HSLU study shows the potential of greenery and solar panels on building facades
Innovations are needed in the construction sector to respond to the effects of global warming. As part of the GreenPV project, a research team from Lucerne University of Applied Sciences and Arts (HSLU) has therefore been looking for solutions for optimal façade design with photovoltaics and greenery. A brochure aimed at planners and building owners shows the possibilities and challenges of these systems on building façades.
The average annual temperature in Switzerland could rise by 3.3 to 5.4 degrees by the end of the 21st century. These are the findings of research by the National Center for Climate Services (NCCS). This development will also have an impact on energy requirements - particularly for cooling - and comfort in buildings. The need for cooling is greatest when solar radiation is at its most intense. This suggests that the required cooling energy should be generated by photovoltaics (PV). Green spaces, on the other hand, are important for cooling the outside air in hot weather. In densely built-up urban areas, however, there is a lack of space to create new green areas. Greenery on buildings is a sensible alternative here. A research team from Lucerne University of Applied Sciences and Arts has therefore investigated the acceptance of PV systems and greenery on façades among building owners and planners.
Investment pays off
"While the benefits of PV systems and greenery are already being increasingly used on roofs, they have so far largely not been used on façades," explains Silvia Domingo, a researcher at Lucerne University of Applied Sciences and Arts. Yet the potential for this on building façades would be high: "The energy yield of a PV system on a south-facing façade is higher than on a roof in the winter months due to the low angle of inclination of the sun caused by the season," says Silvia Domingo. The building façade would also provide an existing, unused area without having to take up additional square meters. In addition, there are the fundamental advantages of PV: on-site electricity production independent of price fluctuations and supply bottlenecks with long-term economic benefits.
According to Silvia Domingo, the main obstacles to such PV systems and green façades lie in financing and a lack of guidelines and experience, for example in the area of fire protection. According to the researcher, this causes uncertainty among building owners. The team has therefore drawn up recommendations as part of the project, which it has set out in a brochure for planners, building owners and interested parties.
The visual appearance also plays a role, confirms Silvia Domingo: "Plastering the building façade with black solar panels does not always correspond to the vision of building owners and planners. Another HSLU project shows that solar panels can also have other colors and textures in the future without significantly reducing their efficiency.
Green façade: valuable contribution to the community
Another use of façade surfaces is greening. In addition to the cooling effect in the summer months, façade greening also offers other advantages: it promotes biodiversity, improves air quality by binding pollutants, produces oxygen, reduces sound propagation in the street, contributes to rainwater retention and thus increases the quality and attractiveness of outdoor spaces. The latter is particularly important in urban areas.
Utilize synergies
Greenery and PV systems can often be combined well on the façades of a building and rarely compete with each other. "PV comes into its own where a high level of energy generation is possible, i.e. on an unshaded façade on the upper floors," says Silvia Domingo. According to the researcher, however, greenery should be close to the people who spend time around the building or in places protected from the wind, such as inner courtyards. "That’s where it has the best heat-reducing and noise-absorbing effect," explains the researcher. According to the study, the two façade uses can therefore be combined well and thus contribute to a more pleasant neighborhood climate and climate-friendly electricity production.
The GreenPV project started under the leadership of Gianrico Settembrini in December 2021 and was completed in mid-2024 with a final report. A brochure with tips and recommendations is available on the
The project was financed with a budget of around CHF 300,000 by the Swiss Federal Office of Energy SFOE, private individuals and foundations such as the Steiner Lab Foundation. The project was also supported by the Department of Buildings of the City of Zurich and the Department of Environment and Energy of the City of St. Gallen. Epro Engineering and Ingold Gartenbau und Begrünungen were involved in the study as external project partners.
