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Meet the oldest air conditioner in the world — it can reduce the temperature of your home by up to 5°C for almost FREE

Published 20/01/2025 às 16:44
temperature, air conditioning
Photo: Reproduction

With cheap materials and an ancient technique, it is possible to reduce the temperature of your home in a sustainable and economical way. Discover this incredible secret for hot days.

Ground-to-air heat exchangers, also known as “Earth Tubes“, which many say is an ancient air conditioner, is a passive heating and cooling technology that uses the relatively constant temperature of the ground to efficiently and efficiently air-condition environments. sustainable.

This solution has attracted increasing attention in Brazil due to the growing demand for sustainable practices and the need to reduce energy consumption in buildings.

In this article, we explore the history of the technology, how it works, benefits and challenges, as well as studies carried out in Brazil that demonstrate its potential.

History of Ground-to-Air Heat Exchangers

According to Laboratory of Energy Efficiency in Buildings (LABEEE) of the Federal University of Santa Catarina, the use of soil as a thermal regulator is not a new idea.

Ancient civilizations, such as the Persians, used underground tunnels to cool buildings during scorching summers.

In Europe, during the Middle Ages, underground ventilation systems were created to control the temperature of cellars.

With the advancement of technology, the concept evolved into more sophisticated systems of heat exchange between air and soil, being widely adopted in countries with extreme climates, such as Germany, France and the United States.

In Brazil, the implementation of these systems is more recent, but is gaining prominence as architects and engineers seek solutions that combine thermal comfort and energy efficiency.

Air Conditioning, temperature
NATURAL Air Conditioning –

Studies conducted by universities and research institutions reveal the potential for application in different regions of the country.

The need for more sustainable construction drives this technology as a viable alternative for commercial and residential buildings.

How Ground-to-Air Heat Exchangers Work

The operating principle of ground-to-air heat exchangers is based on using the ground temperature, which remains relatively constant throughout the year, around 20°C to 25°C in Brazil, depending on the depth and geographic region.

The system consists of pipes buried at a depth of between 1,5 and 3 meters, where the thermal variation of the environment is significantly reduced.

Outside air is drawn through these pipes, exchanging heat with the ground. In summer, the hot air is cooled before entering the building; in winter, the cold air is heated.

This process results in a reduction in the need for conventional air conditioning systems, generating energy savings and promoting a more comfortable indoor environment.

Air Conditioning, temperature
Operation of NATURAL Air Conditioning –

Main system components

piping: It can be made of materials such as PVC, concrete or metal, depending on the desired durability and cost.

art entrance: Generally positioned in elevated locations to avoid contamination by dust and humidity.

Air outlet: Distributed throughout the building’s internal spaces.

Drainage system: Essential to prevent the accumulation of moisture and the growth of fungi and bacteria.

Ventilators: They help with air circulation if there is not enough natural ventilation.

air filters: Can be added to ensure better indoor air quality by removing unwanted particles.

    Studies and applicability in Brazil

    The application of ground-to-air heat exchangers in Brazil has been the subject of research in several regions of the country. Studies conducted by the Federal University of Santa Catarina (UFSC) have shown that the technique can be particularly effective in regions with a large temperature range, such as Brasília and Porto Alegre.

    A study carried out in the city of Alexânia, in Goiás, measured soil temperature at different depths (0,5 m, 1,0 m, 1,5 m, 2,0 m and 2,5 m).

    The results indicated that the ideal depth for installing the pipes would be between 1,5 m and 2,0 m, where the temperature remains more stable throughout the year.

    Another study conducted in Florianópolis evaluated the performance of an experimental system installed in a residence.

    The results showed that the system was able to reduce the internal temperature by up to 5ºC in the summer months, providing greater thermal comfort without the need for air conditioning.

    In addition, researchers have evaluated the impact of ground-to-air heat exchangers on the energy efficiency of commercial buildings, showing that the technology can significantly reduce air conditioning costs in medium and large buildings.

    Challenges and considerations to reduce temperatures in Brazil

    Despite the advantages, the implementation of ground-to-air heat exchangers in Brazil faces challenges, such as:

    Hot and humid climate: In regions such as the Northeast, high humidity can limit the effectiveness of the system, requiring complementary dehumidification solutions.

    Initial cost: Installing underground pipes can have a high initial cost, despite the long-term savings.

    Predictive: Preventing mold and bacteria in pipes requires periodic maintenance to ensure air quality.

    Technical ignorance: Many construction professionals are still unaware of the best practices for the proper installation and maintenance of these systems.

      Advantages and disadvantages of natural air conditioning that reduces the temperature

      Even with challenges, the benefits of ground-to-air heat exchangers are significant:

      • Sustainability: Reduction of energy consumption and carbon emissions.
      • Thermal comfort: Improved air quality and indoor temperature.
      • Low maintenance: When properly designed, systems require little intervention.
      • financial economy: Reduction in operating costs related to the use of conventional air conditioning systems.
      • Energy resilience: Greater independence from non-renewable energy sources.

      Ground-to-air heat exchangers represent an effective and sustainable solution for thermal control of buildings in Brazil.

      Although the technology is still relatively little explored in the country, its potential for application is promising, especially in regions with dry climates and large temperature variations.

      With more in-depth studies, investments in awareness and government support, these systems can become a viable and widely used alternative in sustainable constructions in Brazil.

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      Fabio Lucas Carvalho

      Journalist specializing in a wide range of topics, such as cars, technology, politics, shipbuilding, geopolitics, renewable energy and economics. I have been working since 2015 with prominent publications in major news portals. My degree in Information Technology Management from Faculdade de Petrolina (Facape) adds a unique technical perspective to my analyses and reports. With over 10 thousand articles published in renowned media outlets, I always seek to bring detailed information and relevant insights to the reader. For story suggestions or any questions, please contact me by email at flclucas@hotmail.com.

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