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Passive Solar Design

A passive solar building is one that is designed and constructed by taking use of the factors found in the surrounding environment, particularly the sun’s movement. If planned and built according to a few passive solar building criteria, passive solar structures will be warm in the cold winters and cool in the hot summers. The sun’s thermal energy is used to both warm and cool the structure in a passive solar design, which is built and placed to shelter the sun during the hotter summer months.

A well-designed passive solar home reduces heating and cooling loads first through energy-efficiency technologies, then uses solar energy to partially or entirely meet those reduced demands. Because modern homes have low heating loads, it’s critical to avoid oversizing south-facing glass and ensuring that it’s adequately shaded in the spring and fall to minimise overheating and increasing cooling loads.

Fig 1: Passive Solar Design of a house
Fig 1: Passive Solar Design of a house
Courtesy: Alternative Energy tutorials

Here in this article, you will get a step-by-step guide on incorporating passive solar systems into your designs.

Ways in Implementing Solar Design
Some of the ways that helps in implementing solar design include-

Prioritize Energy Efficiency –
Energy efficiency is the most cost-effective technique for lowering heating and cooling expenditures. Before you add solar technologies to your new home design or existing home, choose building professionals that are knowledgeable about energy-efficient house design and construction, and collaborate with them to improve the energy efficiency of your home. If you’re remodelling an existing home, the first step is to conduct a home energy audit to determine which energy efficiency improvements are the most cost-effective.

Design of the Structure –
The amount of sun that is delivered into a space is determined by the overall form and orientation of a project. During the winter season, it has been found that a building that is extended along the east-west axis absorbs more sunshine on the south side. In this case, you should design accordingly.

Choosing a Location –
Consider future land uses to the south of your site. Small trees can grow to be large trees, and a future multi-story building could block your home’s access to the sun. Zoning or other land use rules in some regions safeguard landowners’ solar access. If solar access is not protected in your location, you can construct on the north end of a lot that is deep from north to south.

Shading –
In the summer, all windows should be shaded by an overhang or other devices such as awnings, shutters, and trellises to limit undesired heat intake. The sun’s rays will be blocked during the summer if an awning on a south facing window protrudes to half of the window’s height, but will still penetrate the home during the winter. Overhangs on east and west facing windows are less efficient because the sun is low on the horizon during sunrise and sunset. If cooling is a big problem, you can try to reduce the number of east and west facing windows. Plants can be utilised to provide shade for such windows. In general, landscaping can be used to prevent undesirable heat gain in the summer.

Cooling via Convection –
The simplest and oldest type of convective cooling is meant to draw cool night air in from the outside while pushing hot inside air out. If night-time breezes are present, a high vent or an open on the leeward side will allow heated air near the ceiling to escape. Low vents on the opposite side will allow cold night air to replace the heated air.

Convective cooling can still be used in places where there aren’t any prevailing breezes by constructing thermal chimneys. Warm air rises, hence thermal chimneys create a warm or hot zone of air and have a high outer exhaust exit. The building’s heated air is vented through a high vent, while cooler air is brought in through a low vent.

Glazing –
Glazed windows and doors have a substantial impact on your home’s thermal efficiency. Up to 40% of a home’s heating energy can be lost through glazing, while up to 87 percent can be gained. You should choose glazing that is appropriate for your climate and orientation.

Thermal Mass –
Thermal mass in a passive solar home collects heat from the sun during the heating season and heats air in the house during the cooling season. Although other thermal mass materials, such as water and phase change materials, are more efficient in storing heat, masonry has the advantage of being a structural and/or finishing material. The thermal mass inherent in home furnishings and walls may be adequate in well-insulated homes in moderate temperatures, obviating the need for extra thermal storage materials. While implementing this, you must ensure that no things are blocking sunlight from reaching thermal mass materials.

Sunspaces –
Sunspaces are not the same as greenhouses, which are used to cultivate plants. Sunspaces give supplementary heat, a sunny space to grow plants, and a pleasant living environment, among other things. These three roles have very distinct design considerations, and satisfying all three functions necessitates tradeoffs. A sunspace that can be closed off from the house with doors, windows, and other moveable openings is the most typical isolated-gain passive solar home design. A sunspace, also known as a sunroom, solar room, or solarium, can be built into a new home or added to an existing one.

Tools –
There are several tools and software that can assist in calculating the amount of sunlight entering the space. The height, azimuth, sky dome, sun’s location, sun’s path, monthly paths, latitude, and magnetic variations are all studied on the cylindrical sun chart. Other tools, such as the solar radiation calculator and shade masks, can assist in determining all necessary estimates prior to the project’s construction.

Conclusion
Passive solar design makes use of the sun’s energy and its predictable seasonal movements to heat and cool a building without the use of any additional mechanical devices. It can be compared to aikido in terms of architecture. To limit summer solar heat gain in most climes, an overhang or other devices such as awnings, shutters, and trellises will be required. During the cooling season, landscaping can also assist keep your passive solar home cosy. Consult an architect who is knowledgeable with passive solar techniques if you are considering passive solar design for a new home or a substantial retrofit.

References

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Kanwarjot Singh

Kanwarjot Singh is the founder of Civil Engineering Portal, a leading civil engineering website which has been awarded as the best online publication by CIDC. He did his BE civil from Thapar University, Patiala and has been working on this website with his team of Civil Engineers.

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