I think most of us have dreamt, a time or two, about receiving an unexpected windfall. That fantasy of winning the Mega Millions lotto, coming into an inheritance or finding out that the fake Picasso you have in that cheap frame is actually authentic.

Let’s let our imaginations run crazy today. Or, perhaps you’ve received an unexpected windfall. Spending at least part of it on home upgrades is a smart move. We’ve rounded up some of the most intelligent upgrades you can make.

Upgrade your HVAC system

“More than half of energy use in homes is for heating and air conditioning,” according to the U.S. Energy Information Administration. Upgrading your current system (especially if it is older than 10 years) to one that is ENERGY STAR® certified is a smart decision that will have a significant effect on your heating and cooling bills.

Since the average U.S. household emits twice as many greenhouse gasses as the average vehicle, upgrading your HVAC system helps the environment as well.

Finally, energy efficiency in most of its forms, from windows to appliances to home systems, is popular with homebuyers. You may just recoup some of the cost of the new system when you sell your home in the future.

For information on ENERGY STAR rated products and how to choose, read the pamphlet online at EnergyStar.gov.

Stop the leaks

It doesn’t make much sense to install a spiffy new, energy conscious HVAC system in a home with air leaks. Especially when we consider that those air leaks cost the average American family about $350 each year.

The biggest leakers? Attics and basements, so those are the best places to start. Then, check your recessed light fixtures. “The Pennsylvania Housing Research/Resource Center pinpointed them as a leading cause of household air leaks,” according to Megan E. Desouza at HouseLogic.com.

It’s easy to find out if yours are stealing air from the home, she says. Look for a label on the fixture, it should be next to the bulb. If it says “ICAT,” it’s already sealed. If not, “assume yours leaks.”

Head to the local home improvement store and buy an inexpensive airtight baffle. “Remove the bulb, push the baffle up into the housing, then replace the bulb … a quick, 1-second fix,” promises Desouza.

Don’t stop there, however.

  • Check windows and doors for leaks and weather-strip and caulk if necessary.
  • Check for air leaks around ducts, plumbing and around the floors and ceilings.
  • “Install foam gaskets behind outlet and switch plates on walls,” suggests the experts at the U.S. Department of Energy. They offer a checklist of ways to snoop out air leaks in the home at Energy.gov.

Consider new windows

You may not be thinking of selling your home right now, but someday you most likely will. Did you know that energy efficient windows are a hot feature with buyers? They can actually help you sell your home for more money.

Look for low-E windows – the “E” stands for “emissivity.” Coated with and invisible-to-the-naked-eye layer of metallic oxides, these windows allow more sunlight into a room, reduce condensation and protect furniture and carpets from fading.

“In general, you’ll save up to 15 percent a year on your energy bill if older double-pane windows in a 2,600-square-foot house are replaced with energy-efficient windows with low-E coatings,” according to the pros at HouseLogic.com.

Beef up the insulation

Adding attic insulation alone to the home can save from 10 to 50 percent on heating costs, according to the U.S. Department of Energy.

Not sure if your home is under-insulated? Look for the following clues:

  • If there are parts of the home that are colder or hotter than other parts, you may need more insulation.
  • Touch the ceilings and walls. It they’re damp and/or wet, you have insufficient insulation.
  • Frozen pipes in the walls.
  • Sky-high home heating and cooling bills are an obvious sign that something is amiss.

Choosing even one of these upgrades will help save energy and, thus, money in the long run.