How did you come up with this topic?
‘I’m originally from Izmir, a city in Turkey. It can get very hot there as well. In secondary school, I became interested in urban heat islands after watching a documentary about situations in the United States. At the time, it was a bit too ambitious for me to do research myself – I didn’t yet have the knowledge or resources to work with satellite data. But the topic always stayed with me, and I knew I wanted to pursue scientific research. Within ATLAS, we have a final assignment – the so-called capstone project – and my now thesis supervisor Monica Pena Acosta was already working on this topic. So, it was a perfect fit.’
Why the O&O square?
‘Many people will recognise how hot it can get here. It is somewhat enclosed by buildings, there is little vegetation, and there is a lot of concrete and gravel. Over the past few years, I’ve attended quite a few barbecues and activities there. The heat can really hit you in the face. On the steps in front of the Zilverling, I know some associations who sometimes poured water over the tiles to cool things down.’
What approach did you take?
‘First, I wanted to test my hypothesis, so I analysed satellite data to assess the situation on campus on three different days. That confirmed my expectations: the cluster of educational buildings including the O&O square, and the boulevard near the Bastille are the main heat hotspots. I then collected field data myself. That meant going out every day for weeks at three fixed times – 5:30 am, 2:00 pm, and 8:00 pm – following a set route with a trolley carrying measurement equipment.’
How hot can it get at the O&O square?
‘I need to allow for a margin, because I measured slightly higher temperatures at times. But I can say with reasonable certainty that the tiles can reach at least 60 degrees Celsius. Those are temperatures where, for example, you probably shouldn’t walk your dog in such a place.’
So is the O&O square our own urban heat island?
‘Essentially what urban heat islands is the difference between temperatures in an urban setting compared to a more rural, reference area, so it depends on your definition of urban. If you were to take Enschede, technically the spots I identified would not be an ‘Urban Heat Island’, as the campus is relatively peripheral. It is a heat hotspot of the campus for sure.’
Did you also investigate how to mitigate the heat?
‘Of course. I analysed the baseline scenario – the current situation – and compared it with three intervention scenarios: adding more trees, installing white roofs on surrounding buildings, and greening those roofs. I tested these scenarios in a simulation software using data from the hottest day of last year, 2nd of July.’
What can you conclude?
‘More vegetation, especially trees, often works best. Scientifically speaking, I need to be cautious, but what I observed is that adding trees on the square itself has the greatest cooling impact. It is worth noting that the cooling of the trees was not widespread over the O&O square but stayed in the area surrounding the trees.’
So: remove the gravel and tiles and plant trees?
‘Yes and no. You shouldn’t see trees as a shortcut to a solution. If you plant too many trees, you may create the opposite effect: reduced ventilation and higher humidity, which means the perceived temperature may not improve much. However, under the exact conditions of 2 July last year, a few large, shading trees on the main gravel area near the abstract benches would certainly have made a difference, even if the effect was mainly felt there.’
Have you shared your findings with Campus & Facility Management?
‘Not yet, but it’s not a bad idea. I first need to defend my thesis on 29 June. The exact interventions that are possible would also depend on agreements with, for example, an architect. And CFM may already be considering interventions, I don’t know. I certainly cannot conclude that I have found a ready-to-implement solution. So, I will give a very academic answer: more research is needed to determine the best way to mitigate heat at the O&O square, and the impact of solutions is very specific to the site of implementation.’
