Passive Solar Gain From South Facing Windows

Sunset through dirty windows, as shown at left, is beautiful. But it's not efficient. Clean your windows, at least the south and west facing windows, and pull those drapes aside to let more sunight in, especially now while outside temperatures are moderate and the sun is still high and able to deliver comforting heat to your home.
You don't have to mortgage your house to get into the passive solar game. Figure out which windows in your house, if you haven't already noticed, get the most sun, and put them to work for you. If you're having trouble locating the most solar-friendly windows, follow your cat around one day. Modest-sized south facing windows can transmit as much as 15% of the house's heat load, depending upon many factors, results will certainly vary. But the gain is always in the positive, and it doesn't cost you anything but a little thoughtful planning.
You can, of course, spend thousands of dollars replacing all the windows in your house with low emissivity argon barrier double glazed windows. And if you want to, go ahead. But if your budget doesn't allow for that, substitute your brain for your credit cards and get those south facing windows working for you. When it's colder, and here in New England it certainly will get colder as the year wanes, we'll check in again and give you some additional strategies for covering those windows at night after they've worked for you all day. Be careful washing those second floor windows, please.