en.Wedoany.com Reported - The Barcelona City Council's Climate Change Office (Oficina de Cambio Climático) has launched a pilot project to assess the effectiveness of reflective roofs in reducing building heat gain, lowering cooling demand, and mitigating the urban heat island effect. As part of the "Heat Plan" (Pla Calor), the project will provide technical data to enhance the city's capacity to cope with the impacts of climate change.

The trials will analyze the performance of different coatings based on two key parameters: solar reflectance (reflectancia solar), which measures a material's ability to reflect sunlight before it is converted into heat; and thermal emissivity (emisividad térmica), which reflects the material's ability to release absorbed heat in the form of radiation. When both values are high, the coating can reduce the amount of heat entering a building while decreasing heat accumulation in urban spaces.

The first study will be conducted throughout the summer on approximately 150 square meters of the roof at the Tres Fonts School (Institut Escola Tres Fonts) in the Les Corts district (distrito de Les Corts). The site will compare three options: white paint, a terracotta-colored paint serving as a control benchmark, and a terracotta-colored paint with reflective pigments.

White paint typically has a higher solar reflectance, but the terracotta option with reflective pigments retains the color appearance common to traditional roofs. These pigments enhance the ability to reflect solar radiation, particularly in the near-infrared spectrum, which plays a key role in surface heating.

By comparing data, the feasibility of improving a building's thermal performance without significantly altering its appearance can be assessed. This approach integrates criteria such as energy efficiency, climate adaptability, and urban integration, which is particularly important in the built environment where roof renovations often impact the landscape.

Pigment manufacturer Vibrantz Technologies will simultaneously conduct a dedicated study to more precisely measure the impact of the two coatings on energy consumption. To this end, the company will paint two identical roof huts: one with traditional terracotta paint and the other with terracotta paint containing reflective pigments.

Both huts are equipped with air conditioning systems set to a maximum indoor temperature of 27°C. This configuration allows for a comparison of electricity consumption in each space, thereby estimating the extent to which reflective pigments can reduce the energy required for building cooling without altering the appearance.

The study will also evaluate the radiative cooling effect of small roof areas. This is a passive process that dissipates accumulated heat by emitting electromagnetic radiation, primarily in the form of infrared rays. Its efficiency increases when radiation is emitted within specific wavelength ranges where the atmosphere is relatively transparent, known as the atmospheric window, which facilitates heat dissipation into space.

Unlike traditional reflective roofs that reduce heat gain by reflecting sunlight, radiative cooling can, under suitable conditions, bring surface temperatures close to or even below ambient temperature. However, its performance is influenced by factors such as humidity, cloud cover, sky exposure, and the system's integration into the building.

All three tests are equipped with continuous monitoring systems to record changes in ambient temperature, surface temperature, relative humidity, and solar irradiance. For the roof huts, electricity consumption related to cooling will also be measured.

This monitoring process will be supplemented by periodic measurement campaigns to obtain supplementary data and validate long-term recorded results. The collected information will help to more precisely analyze the thermal performance of the evaluated solutions and assess their potential for application in future urban projects.