OSRI and City of Lucerne test cooling effect from greened mounds of earth
Lucerne - The spatial development company OSRI has launched a temporary greening project on asphalted areas of the Neubad arts and cultural center in Lucerne. The focus of this Hygroskin project is to scientifically test cooling effects and biodiversity, in addition to determining the maintainment efforts involved.
OSRI AG has initiated a project aimed at increasing greenery and reducing heat in urban environments. Based on an idea from the spatial development experts at OSRI, two green mounds of earth were created in June 2025 on nine asphalt parking spaces of the former Biregg indoor swimming pool in Lucerne. The Neubad arts and culture center has since been temporarily housed here, with OSRI’s offices located on the southern side of the site.
The Hygroskin Neubad pilot project features a special soil structure that stores rainwater, ensuring that the foliage remains moist and cools the surrounding area. A non-woven material with a storage mat laid on the asphalt prevents rainwater from flowing into the sewer system, meaning that irrigation of the 26 to 65-centimeter-high structure comprising sand, gravel, and humus is “essentially unnecessary”, according to OSRI.
Native plants such as wild perennials and some small shrubs able to withstand heat stress have been planted on the site. Deadwood areas and small stone piles are intended to benefit insect life. The project is to be scientifically monitored over a three-year period.
The results will be compared with those of the Basel Hygroskin located at the Dreispitz railway track curve. “In Basel, temperature differences of up to 21 degrees Celsius were registered on and near the Hygroskin during hot periods”, as Timur Babacanli, project manager at Stadtgrün Luzern, an office of the City of Lucerne’s Civil Engineering Department responsable for the green urban spaces, explained at the project launch.
Hygroskin was developed by BIAS.CITY – the Basel Institute for Applied Urban Studies (B/IAS). With Hygroskin, BIAS is pursuing an open source approach for municipalities so that urban climate knowledge can be scaled up cost-effectively and on a large scale. The Ko:Lab at Lucerne University of Applied Sciences and Arts – Näher dran | Lucerne University of Applied Sciences and Arts is also involved in evaluating the scaling and cooperation. Hygroskin is designed for locations where normal unsealing by removing asphalt or concrete surfaces and subsequent renaturation is desirable but not yet possible for various reasons. In this case, Hygroskin is intended to enable cost-effective and rapid greening.
Stadtgrün Luzern is a project partner alongside Netzwerk Neubad and the Basel Institute for Applied Urban Research (B/IAS), which actually developed the Hygroskin. It is designed for areas where conventional desealing processes through the removal of asphalt or concrete surfaces and subsequent renaturation is desired but not yet possible for various reasons. In this case, the aim of the Hygroskin is to facilitate cost-effective and rapid greening.
Further information on Hygroskin is available at hygroskin.ch and https://www.stadtluzern.ch/aktuelles/newslist/2486263
Stadtgrün Luzern is a project partner, as are Netzwerk Neubad, Denkstatt sàrl, and the Basel Institute for Applied Urban Research (B/IAS), which developed Hygroskin and is covering part of the planning costs.
