Initial situation, problems and motivation

Green infrastructure such as green roofs and façades is considered a key measure for climate adaptation, particularly for reducing urban heat and improving the energy efficiency of buildings. Despite political guidelines (e.g. EU Green Deal), there is still a lack of reliable, standardized parameters for the effect on cooling, solar radiation reduction and water balance.

In contrast to static, inorganic components, however, the quantification and standardization of dynamic, organic plant components is much more difficult. In particular, the slow increase in functionality during the first few years of growth poses major challenges for time-limited research projects, and measurement data is usually based on simulations or uninsulated test objects.

Greened window surfaces (bioshading) have hardly been investigated using measurement technology to date. The MARGRET project created an exceptional testing infrastructure throughout Europe with mobile greening test specimens and a highly sensor-supported façade test box as well as a green roof test stand. Initial results confirm the energy potential, but key questions regarding radiation transmission, evaporation and transferability remain unanswered.

Objectives and innovative content

The MARGRET Bioshade project pursues three central objectives.

• Firstly, the shading effect of vertical greening on window surfaces systematically quantified. Parameters such as transmittance and g-value are determined and compared with conventional shading systems in order to derive standardizable values for planning and simulation purposes.
• Secondly, the water balance and the energy effects of different greening systems will be investigated. In addition to the runoff behavior during heavy rainfall, the focus here is on determining characteristic values for evaporative cooling for reduced intensively and extensively greened roofs.
• Thirdly, the project aims to develop transferable parameters that enable the integration of greening effects into energy performance certificates, technical guidelines and energy simulation models.

In addition to the mature testing infrastructure, innovative methods such as pyroscanners, camera-based radiation measurement, g-value measuring device, load cell systems, standardized plant characterization (LAI, degree of coverage) and a digital twin with real-time measurement data visualization are used. Real-scale test stands with reference rooms and modern insulation standards enable highly precise, practical measurements.

Intended results

The project provides well-researched, reproducible characteristic values on the shading effect and energy transmission rates of vertical greening in front of transparent building components as well as on the water and energy balance of roof and vertical greening.

Seasonally differentiated shading factors for energy and daylight simulations, exact water balances for evaluating the cooling capacity and comparative data on the energy effects of intensive vs. extensive green roofs under real conditions are expected. Based on this, recommendations for standards, OIB guidelines and energy performance certificates are derived, and the comprehensive raw data set is published.

MARGRET Bioshade creates the methodological basis for the broad integration of green infrastructure into the energy assessment of buildings and makes a substantial contribution to CO2 reduction in building cooling and urban resilience.

Project management

AEE – Institute for Sustainable Technologies (AEE INTEC)

Project or cooperation partners

• IBO – Austrian Institute for Building and Ecology Ltd.
• University of Natural Resources and Life Sciences, Vienna
• GrünStattGrau Research and Innovation Ltd.
• Lucerne University of Applied Sciences and Arts, Department of Engineering & Architecture

AEE - Institute for Sustainable Technologies
DI Dr.med Martina Majcen
Feldgasse 19
A-8200 Gleisdorf
Tel.: +43 (0) 3112 5886
E-mail: m.majcen@aee.at
Web: www.aee-intec.at