HEDWIG - Collection of measurement data to assess the impact of green buildings | Continuous indoor monitoring

Green infrastructures (GI) are becoming an important strategy for climate change adaptation. Although their positive effects – such as evaporative cooling, shading and biodiversity –are qualitatively recognised, reliable, standardised measurement data for quantitative impact assessment in planning practice are usually lacking. The aim of the HEDWIG study was to determine the effects of standard-compliant greening of buildings and to generate indoor measurement data, which serve as a basis for thermal building simulations and for the optimisation of planning processes. Continuous measurements in indoor environments were carried out in 3 representative green roofs and 4 green facades in Vienna and Lower Austria. A measurement setup for permanent indoor data registering was designed to ensure valid data collection and comparability across sites. Onsite data were collected over a period of 2 years (2024 to 2025), whereby unified sensor settings were installed. Measurements included: indoor air temperature: EnOcean STM 550 and Dragino LHT65N-NE117 indor air humidity: EnOcean STM 550 and Dragino LHT65N-NE117 magnetic contact: EnOcean STM 550 light: EnOcean STM 550 surface temperature: SHT TMP117, Texas Instruments and Sensirion SHT 21 To ensure comprehensive monitoring of climatic parameters across all sites, a hybrid measurement network was deployed. The selection of transmission standards (LoRaWAN, EnOcean, wired, etc.) was based on structural conditions—such as substantial wall thicknesses and signal range requirements—with a primary focus on energy-efficient wireless technologies. Due to the fact that the status of the windows plays an important role in indoor air temperature a combination of magnetic contacts, Air temperature and air humidity sensors were installed at selected locations for monitoring. While the magnetic contacts logged the opening status of the window, the additional sensors placed in the immediate proximity of the windows served to capture the local indoor climate at these points. This allowed for identifying manual ventilation events or uncontrolled infiltration in the respective measurement zones and acknowledging their impact on the thermal balance in the analysis. Since energy consumption is becoming increasingly important these days, a thermal building simulation was carried out to assess the performance of an uninsulated, semi-intensive green roof (35 cm substrate). During the cooling period (target temperature 25°C), approximately 4.8 kWh/m² of cooling energy was saved. However, the heating period resulted in an additional energy consumption of 30 kWh/m² compared to an insulated gravel roof with a U-value of 0.2. This discrepancy highlights that the primary benefit of green roofing lies in thermal protection during the summer. Nevertheless, targeted combinations of green roof types and appropriately matched insulation levels could yield synergistic effects. Furthermore, a comprehensive analysis of building physics was carried out. It showed that window-areas play a dominant role in cooling demands. Comparing these results with the cooling load, generated by solar heat gains through windows underscores the need for a holistic concept. In the analyzed model room “Amtshaus Margareten” (featuring 80 cm thick walls and south-facing windows), an unshaded south orientated window causes an additional cooling load of 116 to 173 kWh/m² of window area, depending on the glazing (g-value of 0.55 or 0.76). These findings are context-specific and may vary substantially for other structures. To address the thermal comfort an adaptive comfort model was applied based on the continuous indoor measurements. The operating room temperatures during the summer months were almost exclusively in comfort categories I (high comfort level) and II (normal standard). Critical overheating hours (category III or worse) hardly occurred. The effect of the façade greening on the opaque façade components was significantly influenced by uninsulated wall thicknesses and the associated thermal storage mass. Conclusions and OutlookThe onsite indoor data collected during the HEDWIG project demonstrates the potential of façade greening in terms of energy consumption and reduction of incoming radiation. For the first time, the HEDWIG project provides a broad, empirically validated database for different types of building greenery under real site conditions. The data obtained enables a more precise integration of green infrastructures into simulation tools and energy certification procedures. Further publicationsStangl Rosemarie; Jalits Nicole; Bintinger Rudolf; Mezger Lars; Spörl Philipp; Scharf Bernhard; Poiss, Maximilian; Pitha, Ulrike; Leitner, Elisabeth; Formanek, Susanne (2026): Projekt HEDWIG Erhebung von Mess-Daten zur Wirkungsabschätzung von begrünten Gebäuden. HEDWIG-Berichtsserie: Ergebnisbericht. Berichte aus Energie und Umweltforschung 59a/2026. Wien. Jalits, Nicole; Mezger, Lars; Spörl, Philipp; Scharf, Bernhard; Poiss, Maximilian; Pitha, Ulrike; Bintinger, Rudolf; Stangl, Rosemarie (2026): Projekt HEDWIG Erhebung von Mess-Daten zur Wirkungsabschätzung von begrünten Gebäuden. HEDWIG-Berichtsserie: Teilbericht Datenkatalog. Berichte aus Energie und Umweltforschung 59b/2026. Wien. Jalits, Nicole; Stangl, Rosemarie (2026): Studie im Rahmen des Projekts HEDWIG zur Abbildung des aktuellen Wissenstands im Bereich Dach- und Fassadenbegrünung. HEDWIG-Berichtsserie: Teilbericht Studie. Berichte aus Energie und Umweltforschung 59c/2026. Wien. Leitner, Elisabeth; Formanek, Susanne; Jalits, Nicole; Mezger, Lars; Bintinger, Rudolf; Stangl, Rosemarie (2026). Projekt HEDWIG Erhebung von Mess-Daten zur Wirkungsabschätzung von begrünten Gebäuden. HEDWIG-Berichtsserie: Teilbericht Ergebnisse aus dem Stakeholder*innenworkshop. Berichte aus Energie und Umweltforschung 59d/2026. Wien.