Browsing by Author "Perera, NGR"

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item: Conference-Full-text
Behavioural adaptations and housing modification: a case study of a low-income high-rise housing estate in Sri Lanka
(Department of Building Economics, 2024) Warakapitiya, GYD; Coorey, SBA; Perera, NGR; Giridharan, R; Sandanayake, YG; Waidyasekara, KGAS; Ranadewa, KATO; Chandanie, H
Rapid urbanisation and population growth have intensified housing challenges in Sri Lanka. In response, the government initiated Urban Regeneration Projects (URPs) to create a slum-free Colombo. These projects involved constructing high-rise housing blocks for relocating low-income settlements and freeing up land for urban development. Unfortunately, several initiatives encountered failures due to inadequate services, limited employment access, substandard living conditions, poor maintenance, and unforeseen social consequences. This research delves into the adaptive behaviours of relocated low-income families in high-rise housing. It examines the challenges they face in daily life and explores the measures they take to overcome these obstacles. The study employs a case study approach, utilising interviews, surveys, and observations within a selected low-income high-rise housing block. Basic housing needs such as sufficient indoor and outdoor space, privacy, social interaction, community living, physical comfort (light & ventilation), safety, and security, are crucial for residents. To meet these needs, inhabitants adapt through behavioural changes, including multifunctional use of space, shared space, family activity organisation, and extending domestic activities into semi-public zones. Privacy emerges as the most critical requirement, often prioritised over social interaction and physical comforts. Residents primarily address these needs through behavioural adjustments rather than extensive modifications, given the challenges posed by mass housing.
item: Thesis-Abstract
The Bio - climatic approach to urban public space: a thermal evaluation of 'streets'
(2014-07-04) Perera, NGR
Public spaces are the heart of civic life in a city; the common ground where people carry out the functional and ritual activities that bind a community, whether in the normal routines of daily life or in periodic festivities. (Carr, et. al, 1992: xi). The physical environment of these spaces must encourage and accommodate the diverse activities that the citizens indulge in. The success of urban public space is based on many factors, of which, the level of thermal comfort is seen as an important component. Although life in the equatorial tropics is largely an outdoor phenomenon, modern urban development has by and large failed to facilitate such living in a climatically pleasant manner. The approach then, should be an attempt to make the equatorial urban outdoors thermally comfortable. The primary concern here is with the spaces in-between buildings, that strictly speaking belong to no building in particular. The research establishes that; Shading or shaded areas of the urban outdoors have a distinct positive bearing on the thermal comfort of the people using these spaces. The orientation and the ratio of building height to the width of the space considered can be consciously modified in order to achieve the above ° Increased height to width ratio of the built mass increases the level of thermal comfort This study is a research initiative that aims at developing urban patterns that facilitate climate-conscious urban design in the equatorial tropics, with special reference to the Sri Lankan context
item: Thesis-Full-text
Climate-sensitive urban public space : a sustainable approach to urban heat island mitigation in Colombo, Sri Lanka
(2016-09-15) Perera, NGR; Mahanama, PKS
Manipulating the urban fabric is fundamental to mitigate and adapt to the warming trend in the growing high-density tropical cities. However, excessive data needs, weak analytical methods and the un-coordinated planning regimes pose barriers to achieving this aim. The main aim of the research is to bridge the gap in urban design-climate links, being translated into guidelines for real-world applicability in a background climate affected by global warming. The study is limited to the warm humid tropical climate of Colombo, Sri Lanka, as the experimental context for the research. The main research questions are related to; the microclimatic background condition under current and future warming scenario; sensitivity of the key urban morphology variables that will define and drive the decision making process; and the planning and policy implications that link climate and urban design. The study employs the Local Climate Zone (LCZ) system as a method of contextual analysis, together with LCZ-based morphology simulations (ENVI-met), utilising Mean Radiant Temperature (MRT) as the key dependent variable. Statistical analyses (SPSS) of the results test the applicability and sensitivity of urban morphological variables to help mitigate / adapt to local and global warming. The findings indicate that the Sky View Factor is the most influential urban indicator of local climate. In general, night-time shows better correlation with MRT. The nature of the Pervious Surface Cover has little or no effect on reducing MRT. And, the correlation of variables with MRT is stronger in a climatic background affected by global warming. The work contributes a ‘conceptual framework’ for the deeper understanding of the effect of building morphology on local level warming in the tropics. Policies that give effect to these findings are presented in a manner that requires minimal data input. Protocols for mapping of LCZs and relative warming effects, and sensitivity analysis of key design parameters for the mitigation of UHI in the tropics are presented. The socio-economic and planning practice implications of a LCZ-based planning approach are explored.
item: Article-Full-text
“Cradle to Gate” assessment of material related embodied carbon: A design stage stratagem for mid-rise housing in Sri Lanka
(Elsevier, 2021) Jayawardana, AS; Perera, NGR; Perera, LASR
Achieving low carbon buildings is seen as a key concept in order to reduce carbon emission and mitigate climate change. In contrast to operational emission, material related embodied carbon (EC) in the built environment plays a pivotal role, with the continuous consumption of high carbon emitting materials. This research relates to the ‘Cradle-to-Gate’ system boundary, while limiting its focus on building design stage decisions. A hybrid analysis approach was adopted - a bottom-up process with steps encompassing mass analysis, EC calculation, highlighting carbon hotspots, and ultimately the identification of critical building components. As a case study, multi-storey housing was selected as a critical building typology, in Sri Lanka. The results reveal ‘walls’ as a carbon hotspot that needs to be explored in strategies for mitigation. Substantial EC savings were seen in the selection of fly ash blocks as an alternate material to clay brick or cement block. Changes to the configuration of walls, specifically, bonding patterns and noninclusion of a plaster layer, also showed savings. This paper, contributes to the understanding of material selection implications - in the cradle-to-gate stage - for the reduction of carbon emissions in mid-rise housing, in the context of Sri Lanka.
item: Conference-Full-text
Daylight variability and human perception
(Faculty of Architecture Research Unit (FARU), 2021-12-03) Pathirage, LY; Perera, NGR
Visual perception of a space is influenced by the composition and behaviour of light. Daylight as a natural element, creates different atmospheres in the same space by its variation of intensity, colour, and direction. It creates dynamic shadow patterns, fluctuating brightness and contrast levels. Although the capacity to create variation - therefore contrast, is an important characteristic of daylight - it is often neglected in research, where comfort and visual performance take prominence. This is a research initiative to emphasise the value of daylight variation on spatial quality and human perception. The research adopts a two-step process, where, digital images are first mapped to generate contrast diagrams, and secondly, the generated digital images form the basis for a survey utilising a seven-point semantic differential scale, to explore the relationship between daylight variability and human perception. The temporal variation of daylight is explored by diagramming the spatial images at selected times of the day and year. The scope of the study is limited to selected contemporary residential spaces and focus on the manner of integrating daylight into spaces. Results show that a direct relationship between daylight variability and human perception for side lit spaces is not evident, yet it is evident in top lit options.
item: Conference-Full-text
The Effect of Street Canyon Geometry on Outdoor Thermal Comfort in Colombo
(2015-10-02) Perera, NGR; Weerasekara, WMSB
Although life in the equatorial tropics is largely an outdoor phenomenon, modern urban development has by and large failed to facilitate such living in a climatically pleasant manner. The approach then, should be an attempt to make the equatorial urban outdoors thermally comfortable. (Emmanuel, 1993) The primary approach to the research is to quantify and compare the thermal comfort implications of critical canyon geometry in warm humid Colombo. It explores street canyons that are currently existing as well as projected under the Sri Lanka, Urban Development Authority Development (UDA) Plan for 2020. Thus, the task is twofold; to report on the thermal comfort effects of the most widespread urban canyons in the city, and secondly to project the change that will occur with the growth of Colombo's built fabric, therefore canyon geometry. The urban fabric simplified using the Local Climate Zone (LCZ) system and surveyed shows the most predominant street canyons essentially encompass the compact low-rise and mid-rise areas of the city. The research reveals that thermal comfort cannot be achieved within the existing and projected urban canyons, for the peak time of the day.
item: Conference-Full-text
Effect of Street Canyon Materials on the Urban Heat Island Phenomenon in Colombo
(2015-10-05) Perera, NGR; Samanthilaka, KPPR
An Urban heat island (UHI) is best visualized as a dome of stagnant warm air, over the heavily built-up areas of the city. These have been observed practically all over the world and Colombo, Sri Lanka is no exception. It is known that the replacement of natural surfaces and radiation trapped in ‘street form’ urban canyons is one of the primary drivers of this phenomenon. This study quantifies and compares the local warming effects caused by materials used in street canyons in the warm, humid climate of Colombo. A process of ascertaining street canyon materials by survey and simulation using a simple force restore model, the Surface Heat Island Model (SHIM) generate data for specific urban canyons and the respective local warming effects they cause. Aluminium cladding in buildings, showed the highest and the lowest intensity. The highest UHI intensity of 2.87oC was recorded In LCZ2-commercial. While, the lowest UHI intensity of 1.78 oC can be seen at LCZ3-sea front zone. Analyses highlight the predominant material occurrence and discuss implications for nocturnal UHI amelioration, in warm, humid, Colombo, Sri Lanka.
item: Conference-Full-text
Good reading light: visual comfort perception and daylight integration in library spaces
(2017) Swaris, WDNP; Perera, NGR
Daylight creates an ambience of quiet tranquillity and visual comfort to link the modern library user, psychologically, with the space they occupy. In order to provide comfortable and glare-free light in reading spaces, volumes and surfaces illuminated with natural light have played a significant role. There should be optimum natural light which provides comfort for the user, albeit without the negative aspects of glare and heat. We Focus on ‘Good Reading Light’: Visual Comfort Perception and Daylight Integration in Library Spaces. Research problems evaluate the ‘Perceived Reading Light Level’, why and in what way daylight should be integrated into the indoor environment in a library space, to realize light-related goals of visual comfort. The research method consists of two parts; the Reading Light Test and the Perceptual Spatial Analysis (PERCIFAL). A group of twenty architecture students were surveyed for both components. The results show that Visual Comfort Perception depends on strategies adopted for daylight integration and that most reading spaces were perceived to be over lit. Conclusions drawn highlight that top lighting strategies and a combination of clerestory and side lighting are more effective than only side lighting via windows - as daylight control in public library spaces are difficult.
item: Conference-Full-text
Indoor comfort implications of urban microclimate: case study of office buildings in Colombo
(2014-01-10) Perera, NGR; Emmanuel, MPR
The equatorial tropics are experiencing an explosive urban grol1Jth. With intensified urbanisation comes a rapid increase in atmospheric carbon, dl1Jindling resources and concerns over energy seainty. In this context the need to achieve thermal comfort I:y the adoption of passive strategies assumes a great significance
item: Article-Full-text
Indoor Comfort Implications of Urban Microclimate: Case study of Office Buildings in Colombo
(Faculty of Architecture University of Moratuwa, 2013-03) Perera, NGR; Emmanuel, MPR; Arooz, FR
The equatorial tropics are experiencing an explosive urban growth. With intensified urbanisation comes a rapid increase in atmospheric carbon, dwindling resources and concerns over energy security. In this context the need to achieve thermal comfort by the adoption of passive strategies assumes a great significance. There is clear evidence to the link between indoor thermal comfort and the urban microclimate. This study is a research initiative that aims at exploring the effects of the urban microclimate on the indoor thermal comfort level. The focus is on office environments along Galle Road, Colombo. The research method initially establishes a representative typology of office buildings along Galle Road, Colombo. The computer simulation tool ENVI-met is used to model the existing urban microclimate and the strategies adopted for its improvement. The simulations establish the base external climatic parameters that effect the indoor environments.The indoor thermal comfort is simulated using DEROB-LTH. The simulated results are presented as comparative ‘Thermal Heat Index’ values.
item: Conference-Abstract
Influence of urban water bodies on microclimate and thermal comfort : case study of Beira Lake, Colombo
Perera, NGR; Liyanapathirana, A
This study explores the possibility of urban water body induced city cooling in the Sri Lankan context, with special reference to the Beira Lake, Colombo. The research method utilises the computer simulation tool ENVI-met to explore o The effectiveness of an urban water body in influencing the microclimate. o A water body in comparison to an urban green space of similar magnitude. o Microclimatic and thermal comfort changes within selected sites of specific orientations, encompassing existing and simulated morphology. o The effect of, and on the wind pattern around the lake in a holistic design scenario. The simulated results and analysis were limited to the peak time of the day of 14.00hrs of a single day in March. Conclusions show that contrary to established thinking the Beira Lake has a negative effect on the thermal comfort, yet will facilitate better wind and evaporative cooling potential in the immediate surroundings.
item: Article-Full-text
Influence of urban water bodies on microclimate and thermal comfort: Case study of Beira Lake, Colombo
(Faculty of Architecture University of Moratuwa, 2014-12) Perera, NGR; Liyanapathirana, A
This study explores the possibility of urban water body induced city cooling in the Sri Lankan context, with special reference to the Beira Lake, Colombo. The research method utilises the computer simulation tool ENVI-met to explore o The effectiveness of an urban water body in influencing the microclimate. o A water body in comparison to an urban green space of similar magnitude. o Microclimatic and thermal comfort changes within selected sites of specific orientations, encompassing existing and simulated morphology. o The effect of, and on the wind pattern around the lake in a holistic design scenario. The simulated results and analysis were limited to the peak time of the day of 14.00hrs of a single day in March. Conclusions show that contrary to established thinking the Beira Lake has a negative effect on the thermal comfort, yet will facilitate better wind and evaporative cooling potential in the immediate surroundings.
item: Article-Full-text
A “Local Climate Zone” based approach to urban planning in Colombo, Sri Lanka
(Elsevier, 2018) Perera, NGR; Emmanuel, R
Integrating climate-sensitive design with the local planning process is fundamental to managing the warming trend in the growing high-density tropical cities. However, the current planning regime is yet to address the challenges posed by local, regional and global warming. An in-depth understanding of the interaction between the physical form and the climatic context is beginning to emerge but, data needs and methods of analysis remain problematic at present to translate this into practical planning applications. In this paper, we showcase a simpler method of contextual analysis using the Local Climate Zone (LCZ) system and draw lessons for climate-sensitive planning in warm humid Colombo, Sri Lanka and other data-poor developing cities.
item: Conference-Full-text
Mapping “wind comfort” in public urban spaces of Galle fort, Sri Lanka
(2018) Wimalarathne, KLL; Perera, NGR; Emmanuel, R; Samarawickrama, S
With a focus on public urban spaces, appropriate design could enrich the quality of urban life. These spaces should be comfortable and safe enough to invite people to stay outdoors, unhindered by numerous impacts of the microclimate, like excess wind. This research maps the influence of local wind behaviour on the users in public spaces of Galle Fort, Sri Lanka - a UNESCO World Heritage Site. The microclimatic context of the Galle Fort is modelled by means of computational simulation utilising the software ENVI-met, with a focus on generating data on dominant wind velocities and wind directions in the study area. Selected urban plots are mapped to identify; discomfort zones created by wind velocities exceeding threshold values. The study is limited to selected simple activity typologies and utilise the thermal comfort indices Predicted Mean Vote to communicate results. The results show that uncomfortable velocities occur at building corners, streets, squares and on the Fort rampart, high enough to disturb activities associated with the sitting position in the South, Southwest, and West wind directions. Conclusions draw on the need for wind assessment in public spaces for comfort and the importance of establishing a holistic approach towards the wind comfort environment.
item: Conference-Full-text
Microclimatic impacts of high-rise cluster developments in Colombo, Sri Lanka
(2017) Vidanapathirana, M; Perera, NGR; Emmanuel, R
Colombo is rapidly expanding both horizontally and vertically. With limited land and infrastructure resources, the adoption of compact forms invariably result in high-rise developments and Colombo is not an exception. Current regulation limits its scope to individual plots rather than an urban area. We map the city and its current developments utilising the Local Climate Zone system, to identify critical zones and select case studies. With a focus on microclimatic impacts at street level, we simulate selected high-rise clusters, typical podium shape changes, within a similar Frontal Area Index (FAI), using the software ENVI-met. Results show that having a block form podium and increasing building height resulted in lower mean radiant temperature (MRT) values. Reducing the FAI or removing podiums increased wind movement, yet resulted in adverse MRT effects at pedestrian levels in the immediate vicinity of the cluster. The theoretical shadow umbrella simulation option reduced MRT by a significant degree while still maintaining comfortable wind speeds. Conclusions highlight that high-rise building clusters have a significant impact on their surrounding environment. Thus, it is essential that urban planning and policy strike a balance between development goals, quality of life of inhabitants and climatic implications.
item: Conference-Abstract
Projected urban development, changing ‘local climate zones’ and relative warming effects in Colombo, Sri Lanka
(Department of Architecture, University of Moratuwa, 2013-10-15) Perera, NGR; Mahanama, PKS; Emmanuel, MPR; Dayarathne, R; Wijesundara, J
Colombo is rapidly developing. This factor is further highlighted by the projected urban growth outlined by the Sri Lanka Urban Development Authority, “Zoning Plan 2020 for the City of Colombo”. The background climate of Colombo is found to be affected by the ‘Urban Heat Island’ (UHI) phenomenon. Together with the projected urbanisation, ensuing changes to land use patterns and building morphology, local climate changes are deemed to make the already barely-tolerable thermal conditions within the city more intolerable. This study quantifies and compares the local warming effects of the projected development of the city in relation to the existing conditions. It employs a land-use / local climate classification system defined as Local Climate Zones (LCZ). Likely local warming effects of the current and the projected urban fabric, classified according to LCZs are simulated using the Surface Heat Island Model. The data is presented as a detailed comparison of the two stages, highlighting the LCZ changes that will most affect the Urban Heat Island intensity of the city. Results and analysis reveal that almost all LCZs that transform to a higher density typology elevate the UHI intensity significantly. The typologies most affected are LCZ7 – Lightweight low-rise and LCZ8 – Large low-rise areas of the current urban fabric.
item: Conference-Full-text
The Role of biophilic design in hotel architecture: a case study of Heritance Kandalama, Sri Lanka
(Faculty of Architecture Research Unit, 2022-12-02) Ariyawansa, DN; Perera, NGR
Humans have a natural affiliation with nature which can even be genetically traced back into history. Biophilia is the inherent human inclination to affiliate with nature, that even in the modern world, continues to be critical to people’s physical and mental health, and well-being. The Hospitality Industry is a sector that can get the maximum benefit from this affiliation. Guests' opinions and feedback are highly valid, as they are the real users of hotel spaces. The primary aim of the research is to correlate the user experience to the role of biophilic designs in hotel spaces. This qualitative study is based on the twenty-five-point biophilic design framework by Kellert and utilises user surveys to collect and collate relationships. Heritance Kandalama, Sri Lanka is analysed as a case study. Results show that users associate biophilic design elements as essential generators of their spatial experience and that the guest experience of study-identified hotel spaces varies according to different biophilic triggers. Further, spaces created within a conceptually cohesive whole can hold a varied experience. In conclusion, the application of the biophilic framework as a guide for architectural meaning and spatial variance of experience is deemed effective.
item: Conference-Abstract
Surface fraction as a variable for urban heat island Amelioration in Colombo
(2015-04-01) Perera, NGR; Langappuli, BLT
Rapid urbanization has resulted in the change of land use and thus land cover from rural natural, pervious green surfaces to impervious urban land. It is identified as a key reason for microclimatic changes that create the Urban Heat Island (UHI) phenomenon that effect many cities. Although, the planning parameters for Colombo, Sri Lanka do specify the building to non-built surface fraction, it does not define the nature of the non-built areas. It is also deemed that such planning and building regulations are not based on any overall climatic goals for the city. In this context, the need is to quantify urban parameters that can be controlled by urban design. This study explores the effect of the building surface fraction, impervious surface fraction, and pervious surface fraction of an urban block, as a strategy for UHI amelioration in Colombo. The range of the combinations of the above are limited to the range defined by the Local Climate Zone (LCZ) classification system. It is further focussed on the predominant LCZs of Colombo, LCZ3 - Compact Lowrise and LCZ2 – Compact Midrise. The study uses the computer simulation software ENVI-met to model the existing as well as the modelled surface fraction of a particular urban block, in Colombo. Results and Analysis will discuss the comparative implications of the changing surface cover on the UHI mitigation possibility in warm humid Colombo
item: Article-Full-text
Vegetation Cover Effects On Outdoor Thermal Comfort Around High-Rise Developments A Case Study Of Havelock City, Colombo, Sri Lanka
(Faculty of Architecture University of Moratuwa, 2021-12) Weerakoon, LRT; Perera, NGR
Colombo, with its rapid development, is experiencing an influx of high-rise developments. These developments create a significant influence on the microclimate of the area around them, and therefore impact outdoor thermal comfort With the intension of mitigating outdoor thermal comfort concerns, the enhancement of the vegetation cover is an often-proposed strategy. This is a research initiative to ascertain the optimum vegetation percentage to achieve outdoor thermal comfort around high-rise developments, utilising Havelock City, Colombo, Sri Lanka as a case study. A computer simulation process is adopted, using the software ENVI-met, to explore the optimum form and coverage of vegetation for outdoor thermal comfort. Results show, overall thermal comfort levels diminish, with the increased infusion of vegetation. Vegetation cover had a little or no impact in the daytime, while the strategy had distinct negative impacts in the night-time. The nature of the built morphology of the development together with the vegetation cover increase is shown to have significant impact on wind movement and nocturnal heat loss, therefore outdoor thermal comfort levels. Conclusions highlight the need for the extensive exploration of morphological studies, while encompassing key amelioration strategies, particularly for the high-rise development typology. cover