What is Passive Solar Energy?

One of the most evident phenomena or changes we have come across in recent times is related to the rapid shift towards sustainable consumption and renewable energy (thanks to global warming). Considering the state of global climate evolution and predicament, this shift is both reasonable and necessary. However, we can’t deny that a good chunk of the global population is still oblivious to what renewable energy is and, hence, many of them are still learning about it.

In this article, we’ll be looking at one particular aspect of prevalent renewable energy: passive solar energy. As time passes, more and more people are shifting towards sustainable consumption, and for a good reason. To understand what passive solar energy is and how it works, continue reading ahead.

Overview: Solar Energy 

Before we dive into the world of passive solar energy, it’s essential that you first understand what solar energy is and how it works.

What Is Passive Solar Energy

Solar energy is merely the energy garnered from the rays of the sun touching the Earth’s surface. Additionally, this energy can further be divided into two broad categories:

(i) Active solar energy

(ii) Passive solar energy

Both of these solar energy types can be leveraged through different solar systems and designs to power homes and appliances without conventional power sources such as electricity and gas. The best thing about using solar energy is that it doesn’t damage our ecological surroundings, ensuring a healthier and happier Earth.

Today, we’ll be focusing on passive solar energy, its core elements, benefits as well as shortcomings.

What Is Passive Solar Energy?

Passive solar energy refers to the ability or technology to harness energy (electricity) from the sunlight without using any external devices or machines. It can be used for cooling and heating purposes of living space. When sun rays strike a structure (home, building, etc.), the structure’s materials can redirect, transmit, and/or absorb the solar radiation. Moreover, the heat created by the sun triggers air movement that can easily be predictable in controlled, designed spaces. These fundamental reactions to solar heat lead to material choices, design elements, and placements that can deliver heating and cooling effects in a space.

Unlike active solar systems, passive solar designs function without relying on external devices. Instead, a passive solar design uses “passive collectors” to convert rays into energy. These collectors are based on “Laws of Thermodynamics” that convey heat from warmer to cooler surfaces.

In addition, passive solar energy design and systems are simple and don’t entail substantial use of electrical and mechanical devices, such as solar photovoltaic technologies like solar panels, fans, pumps, or electrical controls to transfer solar energy. Common examples of passive solar technology include sunrooms and greenhouses.

5 Core Elements of Passive Solar Energy Design 

To efficiently use passive solar energy, a passive solar design must encompass the following elements and ensure they work together effectively. Here are the five core elements of a successful passive solar energy design:

#1: Collector/Aperture

It refers to the massive glass area through which sun rays enter space. The collector(s) or aperture(s) must always face within thirty degrees of true south and should never be shaded by other structures (building, trees, boards, etc.) from nine in the morning to three in the noon every day during the summer season.

#2: Absorber

Refers to the dark, solid surface of the storage element. The surface, which could potentially be a floor, water container, or masonry wall, sits in the direct path of sunrays. When these rays hit the surface, they are absorbed as heat.

#3: Thermal Mass

Includes materials that store or retain sunlight-induced heat. Unlike the absorber, which is an exposed surface, the thermal mass refers to the material behind and below the surface.

#4: Distribution

Refers to the process through which solar heat flows from the collection and storage points to different areas of space. A strictly passive solar energy design will exclusively use the following natural heat transfer modes:

  1. Conduction
  2. Convection
  • Radiation

However, in some cases, blowers, ducts, and fans can also be used to distribute the energy throughout the space.

#5: Control 

In summer, roof overhangs can be utilized to shade the collection area. In addition, elements that control over and/or underheating involve electronic sensing devices, like a differential thermostat, operable dampers and vents, awnings, and low-emissivity blinds.

In a nutshell, a passive solar design accumulates heat as the sun gleams through south-facing spaces (windows) and stores it in thermal mass. The share of space’s heating load that a passive solar design can fulfill is known as the “passive solar fraction.”

It entirely depends on the amount of thermal mass and the space of glazing. The ideal fraction of glazing to thermal mass differs by climate. A well-designed passive solar system can provide adequate heating in winters and cool in summer.

Passive Solar Energy: Benefits & Shortcomings

To help you make an informed decision, we’ll be sharing both the negative as well as the positive aspects of positive solar energy systems:


  • Passive solar energy systems are independent of external equipment and devices, making the entire setup significantly cheap.
  • By utilizing passive solar energy, your energy expenditure costs can be slashed by almost fourteen percent.
  • Passive solar systems don’t trigger allergies or dry out mucous membranes, proving to be a great option for your overall health.


  • The efficiency of passive solar systems depends heavily on the weather. For instance, if you’re living in a warmer area, your space would be more prone to overheating.
  • For maximum success, you must choose the right kind of windows.

Our Final Thoughts

Overall, there’s no denying that switching to sustainable consumption is beneficial for both you as well as our surrounding environment. Using passive solar energy can help you save up on utility bills, limit your carbon footprint, and foster sustainable living.

With the increasing popularity of “Green Real Estate,” passive solar energy design and systems are being used everywhere.

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