As temperatures in Spain’s largest cities continue to climb, architect and professor José Luis Esteban Penelas is challenging conventional urban planning. Rather than rely on temporary fixes like fans or umbrellas, Penelas argues that cities need to change how streets and buildings are designed, along with their public spaces. The challenge is set to grow: an RTVE programme on future city design, published on 22 October 2026, cited a projection that three out of four people will live in large cities by 2050.
Penelas, who teaches architecture and building at Universidad Europea, recently said on La Brújula (Onda Cero) that Spanish cities are ill-equipped to handle prolonged heatwaves. Asphalt streets and treeless plazas are common, while buildings can trap heat for hours, making daily life increasingly uncomfortable and even dangerous. Spain’s Ministry of Health attributed 3,832 deaths to excessive heat between May and September 2025. MoMo estimates put heat-related deaths in June 2026 alone at 1,029. RTVE identifies Penelas as an architect and urbanist and frames his discussion with professor of social anthropology Manuel Delgado around redesigning cities to meet future demographic and environmental pressures.
Green Infrastructure as a Solution
Penelas’s vision goes beyond planting more trees. He proposes a broad shift toward what he calls “humanized forests,” urban environments where vegetation is treated as impressive infrastructure. That means bringing together tree canopies and green facades with pergolas, shaded corridors and spaces that retain moisture and release coolness during the day. Such measures, he says, can help cities break the cycle of heat absorption and retention that now defines their built environment.
AEMET, Spain’s meteorological agency, has documented the urban heat island effect. Asphalt and ceramic rooftops absorb and store solar radiation, while green spaces and vegetated roofs can significantly reduce that energy buildup. Penelas’s approach reflects growing recognition that cities must adapt for public health and ability to recover, as well as comfort. His focus on long-term planning also fits the demographic pressures outlined in RTVE’s October 2026 discussion, which set the redesign of cities against expected growth in urban populations.
Materials and Building Orientation Matter
One reason city centers feel so stifling, Penelas notes, is the widespread use of heat-trapping materials such as black asphalt and concrete. These surfaces store warmth through the day and release it at night, making it harder for residents to cool down and rest. The temperature difference between a city’s core and its outskirts can reach 6 or 7 degrees Celsius, he points out.
Building orientation is another overlooked factor. Well-designed structures can keep interiors cooler and reduce reliance on air conditioning, while making public spaces more usable during the hottest months. Penelas says smarter urban layouts can limit the worst effects of heatwaves, particularly where people gather, including at schools and bus stops, as well as in plazas.
Reviving Traditional Solutions
Penelas also advocates bringing back time-tested methods to make cities more livable. He cites historic water channels that once ran through streets before the construction of the Canal de Isabel II, along with granite and natural stone paving, which reflect rather than absorb heat. He argues that these traditional approaches can be adapted to modern needs and help reduce thermal stress in everyday urban life.
His proposals echo a broader European trend toward sustainable infrastructure. Switzerland’s ambitious underground tunnel network, for instance, shows how rethinking city systems can deliver environmental and social benefits, as described in this report on freight transport new idea.
Penelas says Spanish cities must move beyond short-term fixes and invest in greener, more resilient urban environments, using smarter design to protect public health and quality of life. As climate risks intensify, the way cities are built and maintained will shape the future of urban living.
