Encourage your customers to invest in more efficient heating and air conditioning products.
Let's face it, although HVAC systems usually draw the most complaints from new home buyers and they have the greatest potential to save energy, create comfort, and reduce health-risk factors, upgrades are usually the last thought in a new home buyer's mind - somewhere after cabinets, lighting fixtures, plumbing fixtures, security, marble, swimming pools, etc. So, I have seen million-dollar homes with the very cheapest of builder-model HVAC units and spaghetti ductwork. Yes, it's a problem, not for us, but for the unwary home buyer.