Mapping Building Heat Using Remote Sensing

Mark Altaweel

Updated:

One of the problems with climate change is buildings will become uncomfortable as the planet heats up. This not only makes individual buildings hotter but overall heat from buildings make entire cities and towns hotter, a phenomenon know as the urban heat island effect.

While air conditioning is an option, this energy demand to cool buildings may also prove too much for some areas. Instead of trying to cool all the buildings in an area, efforts may become more targeted towards structures that are the hottest.

Measuring the heat signature of buildings

Now, using a new satellite system, there is a way to measure buildings’ heat signatures remotely and target efforts towards the worst structures. The startup Satellite Vu has recently launched the first in an upcoming constellation of satellites that can measure heat signatures; the goal is that these satellites could help targeted approaches in cooling buildings and help countries reach net zero by 2050.[1]

The new Satellite Vu satellites, which are planned to be eight satellites, are called HotSat. The idea is that these satellites provide wide area monitoring as well as individual buildings to find the worst temperature offenders or heat signatures emitted from buildings.

A remote sensing image showing villages around Delhi in India that are colored red in the image and are much hotter than the surrounding areas which are blues and greens to indicate a cooler surface temperature.
Urban areas with darker surfaces and less vegetation tend to be much hotter than rural and natural areas. This remote sensing image from NASA’s ECOSTRESS instrument shows the urban heat island affect during a recent heatwave in India. While neighboring rural areas were around 40 degrees Fahrenheit cooler, Delhi’s urban “heat islands” and smaller towns reached 102 degrees Fahrenheit (39 degrees Celsius) as their highest temperature on May 5, 2022. Image: NASA/JPL-Caltech.

The satellites can be used to also identify areas such as parking lots that may be contributing heat. The benefit is efforts to mitigate heat from buildings can reduce overall heat island effects in cities and towns by finding the worst, hottest buildings and then cool them to reduce overall heat island effects.[2] 

HotSat uses thermal imaging to map building heat signatures

HotSat-1, the first satellite, was launched in June 2023. The satellite uses thermal imaging using mid-wave infrared; customers can sign up to Satellite Vu to enable buildings to be monitored remotely. Profiles of buildings can be made using 3D imaging capabilities to also pinpoint areas that require the most attention when it comes to what might be overheated in a structure. For instance, faulty valves or boilers could cause leakages in structures that may require attention. HotSat-1 was created by a UK manufacturer (Surrey Satellite Technology Limited).[3] 

Top image is a high resolution thermal image showing sources of heat.  The bottom satellite image is from Landsat and show a lower resolution heat signature.
SatVu’s eight-satellite constellation will provide higher resolution heat signature data for buildings. These two images demonstrate the higher resolution of SatVu’s remote sensing capabilities compared to heat mapping from Landsat. Images: SatVu.

By using thermal imaging, the satellite is able to detect heating at both night and daytime conditions; resolution is purported to be within 3.5 meters. In addition to monitoring for heat signatures, the satellite can be used to monitor infrastructure and patterns of life, such as land use, through thermal imaging.

A need to make buildings more energy efficient to reduce heat signatures

While some have praised the new satellite system as it will help monitor buildings and overall heating in regions that need to minimize heat island effects, some have stated this new satellite may not address the wider concern of heating in cities.

Funding is needed to retrofit buildings to be cooler and the UK has perhaps the most inefficient housing stock among developed countries, with the majority of houses built prior to 1970. Funding for retrofitting older houses could cost an enormous amount of money and funding such efforts might be a higher priority than remotely monitoring such buildings.

However, Satellite Vu argues that targeted efforts that look at the 20% worst structures in contributing to heat islands, for instance, would be a more efficient way to reduce overall heat in cities. The cost benefit would be removing the need to retrofit all or many pre-1970 housing stock in areas.[4] Individual roofs, rather than a coarse heat island, can be observed using HotSat; current monitoring usually identifies wide areas where heat might be high, but they fail to identify specific buildings and their contribution to a heat island.

Efforts to reduce heat islands also could be much lower in cost by using the satellite’s results. Simple measures such as planting trees or building gardens around hot structures could help address some of the problems in coordination with the thermal image results created from HotSat.

Using HotSat to identify water pollutants

Additionally, it is not just buildings but monitoring of pollution might be another benefit. Sudden changes in water temperature could often mean there is contamination or a new pollutant that had been added to water. HotSat satellites could identify surface temperature changes in water that can enable more immediate responses, even in cases where the pollution is odorless or difficult to detect on the ground.

Although this is a commercial venture, data from the satellite will be made available to the Ordnance Survey (OS), which is a government agency in the UK. The data and application of the satellite could also expand to other countries.

With recent heatwaves affecting many parts of the world, cities will increasingly become difficult places to live and uncomfortable for many. Efforts to cool cities will require targeted approaches that efficiently use funding and efforts to cool cities and areas as much as possible.

The HotSat satellites designed by Satellite Vu offer a potential to provide high resolution monitoring of heat using thermal imagery that can help identify the hottest buildings in towns. To reach net zero, minimizing energy use and retrofitting older buildings might be a key goal and HotSat satellites could be an important tool in such efforts. 

References

[1]    For more on Satellite Vu, see: https://www.satellitevu.com/.

[2]    For more on the  HotSat-1 satellites, see:  https://interestingengineering.com/innovation/hotsat-1-thermometer-to-measure-heat-output-from-space.

[3]    For more on the features and capabilities of HotSat-1, see: https://www.satellitevu.com/press/worlds-thermometer-reaches-orbit-hotsat-1-successfully-launches Additionally, more material can be found here:  https://space.skyrocket.de/doc_sdat/hotsat-1.htm.

[4]    A BBC story on HotSat-1 describes the effort, see:  https://www.bbc.co.uk/news/science-environment-65775901

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About the author
Mark Altaweel
Mark Altaweel is a Reader in Near Eastern Archaeology at the Institute of Archaeology, University College London, having held previous appointments and joint appointments at the University of Chicago, University of Alaska, and Argonne National Laboratory. Mark has an undergraduate degree in Anthropology and Masters and PhD degrees from the University of Chicago’s Department of Near Eastern Languages and Civilizations.

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