Rome scraps plans for the bioclimatic tree in Piazza dei Cinquecento

Rome – The bioclimatic tree in front of Termini Station will not be built. Roma Capitale halted the project for Piazza dei Cinquecento on July 9, 2026. Sabrina Alfonsi, the city’s environmental commissioner, cited the cost of approximately half a million euros as the reason for the decision, along with the intention to redirect the funds toward permanent urban green spaces instead.

The installation was never actually set up. There was also no finalized design for the Piazza dei Cinquecento, only an initial architectural concept sketch. The project’s designers—the Stuttgart-based firm haas cook zemmrich STUDIO2050, in collaboration with Transsolar KlimaEngineering and the structural engineers at C4 Engineers—conveyed this in a correction sent to the editorial staff. The „Albero Climatico“ was originally designed for a completely different location: St. Peter’s Square. The suggestion to install it in front of Termini instead did not come from the planners—and they expressly consider the criticism of this location to be justified.

What Roma Capitale Has Decided

On July 9, 2026, the city administration announced that, following technical and economic reviews, it would not be moving forward with the project. Alfonsi cited two reasons for this: the high costs, which were deemed unsustainable for a public investment of this kind, and the administration’s priority of directing resources toward concrete and permanent urban green spaces. Rome needs more trees, more shade, and more green spaces, the department head explained.

The project was not rejected on scientific grounds. Roma Capitale continued to describe it as an interesting contribution to research and innovation in the adaptation of cities to climate change and the mitigation of urban heat islands.

This was preceded by a debate that centered less on the technology than on the order of events: Following the renovations for the Holy Year, the number of trees in Piazza dei Cinquecento had been reduced, and since then, shade has been almost completely absent. Many comments on social media therefore boiled down to the same question—why spend half a million euros on an artificial tree when the real ones are missing?.

How the Albero Climatico Is Supposed to Work

The system is based on adiabatic cooling, that is, evaporation. A cylinder made of recycled brick material is housed within a bamboo tower structure and is continuously moistened with water. As the water evaporates, it draws heat from the air. A fan directs the cooled air downward into the plaza area. Solar panels provide power for the fan, water pump, and lighting—so the system operates off-grid, but not without electricity. According to the climate engineering firm Transsolar, the temperature within its perimeter should be up to ten degrees below the ambient temperature.

This principle is not new. The Ordine degli Architetti di Roma cited Egyptian architecture and historic buildings such as the Zisa in Palermo, where water, ventilation, and the layout of the space worked together to provide cooling.

The estimated cost of approximately 500,000 euros covered the construction and installation of a single unit as a temporary pilot project.

Who is behind the Albero Climatico?

The idea came from Wittfrida Mitterer, director of the master’s program in bioarchitecture at LUMSA University in Rome and president of the Fondazione Italiana di Bioarchitettura. LUMSA donated the project to the City of Rome to mark the Holy Year; it was publicly unveiled as early as 2025 during a joint study day organized by the university and the foundation.

The architectural design is the work of the Stuttgart-based firm haascookzemmrich STUDIO2050, led by Martin Haas, which also designed the opening installation for the Venice Architecture Biennale curated by Carlo Ratti in 2025. The HVAC systems are provided by Transsolar KlimaEngineering, and the structural system by C4 Engineers.

The firm was founded by Martin Haas, David Cook, and Stephan Zemmrich and, based in Stuttgart, focuses on climate-responsive, resource-efficient construction—from the House of Film and Media in Stuttgart to international design competitions. With offices in Stuttgart, Munich, Paris, and New York, Transsolar KlimaEngineering is one of Europe’s best-known climate engineering firms and has been designing buildings for decades that require as little technology as possible. The completed project was donated by LUMSA to the City of Rome.

The Climate Tree was designed for St. Peter's Square

The original design was not a single tower, but rather an entrance arch consisting of two interconnected, freestanding bamboo structures with an internal evaporation element. It was intended to provide shade and cooling at the entrance to St. Peter’s Square, while drawing on an idea by Gian Lorenzo Bernini that was never realized: a dramatic entrance to the square whose colonnades Bernini designed.

The dimensions were tailored to this location. According to the architects, the height of the inner arch was calibrated to preserve the view of St. Peter’s Basilica and its dome, while the overall height was aligned with the surrounding colonnades. The firm stated that a structure developed in such a specific way for a particular location could not be relocated to another site without fundamental redesign.

What do the architects have to say about the location on Piazza dei Cinquecento?

They consider the criticism to be justified. Rather than defending the site, the planners agree with the objections on the key points. At Piazza dei Cinquecento, the spatial composition, height, and proportions of the structure would need to be fundamentally rethought, explained haascookzemmrich STUDIO2050 in its clarification. The firm also agrees with the objection regarding greenery: artificial shading and evaporative cooling should not compete with real trees and their shade. Where natural planting is possible, it is always the better solution.

The situation is different for areas that are already paved and tightly sealed—and that is precisely the case with the forecourt of Roma Termini. For such a site, the team would have liked to develop its own site-specific version, designed to provide noticeable cooling and shade while using as few materials as possible. The published illustration is a preliminary conceptual interpretation, not a design. A robust proposal would require a thorough analysis of the site and its spatial, climatic, and urban planning conditions.

Why Piazza dei Cinquecento Became a Heat Island

The station forecourt is one of the hottest spots in downtown Rome. Following its renovation for the Holy Year, it is largely paved, heavily trafficked, and devoid of structured vegetation—asphalt and stone absorb the sun’s heat and release it well into the night. That is precisely why the site was considered particularly suitable for the experiment in the master plan: the area selected was the northern pedestrian zone near the new entrances to Metro Line B, across from the NH Hotel, and near the taxi circle.

As part of the redesign, a green space project by the firms TVK and IT’S had been planned for the same area, but it has not yet been implemented. The urban heat island effect is exacerbated by the ongoing climate change and affects older people and travelers the most. The current summer illustrates just how tense the situation is: In early August, the Italian Civil Protection Agency reported during the fourth heat wave The highest alert level has been issued for 25 cities, including Rome.

Roma Capitale announced that it would continue to invest in the city’s tree population, the maintenance of existing green spaces, and new plantings. In mid-July, the administration clarified that the funds saved would be allocated to parks and natural areas, and that future calls for bids would prioritize native, drought-resistant standard trees. Discussions with the participating universities regarding technical solutions to combat heat islands are set to continue. It remains to be seen how quickly this will result in shade on the Piazza dei Cinquecento—as of early August 2026, no new plantings have been announced there.