Drone data helps a Minnesota city conserve energy

Warren, a small city in Northern Minnesota, is offering an innovative public service: images that reveal building heat loss, captured by drones. (Courtesy: Lars Nisse/Pixabay)

Originally published at ILSR.org

Maintaining healthy, comfortable buildings can be expensive in Minnesota — especially during polar vortex events. Warren, a small city in Northern Minnesota, is offering an innovative public service: images that reveal building heat loss, captured by drones.

For this episode of the Local Energy Rules Podcast, host John Farrell speaks with City Administrator Shannon Mortenson of Warren, Minnesota. Mortenson and the city partnered with a community college to pilot a novel project; the college, using drones and thermal cameras, captures images that display energy leaks in homes and businesses. Farrell and Mortenson discuss the first-of-its-kind thermal imaging project, lessons learned from the pilot, and how cities can help residents conserve energy.

Listen to the full episode and explore more resources below — including a transcript and summary of the conversation.

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Warren sets its sights on cutting edge tech

Warren owns its utilities, including electric and gas, so Mortenson’s role as city administrator includes oversight of the city’s energy supply. Warren does not generate its own electricity.  Instead, the city is part of a conglomerate of small towns that collectively purchase their electricity from Minnkota Electric Cooperative (and their gas from Constellation Energy).

Warren is also part of the Climate Smart Municipalities Partnership, where cities in Minnesota and Germany collaborate on sustainability and climate issues. Warren is partnered with Arnsberg, Germany. Warren and Arnsberg made a plan to take thermal scans of their communities in order to visualize building inefficiencies and heat loss.

Everyone’s looking to see, ‘how can I save money in my own home?’ And cities are trying to figure out, ‘how can we help our residents? How can they save energy? Our energy costs keep increasing, how can we be good stewards of our energy usage?’

Community college partnership

Northland Community College, in nearby Thief River Falls, has a drone program for students and was a natural partner for Warren. Starting in 2017, students at Northland would take thermal images of every building in Warren using drones.

After the drones take the photos, the students stitch them together and correlate them with a map of Warren. They are currently putting the images together, says Mortenson. The maps will soon be available to Warren residents.

Our plan is to take that data and allow residents to come in, sit down with staff and see where their greatest energy loss is in their homes… that way they can make a decision that would give them the greatest energy savings and cost savings

Data collection through trial and error

Drones fly 200 feet over the city and, using a thermal camera, document how much energy is leaking from buildings. The imaging should be done when furnaces are on, but the air temperature must be at least 32 degrees to sustain the drone’s battery. The air must also be still. Altogether, these conditions leave a small window of opportunity for imaging in late fall.

In their first attempts at imaging, the students also realized that the photos must be taken in the middle of the night. When the photos were taken shortly after dusk, the residual heat on the roofs read as heat loss across the map. Taken early in the morning, the sun would soon heat the roofs. Residents were notified that drones were flying, so there would be no confusion about the flying objects.

Mortenson believes that Warren’s partnership with the college has been essential. She and the supervising professor hope that the students will start a company and offer the thermal imaging service to other municipalities. The COVID-19 pandemic has slowed progress, says Mortenson, since enrollment at Northland Community College is down and students have been away from the classroom.

On-Bill Financing for Energy Efficiency Upgrades

Thermal scans help homeowners identify how their buildings are losing heat. With that information in mind, they can further insulate their home through air sealing, weather stripping, or attic insulation. They may choose to replace their doors or windows altogether.

Energy efficiency upgrades pay off over time, since they reduce energy bills, but many cannot afford the upfront costs of an upgrade. On-bill financing, sometimes called Pay As You Save, ensures that everyone can make their home efficient and comfortable.

In 2019, Warren took part in an inclusive financing feasibility study. Through the program, the building owner takes a loan from the city to make efficiency improvements. They pay the loan back through the savings on their utility bills — and the loan stays with the property, not the resident. Once the loan is paid off, the resident pockets the energy bill savings.

Their bill should not change. But then after the specified amount of time, which would probably be about two to three years, after the loan is paid back, then of course they would still see that savings on their bill.

Because of privacy concerns, the city of Warren cannot use thermal images to target individuals who may benefit from efficiency upgrades. Homeowners and business owners must approach the city and request their data.

Following in Warren’s footsteps

Mortenson says that city officials in Texas, Illinois, and Iowa have all approached her out of interest in Warren’s pilot project. The advice she gives is to find a partner like Northland Community College. The college already had the drones (each with a price tag of $40,000) and used the project as a student learning opportunity.

Warren was also an ideal community to pilot thermal imaging because it owns its utilities. The not-for-profit municipal utility had no incentive to fight the project since energy efficiency only helps city residents. For cities that do not own their utilities, Mortenson believes that thermal imaging is still a worthwhile investment. The data informs residents about their energy use, which they can use to save energy, money, and better afford their other bills.

I think it’s just good to have a handle on where’s your energy loss in the community and how can we be more efficient? How can we be good stewards and try to mitigate climate change and increase sustainability in our community?

Episode Notes

See these resources for more behind the story:

For concrete examples of how towns and cities can take action toward gaining more control over their clean energy future, explore ILSR’s Community Power Toolkit.

Explore local and state policies and programs that help advance clean energy goals across the country, using ILSR’s interactive Community Power Map.


This is the 141st episode of Local Energy Rules, an ILSR podcast with Energy Democracy Director John Farrell, which shares powerful stories of successful local renewable energy and exposes the policy and practical barriers to its expansion.

Local Energy Rules is Produced by ILSR’s John Farrell and Maria McCoy. Audio engineering by Drew Birschbach.

This article originally posted at ilsr.org. For timely updates, follow John Farrell on Twitter, our energy work on Facebook, or sign up to get the Energy Democracy weekly update

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