Heating and cooling systems are some of the most important investments you’ll ever make in your home. Whether you’re buying a new house, renovating an old one, or making an emergency purchase because “old faithful” finally conked out, a lot is riding on the choices you make: Your comfort and safety are at stake, and so is your money.

According to the Department of Energy (DOE), about 45 percent of your utility bill typically goes toward “space conditioning,” or heating and cooling your home. While the purchase price of the equipment and cost of repairs and maintenance are important to consider, so is the operating cost of the system. By choosing the most energy-efficient equipment that meets your needs and fits your budget, you may be able to lower those hefty space conditioning costs.