How do human-made green walls compare to nature in biodiversity and cooling benefits?

Our lab is thrilled to announce our first publication of 2025! In collaboration with Utrecht University and biosea.sg, we’ve published a paper on the biodiversity and temperature-regulating effects of Vertical greenery systems in Singapore. Our study takes a unique approach by benchmarking human-made green walls against natural cliffs—naturally vegetated rocky formations—and using non-vegetated walls as a control. The article is featured in Building and Environment (Vol. 268, Jan 2025). 

(Left) A section photo of each wall type showing findings of temperature regulation and number of animal species. (Right) Shannon-Wiener Index increases with an increase in number of tress within 10m radius.

Here's some of our key findings: 

1. Biodiversity boost: Vertical greenery systems host significantly more animals than bare walls but fall short of the richness of natural cliffs. Biodiversity increases with vegetation thickness and plant diversity. 

2. Temperature regulation: Vertical greenery systems buffer temperatures, cooling building walls during the day and slightly warming them at night. 

3. Actionable insights: Using natural cliffs as a benchmark highlights the gap between urban and natural systems, offering guidance for enhancing green infrastructure performance. 

In a short discussion with Prof. Hamel, she notes: 

"This methodology paves the way for a robust evaluation of blue and green infrastructure in cities, which is critical to help policymakers such as National Parks Board and Urban Redevelopment Authority of Singapore (URA) to make more informed decisions as nature-based solutions gain traction. It's been a pleasure to work with research leads Katharina and Anuj, whose deep expertise in ecology and fascinating insights really made this study possible." 

Read the entire article here and more about the project itself here.