Johnston sponsored a bill, Senate Bill 32, in the 2011 session that creates a loan program for homeowners who want to install energy-efficient improvements. The loans would be facilitated by public utilities like Xcel Energy and banks for installation of energy-efficient windows, doors and insulation. The bill passed on a party-line vote in early May 2011. Consumers would also get eased borrowing criteria that would extend credit to those who may not otherwise qualify.
The Senate Agriculture, Natural Resources, and Energy Committee approved it, sending it to the Senate Appropriations Committee before it can be heard by the full Senate.
In 2010, Johnston was highlighted by Time Magazine as one of the 40 "rising stars of American politics" under the age of 40.