Because your Church is a part of the local community you will need to look at the community's resources.
Have members investigate the following:
What is the extent of your community's recycling and composting program?
Do you have a community garden?
Can a portion of your electricity be purchased from a renewable resource, i.e. wind energy?
Is public transportation to your church available?
Does your community have a program or information available to help lessen utilities?
Does your community have any programs which help provide winterization for low income members?