{"id":12742,"date":"2026-02-19T10:28:06","date_gmt":"2026-02-19T10:28:06","guid":{"rendered":"https:\/\/www.europesays.com\/ch\/12742\/"},"modified":"2026-02-19T10:28:06","modified_gmt":"2026-02-19T10:28:06","slug":"this-city-turned-its-rooftops-into-a-climate-shield","status":"publish","type":"post","link":"https:\/\/www.europesays.com\/ch\/12742\/","title":{"rendered":"This City Turned Its Rooftops into a Climate Shield"},"content":{"rendered":"

\u201cGreen roofs can improve the habitat mosaic of birds and butterflies, providing feeding or nesting sites,\u201d Brenneisen says<\/a>, adding: \u201cWe have been identifying red listed species that exist on green roofs in different countries.\u201d<\/p>\n

One of the most striking examples lies just outside Z\u00fcrich: A century-old roof at the Seewasserwerk Moos, a water filtration plant, which has evolved into 30,000 square meters of an orchid-rich meadow with more than 175 plant species. Brenneisen calls it \u201ca stable, ecological treasure\u201d \u2014 living proof of the ecological oasis long-term roof habitats can become.\u00a0<\/p>\n

Z\u00fcrich\u2019s leadership is nearly matched by Basel in northwestern Switzerland, which turned to green roofs in the early 1990s as an energy-saving measure and now sports more than 4.6 square meters of green rooftop per resident, or almost 50 percent of all flat roofs. Residents agreed to channel part of their utility payments into a fund supporting building retrofits, and the city soon made green roofs mandatory on all new or renovated buildings with slopes under 10 degrees.\u00a0<\/p>\n

\u201cThe solution has to be quantitative,\u201d Brenneisen insists. Cities that try to improve the percentage of green roofs only by offering subsidies are significantly less successful than the cities and communities that make them mandatory. \u201cHere, it\u2019s simply a requirement. Period,\u201d Brenneisen says. \u201cEspecially in bigger cities, it\u2019s the job of city planners to include climate adaptation, and when you simply put gravel on a roof, you haven\u2019t done your job.\u201d<\/p>\n

Basel\u2019s roofs, as a Guardian feature<\/a> recently highlighted, have become complex wildflower communities more akin to brownfield ecological hotspots than decorative lawns. Many of the guidelines that shaped them \u2014 including minimum substrate depths and planting schemes \u2014 were developed by Brenneisen. He calls it \u201ca simple technology,\u201d but also concedes that \u201cin reality, it is not so easy to change a city.\u201d<\/p>\n

If green roofs offer so many benefits, why doesn\u2019t every roof sport one?<\/p>\n

The answer often comes down to economics and planning inertia. Although Z\u00fcrich and Basel require green roofs on new and renovated buildings, the cities provide exemptions for rooftop terraces, restaurant spaces, or technical installations. As a result, in Z\u00fcrich\u2019s dense urban core only about one percent of roofs are vegetated.
Cost also remains a consistent hurdle. While most residential concrete roofs can handle planted roofs easily, large-span industrial buildings often require reinforcement. Replacing gravel with substrate and vegetation adds weight, ranging from 100 kg per square meter for extensive roofs to over 1,000 kg for rooftop gardens with shrubs or trees.\u00a0<\/p>\n

\u201cIf a hall costs 10 million [Swiss francs] and you can demonstrate that spending 12 million on a higher value environment will pay itself back in 15 years, someone always asks: Can we do it for nine million?\u201d Brenneisen told the Neue Z\u00fcrcher Zeitung<\/a>. Gravel roofs, though less sustainable, are cheaper up front. Part of Brenneisen\u2019s work is to convince architects and city planners to factor in the positive impact of green roofs on the long-term ecological footprint of a building, but also to impress on them the beauty of these patches of nature. \u201cI really wish for more courage and creativity in designing green roofs.\u201d<\/p>\n

The thicker the substrate, the more diverse the plants, the greater the ecological relevance. <\/p>\n","protected":false},"excerpt":{"rendered":"\u201cGreen roofs can improve the habitat mosaic of birds and butterflies, providing feeding or nesting sites,\u201d Brenneisen says,…\n","protected":false},"author":2,"featured_media":12743,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[6],"tags":[1208,9318,9319,9320,9321,9322,51],"class_list":{"0":"post-12742","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-zurich","8":"tag-architecture","9":"tag-biodiversity","10":"tag-green-infrastructure","11":"tag-green-spaces","12":"tag-urban-climate","13":"tag-urban-heat","14":"tag-zurich"},"share_on_mastodon":{"url":"","error":""},"_links":{"self":[{"href":"https:\/\/www.europesays.com\/ch\/wp-json\/wp\/v2\/posts\/12742","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.europesays.com\/ch\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.europesays.com\/ch\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/ch\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/ch\/wp-json\/wp\/v2\/comments?post=12742"}],"version-history":[{"count":0,"href":"https:\/\/www.europesays.com\/ch\/wp-json\/wp\/v2\/posts\/12742\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/ch\/wp-json\/wp\/v2\/media\/12743"}],"wp:attachment":[{"href":"https:\/\/www.europesays.com\/ch\/wp-json\/wp\/v2\/media?parent=12742"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.europesays.com\/ch\/wp-json\/wp\/v2\/categories?post=12742"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.europesays.com\/ch\/wp-json\/wp\/v2\/tags?post=12742"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}