Foto: Green facade of MA 48 headquarters; © C. Fürthner, MA 20; https://www.wien.gv.at/
Green façade for heat wave buffering on an administration building
The Vienna environmental department - MA 22, had been dealing with the topic "heat in the city" for more than 15 years. This included a climate assessment and map based on thermal images and the implementation of measures, such as green space networking, roof greening, façade greening and rain water management. This led to the creation of an ecosystem-based adaptation solution; the greening of the building ‘façade’ or front wall.
The greening, which includes the creation of a “living wall” by hanging and planting 17,000 plants, has enabled people to benefit from better climate regulation, air quality and a more attractive environment. In addition, the employees enjoy cooler indoor temperatures in the summer. The knowledge and experience from employing the green façade measures and sharing information through a brochure has helped more people to join in and create their own living walls.
The Adaptation Journey
The positive impact
Climate change can cause heat island in cities, which are pockets in urban areas that have a higher temperature than their surroundings. These affect the health of both people and buildings. To address this, Vienna developed a pioneer program for greening buildings, including the façade of the department for waste management.
This façade has been a great example in helping Vienna to tackle the urban challenges of heat islands and biodiversity loss, as it had a positive impact on both the employees and the local citizens by improving the indoor and outdoor climates. Biodiversity was improved because the plants in the façade have created more urban homes for insects and birds. The facade also allowed them to investigate the effects on the movement of heat during winter, as well as on heat demand in the building.
The investigation provided knowledge to support the creation of a brochure, shared widely to support the creation of more green facades.
How does it work?
In designing such measures, it is important to consider the holistic aspect by valuing all of the possible benefits, such as heat insulation, air purification, improving of the biodiversity, improving the urban design, the human well-being and quality of stay, noise reduction (especially reduction of echoes, eg in courtyards), protection and upgrading of the building substance and the positive influence on photovoltaic systems.
The measures implemented in this project included both the ground-based, non-irrigated building greening (or planting) and the facade-related, irrigated variant as two-dimensional systems or with planters on the façade (“living-walls”). In total, 850 m2 of façade was mounted, which equated to 2,850 metres with 17,000 plants. The plants used were mainly perennials, grasses and herbs. As a pilot project, the state of knowledge on the function of such a measure has been improved, and this monitoring has helped to define the effects of green facades on heat demand. The green part of the wall was shown to improve thermal insulation by 21%, and led to a change in the annual heat transmission losses from the building (of 54.7 kWh to 45.1 kWh per square metre of the green wall). The impact on biodiversity still needs further surveying, however the effect is estimated to be positive. There has also been a strong increase in awareness of this topic amongst planners, residents and developers.
A guideline for façade greening was prepared by the Austrian Association for Building Construction and by the University for Soil Culture on behalf of ÖkoKauf Wien, the program for the ecological procurement of the city of Vienna. The guide offers valuable specialist information to architects, planners, developers, public institutions, as well as interested citizens and serves as a decision-making aid when choosing the ideal type of greenery for different facades. Contents include general information (e.g. target groups, scope, definitions, advantages of a green façade), as well as information on various facade greening systems, their ecological and technical functions and design possibilities. A system overview, funding options and a checklist also serve to help users prepare and plan façade greening by examining the necessary conditions and prerequisites. Finally, the guideline highlights best practice examples from the Vienna area and further references to literature and regulations. This guideline was in high demand and the first edition was out of print within the first year after publication. A new edition was published in early 2017, complimented by other promotional materials.
The successful implementation of the project required the participation and collaboration of a wide scope of individuals throughout all project phases. A public and private partnership approach enabled public administrations to share the tasks and risks of planning, realization and operation together with private partners. The collective effort of experts from different fields further helped the creation of the instructional guideline.
Obstacles and challenges
The vertical greening can demand high costs for construction and maintenance, and they required technical know-how. For example, using rainwater for irrigation is a technical challenge for the supply of water and nutrients to plants. In addition, monitoring impacts on biodiversity can be challenging as it is difficult to access parts of the vertical wall.
How much did it cost?
The costs for the planning and construction were shared by the district and the environmental department MA 22 and the private owner, who is responsible for the maintenance. Financial resources for the guideline, including content creation, print and publication were planned in the annual project budget from the environmental department – MA22. There were no additional funds.
Administrative buildings Public buildings Urban greenery Use of rainwater Heating Green roof Biodiversity Heat waves and thermal island Energy savings