Marc Ottelé

Vertical greening systems, a process tree for green façades and living walls

This study shows that greening the building envelope with vertical greening systems such as climbing plants or living wall systems provides ecological and environmental benefits. Contemporary architecture in fact is increasingly focusing on vertical greening systems as a means to restore the environmental integrity of urban areas, biodiversity and sustainability. Applying green façades, which is an established feature of contemporary urban design, can offer multiple environmental benefits on both new and existing buildings and can be a sustainable approach in terms of energy saving considering materials used, nutrients and water needed and efficient preservation of edifices. To provide a full perspective and a viable case study on vertical greening systems a process tree is developed throughout this research. Elaborating the process tree has proved to be a useful methodology to analyse main parameters as climate and building characteristics, avoid damages and maintenance problems caused by inappropriate design, and compare different elements such as technologies, materials, durability, dimensions, and plant species employed.

Life cycle assessment (LCA) of green façades and living wall systems

Abstract: Greening the building envelope using vegetated (green) facades is a good example of a new construction practice. Plants and partly growing building materials, in the case of living wall systems (LWS), have a number of functions that are beneficial for the built environment. However, the development of LWS is so rapid that various different materials and characteristics are available at the moment. The latter positively or negatively influence the environmental burden as discussed in this chapter. Greening the building envelope can be a sustainable option for new and retrofitted constructions, by using materials with a relatively high influence on the environmental profile, although not all benefits are yet quantifiable. The present study identifies new scientific directions to reduce the environmental costs of green constructions.

DESIGNING GREEN FAÇADES AND LIVING WALL SYSTEMS FOR SUSTAINABLE CONSTRUCTIONS

The integration of vegetation in urban areas is a constantly evolving research fi eld. However, green envelopes (especially the most innovative vertical greening systems) are not yet fully accepted as an environmental quality restoration and energy-saving method for the built environment, due to the lack of data needed to quantify their effects and to evaluate the real sustainability (environmental and economic) of these. The many systems available on the market allow combining nature and built space to improve the environmental quality in urban areas; green facades, living wall systems offer more surfaces with vegetation and, at the same time, contribute to the improvement of the thermal performance of buildings. From a functional point of view, vertical greening systems often demand a complex design, which must consider a major number of variables. In the case of vertical greened surfaces, there are numbers of systems to green facades with or without windows, starting from a simple disposition of climbing plants at the base of the facade. Vertical greening systems’ characteristics and materials involved can either positively or negatively infl uence theirs performances, with respect to the improvement of the building envelope effi ciency and microclimate conditions (cooling potential and the insulation properties), and the environmental burden produced during their life span (installation, maintenance, disposal, etc.). This paper analyses characteristics, advantages and critical aspects of four common vertical greening systems, with special attention to micro-scale benefi ts (the benefi ts most related to the systems peculiarities) and to environmental sustainability.

A Green Building Envelope: A Crucial Contribution to Biophilic Cities

Throughout history, greening of outside walls and roofs of buildings has taken place. Reasons for doing so were the increase of insulation (keep cool in summer and keep cold out in winter), improved esthetics, improved indoor and outdoor climate, adsorption of particulate matter (PMx), as well as increasing ecological values by creating habitats for birds and insects. Green facades and living walls systems can improve the (local) environment in cities. They offer more surfaces with vegetation and, at the same time, contribute to the improvement of the thermal performance of buildings. Although in the past, relatively little attention has been paid to these valuable opportunities of vegetation and its interaction with buildings. More and more attention is shifted to these so-called beneficial relations in especially dense urban areas, which can be considered as deserts in biological terms. This movement from a biophilic perspective point of view includes combining nature and natural elements in the built environment to ameliorate the negative impact of climate change as for example loss of biodiversity, mitigation of urban heat, or air pollution reduction.

Integration of Ecosystem Services in the Structure of the City is Essential for Urban Sustainability

Examining the actual major environmental and social problems of the modern city, e.g., pollution, difficulties in food and water supply, poverty or homelessness, this study argues that insights from the field of ecology could offer structural solutions. In particular, specific ecosystem services could be used to fight/solve specific urban problems. Today, on a large scale, only a few different ecosystem services from outside the urban area are used as ecosystems, as biotopes are insufficiently available inside the city boundary. Their physical absence obstructs the use of their benefits and leaves an important potential of urban ecological space unused. Most vegetation was banned from cities during urban history, what may have been the fundamental cause of several major urban problems emerging today. Therefore, the solving potential was analyzed of 20 ecological services if consistently located inside the urban boundary. According to the results, respectively, 14 and 7 ecosystem services can be linked as solutions to 10 environmental and 8 social problems eminent in contemporary cities. This study, therefore, concludes that structural integrating ecosystem services in the built-up urban space: (1) could solve major urban environmental and social problems; (2) improve urban sustainability; (3) revitalize degraded urban areas.

A review of green systems within the indoor environment

This paper reviews the state of art of vegetation systems and their effect on the indoor environmental quality (IEQ), based on scientific studies from the past 30 years. Some studies have shown that biophilic workspaces and interaction with plants may change human attitudes, behaviours, improve productivity and the overall well-being. Evapotranspiration from plants helps lowering the temperature around the planting environment and this can be utilised for air cooling and humidity control. Also, indoor greenery can be used to reduce sound levels as a passive acoustic insulation system. Living wall systems in combination with biofiltration are emerging technologies to provide beneficial effects on improvement of indoor comfort. Several studies have indicated that green systems may improve indoor air quality and that they have different pathways for pollutant removal of volatile organic compounds. The plant root zone in potted plants may be an effective area for removing volatile organic compounds under controlled conditions. In conclusion, the full capacity of plants in real-life settings will need to be clarified to establish the true pollutant-removal mechanisms and the general effect on IEQ. The effects of green systems in combination with mechanical elements such as conventional heating, ventilation and air conditioning would need to be studied.

A proposal for determining the remaining time to chloride induced corrosion initiation of existing reinforced concrete structures

Asset managers would benefit from knowing when to expect corrosion initiation in a particular reinforced concrete structure. However, accepted approaches to test existing structures for the remaining time to corrosion initiation are lacking. This paper proposes such an approach, based on experience in the field and additional considerations. From say 20 years age, existing structures embody the concrete’s response to actual environmental loads, e.g. in chloride profiles. Based on measuring the actual cover depth, taking (at least six) chloride profiles, some assumed parameters and a simple model, the expected time to corrosion initiation for a particular test area can be predicted. Sampling frequencies are given. Uncertainties can be taken into account by applying a safety margin to the cover depth. Results of at least six tests are classified and suggestions for interpretation are given. Because the accuracy is limited, the results are classified in three broad ranges: 5 years or less, 5 to 15 years, or more than 15 years. The procedure is applied to a field case and results are discussed.

The development of an ESEM based counting method for fine dust particles and a philosophy behind the background of particle adsorption on leaves

The multi scale benefits of urban greenery (green facades and green roofs) have attracted more and more interest of recent research work. The multi scale benefits of vegetation vary from; mitigation of the urban heat island effect, stimulation of the ecological value and biodiversity, aesthetical reasons and for example air pollution reduction. Air pollution control is at the moment mainly focussed on the reduction of fine particle concentrations. Particulate air pollution is damaging for the human health, it causes cardiovascular and lung diseases. Especially dust particles smaller than 2.5 micrometers are of great interest because they can be deeply inhaled into the respiratory system. To determine the effect of leaves on particle adsorption, micrographs are taken of ivy (Hedera helix) leaves using an Environmental Scanning Electron Microscope (ESEM). The examined leaves are exposed to a simulated rainfall in order to determine a method for particle counting on leaves and to determine the self cleaning effect of adsorbed particles on ivy leaves. The self cleaning effect is considered to be an important factor in the effectiveness of particle adsorption by leaves and the potential for resuspension of particles. Particles on pre- and post-rain leaves were counted via the ESEM micrographs using an image analyzer. Results showed that there is no significant effect on particle loss due to rain in the performed experiment. Our findings suggest that a strong Van der Waals bonding between