What Is Passive Solar and How Does It Work
If you are looking for more energy-efficient ways to go solar, the use of passive solar has become a popular and viable option for many homeowners. By utilizing passive solar panels and components to naturally absorb and distribute heat when you need it, you can keep your home an ideal temperature while saving money throughout the year. So, what exactly is passive solar and how do you use it? Learn more about a passive solar design, how it works, and the best use of solar components to capture energy for your home.
What Is a Passive Solar System?
A passive solar system uses your home’s orientation to collect, reflect, store, and distribute solar energy to heat and cool your home. This system harnesses solar energy without the need for solar panels or mechanical systems. How is passive solar stored and distributed throughout your home? Passive solar systems capture energy directly from the sun using these design elements:
- Aperture – This large glass area allows sunlight to enter your home.
- Absorber – This exposure sits in the direct path of sunlight and absorbs heat.
- Thermal mass – This internal material retains and stores the sun’s heat.
- Distribution – This allows heat to circulate from a storage area to different places in your home.
- Fixed control – These are the overhangs and natural shading that control solar energy.
By using natural energy characteristics or materials to warm or cool your home, passive solar systems are typically simplistic in design and require minimal upkeep.
How Does Passive Solar Work?
Passive energy uses the natural environment and the sun’s energy to heat your home without the use of solar panels or electrical systems. Two key designs of passive solar heating systems are essentially the south-facing glass of your home and the thermal mass components that you install to absorb and reflect heat. With the proper orientation of your passive solar system design, you can effectively use the sun’s energy to naturally heat your home.
Passive solar cooling systems work by blocking out excessive heat with proper shading and ventilation that regulate the internal temperature of your home. It uses designs like overhangs, tree shades, and thermal mass to properly cool your home. By creating places where the amount of solar energy your home is reduced, you can keep the temperature cooler without the air conditioner.
What Components Make Up Passive Solar?
Passive solar techniques produce a cooler or warmer air temperature in a building by using the sun’s energy without any electrical equipment or solar photovoltaic technologies (such as solar panels). No more worries about whether to install 60-cell vs. 72-cell solar panels for your home, you can focus instead on the three main components of effective passive solar design:
In a direct gain design, sunlight enters a building through windows or passive solar panels and stores heat in the thermal mass incorporated into floors or interior walls. This is the most common passive solar system design.
To design a direct gain system, you’ll need to calculate how much window area and how much thermal mass is required to provide the desired quantity of heat for the building. In general, the total direct gain glass area should be at least 7 percent but not exceed 12 percent of the house’s floor area.
Key factors for passive solar windows are:
- Glazing – It is ideal that the south-facing glass windows are angled within 5 degrees of true south; however, windows angled within 15 degrees of true south work almost as well. In addition, vertical glass, as opposed to glass titled up or down, is probably the best year-round solution.
- Solar tempering – This basic passive solar technique involves increasing the number of windows on the south side. In a conventional house, about 25 percent of the windows face south, which amounts to about 3 percent of the house’s total floor space. In a sun-tempered house, the percentage is increased to a maximum of about 7 percent. Energy savings are modest with this system, but sun-tempering is very low cost.
- Building or taking out overhangs –Installing or removing shading can greatly change the amount of sunlight that currently shines on the window.
Thermal mass is the material that stores the sunlight during the day and releases it at night. It can be built into floors, interior walls, or fireplaces.Types of thermal mass include:
- Floors or walls made of adobe
- Stone or water
The sun does not need to hit these surfaces directly to store the heat, nor do these surfaces necessarily need to be a dark color. How is passive energy stored with thermal mass? The thermal storage capabilities of a given material depend on the material’s thermal conductivity, specific heat, and density.
Usually, higher density materials can store more heat. Thermal mass can be costly, so it is always best to consider the cost-to-benefit ratio before starting a solar project.
Properly insulating your home holds the heated air inside and cold air out. By simply opening the drapes or insulated blinds on your south-facing windows during winter days, when the sun is low in the sky, you can raise the room temperature. In addition, heat gained from the sunlight increases as it passes through glass.
Night insulation, such as window shades, quilts, or insulating drapes, also can improve energy-efficiency dramatically. If you are designing a house or a remodel, talk to your architect or designer about possible passive solar choices.
Ready to Start Your Solar Journey?
If you’re exploring your solar options, now is the perfect time to consider a passive solar design. Contact our team of solar design experts to help you discover the perfect solar system to fully optimize the power of solar energy.