Those costs can add up fast. Remember that while green appliances will lower your energy bills and upkeep year after year, there's less direct payback from using recycled or salvaged woods and other materials.
Your conscience will be your guide here. Prices can differ, but those in the checklist below are the rules of thumb I generally keep in mind.
To insulate an attic with high-performance foam instead of standard material: Add $4,000
For a top-flight heating plant and four extra heating/cooling zones in a 2,500- square-foot house: Add $6,000
For living room and dining room floors of salvaged wood instead of strip oak: Add $3,000
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Last updated August 22 2008: 9:53 AM ET