The Bio - climatic approach to urban public space: a thermal evaluation of 'streets'

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 contex

Influence of urban water bodies on microclimate and thermal comfort : case study of Beira Lake, Colombo

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

Good reading light: visual comfort perception and daylight integration in library spaces

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

Surface fraction as a variable for urban heat island Amelioration in Colombo

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 Colomb

Microclimatic impacts of high-rise cluster developments in Colombo, Sri Lanka

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

Mapping “wind comfort” in public urban spaces of Galle fort, Sri Lanka

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