After six years of studying energy and training at the best facility that teaches home energy auditing I was relatively certain that I understood what happens within a home. When I began auditing homes as a probationary auditor I was shocked to find the variance in issues from one house to another. There is no one-size-fits-all approach to saving energy within a home. How energy is wasted in your home is different from any other house. This means that where you should invest time or money is very unique, especially if you are on a tight budget. The best place to start is with a home energy audit. I hope this advice doesn't come off as self serving. I certainly benefit from a higher demand for my own services, but as a home owner I have seen my own energy consumption increase over the last few years even as I began replacing compact fluorescent light bulbs with LED bulbs and replaced the dishwasher and clothes washer with more efficient devices.
I understand this can be frustrating for concerned home owners and can make the situation feel hopeless. I now understand that while these are good changes to make, in my home, there are other issues that are increasing my energy consumption rates faster than my attempted changes can reduce my energy use. After examining my own home, the first on my list, I found that the ducts were leaking heated (or air conditioned) air straight into the unconditioned attic. Essentially, I was pouring energy (and money) out the window.
Armed with this new idea of what "really" caused energy problems I audited the first home other than my own with the belief that this home would have the same issues that I did. This home had ducts entirely located between two floors. Any duct leakage would be into a portion of the home that was already being heated. This home was wasting its energy through low efficiency appliances and skylights that allowed sunlight to heat up the home in the summer.
Without a thorough inspection of your home you cannot be sure if you are spending money wisely in your effort to save energy.