Citywide geothermal heat pumps
The most efficient means of heating a house is by using geothermal heat pumps. Check the link below:
The air going into your house runs through an underground tube, and becomes warmer. I.E. less energy required to get the air warmer. Heat pumps are kind of expensive to build, and it takes about 5 years for the energy savings to pay for the initial cost. Most people move within 5 years so the incentive isn't there to install them. City lots are mostly too small for geothermal heat pumps, so city governments should automatically install them under streets just like sewers. Homeowners would just plug into the common heat exchanger, and heating/cooling costs/energy use would decrease dramatically.
Reward: I'd like a city to name a park Bluecube Park.