Passive Solar Design 101: What You Should Know

With the warm days of summer shining down on us, we can’t help but think of the sun and the incredible role it can play in sustainable home design. From heating and cooling to generating power, the impact of designing a site and home around the sun can pay off in many different ways. In this post, we’ll walk you through the concept of passive solar design and its benefits, along with a handful of different ways you can tap into it during your next build or remodel.

At its core, passive solar home design is about minimizing the use of — and need for — energy. Imagine the sun’s rays passing through a south-facing window, for example. If planned correctly, heat from those rays can be retained and stored, which will increase your energy efficiency and decrease the cost of your heating and cooling bills.

In the world of architectural design, our strategizing around passive home design starts at the site level — before building even begins. We’re thinking about things like how we can take advantage of the site and the home’s placement on it to capture the most unobstructed views of the sun. For example, a deep north to south lot with the home situated on the north end is a good way to achieve this. On top of that, we’re considering the nuance of the sun’s movements throughout the year. And we’re taking into account regional differences and the local climate, since we work throughout the United States. Even within our home state of Colorado, placement can vary considerably depending on what area you’re in.

We’re also thinking far ahead to be mindful of things like tree plantings that could eventually block how much sun reaches the house. That being said, we do want to accommodate some shade to prevent overheating. Another way to offset heat from solar gain includes ventilation strategies such as a windcatcher, which is similar to a chimney. Windcatchers have been around for thousands of years and are typically found in countries across the Middle East, North Africa, and Western Asia. In recent years, as people have become more environmentally conscious, modern versions of windcatchers have surfaced as passive and semi-passive ventilation options. Finally, before we get to work, we’ll also begin to think about sustainable materials and how they may play into minimizing energy use.

As we continue with our planning, there are a handful of puzzle pieces that must fit together in order to find the right balance of budget, home style and energy performance. Some of the elements of passive solar design include:

Windows in the right place at the right time

Serving as an entry point for the sun’s rays while not allowing in too much sun is a delicate balance. Most professionals recommend designing window placement to receive full sun during the winter months while providing shade during the summer. And while you don’t want them impeded by shade, you also don’t want overheating. Of course, keeping them clean is also important — don’t let all your design work go to waste!

A sustainable way to store the sun’s heat

The stored heat in a passive solar home is also known as thermal mass. And you want the right materials in place to absorb it — think stone, concrete, brick, or adobe. These materials will play an absorbing role when it’s hot, holding on to it until you need it when it’s cooler. One specific example? A Trombe wall stores heat during the day and then leeches it back during cool nights. Trombe walls are great for arid or semi-arid environments. Remember, materials play a role in efficiently storing thermal mass, but also play an aesthetic role in the final look and feel of the home, so choose wisely.

A plan to distribute the stored heat

Some of the distribution is completely passive, as you might expect with the warmth captured in a sunroom that then spills into the rest of the house. Another truly passive way to transfer heat takes place when you walk on tiles warmed by the sun. Other ways include fans that circulate the warm air, with proper venting and damping to control the temperature flow.

Solutions that keep things from getting too hot

We mentioned the balance of capturing heat without overheating, and one solution to that is roof overhangs. These will change how much of your window or wall is cast in shadow. Or, in the modern home you may coordinate mechanical ventilation paired with high and low operable windows to allow for heat to be pulled out of the home.  Bonus points if the high and low windows are coordinated to pull cooler exterior air and venting from the hotter side, creating a cool breeze.

As you can see, a lot goes into passive solar design. It’s important to start from the very beginning with the end in mind, to take advantage of as many passive heating and cooling options as possible. That’s why it’s always a good idea to find professionals experienced in energy-efficient house design and construction before you start. At KGA, sustainability is important to us, and we’re happy to go on this journey with you. Reach out to our team today to learn more about how we can incorporate passive solar design into your next home build or remodel.

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