Implementation of Vertical Greening as a Double Skin

Implementation of Vertical Greening as a Double Skin Envelop: A Sustainable Approach in Tropical Climates Himalshi Rupasinghe, Rasindu Galagoda, Nilusha Perera, Rangika Halwatura Department of Civil Engineering, University of Moratuwa, Sri Lanka. Department of Agricultural Engineering, University of Ruhuna, Matara, Sri Lanka.

The struggle for a sustainable future on this planet will be won or lost in our cities. by 2010 half of the global population is recorded to be living in cities or towns. if the trend continues by the year 2045, two third of the world population would be living in urban areas. In next 30 years, a doubling of urban population is predicted. This means, More buildings More vehicles More emissions More energy consumption More pollution Less green cover That is a very short window of opportunity to

Vegetation is identified as a solution to overcome the effects of urban heat islands, air pollution and global warming. Vegetative canopy cover with optimum spatial configuration are vital in UHI mitigation (Bao et al. , 2016). Absorption of CO 2 and various air pollutants in varying amounts, cooling effect of evapotranspiration and shading stand out from numerous benefits of trees. Thus, Greenery in urban context is vital in balancing the environmental quality and air quality.

Buildings too have to play a significant role in order to mitigate high greenhouse gas emission and to avoid high energy consumption U. S. Energy Information Administration (2011) Buildings crave for significant amount of energy for heating and cooling purposes Reducing cooling loads of building is a vital need Building design needs to facilitate reducing external gains and removing internal gains Building Envelop is the main component to facilitate this requirement

(Hyde et al, 2013) (Ibrahim, Hayman & Hyde, 2010) (Rajapaksha et al, 2015) (Rupasinghe , 2016) Building envelop : a third skin Building envelops acts as a third skin in mediating between climate and indoors. External Double Skin Envelop : a fourth Skin Allows greater control over natural ventilation and solar radiation through the use of multiple skins as climatic buffer zones. External double skin GREEN WALL : a more environmental , ecological and energy efficient approach Advantageous in TWO WAYS Energy saving, heat reduction, mitigating urban heat island, influencing biodiversity, noise attenuation and many more benefits are associated with the vertical greening along with the benefit of improving building interior

Vertical greening is identified and implemented as an interesting integration in improving urban environmental quality and life standards vertical greening offers the opportunity to restore the greenery lost due to man-made constructions while recreating the link of man and nature. Among the diverse benefits of vertical greening air quality improvement, regeneration of bio diversity and mitigation of heat island effect become prior considerations.

Vertical greening BENEFITS Aesthetics Building protection : shield from heat Improves air quality Energy saving Acoustics Health and wellness Sustainability • Reduces urban heat island effect and smog • Cleans outside air of pollutants and dust and offsets the carbon footprint of people and fuel emissions • Cleans interior air space by removing VOCs and other harmful toxins like benzene and formaldehyde • Acts as a sound proofing barrier • Soil and plants are a natural filter that can clean the water that flows through the wall • Insulates and cools the building envelope, as well as protecting it from the elements • Creates habitats for birds and beneficial insects, increasing biodiversity • Can be used for growing food in urban settings, creating sustainable and local control of food sources • Increased Biodiversity • Speeds recovery time for patients through biophilia • Helps children with ADHD focus better in school • Reduces absenteeism in the workplace and boosts

In urban areas where space on the ground is limited, but vertical spaces are abundant “ vertical greening” is a fruitful merge of nature and structure. Based on the systems and growing methods, vertical greening is categorized as living wall systems and green facades. Vertical Greening Types Direct Green facades Indirect Vertical greening Continuous Living walls Modular

GREEN FACADES simply plant climbers attached to the vertical building walls. Direct greening system (grown climbing plants) Indirect greening system (grown climbing plants + supporting material)

LIVING WALLS Living walls are essentially 'container grown' plants that have been turned vertically (on their side). Living walls; Indirect greening system with planter boxes, foam substrate, felt layers

REQUIREMENT OF FURTHER RESEARCH IN THE FIELD GREEN WALLS Research needs to be conducted on green wall performance ecosystem service valuation and tool development design parameters management ancillary benefits to local environments risks of detrimental effects plant disease pests control and many more.

The Sri Lankan context; a drastically declined green cover in urban areas Declination of green cover at Colombo from 1956 to 2010 (a: 1956, b: 1982, c: 2001, d: 2010) (Wickramasinghe et al. , 2016)

ON-SITE INVESTIGATION ; SRI LANKAN CONTEXT DIRECT GREEN FACADES LIVING WALLS INDIRECT GREEN FACADES Most of the cases the reason for using vertical greening has been to achieve aesthetical appearance, either to enhance the building outlook or to cover up a

LIVING WALLS INDIRECT GREEN FACADES Three cases represented each vertical greening type to further investigate for their thermal performances. Temperature measurements were taken at, wall surface shaded from each vertical greening type and at adjacent bare wall and were compared. Each type was measured 48 h in real time to obtain temperature measurements using

living wall systems ; A temperature difference of 6. 90 o. C to 9. 31 o. C maximum 9. 31 o. C at 1 pm. Indirect green facades: A temperature difference of 7. 19 o. C to 9. 59 o. C maximum 9. 59 o. C at 2 pm Direct green facades: A temperature difference of 5. 14 o. C to 6. 39 o. C maximum 6. 39 o. C at 1 pm Each vertical greening type has signified a considerable temperature reduction at building exterior wall. It is evident that when heat gain from outside to building interior is less, the cooling load too gets reduced thus making the building energy efficient

OCCUPANT SATISFACTION

Sample Questionnaire Results Do you think vertical greening is beneficial and environmental friendly? Indicate your level of satisfaction for following statements Nothing specific Highly Unsatisfactory Satisfactory Highly satisfactory 0 20 40 60 80 100 The effect of vertical greenery on enhancing your mental condition Yes No How do you feel near the green facade? May be What are the main issues related to existing vertical greening? Hard to maintain proper plant health Damaging building walls Insect attraction Regular fertilizing Frequent training and pruning 0 10 20 30 40 50 what would be the purpose of integrating green facades in building? 90 80 70 60 50 40 30 20 10 0 Aesthetics and appearence To reduce heat gain to the building To maintain good To reduce noise from ventilation outside Other

Results indicates the greater potential of vertical greening to be integrated as a sustainable solution which is beneficial in terms of economic, environment as well as health and sustainability. The true potentials of green facades in Sri Lankan tropical context is still not fully explored due to inadequate research evidence and shortage of data to quantify the performance of them.

Selecting the plant type, growth medium and identifying the nutrient requirements Research gap: Though many researches have been conducted to investigate plant performance for environmental benefits no proper research has been done to identify the best suitable plant types for green wall panels Methodology: Experimental design will be Completely Randomized Design (CRD) with 3 replicates from each plant species. Data collection Rooting density, leaf area index, and average leaf dimensions will be collected from all plant species during the study period. After analyzing data 3 to 5 plant species will be selected and cooling potential data will be measure for that selected plants. Temperature data will be collected at 8. 00 am, 12. 00 pm, and 4. 00 pm each day. Relative humidity and rainfall data will be considered when analyzing. Data analysis Data will be analyzed by using Minitab software package(ANNOVA). Objectives: • To select the best suitable plant types for selected medium on vertical green wall panels. • To investigate the different plant physiological parameters (Leaf Area Index, average leaf dimensions, rooting capacity) of the plants, its heat absorption ability and the water retention ability. Green wall panel and the frame will be prepared using timber (2*1 ft. ). And it is bound with the hard plywood. Thickness of the panel is 1 ½ inch. Four coating of the wood care sealer will be applied with thinner solvent to improve the water resistant thus durability.

plant species were selected for the pilot study with the recommendation of expertise on the field. The plants were checked for Plant selection Twelve : their survival, growth rate, plant height, leaf Area Index at the pilot study. Fabrication of green panels Sample panels were prepared by using timber (60*30 cm). Thickness of each panel is 1 ½ inch. Each module represents a repetition, all modules have the same growth medium and protective layer, only different planting plant between the modules. Fertilizer application Nutrient supply is not needed until true leaves appear. Until this time only clean water was applied. However, as the leaves unfolded, the nutrient supply gradually began because the growing medium contains very little plant nutrients. Nutrient solution was prepared by dissolving 0. 5 g of Albert’s mixture in 500 ml of water for each panel and applied twice per week. The Albert mixture is used as a water-soluble production line for drip irrigation and foliar spraying. Limitations: With the time constraints study was limited to selected twelve plant species and based on literature and practical applications the growth media and nutrient supply were selected. The investigation was limited to the plant performance of prevailing climate conditions of the investigated time period.

Experimental design was Completely Randomized Design (CRD) with 3 replicates from each plant species. The twelve plant species (treatments) were placed in panels. Each panel (replicates) held eight plants of each species. Data collection Monthly plant evaluations was conducted for two months. Plant health was rated for all plants using a 3 -point scale of: 1 = thriving 2 = alive, but with signs of pest, disease or other stresses 3 = dead. Plant height was measured along with visual assessments of plant development stages (flowering and seed set) and pest/disease incidence. Leaf length and width were measured from plant species that have linear leaves and broad leaves area was measured by using graph paper method during the study period. Data analysis Data was analyzed by using Minitab and SAS software package (ANNOVA). Vegetation coverage and temperature data were subjected to analysis of variance using a general linear model (SAS statistical analysis software, version 9. 2). Separate analyses were conducted for each evaluation time. Where significant differences (P< 0. 05) were found to be exist between species, a Tukey’s studentised range multiple comparison test was performed.

Results and discussion Vegetal survival rate over the trial period was hieghest in Rhoeo spathacea species whereas Axonopus compressus, Ophiopogon japonicas, Portulaca grandiflora, Axonopus fissifoliu and Elusine indica too showed a high survival ability. Tectaria spp and Desmodium triflorum displayed a decline from 100% in to 33% and 62% respectively. Centella asiatica displayed comparatively slow growing rate and were not capable to survive in this environment. Begonia spp did not show any significant growth rate. Even though Dieffenbachia spp did not survived in the vertical environment, it has indicated that 100 % survival rate in the horizontal environment over the trial period. Plant survival rates during the trial period In terms of actual performance, Roheo spathacea, Axonopus compressus and Elusine indica showed highest rate of survival and coverage on the vertical green wall and they achieved full coverage within 12 weeks of transplanting. . Ophiopogon japonicas, Portulaca grandiflora too survived well during the trial period. Desmodium triflorum, Centella asiatica, Axonopus compressus, Dieffenbachiae spp, Tectaria spp, and Bigonia spp have declining survival rates in the vertical green walls. Mean plant height of the plant species

Green wall thermal performance Plant species that showed the best growth performances were selected to the initial study of thermal performances of green wall plants. Selected plant species were Rhoeo spathacea, Axonopus compressus, Portulaca grandiflora, Ophiopogon japonicas and Elusine indica. Canopy temperature for each species, substrate surface temperature and ambient air temperature (20 cm above canopy level) were measured for day time on a clear day using a data logger GL 820 midi. Mean air temperature 20 cm away from the panel surface level Mean temperature of the backside of the panel Mean temperature of the substrate surface

SIMULATION STUDY The results indicated a greater reduction in indoor temperature and cooling load with introduction of green wall at each side. As per the simulation results, with the introduction of green walls the cooling load requirement of building was reduced significantly.

“Nowadays, at a time when over half of humanity lives in cities, we need to show that nature can find expression in our urban environment and that the perception of its untrammeled and exuberant vigor will sensitize all those who live in cities to the need to safeguard what remains of the worlds natural environments. ” Patrick Blanc THANK YOU

Reference Di, H. , Wang, D. , (1999) Cooling Effect of Ivy on a Wall. Experimental Heat Transfer 12(3): (pp. 235 -245) Dunnett, N. & Kingsbury, N. , (2008), Planting Green Roofs and Living Walls, Timber Press: Portland, OR Halwatura, R. U and Jayasinghe, M. T. R (2009) Influence of insulated roof slabs on air-conditioned spaces in tropical climatic conditions-A life cycle cost approach, Energy and Buildings 41, 678– 686. Halwatura, R. U. and Jayasinghe, M. T. R. (2007), Strategies for improved micro-climates in high-density residential developments in tropical climates, Energy for Sustainable Development , Volume XI No. 4 (44 -55). Hyde, R. , & Rajapaksha, U. (2013). An evidence based design approach to select retrofitting strategies: what sources of evidence can be used to select retrofitting strategies. In R. Hyde, Sustainable retrofitting of commercial buildings: warm climates (pp. 107 -133). London: Routledge. Holm, D. , (1989), Thermal improvement by means of leaf cover on external walls: a simulation model. Energy Build, 14. Hoyano A. (1988), Climatological uses of plants for solar control and the effects on thermal environment of a building. Energy and buildings. 11, (pp. 181199) Ibrahim, N. L. N. , Hayman, S. , & Hyde. R. (n. d. ). A Typological Approach to Daylighting Analysis. Jayasinghe, M. T. R, Athalage, R. A and Jayawardena, A. I. (2003) Roof orientation, roofing materials and roof surface colour: their influence on indoor thermal comfort in warm humid climates, Energy for Sustainable Development, VII, pp. 16– 27 Jim, C. Y. , (2015), Greenwell classification and critical design-management assessments, Ecological Engineering, 77, (pp. 348– 362) Jim, C. , He, H. , (2011), Estimating heat flux transmission of vertical greenery ecosystem. Ecological Engineering, 37. Kenneth, I. p. , Lam, M. , Miller, A. , (2010), Shading performance of a vertical deciduous climbing plant canopy, Building and Environment, vol 45, (pp. 81– 88). Köhler M. (2008), Green facades – a view back and some visions. Urban Ecosyst. 11, (pp. 423 -436). Loh, S. , ( 2008), Living Walls – A Way to Green the Built Environment, Environment Design Guide, Australian Institute of Architects Manso, M, Castro-Gomes, J. (2015). Green wall systems: A review of their characteristics. Renewable and Sustainable Energy Reviews 41, (pp. 863– 871). Retrieved from www. elsevier. com

Ottelé, M. , Perini, K. , Fraaij, A. L. A. , Haas E. M. , Raiteri R. , (2011), Comparative life cycle analysis for green façades and living wall systems. Energy and Buildings Parker, J. H. , (1987), The use of shrubs in energy conservation in plantings. Landscape J, vol 6(pp. 132– 139). Pérez, G. , Rincón, L. , Vila, A. , González, J. M. , Cabeza, L. F. , (2011). Green vertical systems for buildings as passive systems for energy savings. Appl. Energy 88, (pp. 4854– 4859). Perini, K. , Ottelé, M. , (2014), Designing green façades and living wall systems for sustainable constructions, Int. J. of Design & Nature and Ecodynamics. Vol. 9, No. 1 Perini, K. , Ottelé, M. , Fraaij, A. L. A. , Haas, E. M. , Raiteri, R. , (2013). Vertical greening systems and the effect on air flow and temperature on the building envelope. Build. Environ. 46, (pp. 2287– 2294). Perini, K. , Rosasco, P. , (2013), Cost benefit analysis for green façades and living wall systems, Building and Environment 70. Retrieved from www. elsevier. com Perini, K. , (2012). The integration of vegetation in architecture. Innovative methods and tools. Dissertation, University of Genoa Perini K, Ottelé M. , (2012). Vertical greening systems: contribution on thermal behavior on the building envelope and environmental sustainability. In: Eco architecture IV. Harmonization between architecture and nature WIT transactions on ecology and the environment, vol. 165, (pp. 239) Perini, K. , Ottelé, M. , Haas E. M. , Raiteri, R. , (2011). Greening the building envelope, façade greening and living wall systems. Open Journal of Ecology. Retrieved from http: //dx. doi. org/10. 4236/oje. 2011. 001. Rajapaksha, U. , Rupasinghe, H. T. , and Rajapaksha, I. , (2015), Resolved duality: external double skin envelopes for energy sustainability of office buildings in the tropics, in Proceedings of 31 st International conference of Passive and Low Energy Architecture conference held in September 9 -11, Bologna, Italy Rupasinghe, H. T. , (2016), Assessing external double skin envelopes coupled with night ventilation and thermal mass for passive cooling in the tropics, in Proceedings of 50 th International conference of the Architectural Science Association 2016. Stec, W. , van Paassen, A. , Maziarz, A. , (2005), Modelling the double skin façade with plants. Energy Build, 37. United Nations, “World Urbanization Prospects: The 2014 Revision”, Department of Economic and Social Affairs, Population Division, United Nations, New York, 2014. USEPA Green Building Strategy. (2008). Retrieved February 17, 2015, from USEPA (United States Environmental Protection Agency): Environmental Protection Agency) (2008). IEA, 2008.