These days there seems to be a push to “go green” when it comes to your home energy solutions. Solar panel arrays, super-efficient HVAC systems, and tankless water heaters are all the rage. But before you jump on the renewable energy bandwagon, look to thine own house. Literally.

Studies have found that nearly two out of every three homes suffer from low airflow, mainly due to leaky ductwork. This can rob your current heating or cooling system of 20% of its efficiency, and possibly even more, depending on the extent of the leaks.

If the idea of renewable energy appeals to you as a means to cut your energy bills, then your first step is to examine the ductwork and overall airflow of your home right now, whatever your HVAC setup.

Installing a shiny new furnace or air conditioning unit might drop your bills a little bit, and make your home more environmentally friendly, but if your ducts are leaking, your system is still inefficient. And financially speaking, it will take much, much longer for your energy savings to recoup the cost of the new system.

Experts recommend addressing your ducts and insulation before overhauling your HVAC system, even if the system you plan on installing runs on renewable energy. The source of the energy doesn’t matter much if you’re wasting it either way.

For example, let’s say you want to reduce your energy bills by x amount of dollars, a number you arrive at by reviewing your past energy bills. If a significant portion of your energy consumption is to account for inefficiency due to leaky ducts or poor insulation, then you’re going to be paying for a larger system than you actually need, if your home were more energy-efficient to begin with.

While energy sources such as solar, wind, or geothermal power are completely renewable, they can still be wasted. Installing more of a system than you actually need won’t necessarily cut your bills if your home is leaking heat. So while you may not be wasting money and non-renewable fossil fuels, you’ll still be wasting money.