I used MASSSAVE too. The company I work for is doing several energy saving projects with them and we have liked them very much. At my house, I had insulation blown in a few walls and attic that I had not finished renovating. After the job was done, an auditor came out and re-estimated what was done and he discovered a simple error in their first estimate. I received a check back for over $150.00 in a few days with a nice apology.