Tuesday, July 1, 2025
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The NZEB rating, increasingly commonplace, ensures that any building has near-zero energy consumption
By Miguel Ángel García Vega
Sometimes, behind the most complex acronyms lies true beauty. NZEBs. These are buildings with near-zero net energy consumption. Architects and engineers design them to minimize energy use, employing high-efficiency insulation, windows, and ventilation systems, together with renewable energy sources (such as solar, wind, or geothermal power), to fully meet their energy needs. Think of it as a math equation: there’s always a solution. “NZEBs drastically reduce greenhouse gas emissions and significantly lower the environmental footprint,” explains Eric de Tessières, Chief Sustainability Officer (CSO) at asset manager Rothschild AM. Carlos Lamela, co-founder and executive president of the architectural firm Estudio Lamela, notes that NZEB buildings can achieve up to a 90% reduction in operational CO2 emissions and over 75% less consumption of non-renewable primary energy compared to conventional buildings, thanks to their high energy efficiency and use of renewable sources.
While the initial investment may be high, the long-term benefits are considerable. NZEBs represent both the future and the present of sustainable architecture. They offer exceptional energy efficiency, reducing energy demand by up to 75% compared to conventional buildings, according to the cited firm. Their remaining energy needs are largely met by renewable sources such as photovoltaic solar panels, aerothermal systems, and geothermal energy. Their goal is to minimize environmental impact and limit greenhouse gas emissions, while ensuring occupant comfort and indoor environmental quality.
It’s important to remember that most emissions in a building’s life cycle occur within the first two years, during raw material extraction, manufacturing, transportation, installation, and waste disposal. As Ferrovial points out, these buildings are still relatively uncommon in Spain, but their development is expected to accelerate, driven by public sector initiatives, environmentally conscious property owners, and projects already being launched under this standard.
To meet these requirements, architects must optimize the thermal envelope (the building's outer shell), incorporate high-efficiency HVAC systems, use sustainable energy sources, and adopt passive design strategies that leverage local climate conditions. It has been quite some time since Brussels established regulatory benchmarks in this area. Buildings must comply with the requirements of Directive 2010/31/EU, which addresses the energy efficiency of buildings and their renovations, setting consumption limits and mandating the integration of renewable energy sources. In fact, the United Nations estimates that in order to limit the global temperature increase to less than 2ºC by 2030, the real estate industry must reduce the energy intensity of buildings by at least 30%.
Architecture has clearly stepped up to the challenge. A clear example is the Madnum building (Madrid), designed by Estudio Lamela, which was planned entirely according to these principles: sustainability, reduced energy consumption, and the integration of renewable energy sources. The core of NZEB standards. “It’s not about eliminating consumption, but about consuming better—aiming for energy savings, efficiency, and renewable energy,” explains Carlos Lamela, the company's founder.
Multinational corporations are also spearheading this change. Initially, they aim to expand their offices, especially in iconic buildings. “And they rule out any buildings that fall below certain energy efficiency thresholds,” says Roberto Scholtes, Head of Strategy at Singular Bank. Buildings certified A, LEED Platinum, or NZEB repeatedly demonstrate the value behind the acronyms. These are the properties with the highest demand and lowest vacancy rates. Their advantages fall into place like a perfectly aligned domino effect. Although, according to Ferrovial, the cost of constructing a NZEB can be between 5% and 10% higher than a conventional building, this premium is offset by energy savings between 80% and 90%, reduced maintenance costs, and increased property value: efficient buildings command higher demand and market prices.
This is the context surrounding those structures bearing a complex acronym: NZEBs. Their details resemble a checklist of environmental best practices. They use high-performance insulating materials, efficient heating and cooling systems, precise lighting mechanisms, solar panels or wind turbines as energy sources, and smart building technologies. It's a three-way dialogue between civil society, engineering, and architecture.
A bit of historical perspective is also important. In 2003, Edmond de Rothschild Real Estate Investment Management (EDM REIM), the real estate investment arm of the Rothschild group, completed a sustainable renovation of a historic building dating back to 1765, located alongside the canals of Amsterdam (Netherlands). The project aimed to modernize the office, make it more sustainable, and look toward the future. It achieved an energy rating of A. The key lies in using the most advanced materials—high-performance, as industry experts call them—while still incorporating traditional materials like wood. Wood serves as a natural sound insulator and a pathway to eco-friendly construction. The OMBU building in Madrid, commissioned by Ferrovial and designed by Foster & Associates, is based on this premise.
NZEB examples
If we used to focus on financial concerns, now sustainability is front and center. Cities need to become more inclusive, safe, and efficient. Urbanization is accelerating worldwide. According to the United Nations, by 2030, around 60% of the world's population will live in cities. Are we ready? Because it’s a double-edged sword. Cities generate nearly 60% of the world’s GDP; however, they also account for 70% of global carbon emissions and over 60% of resource consumption. How can we find balance as urbanization accelerates? The answer brings us back to those familiar initials: NZEBs. Building sustainably. The former pavilion of the 1992 Seville Expo is being renovated according to these principles. Meanwhile, two buildings at the city’s Congress Palace are pioneers in applying the now well-known Energy Saving Certificates (CAEs) in Andalusia. It’s a document that guarantees energy savings have been achieved. How? “From installing renewable energy systems in buildings to windows with thermal break technology,” explains Enric R. Bartlett Castellà, Professor of Public Law at Esade Law School. Countless standards and certifications are heading in the same direction.
Other examples come again from history. In Europe, around 90% of buildings were constructed before 1990, and 40% before 1960. A standout case, notes Zsolt Kohalmini, Global Head of Real Estate Assets at Pictet Alternative Advisors, is the project Bosco Verticale (Vertical Forest), a residential complex in Milan, Italy, featuring 20,000 trees, shrubs, and perennials that capture carbon, produce oxygen, and reduce energy consumption. And it all ties back to a rather intricate acronym: NZEB.
Miguel Ángel García Vega
He has been writing for EL PAÍS for some 25 years, currently for Cultura, Negocios, El País Semanal, Retina, Suplementos Especiales, and Ideas. His texts have been republished by La Nación (Argentina), La Tercera (Chile) or Le Monde (France). He has received, among others, the AECOC, Accenture, Antonio Moreno Espejo (CNMV) and Ciudad de Badajoz awards.
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