Bills

The frugal trait from the aspiration panel for 2,000 rewards points lowers the bills by 25% and it stacks so the more sims that have it the lower the bills will be in total. If your sims have high enough handiness skill you can upgrade appliances like the fridge, cooker, toilet, shower and bath etc to use less power and water when in use. Anything that uses power or water has a consumption rating so if a item that uses power like a stereo or TV has a power consumption rating of 10 it'll make the bills higher, same applies to showers, baths etc with their water consumption rating. 

If you do have the Eco lifestyle pack, the geothermal and water well lot traits completely remove the charge for water and power.