Passive solar home design

Main elements of passive solar architecture

Commonly accepted passive solar home design principles say that you should orient a house in a way that allows it to collect heat from the sun and then use good heat insulators, such as concrete or brick, in the home’s construction. This helps reduce the home’s reliance on utility power for heating and cooling, which, in turn, lowers energy costs and helps the environment.

These principles are exemplified in two of passive solar architecture’s main elements: south-facing windows and thermal mass.

South-facing windows

Site selection and home orientation are important to the success of passive solar architecture. These designs optimize the amount of sun coming in by placing windows and skylights in the right places and using awnings, overhangs and adjustable window coverings to control how much sunlight is absorbed.

In the U.S. and other places in the Northern Hemisphere, south-facing windows get the most reliable sunlight all day long. That’s why those with passive solar home designs usually try to face their systems toward windows and other surfaces that collect solar energy within 30 degrees of true south and away from any shade that may limit their intake between 9 a.m. and 3 p.m.

Thermal mass

The general idea of thermal mass as an architectural element is that certain types of building materials hold on to energy better than others, and large amounts of these materials can store heat for long periods of time.

Thick concrete or brick walls, for example, are good heat absorbers that can help regulate the temperature in your home, keeping it warmer in the winter and cooler in the summer. Other examples of thermal mass commonly used in passive home design are water containers and phase-change products.

These materials need to be used correctly, though. “One of the key considerations you'll need to keep in mind is that the home build will require advanced framing to eliminate thermal bridging,” said Karyna McLaren of Hybrid Power Solutions, a company that specializes in portable battery systems, solar installation and energy storage. Thermal bridging is when heat moves across an object that is more conductive than the materials around it. In this case, it could mean that your solar home loses the energy it’s taking in, which hurts efficiency.

Not all contractors are familiar with the necessary building methods to avoid thermal bridging, McLaren told us, which is why it’s important to work with experts who understand thermal mass and the appropriate heat absorbers.

Are solar homes expensive?

Passive solar homes have generally been more expensive to build than standard homes, but they don’t necessarily have to be. Pennsylvania architect Richard Pedranti, who created a passive house in Scranton, said the house cost only $165 per square foot to build. “We typically use between $175 and $200 per square foot for standard new home construction costs in our area,” he said.

Also, keep in mind that energy-efficient upgrades can eventually pay for themselves when measured against the cost of utility bills over time. A solar panel system can offset its upfront cost in five to 15 years, depending on the price of your system and your energy consumption.

Solar tax credits, net metering and other incentives, like solar renewable energy certificates (SRECs), can also help make going solar significantly more affordable. The federal solar investment tax credit (ITC) offers a 30% tax credit for systems built from now until 2032. The credit decreases to 26% in 2033 and 22% in 2034 before expiring in 2035.

» MORE: Cost of solar panels

Benefits of a solar home

Solar homes are getting more efficient and more affordable, providing major benefits to homeowners. Here are a few of the main benefits of going solar:

Lower utility bills

If you own your solar panels, the energy they produce is essentially free, so every unit of electricity they produce is one you don’t have to buy from the utility company. How much a given system can save you depends on a number of factors, but if you go fully solar, you can eliminate your energy bill entirely.

Possible tax benefits

There are tax credits and other incentives available from the government and other institutions for installing and maintaining a solar energy system. These can lower your overall tax bill and help maximize your investment.

Increased home resale value

Often, the cost of installation can be partially recouped when you sell your home. According to Sunrun, solar homes are commonly listing for at least 3.74% more than comparable, non-solar homes.

Increased sustainability

Being environmentally friendly is arguably the biggest benefit of a solar home. “Each kilowatt-hour (kWh) of solar that is generated will substantially reduce greenhouse gas emissions like CO2, as well as other dangerous pollutants such as sulfur oxides, nitrogen oxides and particulate matter,” according to the U.S. Department of Energy.

New-build solar home vs. retrofit

Newly built solar homes generally use energy efficiency as the starting point for their designs, then add on other solar technologies, such as solar panels, to compensate for any other energy needs. Some building plans also supplement passive solar elements with fans or other mechanical conductors to help circulate heat throughout the home as needed.

» LEARN: How solar panels work

Solar home concepts don’t have to be limited to new construction, though. “While the best solar homes are built with [passive solar architecture] in mind from the ground up, there are definitely some ways to take the same ideas and implement them in your own home,” said Leonard Ang, CEO of iPropertyManagement, a national resource center for landlords and tenants.

He says property managers use passive solar concepts such as dark, heat-conducting colors and materials to take advantage of readily available energy, saving on energy costs for both landlords and tenants.

While it may be difficult to achieve the overall efficiency of a purpose-built solar home with a retrofit, there are design principles that you can incorporate into your current home, and installing a solar panel system can help offset your reliance on utility power and give you a different type of solar home.

Other types of solar homes

While passive solar designs often use solar panels and other active solar technologies to complement their existing efficiency, other types of solar homes rely on these technologies more heavily because they aren’t as efficient. This is especially true in cases where you’re trying to retrofit a traditional home into one that relies on solar power.

A reviewer from Arizona told us that when they moved to a new home, they knew they wanted to add solar panels. “I like that it helps the environment. I like that I can get batteries and if a power outage happens I won't be affected,” they said.

If you’re also interested in adding a solar home energy system to your house, there are three main types you should be aware of:

• Grid-tied solar energy systems: Grid-tied systems generate their own electricity, but they're still connected to a traditional electric utility grid. This means you can switch between solar energy and traditional energy as needed and sell any excess back to the utility company through net metering (in places where it’s available). These are often the most cost-effective solar energy systems.
• Off-grid solar energy systems: These systems rely solely on solar energy and are not connected to an electrical grid; instead, they utilize battery storage systems to address energy demands throughout the year when solar energy isn’t as readily available. Purchase and installation costs tend to be higher with these systems because they’re often larger and more intricate, though.
• Hybrid solar energy systems: Hybrid systems are basically grid-tied systems with battery backups, so you can choose which to draw energy from as needed. Hybrids offer the most flexibility, but they may involve some complex design requirements and maintenance.

Bottom line

There are many ways to go solar when it comes to green architecture. From passive solar designs to off-grid solar panel systems, homeowners, builders and architects have a lot of options for taking advantage of sustainable energy. While it’s arguably easiest to build a passive solar home from the ground up, there are a few strategies you can implement in your existing home to harness the benefits of solar energy and create a more sustainable future.