Back in 2022, a Swedish startup called Corvid Cleaning made headlines by launching a pilot program in the city of Södertälje involving an operant conditioning device in the city's public realm. The machine allowed crows — which, it turns out, are pretty smart and social animals — to deposit discarded cigarette butts in exchange for food.

The machine itself would scan whatever the crows brought in, and if it was, in fact, a dirty butt, the machine automatically dispensed a small piece of food, such as a peanut. And because crows are social animals, the thinking was that they would then run and tell their friends, "Hey, I found us a great dinner spot!"

It's an alluring and unexpected concept. The hope was to slash the city's annual cleaning bill by getting the crows to do our dirty work. And that's why this "new pilot" seems to go viral periodically. But the reality is that Corvid Cleaning filed for bankruptcy in 2025 and, as far as I'm aware, this has in no way taken off as a viable solution for keeping our streets free of cigarettes.

The obvious problem is that cigarette butts are highly toxic, and so encouraging animals to transport them around is a suboptimal solution. Supposedly, crows are also a little too smart, and they started to try to game the system. Regardless, the prototype is dead. If only more of us could be like the Japanese, and not throw our garbage on the street.

Cover photo by Fatemeh Heidari

Many years ago, I was in a design meeting for a tall building we were working on and I brought up the idea of planting greenery all the way up the tower. You know, something like the Bosco Verticale in Milan.

But after I said this, our landscape architect looked at me and simply said, "No, it doesn't work, not in our climate." And that was it.

Of all the people in the room, I thought I could get the landscape architect excited about this suggestion, but nope. It got immediately shot down, and for good reason.

The greenery would be dead here in Toronto for not an insignificant part of the year, and the additional dead loads created by water-saturated soil and structural planters raise questions about whether it's the most sustainable way to build tall buildings.

But there are climates where green towers make a lot more sense, namely in places like Brazil. In fact, São Paulo rewards developers for integrating features such as green facades.

Here's a specific project example: The Rosewood Hotel in São Paulo, designed by Jean Nouvel. The 25-storey tower features an extensive lattice system on its exterior that, over time, is expected to fill in with greenery from adjacent roof gardens.

The hotel opened in 2022, and street view images from 2024 reveal that it still has some growing to do, but clearly it's a popular idea. I was just in the wrong city.

Photos via Rosewood São Paulo

A residential community in China's Shanxi province has been in the news recently for a cooling system that sprays mist from its rooftops to lower the surrounding surface temperatures. Here's a video in case you missed it.

As I understand it, this evaporative cooling technique can lower nearby surface temperatures by 5°C to 8°C within minutes, and it uses significantly less electricity than air conditioning.

This, by the way, is the same scientific principle behind how sweat cools human skin. We sweat, the sweat then evaporates, and in the process it helps to lower our body temperature.

But the obvious question here is: Doesn't this waste a bunch of water?

Generally, these systems tend to rely on (1) very fine mists of water (so as little water as is necessary) and (2) collected rainwater and/or recycled greywater. The general idea is to just lower surface temperatures so that less air conditioning is needed.

Next, it becomes a question of electricity saved vs. water consumed. A study done on a 5-storey apartment building in Osaka found that outdoor misting reduced the building's cooling loads by an average of 36%, and from a financial standpoint, the value of the electricity saved was greater than the cost of the water consumed.

Importantly, it also helped reduce the overall urban heat island effect in the area. The amount of waste heat trapped in the nearby city streets decreased by over 60%.

Hotter streets are a byproduct of air conditioning because the cooling process effectively sucks heat out of interior spaces and transfers it outside. Misting counteracts that and also reduces peak AC loads.

So, as wild as these sweating towers may appear online, there is some logic behind them.

Cover photo via this Twitter post