Minnesota-based Wolf River Electric makes their money installing solar panels, but they're also happy to hand out a free tip for reducing your energy bill. Noting that windows are a key source of heat loss in a home, company founder Justin Nielsen points out: "One of the simplest and most overlooked ways to keep heat in your home this winter costs almost nothing, bubble wrap on your windows."

"It sounds unconventional, but the science is solid. Bubble wrap works as an extra layer of insulation by trapping air between the bubbles, slowing down heat transfer through the glass. Windows are one of the biggest culprits for heat loss in a home, and this is a near-zero-cost fix anyone can do in minutes.

"All you need to do is cut a sheet of bubble wrap to fit your window, lightly mist the glass with water, and press it against the pane, the surface tension holds it in place with no tape or adhesive needed. It lets light in while keeping the cold out.

"It's not something I'd recommend for your main living areas, but for rooms that don't see much use during winter, a guest bedroom, a basement, a utility room, it's a genuinely effective hack. You'd be surprised how much of a difference it makes to the feel of a room and potentially your energy bill."

"Two important tips I'd give though are firstly not to overly mist your windows. Too much moisture behind the bubble wrap can cause condensation. And secondly, make sure that you lay the bubble wrap bubble side to the window.

"It seems counter intuitive, as you'd presume that the other side has more area to stick... but by doing it this way, you get an extra layer of insulation."