I read a lot of reviews, but don't write many unless product or service compeles me too. I've had green design perform work on our home on two different occasions. My initial goal was to improve efficiency of our 30 yr old house. I installed cfl bulbs, programmable thermostat, eliminated some "vampire" loads and sealed leaks around windows, outlets etc.. We then had David's crew replace some bad duct work, AC tune up and tint windows after two years in the house. There was a noticeable improvement in the comfort of our home and a small decrease on electric usage. About a year later we got remaining duct work sealed and replaced, fixed damaged/fallen insulation and added attic insulation to a level of R38. We have again noticed a marked improvement in the comfort level of our home, heat pump runs less, temperature is more uniform throughout house. In the last year my wife has started working at home w/several children, and we have still noticed a decrease in our electric bill. The install crew showed up on time, were friendly and did a good job w/no damage then cleaned up when done. I have recommended them to others and would be happy to have them back.