press Calculator based on selected product in cart

The site sells LED Lights and each light has an individual wattage. I would like a energy savings calculation to show up on each product page based on the product selected. I am currently using Calculated Fields Form plugin to show the savings, but this only works manually. It does not auto-populate data from the selected / displayed product. ( However I have all the calculations working both with this plugin and also as a separate working php / phpgraphlib page to illustrate the calculations. An example of this feature can be seen on this site [login to view URL] When you select a product you get the following.......... Based on your bulb selection today: SAVE £150.00 per year* ON YOUR LIGHTING BILL Current energy spend £450 New Energy Spend £300.00 *Based on 8 hours use per day and 10 lights If you can throw in a bar graph too would be great This site also uses woo commerce and the product layout page will most likely need to be changed as well as the current theme idstore is not that pretty.