Your house is a glutton, gobbling energy like a starved elephant. Gain control by trimming energy use.

A good place to start is your HVAC ductwork. Ducts are notorious energy-wasters, leaking your heating and cooling air through holes and loose connections.

Sealing and insulating your ductwork can improve the efficiency of your heating and cooling system by as much as 20%, saving you $200 per year or more, according to Energy Star. You’ll make your home more comfortable, and a more-efficient system helps extend the life of your furnace, air conditioner, or heat pump.

Because ducts are usually hidden inside walls, ceilings, attics, and crawl spaces, sealing and insulating them may be a difficult and time-consuming DIY job. If you can’t reach all your ducts, concentrate on those that are accessible.

Use duct sealant — called mastic — or metal-backed tape to seal the seams, holes, and connections. Don’t use the confusingly named “duct tape,” which won’t provide a permanent solution. Be sure to seal connections at vents and floor registers — these are likely places for leaks to occur.

After sealing your ducts, wrap them in fiberglass insulation. Most hardware stores and home improvement centers have insulation wrap products made for ducts.

A professional heating and cooling contractor will charge $1,000 to $4,000 for the work, including materials, depending on the size of your home and accessibility to your ducts.

Insulating your ductwork may qualify for a rebate from your state or local municipality. Check the Database of State Incentives for Renewables & Efficiency.