Public Health - Various research and articles indicate exposure to light at night can have a negative impact on public health. Lighting installations located near where people are expected to sleep (private homes, apartments, hospitals, hotels, etc...) need to assign a value to these costs.
Wildlife - A light doesn't need to be located next to a protected habitat to affect wildlife. Many species such as endangerd birds migrate great distances at night.
Environment - Lights require electricity to run. Much of this electricity is produced using coal. You can calculate the pollutants that will be produced based on the wattage of the light.
Operation and Maintenence - Annual electrical costs and maintenence should be included. This should include lens cleaning, light bulb replacement, photosensor repairs and such.
Safety and Security - Streetlights are generally installed for public safety, not private security. Streetlights are typically located adjacent to the street and may provide a collision hazard. Accidents and fatalities involving lampposts should be included in the overall costs. Streetlights are becoming targets for theft due to their copper and aluminum content.