"We do it here at the office a couple of times a year, and I'm always amazed at the impact," Gillingham-Ryan says. "It's about the most affordable thing you can do for your house that makes such an impact."
"In the daytime, it makes a difference because you can see more of your outside," he says. "It makes you feel more connected to the outside. At night, clean windows are more reflective. They act as mirrors." And that gives you a "lovely effect" when you throw a nighttime party and use soft lighting or candles, he says.
Rather than deep-sixing curtains entirely, selecting the right curtains can bridge the indoor-outdoor connection, he says.
Go with something billowy in a sheer or natural fabric, Gillingham-Ryan says. It filters the light "and shows that beautiful balance of how the outside melts into your room," he says.
Pro tip: Use floor-to-ceiling curtains, even if the window doesn't extend that far, "to make the wall look taller and the window look bigger," he says.