Are Green wall systems sustainable? Lučka Kajfež Bogataj University of Ljubljana

Direct green facade, Portugal Continuous living wall system, Madrid M. Manso, J. Castro-Gomes, Green wall systems: A review of their characteristics, Renewable and Sustainable Energy Reviews, 2015 Indirect green façade, Hong Kong

Indoor living walls Analysis of environmental performance of indoor living walls using embodied energy and carbon Int J Low-Carbon Tech. 2016;12(2):67-74. doi:10.1093/ijlct/ctw021

Positive effects on landscape aesthetics

Green wall systems but there are so many types Green walls Green facades Direct Indirect Continuous Traditional green facades Continuous guides Modular trellis Lightweight screens Living walls (LWS) Trays Modular Vessels Planter tiles Flexible bags

Vertical greening systems A. Medl et al. / Building and Environment (2017)

So many types of climate

COMMONLY CITED ADVANTAGES a work of art more options for those with limited space increasing the biodiversity and ecological value mitigation of urban heat island effect outdoor and indoor comfort insulating properties improve of air quality improve social and psychological well-being of city dwellers new jobs, profitable business

Executive Office Building at Nanjing University (Yin et al., 2017)

Green wall systems disadvantages Green facades Living walls Direct greening Indirect greening Continuous systems Modular systems Traditional green facades Continuous guides Modular trellis Felt Pockets Vertical gardens Trays Planter tiles Flexible bags Limited plant selection /Climate adaptability Spontaneous vegetation development Slow surface coverage Scattered growth along the surface Surface deterioration /Plants detachment Maintenance problems Limited plant selection /Climate adaptability Slow surface coverage Scattered growth along the surface High environmental burden of some materials Limited plant selection /Climate adaptability High environmental burden of some materials High installation cost Complex implementation High water and nutrients consumption Frequent maintenance Limited space for root development High installation cost Complex implementation Heavier solutions Surface forms limited to trays dimensions High environmental burden of some materials High installation cost Complex implementation Limited space for root development Surface forms limited to tiles dimensions High installation cost Complex implementation Heavier solutions due to growing media/ Limited to buildings maximum load High installation cost

Are Green wall systems sustainable? NUMBERS NEEDED!!

Life-cycle Analysis Any attempt to evaluate the benefits of green facades must follow the framework established by a standard LCA methodology with a reasonably realistic set of assumptions.

LCA Defined ISO 14040 ( 97) Life Cycle Assessment Framework Goal & Scope Definition Inventory Analysis Impact Assessment Interpretation Direct Applications: * Product Development & Improvement * Strategic planning * Public policy making * Marketing * Other

The Three Steps of LCA 1. The Life-cycle Inventory What are the energy, raw materials, emissions, & wastes? What data are needed? 2. Life-cycle Impact Analysis Assess environmental impacts identified in the life-cycle inventory. 3. Life-cycle Improvement Analysis Identifies opportunities to reduce the environmental impacts by modifying of the lifecycle inventory. 16

Green wall systems composition Green wall systems by their nature are complex systems, as are the sustainability issues to which they connect such as climate change, peak resources and land occupation. Life cycle assessment (LCA) can drive reduction of environmental impacts, by tying design decisions to impact reductions for contexts now, and those envisaged for the future.

Energy requirements and payback periods for three climates

One example of Life cycle inventory model components

2 environmental accounting methods Life Cycle Assessment (limited to the Carbon Footprint) EMergy Evaluation (EME) performance of VGS in a Mediterranean climate.

Carbon Footprint: results from the LCA compared to energy saving

Energy saving for heating, cooling and temperature decrease for Mediterranean and temperate climate

Concluding thoughts There is still a huge research gap regarding sustainability of Green wall systems (more climates, over the whole year, lack of research on orientation, evapotranspiration and shading must be analysed, lack of studies, especially in arid climate) Green wall systems must evolve to become more sustainable solutions, through the use of materials with less incorporated energy and CO 2 emissions and the application of climate adapted plant species with less irrigation needs

Concluding thoughts Some examples already show sustainability concerns by using natural or recycled materials and native plants, integrating water recovery systems and sensors for water and nutrients minimization. The decision of which green wall system is more appropriate to a certain project must depend not only on the construction and climatic restrictions but also on the environmental impact of its components (e.g., energy or water used and materials recyclability) and associated costs during its entire lifecycle.