The heat trap in the heart of Chatswood

⏱️ This story is a three-minute read.

How hot is Chatswood? Last Friday, on an overcast spring day, the Lorikeet recorded temperatures of 31.5C, 34.1C, and 34.5C on various surfaces around highly urbanised parts of the suburb. 

It’s not even summer yet, but the impact of urban heat can already be felt.

🔥 Hot surfaces 

The Lorikeet reported recently about concrete and asphalt, two common urban building materials known for their ability to absorb heat and subsequently radiate it back into the local atmosphere. It’s known as the urban heat island effect, and explains why it's so hot in concrete jungles.

But there's one other less common, but equally significant material: synthetic turf, or fake grass. 

Sitting in the middle of The Chatswood Concourse outdoor area is a large patch of synthetic turf, in direct sunlight for most of the day. And its days may be numbered, with Willoughby councillor Kristina Dodds putting forward a motion asking the council to consider options for replacing the synthetic turf.

‼️ A contentious topic

 Synthetic turf can be a controversial material, especially on the North Shore. Typically, its proponents argue that in a sports setting you can get more overall playtime from the pretend grass, where natural grass might wear out from use or get bogged down and damaged by rain.

People opposed to synthetic turf put forward environmental concerns, like those outlined in a Swedish report from 2022, which found the average synthetic turf field releases 550kg of microplastics every year. 

What both sides agree on is the heat absorbent quality of synthetic turf. 

🌡️ Heat absorbent

In summer, especially, it can be unusable due to its heat. This is why, for example, Football NSW factors the playing surface in when deciding whether particular fixtures can go ahead.

Just down the road at Chatswood Park, we recorded surface temperatures of 25.5C on the natural grass, nearly 10C cooler than the synthetic turf.

While the synthetic turf at the concourse might be cheaper to maintain, it can become hotter than the concrete pavement surrounding it. And it is this temperature difference that has led Dodds to raise the matter of alternatives.

The motion will be discussed at the next council meeting, on October 27.