Oriol Muntané advocates for rehabilitation and the inclusion of cool, green roofs as measures of sustainable architecture

Sustainable architecture is increasingly gaining ground and priority when it comes to planning and urbanizing our cities. Building in an environmentally friendly way, reducing the carbon footprint, and generating the minimum ecological impact have become key vectors on the path to sustainability.

At Núñez i Navarro, we want to amplify the voices of those professionals who contribute to improving people's environments through sustainable measures. For this reason, today we wanted to chat with Oriol Muntané, an architect at the firm specializing in efficient rehabilitation POMA arquitectura, about how architecture can contribute to minimizing the effects of climate change if applied in eco-efficient terms.

From the beginning of his professional career, Muntané showed a special interest in the field of energy applied to the operation of architecture and the construction with low environmental impact materials. The architect values the evolution that this field of study has undergone, increasing its popularity exponentially in recent years: “When I started practicing, there was hardly any connection between architecture and energy, so the field of study was not much explored”. Now the synergy between the two fields arouses more interest among the population every day.

The fusion of architecture and energy led Muntané to analyze an increasingly common problem in densely populated cities like Barcelona: the heat island effect. This phenomenon causes an increase in temperatures in the more urbanized areas compared to the non-urbanized areas around them. The rise in temperatures is especially pronounced during winter nights, although “as a general rule, we all downplay it because a few extra degrees don’t bother us. In reality, we should be as concerned about it as we are about the increasingly hotter summers,” warns.

When asked about the reason for such anomaly, Oriol Muntané points to solar radiation and the composition of common architectural materials as the main triggers of the effect: “Solar radiation hits buildings and their roofs, squares, and streets. These surfaces absorb the radiation, convert it into heat, and re-emit it to the environment, heating it up”, he explains.

However, the reflection of sunlight on architectural materials in urban cores is not the only reason for the increase in temperatures in urbanized areas, but other architectural, urban planning, and human issues also maximize the effects of heat islands. In general terms, every activity has an impact on the environment, whether it is minor or major; and as the expert exemplifies: “from the cars that drive through our streets to the height of the buildings contribute to the urban heat island effect. This phenomenon is further aggravated by the density of buildings, which prevents heat from dissipating easily”.

Following the explanation about the warming of cities, we understand that Barcelona suffers from the urban heat island effect, and it's not surprising. In our city, around 1.6 million people live within 100km2, which amounts to 16,420 inhabitants per km2. Poblenou, Raval, and Ciutat Vella are the top three densest neighborhoods. This demographic snapshot allows Muntané to clarify that the main obstacle to dissipating heat in the city is not the number of people per se, but the number of buildings constructed and, especially, their height. The taller the ratio between the buildings' height and the street width, the more difficult it becomes to dissipate the heat, in other words, "the less sky we see, the greater the density".

When asked about the reason for such anomaly, Oriol Muntané points to solar radiation and the composition of common architectural materials as the main triggers of the effect: “Solar radiation hits buildings and their roofs, squares, and streets. These surfaces absorb the radiation, convert it into heat, and re-emit it to the environment, warming it up”, he explains.

Faced with this widespread issue in urban areas, we try to sketch out solutions, although Muntané quickly presents what would be the ideal solution: “We should transform the rooftops of almost all our buildings and turn them into cool roofs. The rooftops are the surfaces that receive the most radiation - especially in summer - and that heat up the most in buildings, contributing to the rise in temperature in particularly dense cities. So I, as an architect, wondered: what if we tried to prevent the rooftops from heating up in that way?”

Muntané uses a rather graphic example to explain the amount of radiation that roofs usually finished with reddish tiles receive: "How many times have we been told in summer that we shouldn't wear black? Many, right? The dark color attracts heat and the same happens with roofs". Just as we pull out our 'more Ibizan' clothes during the hot seasons, the expert suggests transforming the roofs "by changing the traditional type of reddish tiles for light-colored or white tiles that would allow the temperature of the tiles to resemble the ambient temperature". And it is that in practical studies, differences of up to 20 degrees have been evaluated between a white roof and a roof with ceramic finishes.

The architect lists other advantages of using light pigments, arguing the low economic cost that changing the color of surfaces would entail: “As it is exclusively about paint, the process is not particularly expensive. Obviously, it requires maintenance because pollution and dust blacken the surfaces, but their upkeep is not a defining obstacle when it comes to using them”.

Unfortunately, Barcelona's urban planning legislation does not allow for the modification of roof colors today in order to preserve the urban landscape. However, Muntané positively values the implementation of a tactical urban planning project that encourages the greening of building rooftops in the face of the impossibility of painting them with light colors. In this way, the green roofs would help absorb moisture, noise, dust, etc., and could even serve as recreational spaces, he comments.

Having presented these two solutions to reduce the high solar radiation absorbed by current terraces, Muntané states that “both solutions are appropriate” although for him, the ideal is “to combine both techniques as much as possible since not all roofs can undergo a complete gardening process - whether due to weight issues or accessibility for their maintenance. However, combining the two solutions would allow for the mitigation of solar radiation and the purification of the air. In the case of having photovoltaic panels combined with reflective roofs, the production of the panels would increase. These are all advantages that promote sustainability.”

Muntané is committed to these types of sustainable actions in the architectural projects he participates in as much as possible and acknowledges that, although there is still a long way to go on the path to sustainability, we must set goals that ensure sustainable architecture in the future: “Firstly, we must reduce the use of air conditioning and heating systems. As temperatures continue to rise, we increasingly use cooling systems which, in turn, cause the warming of cities”.

Secondly, “We must also reduce construction demands and opt more for the rehabilitation of spaces, as it allows building without using a high amount of energy; as well as promoting the use of materials with low environmental impact such as wood or others that have a minimal ecological footprint”.

Without a doubt, talking with Oriol Muntané makes us see eco-efficient architecture as a fundamental tool to respond to the climate crisis that affects us. The cities of the 21st century must rethink their urban models and commit to the rehabilitation of spaces and buildings as a sustainable and valuable solution, in addition to "increasing green areas in cities, reducing the density of cities and improving the architectural quality of their buildings, among other aspects" as the architect concludes.

There are many actions we can take to transform our cities into more sustainable ones, and we can all contribute to their improvement. We show you some environments we have rehabilitated to promote sustainable construction.

And you, how do you contribute to improving the environment of your city?

**Source: Akbari, H., Menon, S. & Rosenfeld, A. 2009, ‘Global cooling: increasing worldwide urban albedos to offset CO2.’