Which Windows Are Best for a Passive Solar Home?

Reader Contribution by Jennifer Kongs
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The Small Home, Big Decisions series follows Jennifer and her husband, Tyler, as they build a self-reliant homestead on a piece of country property in northeastern Kansas. The series will delve into questions that arise during their building process and the decisions they make along the way. The posts are a work in progress, written as their home-building adventure unfolds.

We are by no means experts when it comes to window selection for best passive solar home design and function. Depending on your location, budget and climate, what works for us may not work for you. But, based on our experience and some research, we’ve found a few tips that make sense to us and that we’re incorporating into our home. The image above is of our south-facing wall, so you can get a basic idea of how many windows (a lot) we’re including, and their sizes and which are double-hung and which are not.(The overhangs for the windows, which are an important passive-solar detail, are not shown and will be added later, and they will be discussed in a later post.)

First, many of our larger windows are fixed, meaning they don’t open. While we won’t do this with all the windows because we want some fresh air to circulate through the house, fixed windows are more airtight (which means they’re more efficient) than operable (openable) windows.

We have hinged windows that crank open for several of our windows, including ones that are located high near the ceiling. The crank windows are more airtight than double-hung-style windows, generally speaking. By placing these smaller, crank-open windows up high, we’ll be able to open them to vent the hot air that rises to the top of our vaulted living room ceiling (the highest space in the house). This will take advantage of the inherent flow of warm air rising to naturally push out warmer air in summer months.

Some of our windows are double-hung, partly for aesthetic, but we invested in really high quality. All are EnergyStar windows with wooden frames, are double-paned with an argon filling, and do not have a low-emissivity (low-e) glazing. Most new windows now come with the option for a low-e glazing that is meant to protect your furniture, floors and carpets from UV rays. The transparent, heat-reflective coating also prevents heat from escaping in winter and from entering in summer. Sometimes, this isn’t a good thing, as it can mean less heat gets in during cold months, so you have to pay attention to the solar heat gain coefficient of the window you’re choosing. The overhangs we will add will prevent the high summer sun and its heat from hitting the windows and heating up the house, while still allowing the low winter sun rays into our home. The choices we’ve made put our windows in the recommended SHGC range for our location, according to the ratings by the National Fenestration Council.

An excellent article that summarizes much of what we’ve covered here is High-Performance Windows. It covers all the details you’ll want to look up before deciding if low-e, fixed or even tinted windows will work best for you.

Digital rendering above by John Roe is copyrighted and not available for reuse.

Next in the series:Sourcing Sustainable Bamboo Flooring
Previously in the series:Financing Renewable Energy: Home Wind and Solar Power

­­­Jennifer Kongs is the Managing Editor at MOTHER EARTH NEWS magazine. When she’s not working at the magazine, she’s likely in her garden, on the local running trails or in her kitchen instead. You can connect directly with Jennifer and Tyler by leaving a comment below!