HEDWIG - Collection of measurement data to assess the impact of green buildings | Measurement Campaigns

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 HEDWIG project addressed this gap by carrying out measurement campaigns on 8 representative greened roofs and facades in both Vienna and Lower Austria. The aims were to determine the effects of standard-compliant greening of buildings and to generate representative vegetation and plant performance parameters, which serve as a basis for thermal building simulations and for the optimisation of planning processes.

The measurement campaigns were carried out during the summer months of 2023 and 2024 on 8 green roofs and facades each between 09:00 and 17:00. The primary goal was to record the characteristics of the greening objects and to evaluate and document their appearances, dimensions, vitality and relevant foliage information to relate measured sensor values from permanent recordings to the green structure. Following data were collected:

• air temperature [in front of/above and behind/under greenery]: ATMOS 14, (METER Group, Inc.)
• humidity [in front of/above and behind/under greenery]: ATMOS 14, (METER Group, Inc.
• solar radiation [in front of/above and behind/under greening]: PYR Cell SP110 (Apogee Instruments, Inc.)
• radiation balance: SN-500 SP110 (Apogee Instruments, Inc.)
• transpirations rate: LCiT (ADC BioScientific Ltd.)
• stomatal conductance AP 4 (Delta T-Devices Ltd.)
• (wall) leaf area index (WLAI): AccuPAR LP-80 (METER Group, Inc.)

The determined parameters and plant characteristics serve to document the physiological behaviour of the different plant species and the dominant climatic parameters.

On basis of the data generated during the measurement campaigns, approximate short-wave radiation balances were determined at all HEDWIG objects. The results indicated that the green bodies absorb up to 59 % of the incoming radiation and convert it into non-perceptible (latent) heat. The transmission rates ranged from 5,8 to 34,5 % and the reflexion from 6,8 to 28,2 %.

Highest plant coverage rates referring to target area up to 100 % were found in living walls while projected coverage rates were recorded to be78 to 98 %. WLAI were found to be up to 5,6 for Wisteria sinensis, and up to 4,1 with Parthenocissus tricuspidata. Living walls with mixed species variations (grasses, herbs, perennials) revealed a WLAI up to 5,3.

Electric conductivity ranged from 51,0 – 119,0 mmol/m/s with different vertical greening systems. These data were extrapolated for assessment of transpiration using WLAI and coverage. Soil- or planter-based Wisteria sinensis, if sufficiently watered, can transpire up to 10 l/m² per day. Heterogeneous plant stands (biodiverse grass-herb-perennials) that are located in irrigated wall-based greenery systems achieve transpiration quantities of up to 8 l/m² per day. Parthenocissus tricuspidata evaporates about 3 l/m² per day on natural soil, however this value is reduced by 2/3 in sealed courtyard locations.

Conclusions and Outlook

The onsite data collected in the HEDWIG project demonstrates the potential of facade greening in terms of transpiration performance and reduction of incoming radiation. The HEDWIG project provides a novel broad and empirically validated database for different types of building greenery under real site conditions. The derived plant and performance parameters enable a more precise integration of green infrastructures into simulation tools.

Further publications
Stangl 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.