How Graz Uses Aerial Surveying and Digital Twins to Tackle Urban Heat

EAASI Company: AVT Airborne Sensing

Project Overview

As European cities adapt to rising temperatures and increasingly frequent heatwaves, access to accurate, high-resolution geospatial data is becoming essential for climate-resilient urban planning.

The Austrian city of Graz has long been recognised for integrating climate science into urban development. Building on decades of environmental research, the city has recently advanced two complementary initiatives that combine digital twins, climate analytics and crewed aerial surveying to better understand urban heat islands, improve access to green infrastructure, and support energy efficiency.

Both projects involve EAASI member AVT Airborne Sensing, demonstrating how aerial surveying provides the reliable geospatial foundation required for climate adaptation at city scale.

Technical Solution

The first initiative forms part of USAGE (Urban Data Space for Green Deal), a Horizon Europe project helping cities use integrated data to support Green Deal objectives.

Within the project, Graz developed two practical applications.

• The first focused on urban heat island analysis. Existing satellite-derived thermal information was validated using high-resolution aerial thermal imagery, allowing researchers to assess estimation errors across different surface materials such as asphalt, vegetation, and built-up areas. The comparison significantly improved confidence in thermal mapping products used for urban planning.
  

• The second application implemented the internationally recognised 3-30-300 rule, assessing whether residents can see at least three trees from their homes, live in neighbourhoods with 30% tree canopy cover, and have access to public green space within 300 metres. By integrating multiple geospatial datasets, the city produced intuitive visualisations highlighting areas where green infrastructure could be strengthened.
  

These analyses feed directly into Graz's Climate Information System (KIS), which combines climate observations, thermal imagery and predictive climate scenarios to support evidence-based urban planning.

Alongside these analytical developments, Graz commissioned a dedicated aerial thermal survey to improve building energy efficiency across the city.

AVT Airborne Sensing carried out the acquisition during optimal winter night conditions using a crewed aircraft equipped with dual long-wave infrared (LWIR) thermal cameras. During a four-hour mission, the aircraft flew approximately 600 kilometres while acquiring more than 13,000 thermal images.

The resulting thermal mosaic achieved a ground resolution of approximately 35 centimetres, enabling detailed rooftop-level analysis. By combining thermal imagery with existing geospatial building data, the city developed an online platform allowing property owners to identify potential heat loss and support renovation decisions.

Project Benefits

The combination of digital twins, advanced climate modelling and high-resolution aerial surveying has provided Graz with a robust framework for climate adaptation.

The projects enable the city to:

• Improve urban heat island analysis through validated thermal datasets.

• Assess access to green infrastructure using measurable indicators.

• Support climate-informed urban planning through digital twin technologies.

• Identify rooftop heat loss at building level.

• Provide citizens with practical information to improve building energy efficiency.

• Strengthen evidence-based decision-making for long-term climate resilience.
  

The initiatives demonstrate that while satellite observations provide valuable regional information, crewed aerial surveying delivers the spatial accuracy and level of detail required for operational urban management.

Future Outlook

As cities seek practical responses to climate change, integrating aerial surveying with digital twins and environmental modelling is becoming an increasingly powerful approach.

The Graz projects illustrate how high-resolution airborne data can support not only climate monitoring but also public engagement, sustainable urban planning and energy transition. By combining decades of climate expertise with modern aerial sensing technologies, Graz offers a replicable model for municipalities aiming to build more resilient, liveable cities.

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A longer version of this case study can be found in the article From Heat Islands to Green Spaces: Graz's Comprehensive Climate Strategy on Geo Media, published in October 2025.

Learn more about how EAASI members apply crewed aerial surveying technologies to support climate resilience, environmental monitoring and sustainable urban development through the EAASI Use Cases series.