White Paper: «Geothermal Energy for the Architecture of Tomorrow»
Editorial
«In the face of increasingly urgent climate and energy crises, it is crucial to rethink our approach to building design and management and seek out local, resilient energy systems. The ELIXAIR® Earth-Air Heat Exchanger (EAHX) provides an innovative response to these contemporary challenges.
Unlike traditional air conditioning systems, which recycle air and consume significant amounts of energy, EAHXs operate as a passive solution, harnessing the stable temperature of the ground—its warmth in winter and its coolness in summer—to regulate indoor climate. With no limitation on building volume, they are ideally suited for non-residential applications.
Table of Contents
We integrate these systems into large-scale projects such as airports, hospitals, and data centers, where airflows reaching several hundred thousand cubic meters enable substantial energy savings. Our largest installation operates at 110,000 m3/h.
EAHXs deliver a rapid return on investment through energy savings and reduced costs associated with thermal discomfort. Manufactured from cast iron, the ELIXAIR® range stands out for its superior lifespan and energy efficiency while minimizing installation costs and land-use requirements.
By adapting this time-tested solution to today’s technical and thermal standards, Pam Building has made ELIXAIR® one of the most forward-thinking solutions for the future of architecture. This technology represents a major step toward durable, resilient buildings. It is an infinite source of energy savings and comfort.»
Maxime Pappens, ELIXAIR® Product Manager at Pam Building
Geothermal Energy Overview
Geothermal energy harnesses the Earth’s internal heat for various applications, including heating, cooling, and electricity generation.
Active geothermal systems use heat pumps (HPs) to extract thermal energy, requiring an external electricity source.
Passive geothermal solutions, such as Earth-Air Heat Exchangers (EAHXs), rely on proven techniques that operate without external energy input. These systems leverage the ground’s stable temperature to precondition incoming air, offering significant benefits in energy efficiency and thermal comfort.
A Solution Aligned with Environmental Regulations
In France, the RE2020 environmental regulation imposes strict energy performance requirements for buildings, encouraging the adoption of geothermal solutions. EAHXs positively impact three key RE2020 indicators in new constructions:
• Icénergie: Assesses the building’s carbon footprint related to energy consumption over its lifecycle.
• Cep,nr: Evaluates the consumption of primary energy from non-renewable sources.
By integrating EAHXs, buildings can achieve superior energy efficiency, reduce their environmental footprint, and enhance occupant comfort.
ELIXAIR® Earth-Air Heat Exchanger
The ELIXAIR® EAHX utilizes a network of underground pipes buried at a minimum depth of 2 meters to harness the thermal inertia of the soil. Acting as an air-to-ground heat exchanger, this system provides:
• Heating and preheating in winter: Reduces heating demand by up to 30%.
• Cooling in summer: Covers up to 100% of cooling needs without requiring air conditioning equipment.
• Distribution of tempered and filtered air: When integrated with an Air Handling Unit (AHU), the EAHX ensures a consistent indoor temperature without sudden fluctuations or drafts.
Technical Certification
The ELIXAIR® EAHX has been certified by the CSTB (Scientific and Technical Center for Building) under Technical Approval AT 14.5/23-2310 since 2011. The CSTB is an independent French organization that evaluates the performance, safety, and compliance of innovative construction solutions. This certification provides a regulatory framework covering thermal, technical, and hygienic aspects, ensuring that the system meets the highest industry standards. Additionally, it qualifies the installation for a 10-year liability guarantee, offering long-term reliability and security for building projects.
Your Partner from Start to Finish
Pam Building provides comprehensive support throughout the implementation of ELIXAIR® Earth-Air Heat Exchanger projects, from design to installation. As designers and manufacturers, we offer strategic guidance to efficiently integrate EAHXs into architectural projects while ensuring seamless coordination between all stakeholders on-site.
Interview
Jean-Jacques Graff has been the President of the French Association of Geothermal Professionals (AFPG) since 2010 and is a key figure in the development and promotion of geothermal energy in France. The AFPG was founded to give a voice to this often-overlooked renewable energy technology. With over 20 years of experience in the sector, including roles at Électricité de Strasbourg and the Arverne Group, Jean-Jacques Graff has been a pioneer in deep geothermal projects. Through his expertise, he highlights the benefits of geothermal energy and the challenges to overcome in making Earth-Air Heat Exchangers (EAHXs) the new energy standard for nonresidential building projects.
«Earth-Air Heat Exchangers are on track to becoming a key standard in the non-residential building sector.»
Why are geothermal solutions currently gaining traction?
Geothermal energy is attracting growing interest due to today’s climate and economic challenges. Despite its long-term profitability, it has historically been underutilized, lacking sufficient support in France, where short-term solutions like gas and nuclear electricity have long been prioritized.
As renewable energy sources mature, traditional options are revealing their limitations, making geothermal and solar thermal increasingly relevant alternatives. While geothermal energy harnesses a free heat source from the ground, its development has been hindered by a lack of commercial backing, unlike other energy sources such as wood or gas.
Today, the need for a long-term energy strategy is increasingly recognized. Geothermal energy, which enhances energy sovereignty, has proven its benefits in countries like Sweden, which have withstood the energy crisis and rising gas prices more effectively. This awareness, intensified by escalating energy costs, is leading many decision-makers to consider geothermal energy as a sustainable and viable solution.
Why are Earth-Air Heat Exchangers a relevant solution today for heating, cooling, energy savings, and building comfort?
One of the main advantages of Earth-Air Heat Exchangers is their ability to leverage the ground’s stable temperature for efficient cooling, even during extreme heat. This technology is particularly suited for large-scale cooling applications.
A key challenge today is shifting mindsets toward long-term planning. Energy analyses and comparisons are often conducted over 20-year periods, whereas geothermal installations, such as boreholes and Earth-Air Heat Exchangers, can last for several decades. When business plans are recalculated over longer periods, the profitability and efficiency of geothermal solutions become undeniable, requiring a fundamental shift in perspective.
Fortunately, awareness is growing. More and more decisionmakers, investors, and engineering firms recognize the longterm benefits of these technologies. Over a 50-year horizon, the advantages of Earth-Air Heat Exchangers are indisputable.
How are today’s Earth-Air Heat Exchangers more efficient than those from fifteen years ago? What challenges have manufacturers successfully addressed?
Fifteen to twenty years ago, the idea of leveraging the thermal stability of the ground to create EAHXs was already being explored. However, the available equipment at the time was inadequate, leading to underwhelming performance.
Fortunately, the market has evolved thanks to the initiatives of specialized companies. Around 2010, technically adapted products were developed, supported by detailed documentation.
These advancements marked a turning point, as today’s equipment is significantly more efficient than that of fifteen years ago. This progress stems from an industrialization process driven by research, innovation, and field experimentation.
The development of EAHXs follows a virtuous cycle: past mistakes inform product improvements, and user feedback refines solutions. This natural evolution has made Earth-Air Heat Exchangers a high-performing and reliable solution, perfectly suited to modern energy efficiency needs.
Earth-Air Heat Exchangers are increasingly being integrated into ambitious non-residential building projects. Can you tell us more about this growing trend? What key challenges do EAHXs address that make them so relevant today?
The growing adoption of EAHXs in non-residential building projects is largely due to the support and advocacy of key industry players, such as the French Association of Geothermal Professionals (AFPG), which has proposed their inclusion in the ADEME (a French public institution dedicated to supporting the implementation of environmental policies in France) Heat Fund.
This fund, dedicated to decarbonation and renewable energy, has increased the visibility and credibility of Earth-Air Heat Exchangers among decision-makers and project owners. By incorporating these technologies into the scope of subsidized equipment, they become more accessible and standardized. This official recognition enables engineering firms to recommend EAHXs as a viable solution. Additionally, their efficiency and low operating costs make them particularly attractive. The longterm savings, combined with their proven performance, are driving more and more investors to adopt this solution.
As a result, Earth-Air Heat Exchangers are on track to becoming a key standard in the non-residential building sector. The growing adoption of these technologies is creating a positive momentum that is expected to continue strengthening.
Do you think Earth-Air Heat Exchangers will gain more traction in the coming years? Why?
Earth-Air Heat Exchangers are a highly efficient cooling solution, and their development is expected to accelerate in the years ahead. The current generation of products is of high quality, and the technology is well-established, supported by rigorous oversight, including training and technical documentation. With increasing cooling demands, EAHXs present themselves as a sustainable and cost-effective option. They ensure longterm thermal comfort at a very low operating cost. Alongside geothermal energy and solar thermal, Earth-Air Heat Exchangers form a promising trio for sustainable construction. Ideally, public authorities should mandate their integration into new buildings, as some Swiss cantons have already done. While the initial investment is higher, it is quickly offset by operational cost savings. With public policy support and a strong regulatory framework, Earth-Air Heat Exchangers are well-positioned to become a mainstay in the building sector.
Geothermal Energy: A Source of Comfort
Comfort for People
Investing in Earth-Air Heat Exchangers (EAHXs) is not only justified by economic considerations but also by the comfort and well-being of users. For SMEs, offices, and educational institutions, poor working or learning conditions have significant social costs.
With rising temperatures and increasing energy costs, EAHXs offer an efficient solution for passive preheating and cooling, making the investment increasingly beneficial in the long run.
Among all ELIXAIR® Earth-Air Heat Exchangers installed worldwide by Pam Building in recent years, 16% have been implemented in office spaces, including coworking facilities and corporate offices.
Comfort for Goods
EAHXs play a crucial role in preserving goods while minimizing energy consumption. By reducing humidity and temperature fluctuations, they improve storage quality for various buildings.
They are particularly well-suited for farmers and market gardeners, where stable conditions are essential for produce preservation.
Earth-Air Heat Exchangers are also an ideal solution for wineries, where precise temperature and humidity control is critical to maintaining wine quality.
Additionally, these systems are used in pharmaceutical storage and raw material preservation for perfume production, demonstrating their effectiveness in any industry requiring strict climate control.
Comfort for Machines
EAHXs enhance the efficiency of industrial machinery, which is essential for production.
For example, in a wastewater treatment plant that uses lime for sludge drying, temperatures can reach 80-90°C. Traditionally, these facilities require largescale ventilation with outside air, leading to high operational costs.
By integrating an EAHX, the need for fresh air renewal is significantly reduced, resulting in substantial cost savings in plant operations.
Comfort for Animals
Earth-Air Heat Exchangers also contribute to animal welfare in indoor farming environments.
In Quebec, a goat farm replaced its air conditioning units with an EAHX system, drastically reducing the summer mortality rate of young goats from 62% to 15%.
This demonstrates the potential of EAHXs to improve living conditions for livestock while offering energy-efficient climate regulation.
«For our direct-sale store, the Earth-Air Heat Exchanger has been a true game-changer. It allows us to maintain an ideal temperature year-round—22°C during a heatwave when it’s 35°C outside—providing natural and cost-effective cooling while creating a pleasant atmosphere for our customers.
In winter, it also ensures a stable and comfortable freshness, perfectly suited for preserving our fruits and vegetables. With rising energy costs, the EarthAir Heat Exchanger has become essential for controlling our expenses without compromising comfort. It’s a winning investment on every level.»
Nicolas Richaudeau, Owner of Vergers d’Attainville (95)
Earth-Air Heat Exchangers: Driving Change
Earth-Air Heat Exchangers address the evolving needs of nonresidential building construction in response to climate change. This low-tech and long-lasting approach ensures optimal ventilation and thermal regulation, making it an ideal solution for smart buildings.
EAHXs integrate seamlessly into energy-autonomous projects, such as Earthship homes, which rely on recycled materials and bioclimatic systems to achieve self-sufficiency.
Additionally, they provide a strategic energy advantage. The French military, a key client of Pam Building, values the ELIXAIR® Earth-Air Heat Exchanger for its ability to reduce or even eliminate dependence on external energy sources.
Earth-Air Heat Exchangers align with a sustainability-driven mindset, offering a passive alternative that lowers operational costs while meeting modern demands for durability and environmental responsibility.
A Key Material for Circular Economy
The latest ELIXAIR® Earth-Air Heat Exchanger range is made of 99.4% recycled scrap metal, sourced from materials such as car wheels and washing machines, collected within a 250-kilometer radius of the Pam Building factory. ELIXAIR® cast iron is fully recyclable without losing its properties, making it a sustainable and long-lasting choice.
Technical Properties
• High thermal conductivity: 46 W/mK
• Heat capacity: 450 J/(kg·K)
• Mechanical strength: Cast iron withstands 350 MPa (equivalent to 3,500 bars of pressure)
• Longevity: 70 to 100 years of service life
They Chose Geothermal Energy
Built in 2022 in Bruges (France), the Frida Kahlo school group was awarded the E4C2 label, one of the most demanding environmental certifications in France. The E4 rating represents the highest level of energy performance, while C2 denotes the lowest environmental footprint for a building.
Thanks to the ELIXAIR® EarthAir Heat Exchanger, this school benefits from passive cooling in summer and preheating in winter, while ensuring optimal indoor air quality for students and staff.
Client: Ville de Bruges (France)
Architect: Compagnie
Architecture
Engineering Firm: Albert & Co
Segmentation of 180 ELIXAIR® Installations
(in number and airflow capacity)
For more details on the technical properties of ELIXAIR® Earth-Air Heat Exchangers, refer to our technical brochure.
Easy Installation with Certified Standards
The installation of ELIXAIR® EAHXs follows the NF EN 1610 standard, which applies to sanitation and drinking water networks, ensuring a straightforward and compliant implementation. Cast iron also reduces installation costs and land requirements thanks to its energy efficiency and ability to maintain higher airflow velocity.
Geothermal Energy: A Source of Savings
In a context of growing pressure on traditional energy sources, rising material costs, and overall inflation affecting various sectors, energy savings have become a priority—not only for the planet but also for the economic viability of projects and the well-being of end users. As energy demands continue to rise, finding long-term, efficient solutions is essential to balance budgets and meet environmental commitments.
An Innovative Solution
Earth-Air Heat Exchangers provide an innovative and cost-effective response to modern energy challenges. By harnessing infinite natural resources—the air and the stable temperature of the ground—these systems enable substantial energy savings for buildings. Thanks to their geothermal-based operation, EAHXs use the ground’s stable temperature to precondition incoming air, significantly reducing the need for additional heating or cooling.
Energy Savings
The energy savings achieved with Earth-Air Heat Exchangers are considerable. These systems can cover up to 100% of cooling needs and reduce heating demand by up to 30%, depending on sitespecific conditions.
This ability to efficiently regulate indoor temperature not only reduces energy consumption but also lowers costs associated with traditional heating and cooling systems.
Simplified Installation
The economic benefits extend beyond energy savings. On construction sites, ELIXAIR® Earth-Air Heat Exchangers offer significant cost and time advantages. Their installation is faster and less expensive than other EAHX systems on the market, thanks to their straightforward design and the use of cast iron, a highly durable material. This time efficiency and reduced installation costs help improve the financial viability of projects, making ELIXAIR® a strategic and cost-effective choice.
The ELIXAIR® Earth-Air Heat Exchanger: A Source of Comfort
In a context where indoor air quality (IAQ) and occupant health are critical concerns for non-residential buildings, the ELIXAIR® Earth-Air Heat Exchanger (EAHX) stands out as an exemplary solution.
Its components are specifically designed to prevent the long-term development of bacteria and fungi, as confirmed by testing conducted by the MEDIECO Institute.
Filtration and Certification
The ELIXAIR® range is chemically inert and equipped with a coarse ISO 60% (G4) filter at the intake, ensuring effective filtration of incoming air. Additionally, ELIXAIR® EAHX is VOC free VOC emissions the highest distinction for low volatile organic compound emissions, guaranteeing superior indoor air quality.
Odor Prevention
To prevent odors caused by condensation, ELIXAIR® separates the water flow from the airflow using a consistent 1.5% slope within a sealed inspection chamber. This technical design ensures that air remains pure and healthy, maintaining a comfortable indoor environment.
Performance and Reliability
Following four years of extensive studies, ELIXAIR® obtained its Technical Approval in 2011, validating both its performance and reliability. This approval serves as a recognized validation for the construction sector, similar to technical assessments and certifications in other countries. Laboratory tests and biannual field measurements have demonstrated that this system effectively manages condensation, prevents the growth of bacteria and mold, and limits the accumulation of volatile organic compounds. As a result, ELIXAIR® Earth-Air Heat Exchangers ensure impeccable indoor air quality, while delivering high energy efficiency and optimal comfort for building occupants.
How does an Earth-Air Heat Exchanger improve indoor air quality?
The Earth-Air Heat Exchanger uses a coarse ISO 60% (G4) filter to clean incoming air and regulates humidity, preventing the growth of bacteria and mold. Tests confirm that it ensures optimal indoor air quality.
What are the health benefits of an Earth-Air Heat Exchanger?
The temperature and humidity conditions within an Earth-Air Heat Exchanger inhibit the development of diseases such as salmonellosis. It provides a healthy indoor environment through specific design and inert materials.
Is an Earth-Air Heat Exchanger suitable for all types of buildings?
Yes, while often associated with single-family homes, Earth-Air Heat Exchangers are also widely applicable to various non-residential buildings, with no airflow limitations.
How important is the ventilation system for the efficiency of an Earth-Air Heat Exchanger?
A well-designed and properly integrated ventilation system is essential to maximize the performance of an Earth-Air Heat Exchanger. Pam Building collaborates with industry experts to ensure optimal synergy between both systems.
For more information about the ELIXAIR® Earth-Air Heat Exchanger, refer to our technical brochure.
Interview
Michel Le Sommer, a trained wood engineer, founded Le Sommer Environnement in 2002. Over the past 20 years, this environmental engineering consultancy has specialized in energy and water resource management, contributing its expertise to more than 200 prestigious international projects at the forefront of energy innovation.
Some of the firm’s notable projects include: European Space Agency headquarters in Paris, Diar el Djenane Eco-District in Algiers et Nice Méridia office complex, winner of the Mies Van der Rohe European Contemporary Architecture Award. He explains how Earth-Air Heat Exchangers align with the sustainable approach that he and his team advocate.
«The Earth-Air Heat Exchanger is destined to become widespread in response to an increasingly severe resource crisis.»
What is the benefit for your clients in choosing an Earth-Air Heat Exchanger?
For over 40 years, have been studying carbon impacts and passive construction techniques. Earth-Air Heat Exchangers perfectly illustrate how to make the most of local resources.
They offer a primarily economic advantage, with short-term benefits. In terms of summer comfort, they are also highly effective, maintaining indoor temperatures as low as 18°C even when outdoor temperatures reach 42°C, provided that bioclimatic building design is well-executed.
They also provide a strategic advantage in preparing for climate change. Adopting local passive systems will ensure both comfort and resilience in the face of future crises.
For what types of projects have you chosen to integrate Earth-Air Heat Exchangers?
have worked on the design of several projects, including wine cellars, office buildings, and vineyards.
The most recent project, inaugurated in April 2024, is Château Cantenac Brown in Margaux. Alongside the architect and project owner, we aimed to create a highly autonomous building, anticipating climate change by integrating Earth-Air Heat Exchangers, alongside highly insulated building materials such as rammed earth, raw earth bricks, cork, and wood.
Another significant project is a château in Malraux, Bordeaux region, where summer heatwaves pose serious challenges. We installed EAHXs to supply offices, wine cellars, and the vat room, ensuring both wine and occupant comfort while reducing operational costs.
Is it easier to install Earth-Air Heat Exchangers today than it was 20 years ago?
Absolutely! The increasing number of installations and accumulated experience have led to a better understanding of thermal exchanges between the ground and the heat exchangers, simplifying implementation. Additionally, manufacturers like Pam Building have developed specialized expertise, advanced engineering, and digital tools that allow for better predictions of EAHX performance. Among these digital tools, dynamic thermal simulations enable us to model buildings to understand thermal exchanges, optimizing the function of Earth-Air Heat Exchangers. We also conduct global cost studies to evaluate return on investment, quantifying savings in cooling and heating demands, as well as financial savings.
Do you think the architecture of the future will see a rise in EarthAir Heat Exchangers?
Earth-Air Heat Exchangers are bound to become widespread in response to the increasing resource crisis and climate instability.
With ground temperatures remaining stable at around 15°C at a depth of 2 meters, EAHXs are an ideal passive solution to ensure optimal building comfort.
The main barrier remains the lack of awareness of this technique and historically low energy costs that have slowed its adoption. However, as resource scarcity becomes a more pressing issue, Earth-Air Heat Exchangers will become indispensable. This long-term, highly efficient solution will become essential as mindsets and needs evolve.
For over 160 years, Pam Building has been a leading expert in cast iron piping systems and water supply solutions. Leveraging its extensive experience, the company designs, manufactures, and markets highquality systems for sanitary and rainwater drainage in buildings.
As a specialist and market leader in cast iron, Pam Building is committed to excellence in its processes, products, and services.
Dedicated to innovation and sustainability, the company prioritizes the development of high-performance technologies that contribute to the creation of safe and environmentally friendly buildings
Pam Building’s mission statement reflects its vision: to build reliable structures for occupants while making a long-term positive impact on the planet.
With operations in France, England, and Germany, Pam Building is an internationally recognized company, known for its expertise and ability to address global challenges in the construction sector. Through the strength of its teams and its unwavering commitment to quality, Pam Building strives to shape a more sustainable and efficient future for the building industry.
Decarbonization: Committed to Even Greater Efficiency
Our Key Figures
2 manufacturing sites
Bayard-sur-Marne, France & Telford, Englan
1 logistics platform Cologne, Germany
€110 million in revenue in 2023
Distribution in over 50 countries
More than 360 employees
35% of management positions held by women
1/3 of internships and apprenticeships converted into permanent contracts
+38 «Net Promoter Score» (NPS) Reflecting the number of employees willing to advocate for the company (on a scale of -100 to +100)
First company in the cast iron industry to publish an Environmental Product Declaration (EPD) validated by a third party
To reduce its environmental impact and achieve its goal of an 80% reduction in carbon emissions by 2030 (compared to 2017), Pam Building has implemented several key initiatives:
• Innovating to lower the carbon footprint of its products: After years of development and backed by a patent, the Agilium® range, launched in 2022, reduces CO2 emissions by 30% compared to the standard range (according to Environmental Product Declarations (EPDs) available on INIES and ENVIRONDEC databases).
• Reducing carbon emissions from the cast iron pipe manufacturing process: In 2024, Pam Building launched a project to develop an electric-powered furnace, utilizing France’s low-carbon electricity mix, with commissioning planned for 2028-2030 at the Bayard-surMarne site. This is a major step toward advancing the company’s circular economy and environmental responsibility goals. Cast iron is already a sustainable and fully recyclable material, and Pam Building’s products contribute to global environmental certifications such as HQE, BREEAM, LEED, and others.
• Sourcing green electricity for its Telford site in England, which has already been operating an electric furnace for several years.
