The essential role of green roofs in urban blue-green infrastructure – a step towards sustainable cities

We would like to sincerely congratulate the team behind the guide “Urban Green-Blue Infrastructures – Best Practices Guide for Their Arrangement and Integration in the Urban Space of Romania”, authored by landscape architect Dr. Diana Culescu and landscape architect Dr. Alexandru Ciobotă.

Such a work was essential and fills a major gap in Romania’s legislative and urban planning framework. We highly appreciate the effort invested and believe that, through media coverage and promotion to decision-makers – especially the Ministry of Environment, the Ministry of Development, and local authorities – the guide has the potential to become an officially adopted standard within a few years.

As rightly mentioned in the guide, the recommendations are a first step, but true transformation begins when they become mandatory standards in practice.

A coherent green-blue infrastructure needs green roofs

In the context of climate change and accelerated urbanization, the concept of green-blue infrastructure has become essential for designing and developing the cities of the future. A well-integrated green-blue infrastructure includes green spaces (parks, gardens, urban forests, green roofs) and blue spaces (rivers, lakes, canals, rainwater collection and infiltration systems) that work synergistically to improve urban quality of life and climate resilience.

Unlike grey infrastructure (concrete, asphalt, underground pipes), green-blue infrastructure uses natural processes to manage water, heat, and pollution. For example, green roofs, permeable parking lots, and vegetated swales retain rainwater, reduce flood risk, and ease the load on the sewage system. Renaturalized rivers and urban wetlands filter pollutants, support biodiversity, and create cooler microclimates. In the context of climate change, green-blue infrastructure becomes essential: it reduces the urban heat-island effect, limits urban flooding episodes, improves air quality, and creates more pleasant public spaces, positively impacting physical and mental health.

We need more than just green space. This is where the strategic role of green roofs becomes evident!

One of the key statements in the guide is:

“Green roof systems are much more effective in serving green-blue infrastructures when implemented at street level.”

This observation is correct and welcome, but we consider it important to add another aspect: green roofs, even at greater heights and without public access, can play a major role in a city’s ecological connectivity. International studies and practical observations show that biodiverse green roofs, integrating a variety of plant species (not only Sedum monocultures), can function as true “aerial green corridors,” connecting isolated ground-level habitats.

As is well known, green roofs can be classified by several criteria: extensive, semi-intensive, and intensive. Each type comes with its own set of benefits and technical requirements. Their wider implementation must take into account the building’s purpose, structural capacity, and local urban planning objectives. Within green-blue infrastructure, they can have ecological, hydrological, climatic, aesthetic, and social functions.

One aspect we wish to emphasize is the need to think of green roofs not as isolated solutions, but as integrated parts of a coherent urban system. When green roofs are designed in close connection with ground-level green spaces – parks, community gardens, green walkways – an active symbiosis is created that maximizes the benefits of both.

As proactive specialists and promoters of green roofs in Romania for over 20 years, we firmly support the idea that cities must rethink their investment priorities. As the authors of the guide point out, parking areas and above-ground parking structures occupy enormous spaces and are rarely used as public spaces. The City Hall of Cluj-Napoca is a pioneer in this regard, working for years on greening public parking areas. The obvious solution is to move parking underground, or to green multi-level parking structures and convert the resulting platforms into parks, public gardens, or intensive green roofs with 2–4 meters of substrate, capable of supporting mature trees and complex vegetation.

Our goal is to create vast green areas in which people will not even realize that beneath them lies a building serving a societal purpose, allowing them to lose themselves in urban nature.

Underground parking facilities are much more than just “a place to leave the car.” In a city that aims to be healthy, quiet, and people-friendly—rather than traffic-oriented—they become an important piece of urban infrastructure. Beyond the obvious convenience for drivers, underground parking brings clear environmental and social benefits, making it far preferable to surface parking lots or the “oceans of asphalt” found around malls and apartment blocks.

First of all, underground parking frees up ground-level space. Where endless rows of parked cars would otherwise stand, the city can gain green spaces, playgrounds, bike lanes, pedestrian squares, or public gardens. This means less overheated asphalt in summer, more shade, evapotranspiration, biodiversity, and a more pleasant microclimate. Simply put, parking goes underground, and urban life rises to the surface. This translates into more time spent outdoors, more social interaction, and a healthier relationship between residents and their city.

Beyond freeing space, underground parking significantly reduces the visual impact of cars. A city center or neighborhood where sidewalks are occupied, green spaces are blocked, and improvised parking lots appear between buildings conveys congestion, chaos, and a lack of care for the urban landscape. A space where cars are “hidden” underground appears more orderly, airy, and welcoming. This directly influences quality of life, safety perception, and even property values.

Another important advantage is noise reduction. Car movements at street level, the search for parking, repeated maneuvers—all contribute to noise pollution. Moving parking-related traffic underground reduces noise in public spaces. Residents of nearby buildings enjoy a quieter environment, and pedestrian areas become more pleasant. From a health perspective, underground parking—when well ventilated and properly designed—can contribute to reducing street-level air pollution. Instead of cars and asphalt, you see green space when looking out the window. You breathe clean air! All thanks to a park-like green roof situated above the parking facility.

Lastly, there is also a safety and social comfort dimension. Modern underground parking facilities are video-monitored, well lit, and equipped with controlled access. For many users—especially families, the elderly, or women arriving home late—being able to park in a secure, weather-protected, and discreet space is extremely important.

The future of urban planning is green and blue

Without the systematic integration of green roofs and blue (rainwater-retention) systems into urban infrastructure, Romania risks missing a crucial opportunity to build more resilient, healthier, and more livable cities. We express our hope that this approach will be continued through bold public policies and concrete investments.

At ODU Green Roof, we believe that every square meter counts—both on the ground and on buildings. You, as a citizen with the right to a healthy life, demand your rights! Ask your elected officials for a locality with green-blue infrastructure, with as many green roofs and green façades, and with renaturalized waterways!