Passive Solar Energy: The Brighter Path to a Greener Future

Passive Solar Energy

Since ancient times, the heat and light energy contained in sunlight has been used by humans for their daily needs. From sun-drying foods as a method of preservation to heating and treating water, the sun’s energy has helped our ancestors in their everyday lives.

The invention of solar panels made it possible for us to harness solar radiation and convert it into electrical energy. With the addition of a solar battery, we can even store it and use it later. Though solar energy is considered the most popular among renewable energy sources, it necessitates initial investment in solar panel installation and its periodic maintenance.

This is where passive solar energy scores big. In this, there is no involvement of additional devices or conversion of solar energy to other forms of energy. Passive solar energy is its direct use for solar heating and cooling. 

In this article, you’ll learn everything about passive solar energy. The topics covered in this article are:

  • What is passive solar energy?
  • About passive solar design in architecture
  • Examples of passive solar energy
  • Advantages of passive solar energy
  • Techniques used to capture passive solar energy
  • Difference between active and passive solar energy
  • How passive solar energy transfer happens?

After reading this article, you’ll be aware of how you can harness and use passive solar energy and why it is important to incorporate it in buildings.

What is passive solar energy?

This is the use of solar energy without getting help from external devices. The sun’s energy is directly used to heat and cool the interiors of buildings. This forms the basic principle in bioclimatic architecture. 

When a building is designed to make the most of passive solar energy, the building materials used must be able to:

  • Capture, store, and use the heat energy in solar radiation during winter
  • Deflect heat energy contained in solar radiation during summer

A building design that conforms to these conditions is known as a passive solar design. The most important aspect of a passive solar design is the exclusion of electrical and mechanical devices in the capture of solar energy. This is immensely helpful in heating and cooling living spaces inside buildings.

More about passive solar design in architecture

Incorporating passive solar energy in a building design involves making the most of the local conditions and climate. This necessitates an accurate and extensive analysis of the building site. Though it is much easier to apply passive solar design elements in new buildings, it is also possible to adapt existing buildings.

The major elements in a passive solar building are:

  1. The position and size of windows. Sun-facing large windows help with gaining heat.
  2. The glazing used on window panes. This will significantly affect heat transference.
  3. The quality of thermal insulation. Better insulation can bring down the cost of heating and air conditioning.
  4. The existence of thermal mass. This can help in storing heat and reduce the burden of the heating system.
  5. The presence of shades, offered by trees and eaves of homes. This prevents the heating of interiors in summer.
  6. The availability of natural ventilation. This helps with air movement and brings down the temperature inside.

Absorption and transfer of heat are the foundation of passive solar building design. As such, the laws of thermodynamics need to be understood and followed while designing such buildings.

As the passive solar design doesn’t involve external interference, the few drawbacks of solar energy are eliminated. Such as its environmental impact. No solar panels or solar batteries are involved in the collection, storage, and distribution of passive solar energy. The non-inclusion of batteries filled with toxic chemicals is a huge gain for the environment.

Examples of passive solar energy

The most obvious examples of passive solar energy can be seen in the design and architecture of a building.

Thick and well-insulated walls: Better the insulation, the less chance of heat loss in winter and heat gain in summer. 

Ceiling and ventilation: The roof of a building bears the brunt of the harsh heat of solar radiation in the summer months. Proper ventilation means this heat is dissipated and doesn’t stay inside. 

Orientation of the windows: The southern side of the building receives the most sunlight. Having south-facing windows helps bring the sunlight into rooms and heat it up naturally in winter. 

Trees and plants: Vegetation offers shade. This prevents sunlight from falling directly on the building. This is beneficial in summer and not good in winter.

Dark-colored exteriors: Black and other darker shades absorb more heat energy in the sunlight while white and lighter shades deflect it. This is helpful when choosing exterior wall paints.

Exposing water pipes to sunlight: Water in the pipes gets heated naturally when they are exposed to the heat of the sun.

Advantages of passive solar energy

The benefits of harnessing passive solar energy are:

Minimal expenses: Most often, it involves no cost as it is all about making the most of what nature has provided free of cost for us.

Low maintenance: No extra devices or infrastructure is required in the process. This means little or no maintenance.

Eco-friendly: The whole idea behind passive solar energy is to work with nature and not tamper with it or manipulate it to our advantage. This means no pollution or greenhouse gas emissions, thereby no contribution to climate change.

Energy-saving: Passive solar techniques like space heating can bring down energy consumption significantly. When deployed in combination with active solar energy devices like solar panel systems, it can make a substantial reduction in your energy bills.

Passive solar technologies are more beneficial if they are incorporated into building design and architecture. Though it is possible to alter a building to take advantage of passive solar energy, it can never be as effective as if it is an integral part of the building design.

Techniques used to capture passive solar energy

Passive solar technologies use the building components to heat and cool building interiors using the Sun’s heat. The ceiling, walls, floor, windows, doors, south-facing walls/windows, elements in the building exterior, and landscaping are all components that can help in trapping passive solar energy.

While passive solar heating techniques collect and store the heat of solar radiation directly in the building’s components, passive cooling techniques are aimed at minimizing the heat absorbed from solar radiation with shades and ventilation.

Managing heat inside a building without additional devices involves mastering the technique to manage airflow in its interior. In fact, this forms the core of bioclimatic building design. In winter, it is all about trapping the warm air, while in summer, it is about dispersing and expelling the hot air.

Though passive solar energy involves only managing the heat energy in the sunlight, it can also help in energy saving to make the best use of natural light in the building design. By allowing the sunlight to light up the interiors, it is possible to reduce energy bills substantially. 

Incorporating natural sunlight in the building design can help create a naturally pleasing atmosphere, reduce expenses on air conditioning, and reduce the heat produced by light fixtures.

A Trombe wall is one such feature that can be added to the sun-facing side of the building to capture the heat. This massive wall is painted in dark color to absorb the maximum heat. It comes with an external glazed glass with an insulating air space from the wall. The Trombe wall helps with the heating, cooling, and ventilation of the building interior.

Types of passive solar collection

Not all passive solar collection techniques work the same. They can be classified based on the elements used in collecting and storing.

Passive solar collectors, as the name indicates, collect solar radiation. The elements used in the passive solar collection can be direct or indirect. In the direct technique, the collection happens directly and the heat is passed on to the room interiors also directly. The indirect passive solar technique involves the participation of building elements in the capture, storage, and distribution of heat to all parts of the interiors.

Passive solar accumulators store the collected heat energy for use at a later time. Typically, collection happens in the daytime and dispersion at night. Some accumulators are even capable of storing heat energy for longer durations.

Difference between active and passive solar energy

As their name suggests, the difference between the two is the way they collect and store solar energy. The solar energy transfer happens actively with active solar energy techniques. On the other hand, there is no active involvement of an external device, either electrical or mechanical, in the passive solar energy transfer.

One of the common examples of active solar energy devices is photovoltaic panels. In this, the heat energy captured is converted into electrical energy. In thermal solar devices, solar radiation is converted into heat energy. 

Passive solar energy is captured directly and used without processing it. These techniques are incorporated into the building design and architecture to make the best use of natural heat energy contained in the sunlight. 

Final thoughts on passive solar energy

Everything about passive solar energy is natural. There is no involvement of external devices in the collection, storage, and distribution of solar energy. All that you need to do is optimize the placement and dimension of various building elements such as walls, ceilings, and windows for passive solar energy collection and storage.

When made part of a building’s design and architecture, this technique can make huge savings on your energy bills.

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