Browsing by Author "Weerasinghe, KGNH"

Now showing 1 - 3 of 3

item: Conference-Full-text
Design and development of a green roof substrate for the tropics
(Department of Building Economics, 2024) John, GKP; Munasinghe, AMMG; Weerasinghe, KGNH; Halwatura, RU; Sandanayake, YG; Waidyasekara, KGAS; Ranadewa, KATO; Chandanie, H
Green roofs can be used as an effective climate change adaptation tool in South Asia. However, there is limited information on the type of substrate and the substrate depth best suited for extensive green roofs in this tropical climate. In this research, sixteen potential substrate mixtures were prepared using locally available materials and waste materials. The properties of these substrate mixtures were tested under laboratory and field conditions to identify the substrate mix best applicable for extensive green roofs for the tropical climate of Sri Lanka. Based on the results obtained from laboratory testing it was observed that substrate mixtures that contained coir and crushed recycled bricks displayed the properties most suited for a substrate in the tropical climate. Three different substrate depths (2.5cm, 5.0cm and 7.5cm) were also tested, in order to study their suitability for adequate plant development under tropical conditions. It was observed that the 2.5cm substrate depth had successful plant establishment and adequate plant coverage. Moreover, the 2.5cm depth substrate could be easily supported on an existing roof with little/no modifications. Therefore, for the tropical climate of Sri Lanka, a 2.5cm depth substrate composed of 10% compost, 5% coir, 5% rice husk, 40% sand and 40% crushed recycled bricks is recommended.
item: Thesis-Abstract
Development of a hybrid air purification unit for the indoors in tropics
(2023) Weerasinghe, KGNH; Halwatura RU
Indoor air pollution poses a critical concern in today's world, influenced by various factors. Ensuring a safe indoor environment demands addressing the profound impact of pollution. Multiple strategies have been deployed to mitigate indoor air pollution, with a focal point emerging as biofiltration using indoor plants. This prompted a thorough exploration into the capacity of NASA-recommended indoor plants, which had undergone minimal experimentation in tropical climates. Simultaneously, an assessment was made on the efficacy of indigenous herb plants in curbing indoor air pollution. The plant selection process involved using a plant selection matrix to identify the most suitable plants for the study. Individual plant performances were rigorously tested within controlled chamber studies, evaluating their abilities to reduce carbon dioxide and other pollutant gases. The net performance of plant leaf area in carbon dioxide assimilation was measured and compared, resulting in a ranking of plants based on their performances. Among these categories, the Peace Lily (Spathiphyllum blandum) and Thippili (Piper longum) plants emerged as the top performers. Using these selected plants, a hybrid air purification unit was innovated, combining natural plant-based purification with modern technology and additional functionalities. Subsequently, the actual-scale performance of this developed system was assessed to determine its environmental sustainability. A comprehensive questionnaire was employed to gauge the social sustainability aspect. The plants' performances were also evaluated in air-conditioned settings, followed by an economic comparison to ascertain practical feasibility. The culmination of these endeavors has revealed that employing specific combinations of indoor plants facilitates achieving desired indoor air quality levels, particularly in terms of reducing carbon dioxide levels. This practice is beneficial economically and is highly recommended for indoor spaces where individuals spend approximately 90% of their time. Ensuring indoor safety becomes paramount, and this Hybrid Air Purification Unit not only contributes to energy savings and enhances environmental air quality but also encompasses the immeasurable aesthetic and therapeutic effects of plants. Keywords: Air Purification, Carbon Dioxide, Hydroponic Cultivation, Indoor Air Quality, Indoor Plants
item: Article-Full-text
Economical sustainability of vertical greeneries in tropical climate
(2023) Jayakody, GDC; Weerasinghe, KGNH; Jayasinghe, GY; Halwatura, RU
Vertical greening is recognized as a fascinating integration in enhancing urban environmental quality and living standards. A research series was initiated with the aim of implementing a Vertical Greening System (VGS) to achieve the maximum benefit in terms of thermal performance in Tropical Sri Lankan context. However, it is unknown if vertical greeneries are economically sustainable. The current research vacuum should be filled by assessing the economic benefit of various vertical greenery systems. This study assesses the economic value of direct green façade (DGF), indirect green façade (IGF), and living wall system (LWS) by considering installation and maintenance costs and energy-saving benefits during their life cycle, through a cost-benefit analysis (CBA). CBA is computed under three distinct circumstances: worst, middle, and best. Net Present Value (NPV), Internal Rate of Return (IRR), Payback Period (PBP), and Benefit-Cost Ratio (BCR) are the four indicators used to calculate CBA. According to the study, DGF have positive NPVs for all scenarios and have acceptable IRR and BCR values with 6 years payback period. With best and middle scenarios, acceptable NPV, IRR and BCR values with 6–7 year payback period. Over three situations, LWS exhibits negative NPVs and indefinable IRR values. From An economic point of view, DGF and IGF are economically viable and living wall systems are not viable.