Is It Too Late to Retrofit Your Home with Passive Solar Design?
Passive solar design describes one of the oldest and most cost-effective ways to naturally warm your home during cold winter months and cool it during the summertime. Although any number of ancient civilizations understood the basic concept behind passive solar, the Anasazi helped standardize the practice in the American Southwest. They built their homes facing southward to optimize direct sunlight, thus, warming their interior living spaces with natural heat.
In the centuries since, incorporating passive solar when building luxury custom homes hasn’t changed radically. In most cases, new building plans typically position homes with south-facing windows to capture sunlight. For passive solar cooling, builders outfit the roofs with overhangs to shield these windows when the sun is higher in the sky during the summer months.
However, what happens if you already have a home?
It’s one thing to incorporate passive solar design concepts when drafting building plans for new structures. It’s another thing entirely if your current home doesn’t already have south-facing windows. Is your only option to start from scratch with a new luxury custom home building?
Fortunately, it is possible to retrofit existing homes with passive solar techniques.
Energy Audits to See If Your Home Is Ready for Passive Solar Design
The first, and arguably most important, step involves getting a home energy audit. The goal here is to identify cost-effective ways of increasing the energy efficiency of the home you already have. The less energy consumed, the fewer modifications you’ll need when drafting the building plans for your retrofit.
Common improvements include:
- Outfitting your home with energy efficient appliances, including smart-devices that can power off automatically when not in use.
- Insulating your home properly so that it stores heat during the winter and blocks it during the summer.
Your home auditor might also recommend switching out building materials (like aluminum siding) that do a poor job of capturing and storing heat. Instead, he or she might suggest retrofitting portions of your home with building materials that have a high thermal mass – i.e. the ability to store heat by resisting erratic temperature fluctuations. When strategically integrated into areas with direct sunlight, materials like stone, brick, and concrete are incredibly efficient at:
- capturing solar radiation during the winter months
- mitigating warmer temperatures during the summer months
Customizing Building Designs to Maximize Southern Exposure
Bay windows and skylights are probably the cheapest and most popular way of inviting sunlight into your home. However, many retrofits use a Trombe wall – a thick, multi-layered barrier that combines glass with dark absorbent material to capture and store solar heat.
- During the winter, these techniques provide you with direct access to the sun between 9am and 3pm (depending on your location).
- During the summer months when your goal is to “block” sunlight, you can use roof overhangs, awnings, or low-emissivity blinds to keep heat out of your home.
What If Your Current Home’s Solar Exposure Is Limited?
In the northern hemisphere, the sun travels along an arc best visible in the southern sky. And thus, your passive solar retrofit should optimize exposure within 25-30 degrees of true south.
If you have an existing home with south-facing walls, adding bay windows or a Trombe wall is fairly straightforward. But what if your home’s exposure to the sun is restricted?
Ideally, you want as much direct sun as possible. But even if only a portion of your home receives sunlight, you can still redistribute captured heat throughout the rest of your home provided your renovation building plans include energy efficient vents and fans.
Many luxury custom home building projects also integrate a number of retrofit techniques for further optimizing sunlight, including:
- Building custom windows into existing south-facing walls.
- Removing (and of course replanting) trees that may obscure the sun.
- Attaching a solarium (i.e. sunroom) to the side of your home as long as this external add-on receives at least some sunlight.
With the Right Approach, Passive Solar Design Is Never Too Late
Obviously, you’ll receive the most gains if you have the luxury of designing your next home with passive solar already in mind. Starting from scratch is optimal.
But even if you have an existing home – one whose solar exposure is limited – it’s possible to incorporate retrofits that quickly pay for themselves by dramatically reducing the energy needed to heat and cool your home.
Contact Kurt Faust