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How a $50 Homemade Sensor Could Change the Way We Fight Urban Heat

How a $50 Homemade Sensor Could Change the Way We Fight Urban Heat

“The coolest thing about the Harlem Heat Project is how people experience the heat using these custom-made sensors.”

The sensor at the heart of the Harlem Heat Project. Its parts cost $50 to source and about two hours to piece together. Source: Adam Glenn
The sensor at the heart of the Harlem Heat Project. Its parts cost $50 to source and about two hours to piece together. Source: Adam Glenn

New York: “#117 is back with me. The host has been traveling,” Carlos Jusino says to his colleague while I hang around hoping to chat with him about a tiny contraption in his hand. We are standing on polished wooden floors in the basement of the 21st Century Academy for Community Leadership, a glass fronted building that looks entirely out of place on 152nd Street in Harlem, New York city. Some community members are here to attend a meeting about participatory budgeting and have just broken off into little groups to brainstorm based on which part of Harlem they reside in.

Harlem, a large neighbourhood in the northern part of Manhattan, is one of the worst places to spend the summer in the megacity. It has a high concentration of brick, concrete and asphalt structures. All these materials trap heat during the day and keep the mercury high at night. I read that in a report on WNYC’s site, a public radio station in New York. And among several startling facts about the “heat vulnerability” of Harlem, which is populated mostly by African Americans, is this: “Twice as many people from Central Harlem visit the emergency room for heat stress each year compared to the rest of the city.”

The day I met Jusino, the temperature was up in the “high eighties” as New Yorkers say (between 30º and 35º C), so we found a cool corridor near the stairwell to have a chat about the ‘Harlem Heat Project.’ Jusino is the IT guy for the Harlem-based ‘WE ACT for Environmental Justice’ and got roped into this project for his technical skills. He’s holding a two-centimetre-long sensor in his palm.

“The sensor itself is in three parts,” he begins. “A lithium polymer battery, a central micro-controller and a temperature and humidity monitor.” In all, the device is the size of a thumb with parts soldered onto a circuit board. Every component had been purchased from a hobby electronics website by John Keefe, the data news editor at WNYC. The parts for each sensor add up to $50, and took less than two hours to put together.

“Most of it was done by John,” says Jusino. “He even had a soldering party where people who knew how to solder or those who wanted to learn could come along. It was like a ‘Do it Yourself’ kit and the idea is to put together a cookbook of sorts so people can make their own sensors at home,” he says. The code is available freely on GitHub. It’s currently programmed in a way that wakes up the sensor every 15-20 minutes, checks the temperature and humidity around it, then writes down the data onto a little memory card along with the time of the measurement, and goes back to sleep.

“We wanted to tighten our focus to a neighbourhood and understand better at a community level about how heat affects people,” Adam Glenn, editor of Adapt NY, one of the partners on the project, had told me the day before I met Jusino. “Heat is a silent killer and we wanted look at ‘urban heat islands’, which are pockets within any city and are often not very well documented. There is very little data on indoor air temperatures and how it’s harmful to people’s lives.”

Essentially, how do people cope with the heat indoors? “Here was a public health crisis in the making and this project helps provide data that can affect change and help the community affect change. The city authorities acknowledged that they don’t have the kind of neighbourhood-specific data to understand what was happening in sections of the city.”

So, 30 odd-looking sensors went to live in different parts of Harlem and Washington Heights for the first time this summer. Many were hosted around 150th street, between Broadway and Amsterdam Avenues. Like on Diane Lane-Hyman’s night stand in her three-storey walk-up on 150th street. The elderly Diane is both a ‘host’ and an ‘ambassador’, which is how the project has been organised. Core ambassadors are connected to hosts and can be hosts themselves. They go to their individual hosts, know them personally, pick up data from sensors, and ask them a few questions about how they’ve been doing.

“We also want to collect people’s personal stories on how they are coping with the heat and match that with internal temperature data that is collected by the sensor and also the external satellite data that is collected from NASA satellites,” Jusino says.

While the main experiment was to work with the community on the placement of sensors, the team also picked up metadata on things like the type of building: was it a brownstone or a high rise; the orientation: is it south facing or east facing; presence of an air-conditioner, which would help scientists analyse the data within context; and so forth. However, Glenn had pointed out to me that going forward the project will have to “establish its own ground team to collect data rather than have ambassadors do it. He thinks “the biggest challenge has so far been the community engagement part of the project.”

It’s a pilot “research project” for now, centred around those community members who offered to volunteer for the project. “The coolest thing about the Harlem Heat Project is how people experience the heat using these custom-made sensors. A lot of people die because of heat ailments and mortality in general goes up in these heat wave situations,” says Prathap Ramamurthy, an assistant professor at the City College of New York and an informal advisor to the project. His research involves urban climate and urban heat islands.

“As a physical scientist, I am keen to understand how the building really modulates the climate and on an average summer day, even if you see temperature fluctuations outside, the average temperature inside buildings ends up being the same all day long.”

Ramamurthy is from Chennai, India. He believes such a project can be adapted to urban areas in India, too, especially given the huge numbers who fall prey to heat waves. “India is experiencing rapid urbanisation that is pulling people into cities with no concept of how it will affect temperatures. The construction that has been happening in urban spaces has amplified temperatures a lot,” he says. “The thing about India is that instead of engaging the government, a lot of private entities might be willing to do these kind of things using sensors that don’t even cost that much money.”

Jusino told me he is eager to see how years two and three go. “Imagine, by year three we could have 200 sensors on the ground with real time data.” The tech will evolve too. “The next generation of this sensor is going to be connected to a GSM network so it can send the data wirelessly through a cellular network to a central data warehouse. Though the board will be more expensive, the hope is that we can set up sensors in certain highly impacted hosts.”

“And say our host is very elderly and the temperature and humidity gets above a certain level – you can potentially receive a warning where we can pick up the phone, call the person to check on them and make sure they are drinking enough water and have someone to help them out and let them know of a cooling centre nearby.”

Since the last week of August, the sensors are being picked up by Jusino or dropped off by hosts for the data to be downloaded and analysed in WE ACT’s office in Harlem. The project’s partners will get together in the fall with community members to discuss what can be done to mitigate heat illness in Harlem. Two of the sensors that have come back with the hottest temperatures were actually in the public housing tenements. “There is also a parallel project that has been running for three years now called ‘Heat Seek’, which is the opposite, where sensors are used to identify how cold it gets within homes during the winter. So we could work towards connecting these two projects in the future.”

One short-term goal is to iron out some absurd data that Jusino has had to grapple with this year. “Some of the hosts are elderly and they end up picking up the sensor and bringing it in after a long walk around the neighbourhood to pick up groceries, so there is a little bit of a disconnect between what the sensor is actually doing and how it should remain stationary in their homes.” Ideally somewhere in the bedroom.

“We advise that the sensors are placed somewhere high up away from small hands… We had one sensor fly out the window because a kid got to it and another host misplaced her sensor and for about two weeks we were collecting data from inside her car!”

Sowmiya Ashok is an independent journalist based in New York. She tweets at @sowmiyashok.

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