Passive solar is an approach to keeping a house warm by taking advantage of the sun's rays. It differs from other solar technologies because it's basically a low-tech approach. Passive solar simply takes the warmth from the sun directly and keeps it inside the house for heating purposes, primarily using windows and good insulation. A passive solar system can keep a house warm enough to drastically reduce heating costs, and in some areas, it can completely replace other heating methods.
Elements of a Passive Solar System
A passive solar system is a collection of various building elements designed for the collection and conversion of solar energy in order to power a building's energy needs. Such a system includes specially designed windows, walls, and floors, all working together. Depending on the environmental climate and the building's orientation during peak periods of sunlight, these elements work together in various ways to absorb and distribute solar energy. This might enhance climate control or limit the effect of environmental extremes. A passive solar system may also consist of thermal insulation, mass and shading properties of materials, treatments, and technologies.
Windows in Passive Solar Design
The most fundamental aspect of most passive solar designs is a focus on windows. Usually, designers will install a huge number of windows facing to the south to capture as much heat as they can during daylight. The windows are also usually made of special glass that takes in as much heat as possible and keeps it in the house as long as it is able.
Passive Solar Design Configurations
Passive solar designs rely on architectural cooperation with nature instead of energy-hungry appliances. In order to efficiently manage solar energy in a house or commercial building, a passive solar system may be designed around one of six design configurations. These include direct, indirect, and isolated solar gains. Heat storage and thermal insulation both extend a property's energy capabilities. Passive cooling techniques round out the designs.
Heat Storage in Passive Solar Houses
Another aspect of passive solar designs is keeping the heat during nighttime hours, and this is usually done by installing a concrete wall or floor or sometimes both. Bricks and materials like adobe will also work. The heat-collecting walls or floors are typically installed in the same areas where the windows are located. These materials absorb heat and release it very slowly. That means that once night falls, the concrete will still be radiating heat constantly for a good portion of the evening, and making the house warmer in the process.
Using the heat storage technique, thermal energy can be captured by a specially designed floor, a water wall, or a roof pond. These may be designed to emit heat over periods when the sun may be absent. Thermal insulation and window glazing techniques help enhance or prohibit direct gain energy.
Trombe Walls and Other Passive Solar Features
In some cases, designers may also use a special kind of wall called a trombe with a glass pane in front of it. The basic idea behind a trombe is to capture heat inside the gap between the wall and the glass. These generally work more efficiently than simply using concrete. Designers also sometimes paint their concrete walls black so they'll be more absorptive, or they may even put water containers, which can also capture heat, inside walls made of other materials.
Passive cooling occurs with the use of reflective windows and ventilation, such as with a solar chimney. This is a structure that uses convection to create an updraft to remove warmer air and pull cool air into a room from the ground via heat-exchange tubes. It is sometimes called a thermal chimney. On a larger scale, it may be designed as a passive downdraft cool tower.
Passive Solar House Plans
Sometimes houses that use passive solar design are built in a more open way so that more heat can get from the windows to other parts of the structure. They also occasionally make the window area one large room and connect it to every other room in the house if possible. In order to keep houses from getting too hot in the summer, designers may install awnings that can block the sun when desired and design the house for easier ventilation.
The best passive solar house plan usually will integrate the unique sunlight patterns of the potential house location. For every location on Earth, the sun's angle is a little different throughout the year. For instance, in the northern hemisphere, the best passive solar house plan will usually face south, where the sun will be all year, but a passive solar house in the southern hemisphere usually will face north. The best passive solar house plan will take full advantage of any available sunlight while simultaneously optimizing interior spaces to regulate the sunlight.
Adapting to Seasonal Changes
Throughout the year, a building can undergo a wide range of light and temperature variations. Days and nights give way to seasons. Instead of working against these trends, a passive solar system attempts to work within them. It helps moderate energy use by working smarter and not harder.