It includes a variety of methods that use no human-made energy to operate and can reduce the amount of energy needed for heating and cooling by considerable amounts. If you have ever spent some time in the sun on a hot day, you know that the sun has an incredible ability to heat things up.
Think of how hot the inside of a car gets after it has been in the sun for awhile. Tapping the sun's power is useful in working towards becoming more energy efficient because its energy is free and in near endless supply.
That's why we consider solar energy a "renewable" source of energy. The simplest method of passive solar heating is sunlight shining through windows. Since we know that the sun rises higher in the sky during the summer than in the winter, engineers and architects design buildings that allow sunlight through the windows during the winter months when the building needs heating, but block the sunlight during the summer to help keep the building cool see Figure 1.
Students can apply their own creative thinking to design, build and test model houses using methods of passive solar heating including insulation, window placement, thermal mass, colors, and site orientation with the associated activity Zero-Energy Housing.
Figure 1. Notice the differing angles of the sun between winter and summer. After sunset, have you ever felt the warmth from a big rock or a concrete bench that has been in the sun all day? The rock and the bench absorbed and stored the heat, and released it slowly. Working in the same way, a key passive solar technique is for the radiant heat of sunlight that enters a building to be absorbed by a thermal mass inside the structure.
A thermal mass might be a big wall or area of floor that is composed of a construction material that is able to absorb large amounts of heat, such as concrete, brick, tiles or even water. As the sun sets and the air temperature lowers, the thermal mass slowly releases the heat it gathered all day to help maintain a comfortable indoor temperature through the night. In the summer, the same thermal mass can draw warmth from the surrounding air to cool a space.
In all seasons, the ability of thermal mass to store heat helps to maintain a uniform temperature. Working with these ideas, the most successful human-engineered product using the sun's energy for heating is called the SolarWall. This construction product uses sunlight to heat up metal panels attached a short distance away from the wall of a building.
The air in the void between the panels and the building heats up as the metal panels heat up. The heated air naturally rises to the top of the building and into heating ducts that distribute it throughout the building.
Unfortunately, passive solar cooling has not made as much progress as passive solar heating. The two main ideas behind solar cooling are ventilation and the prevention of heat from entering the building. Proper ventilation is achieved by strategically placing windows so that as much air as possible can be circulated when open. One way to prevent heat from entering a building is to design the building with thermal mass on the outside so that it absorbs the heat before entering the building.
Another method is to plant large deciduous trees so they shade the building from direct sunlight during the summer months. Whether we are discussing passive solar heating or cooling, the buildings' geographical location and orientation play important roles.
For example, to take advantage of passive solar heating and cooling, a building in the US must be designed so its windows and main living spaces are located on the south side of the house.
That way, the windows that face the sun can heat up the spaces people are in more often. Windows located on the north side do not let in any direct sunlight and allow more heat to escape than a solid wall. This is one reason that building orientation is important. Geographical location must be considered because different places have different climates. In some regions, clouds block the sun more often than not, so they would not be good locations to rely on the sun for heating.
If a region's prevailing wind comes from the west, windows placed on the west and east sides would allow for the greatest airflow. When considering all the passive solar techniques, it is important to use the correct ones based on the climate.
Is your house benefiting from passive solar design, or not? Notice where the sun strikes your windows on different sides of your house at different times of the year. The south-facing window under the eaves of this house adds no solar heat gain to the inside space when the summer sun is high in the sky.
Talking about heating and cooling would be incomplete if we did not talk about another important aspect of any HVAC system, passive or not, and that is insulation.
Without a properly insulted building, no matter how good its heaters and air conditioners are, the hot or cold air will escape to the outside. It can be thought of as the aikido of architecture.
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Learn how your comment data is processed. Solar Design. Distribution is the method by which solar heat circulates from the collection and storage points to different areas of the building.
A strictly passive design will use the three natural heat transfer modes exclusively—conduction, convection, and radiation. In some applications, however, fans, ducts, and blowers may help with the distribution of heat through the building. Elements to help control under- and overheating of a passive solar heating system include roof overhangs , which can be used to shade the aperture area during summer months, electronic sensing devices, such as a differential thermostat that signals a fan to turn on, operable vents and dampers that allow or restrict heat flow, low-emissivity blinds , and awnings.
Passive solar buildings are designed to let the heat into the building during the winter months, and block out the sun during hot summer days. This can be achieved by passive solar design elements such as shading, implementing large south-facing windows, and building materials that absorb and slowly release the sun's heat.
Incorporating shading concepts into your landscape design can help reduce the solar heat gain in the summer and reduce cooling costs.
The leaves of deciduous trees or bushes located to the south of the building can help block out sunshine and unneeded heat in the summer. These trees lose their leaves in the winter, and allow an increase in the solar heat gain during the colder days. Incorporating overhangs, awnings, shutters and trellises into the building design can also provide shade.
A trellis with a climbing vine can shade a home and allow air circulation. Photo by John Krigger, Saturn Resource. Effective thermal mass materials, like concrete, or stone floor slabs, have high specific heat capacities, as well as high density. It is ideally placed within the building where it is exposed to winter sunlight but insulated from heat loss. The material is warmed passively by the sun and releases the thermal energy into the interior during the night.
The most important characteristic of passive solar design is that it is holistic, and relies on the integration of a building's architecture, materials selection, and mechanical systems to reduce heating and cooling loads. It is also important to consider local climate conditions, such as temperature, solar radiation, and wind, when creating climate-responsive, energy conserving structures that can be powered with renewable energy sources. In climates that are appropriate for passive solar heating, large south-facing windows are used, as they have the most sun exposure in all seasons.
Although passive solar heating systems do not require mechanical equipment for operation, fans or blowers may be used to assist the natural flow of thermal energy. The passive systems assisted by mechanical devices are referred to as hybrid heating systems. Passive solar systems utilize basic concepts incorporated into the architectural design of the building. This typically includes buildings with rectangular floor plans, elongated on an east-west axis, a glazed south-facing wall, a thermal storage media exposed to the solar radiation which penetrates the south-facing glazing, overhangs, or other shading devices , which sufficiently shade the south-facing glazing from the summer sun, and windows on the east and west walls, and preferably none on the north walls.
To achieve a high percentage of passive solar heating, it is necessary to incorporate adequate thermal mass in buildings. Specific guidelines for this include the following:. Sizing of glass areas, insulation values, shading, and mass will depend on climate. Higher solar savings contributions will require greater amounts of glazing and mass.
Be aware that the relationship between glass area and mass is not linear. For example, a doubling of glass area may require a tripling of effective thermal mass. First of all, taking advantage of passive solar heating does take some upfront investment and legwork to get everything in place. But so do most home improvement projects, and this one can save you lots of money. That leads us to the second reason:. Not enough people have heard about passive solar. The practicality is there—passive solar leads to reduced greenhouse gas emissions and savings at the same time.
As the world becomes more environmentally conscious, we should expect more folks to take advantage of reducing their ecological footprint and saving money on their heating bills. And as our technology gets more efficient, the reasons to take advantage of solar only grow. As a content marketing fellow, Ian created and worked with all front-facing aspects of Solstice's content, ranging from social media to email newsletters.
Ian studied environmental science at the University of Massachusetts Boston, where he applied his passion for climate change mitigation. In school, he became interested in discovering better strategies for environmental communication and pursued his career in digital and content marketing. When not at work, Ian can be found either playing sci-fi video games or going out to enjoy many of Boston's attractions and live events.
Skip to content. Passive solar works according to a 5-step process. With passive solar heating, this heat can be released into the home in 3 ways: Radiation — Heat that travels in the form of waves, think of your microwave. Diagram of Passive Solar Heating Home.
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