Purchase an ecobee4 with 2 free room sensors (valid until 6/26/17) from the ComEd Marketplace and validate that you are a ComEd customer to receive $100 instant savings and free shipping.
https://www.comedmarket
Then go to the link below for the Nicor Rebate:
https://www.nicorgasreb
Additional rebates could apply depending on your service area:
https://www.ecobee.com/rebates