Green Walls as element of bioclimatic design in Mediterranean Urban Buildings Georgia I. Papadopoulou SID: 3302120010 Supervisor: Prof. Agis M. Papadopoulos SCHOOL OF SCIENCE & TECHNOLOGY A thesis submitted for the degree of Master of Science (MSc) in Energy Systems NOVEMBER 2013 THESSALONIKI – GREECE Abstract Green walls can be considered as building retrofit contributing mostly in indoor and outdoor thermal reductions as well as energy savings, both for heating and cooling. The term itself is very descriptive: a wall that is either free-standing or part of a building, featuring several kinds of vertically installed vegetation. Two distinct concepts constitute the green wall technology: Green façades and Living walls. Living walls provide a wide range of benefits according to Literature. On the other hand, green façades are not such an effective concept, a fact that was corroborated during an energy study on a Multifamily Building in Cyprus, conducted for the purposes of the present thesis. If important barriers -including both technological and economical obstacle-will be surpassed and additional improvements –including subsidization and advertising- occur, then much more green wall projects will be installed, proving thus their beneficial nature in the environmental, economic as well as social and aesthetical field. 2 Table of Contents Abstract..............................................................................................................................................2 1. Introduction ...................................................................................................................................6 2. General Background .......................................................................................................................8 2.1 History and evolution of Green Walls ........................................................................................8 2.2 Green Façades ......................................................................................................................... 10 2.3 Living Walls ............................................................................................................................. 12 2.4 Subsidies and other Initiatives ................................................................................................. 19 2.4.1 The Case of Amsterdam .........................................................................................................19 2.4.2 The Shanghai Case .................................................................................................................20 2.4.3 The “Green Area Factor Project” .......................................................................................... 21 3. Benefits, Problems and Concerns ................................................................................................. 23 3.1 Benefits ................................................................................................................................... 23 3.1.1 Reduction of the Urban Heat Island (UHI) Effect .....................................................................24 3.1.2 Energy Savings.......................................................................................................................25 3.1.3 Building Envelope/Façade Protection .....................................................................................26 3.1.4 Noise Reduction .....................................................................................................................27 3.1.5 Storm water Management.....................................................................................................27 3.1.7 Increased Biodiversity ............................................................................................................28 3.1.8 Improved Exterior Air Quality/Pollutants removal ..................................................................29 3.1.9 Economic ...............................................................................................................................31 3.1.10 Reduced Footprint ...............................................................................................................32 3.1.11 Improvements in health and well-being ...............................................................................32 3.1.12 LEED® Credits.......................................................................................................................32 3.1.13 Urban Agriculture ................................................................................................................35 3.1.14 Property Value .....................................................................................................................36 3.1.15 Social ...................................................................................................................................36 3.1.16 Local Job Creation ................................................................................................................36 3.1.17 Aesthetic Improvement ........................................................................................................37 3.1.18 Plants as shading devices .....................................................................................................37 3.1.19 Weight ................................................................................................................................37 3.2 Problems and Concerns ........................................................................................................... 37 3 3.2.1 Cost Barrier ...........................................................................................................................38 3.2.2 Lack of Knowledge .................................................................................................................38 3.2.3 Lack of motivation and incentives ..........................................................................................38 3.2.4 Inappropriate Irrigation .........................................................................................................39 3.2.5 Mould and Moisture Problems ...............................................................................................39 3.2.6 Wall Damage .........................................................................................................................39 3.2.7 Salt Accumulation ..................................................................................................................39 3.2.8 Attraction of insects ...............................................................................................................40 3.2.9 Excessive Pollen .....................................................................................................................40 4. Design, Installation, Maintenance and Costs ................................................................................ 41 4.1 Green Façades: Design, Installation and Maintenance ............................................................. 43 4.2 Living Walls: Design, Installation and Maintenance .................................................................. 46 4.3 Types of Plants ........................................................................................................................ 50 4.3.1 Living Walls Case ...................................................................................................................50 4.3.2 Green Façades Case ...............................................................................................................52 4.4. Cost and Environmental Burden ............................................................................................. 53 4.4.1 Costs and System Comparison ...............................................................................................54 4.4.2 Environmental Burden ...........................................................................................................57 5. Building Physics ............................................................................................................................ 62 5.1 Thermal Balance of a Building ................................................................................................. 62 5.2 The Evapotranspiration effect and its contribution .................................................................. 65 5.2.1 Quantification of thermal reduction .......................................................................................66 5.2.2 Other Effects..........................................................................................................................70 5.3 Heat Transfer Mechanisms ...................................................................................................... 72 6. Quantification and Sensitivity Analysis-Examining the effect of a green wall on a typical residential building in Cyprus ........................................................................................................... 76 6.1 Methodology........................................................................................................................... 76 6.1.1 The Typical Building ...............................................................................................................76 6.1.2 Building Simulation ................................................................................................................76