Sky Gardens Research Articles

The Improving of Sky Gardens’ Environmental Quality from a Health Promotion Perspective

The Improving of Sky Gardens’ Environmental Quality from a Health Promotion Perspective

Research on the restorative benefits of sky gardens in high-rise buildings based on wearable biosensors and subjective evaluations

BackgroundThe design of sky gardens in high-rise buildings to promote health has recently attracted increased attention. However, little is known about the specific physiologically and psychologically restorative benefits of sky gardens. MethodThis article defined sky garden types according to five indicators in three dimensions based on the characteristics of the high-rise buildings where sky gardens are located: plaza-park, rest-stay and move-pass sky gardens. Typical sky gardens of each type were selected for the subsequent experiment. Thirty-six participants experienced 12 typical case scenarios (432 pictures), and data were collected on physiological responses (skin conductance resistance, SCR; heart rate variability, HRV; electroencephalogram, EEG; and eye movement) and psychological evaluations (emotional valence & arousal self-esteem scale, perceived restrictiveness scale) during the sky garden spatial experience. ResultsThere are significant differences in plaza-park, rest-stay and move-pass type sky gardens, especially in the internal spatial characteristics (size scale, shape index, and elementary richness). The plaza-park sky gardens had better restorative outcomes in visual-physiological (average pupil diameter, average blink count), emotional valence and restrictiveness components of being away, fascination, and coherence. The rest-stay sky gardens had better restorative effects on SCR, HRV, emotional arousal, and compatibility. The move-pass sky gardens had the greatest restorative benefits in the average saccade count. ConclusionsSky gardens in high-rises impact people's physical and psychosocial well-being. The restorative qualities of the three types of sky gardens differ based on their spatial heterogeneity, with large-scale sky gardens, diverse natural landscapes, public facilities, and high void-to-solid ratios having greater restorative potential.

EXPLORATION OF HIGH-RISE RESIDENTIAL TOWER CONCEPT BASED ON ARCHITECTURAL SCIENCE: SKYVILLE AT DAWSON, SINGAPORE

An environmentally friendly multi-storey residential design approach has been revealed by various studies since 2009. However, many multi-floor residential designs need to strike a balance between economic needs and the sustainability of the building. Skyville @ Dawson was designed by WOHA consultant with the principles of sustainability (sustainable design based on architectural science), community and diversity in mind. Therefore, Skyville @ Dawson has a flexible apartment design with columns positioned on the building perimeters, and has three horizontal sky gardens that facilitate cross ventilation. The Skyville @ Dawson facade was designed with unique windows (monsoon windows), which facilitate cross ventilation but reduce the impact of wind on the workbench. It can be concluded that ventilation can reduce occupants' dependence on air conditioning and ultimately become energy efficient. WOHA offers an architectural science approach in Skyville @ Dawson to a sustainable design concept with a balanced consideration of social aspects.

Sky Gardens, Public Spaces and Urban Sustainability in Dense Cities: Shenzhen, Hong Kong and Singapore

This paper studies the spatial characteristics of sky gardens as public spaces to explore their potential to support urban sustainability in dense cities. This research understands public spaces as spaces that are open and available in different levels of access and use. The research focuses on 982 sky gardens in Shenzhen, Hong Kong, and Singapore. It adopts a mixed methodology, including site visits and observations, statistic measurements (based on SPSS software), and Grey Relation Analysis (GRA) methods. The research follows three steps: first, it studies the urban context, including urban density, land uses, and policy regulations regarding sky gardens and sustainability. Second, it examines sky gardens’ spatial characteristics in terms of form (morphology, typology, size, affordances, configuration), openness quality (accessibility, ownership, permeability), and geometry (open space ratio, height of space-to-building, void-to-solid ratio, shape index). Third, the research compares the findings in three case cities and discusses their potential to support urban sustainability. The results suggest that despite the limitations of sky gardens, they may play, to different degrees, fundamental roles as open public spaces in high-density urban environments supporting cities’ sustainability. High-density environments offer more opportunities for the sustainable development of sky gardens, which creates a new spatial paradigm for compact vertical greenery in high-density cities.

Research on the spatial characteristics of sky gardens based on networked pictures: a case study of Singapore

ABSTRACT As alternative public spaces in vertical public realms, sky gardens have become an increasingly important spatial element and part of the urban vocabulary in high-density environments worldwide. However, the public's spatial experience, social behavior and aesthetic needs in sky gardens have not been thoroughly explained. This paper takes Singapore, which has a rich social public space in the air, as an example where studies estimating spatial perception have used networked images instead of user preference survey results. Manual image identification and image recognition were performed with a computer vision application programming interface (API) to recognize networked images. Then, we extracted the sky gardens’ main elements in Singapore’s urban environment using clustering analysis, principal component analysis and factor analysis with SPSS. Finally, we discuss the spatial distribution, role and composition of sky gardens in high-density cities and people’s emotional preferences. The study shows that sky gardens are effective alternative public spaces in Singapore's vertical city, and their physical elements occupy a dominant position in the public’s spatial perception; there is a strong tendency for different buildings’ sky gardens to have spatial demand characteristics, while public facilities and cultural activities are key factors that affect sky gardens’ quality.

Tree species composition, growing space and management in Hong Kong’s commercial sky gardens

Sky gardens, a type of above-ground urban green space, have been increasingly welcomed and installed in cities. However, few studies have assessed tree planting, management and health in high-rise greenery. This study investigated tree species composition, planting space design and management, and their relationships with tree health in sky gardens in 15 commercial sky gardens with 480 trees in Hong Kong. We assessed the differences between old and new sites regarding tree species, height, crown diameter, and health. We also evaluated selected planting and management factors, including planter type, distance to neighbor trees, root-growth obstacles, canopy barriers, canopy overlap and topping history. Tree species selection in commercial sky gardens was substantially different from public and private residential green spaces. Older sky gardens had more palm trees by species and tree counts. Newer gardens had increased adoption of broadleaf and conifer species with high ornamental value and compact form but fewer native tree species and lower species diversity. The widely planted Ficus spp. had created long-term management issues. Trees were often densely planted, particularly in newer sky gardens. The common practice of topping indicates poor species selection and mismanagement. Planter types with insufficient growing space had dampened tree health. Our findings reveal the trend of tree species adoption, narrower planting spaces and wider adoption of the sunken planter. Improvements in species selection, growing space design and management practices could promote healthy, stable and safe trees in sky gardens with contributions to biodiversity and other ecosystem services.

Urban Living with Nature: Design for Human-nature Interactions in Communal Green Spaces at Residential High-rises

The higher we live from ground level, the more disconnected we feel from the natural environment and community. Compared with people residing away from the metropolitan area, urban dwellers lack personal and open space and may seek room to escape from the hustle and bustle of the city. A new typology of sky gardens has been driving designs of residential high-rises to offer communal green spaces at high levels. Its potential benefits consist of improving human thermal comfort and urban microclimate; promoting social cohesion by serving as a community green space. It would provide a place for individuals escaping from the busy city life, improve the community integration for all age groups and improve the health and well-being of residents. In addition, it may enable and raise awareness of intimate contact with nature.

The Ventilation Improvement Assessment of Sky Gardens-A Case Study of Hysan Place

With the modernization and urbanization in recent decades, a mounting number of buildings has been built. Due to the limited land, these buildings were built higher and higher and side by side which created ‘Wall Effect’ blocking the wind and reducing air ventilation. It eventually led to bad thermal comfort of people. Therefore, sky gardens are increasingly important today, as they can significantly contribute to improving air ventilation by reducing ‘Wall Effect’. In order to know better about the influence generated by sky gardens to natural ventilation improvement, I selected the Hysan Place as a case study based on CFD simulation. I built two models --- the original model and the model without sky gardens for the simulation in different height. By comparison of different models, I found that the sky gardens of Hysan Place did can slight improve air ventilation of surrounding areas. Sky garden is an effective method to alleviate urban heat island effect, which is important to improve urban living quality, especially extreme high construction density.

Study on the influence of voids on high-rise building on the wind environment

The purpose of this study was to investigate the effects of voids in tall buildings on the surrounding wind environment. With the development of modular technology, there has been a new method of building high-rise buildings. Currently, more and more high-rise buildings often use void spaces to reduce the wind resistance and utilize wind turbines by using wind power to create sky gardens. In this study, CFD (computer fluid dynamic) technology was used to simulate the wind environment around the buildings. The research focuses on the size, distribution and quantity of the concavity, which usually is defined as sky gardens. It is found that when the area of the opening is the same, the more number of opening, the more strengthened and distributed vertical wind velocity behind the building can be. The wind shadow area at the pedestrian height is further reduced. For holes distribution, the optimum ratio of the spacing between concavities to the void size for wind environment of tall buildings ranges from 1 to 3, which can disperse the surrounding heat in more efficiency and weaken the wind velocity in the lowest level. Therefore, in high-rise buildings, the number and distribution of the openings will have different effects on the wind environment around the buildings.

Numerical Investigation of the Wind and Thermal Conditions in Sky Gardens in High-Rise Buildings

High-rise buildings are known to be highly energy intensive, adding stress on already stressed resources. Alternatively, designers are looking at passive strategies and investing in architectural elements, such as sky gardens, which could improve the performance of buildings. Sky gardens are green areas located in a building which are exposed to the outdoors. They could provide multifaceted improvements in buildings by introducing environmental benefits to occupants and altering microclimate. This study aims to determine the wind comfort and thermal condition in sky gardens in high-rise buildings using numerical modelling. Different geometrical configurations of sky gardens were simulated and analysed. Based on the initial results, the study reveals that sky gardens can generate high wind velocities of the order ~10 m/s when located on a high-rise building. The addition of features such as trees and other architectural elements, which can act as a buffer, can help attenuate the high wind speeds and creating habitable spaces. The reduction varies 50%–80%, depending on the location and spatial domain of the sky garden. Furthermore, the study also investigated the reduction in air temperature due to the addition of trees, which can further reduce temperature in hot weather.

Case studies of high-rise buildings: A comparative study: Design strategies for energy-efficiency of high-rise office buildings

Tall buildings are being designed and built across a wide range of cities. A poorly designed tall building can tremendously increase the building’s appetite for energy. Therefore, this paper aims to determine the design strategies that help a high-rise office building to be more energy efficient. For this purpose, a comparative study on twelve case buildings in three climate groups (temperate, sub-tropical & tropical) was performed. The exterior envelope, building form and orientation, service core placement, plan layout, and special design elements like atria and sky gardens were the subject of investigation. The effectiveness of different design strategies for reducing the cooling, heating, ventilation and electric lighting energy were analysed. Finally, lessons from these buildings were defined for the three climates. Furthermore, a comparison of building energy performance data with international benchmarks confirmed that in temperate and sub-tropical climates sustainable design strategies for high-rise buildings were performing well, as a result leading to lower energy consumption. However, for the tropics the design of high-rise buildings needs higher concern.

A COMPARATIVE STUDY: DESIGN STRATEGIES FOR ENERGY-EFFICIENCY OF HIGH-RISE OFFICE BUILDINGS

Tall buildings are being designed and built across a wide range of cities. A poorly designed tall building can tremendously increase the building's appetite for energy. Therefore, this paper aims to determine the design strategies that help a high-rise office building to be more energy efficient. For this purpose, a comparative study on twelve case buildings in three climate groups (temperate, sub-tropical & tropical) was performed. The exterior envelope, building form and orientation, service core placement, plan layout, and special design elements like atria and sky gardens were the subject of investigation. effectiveness of different design strategies for reducing the cooling, heating, ventilation and electric lighting energy usage. Finally, lessons from these buildings' were defined for the three climates. Furthermore, a comparison of building energy performance data with international benchmarks confirmed that in temperate and sub-tropical climates sustainable design strategies for high-rise buildings were performing well, as a result leading to lower energy consumption. However, for the tropics the design of high-rise buildings needs additional consideration.

Effect of a through-building gap on wind-induced loading and dynamic responses of a tall building

Many tall buildings possess through-building gaps at middle levels of the building elevation. Some of these floors are used as sky gardens, or refuge floors, through which wind can flow with limited blockage. It has been reported in the literature that through-building gaps can be effective in reducing across-wind excitation of tall buildings. This paper systematically examines the effectiveness of two configurations of a through-building gap, at the mid-height of a tall building, in reducing the wind-induced dynamic responses of the building. The two configurations differ in the pattern of through-building opening on the gap floor, one with opening through the central portion of the floor and the other with opening on the perimeter of the floor around a central core. Wind forces and moments on the building models were measured with a high-frequency force balance from which dynamic building responses were computed. The results show that both configurations of a through-building gap are effective in reducing the across-wind excitation with the one with opening around the perimeter of the floor being significantly more effective. Wind pressures were measured on the building faces with electronic pressure scanners to help understand the generation of wind excitation loading. The data suggest that the through-building gap reduces the fluctuating across-wind forces through a disturbance of the coherence and phase-alignment of vortex excitation.

Challenges and Strategies for Greening the Compact City of Hong Kong

A compact city is a special urban form with inherent physical, social, and institutional constraints on greenery that obstruct the achievement of sustainability. In this study, Hong Kong is used as a case to assess the constraints and challenges related to urban green spaces (UGS) development in compact cities. Strategies to overcome these obstacles and improve the UGS conditions are developed. Opportunities to implement the strategies are then evaluated. Because compact cities have extremely limited space allocated for UGS on the ground level, strategies to optimize the layouts of green spaces and seek additional spaces above or below the ground level, such as vertical green surfaces or structures, green roofs, and podiums, are possible solutions. Measures to implement the strategies are summarized as (1) reorganizing the departments and offices related to UGS and clarifying their individual responsibilities to increase their efficiency; (2) encouraging citizen participation; (3) establishing proper legal basis; (4) forming a comparatively connected comprehensive green network of green sources and green sinks with ground-level green spaces, skyscraper farms, and sky gardens, all with optimal layouts; (5) maintaining and repairing UGS after construction; and (6) selecting species of plants that will thrive in specific green spaces. The compact form of Hong Kong provides many chances to implement these strategies. The study increases understanding of the critical factors behind the success or failure of UGS develop- ment in one of the most compact cities in the world and provides suggestions for strategic and policy-related measures for the provision and management of UGS in other congested areas. DOI: 10.1061/(ASCE)UP.1943-5444.0000076. © 2012 American Society of Civil Engineers.

Development potential of sky gardens in the compact city of Hong Kong

Sky gardens have been actively studied and installed in different cities. Their development potential in compact developing cities has received little attention. Using remote sensing and GIS techniques, this study evaluates the vegetation configuration and development potential of sky gardens in urban Hong Kong, their underlying location, land use and building factors, and future planning and implementation concerns. Existing sky garden area is limited with sparse vegetation cover and low biomass. Existing podium gardens exceed roof gardens by about nine times. District development age has little effect on existing and potential sky gardens. Old towns have higher potential roof and podium gardens than new towns in most land uses. The effect of land use on potential sky gardens varies greatly by districts. Buildings with 10–20 floors have higher potential roof gardens in most districts. Building area is the main determinant of potential roof garden, and population density of potential podium gardens. Three scenarios of realization, namely minimum (20%), medium (50%) and maximum (80%), are adopted to project sky garden provision in individual districts. The projection extends to the contribution of new sky gardens to urban greening in terms of green cover and greening rate in districts. The challenges include susceptibility to typhoon damage in high-rise exposed sites, aggressive weed invasion, lack of roof-slab loading data in old buildings, and poor building maintenance. The opportunities include affordability of the new technology, enabling government policy, and establishment of scientific and research foundation in the local context. The development strategy could aim squarely at stringent technical standards and contractor skill requirement, and programme prioritization based on research findings. The study provides useful hints, approaches and recommendations for a systematic sky-garden action plan in Hong Kong and other similar compact cities.

Factors influencing the spatial pattern of sky gardens in the compact city of Hong Kong

Sky garden is a hot topic in current research in urban ecology and landscape planning. However, due to the difficulty of data collection and processing, there are surprisingly few published guidelines exploring the spatial distribution of sky gardens and the factors that influence their presence in compact cities. By matching maps of buildings, green cover, district boundaries and roof and podium level layers, the spatial pattern of sky gardens and the factors in Hong Kong were analyzed. Suggestions for future development of sky gardens were also discussed. The results indicate that both roofs and podiums are not adequately utilized by green spaces. High green ratios of roof gardens exist on 5–20-floor buildings or buildings located in areas of low density for most land uses and most districts. Several factors play significant roles in the green ratios of podium gardens in some districts, such as building density in WC, S, E and HKI as a whole and podium areas in WC, SSP and KC. The development of sky gardens has not improved with town development and has not adequately compensated for limited ground-level green spaces. The spacious roof and podium areas that are available provide the potential for the extensive development of sky gardens with high green ratios and biodiversity. Systematic planning on a large scale that incorporates measures for increasing biodiversity and forming green networks may be an effective strategy to solve the problem of the extreme shortage of sky gardens in compact cities.

The Application of Computational Fluid Dynamics to the Assessment of Green Features in Buildings: Part 2: Communal Sky Gardens

Sky garden is regarded as one of the green features in high-rise building design. Located in the mid-level of a high-rise, it serves as recreational garden for communal use. Amplifying the natural wind, and combined with the shading effect, a sky garden has its own thermal and wind environment. In this paper, CFD (computational fl uid dynamics) technique is applied to model the wind and thermal comfort of two possible confi gurations of a sky garden: one with 4 sides open and the other with 2 sides open. The wind data obtained from the Hong Kong Observatory are analysed and divided into three cases: i) summer, ii) winter, and iii) days affected by tropical cyclone (TC). For typical summer and winter wind conditions, thermal comfort is analysed, and for the tropical cyclone wind conditions, the wind comfort is analyzed. It is found that the thermal comfort with four openings is better than that with two openings in summer and vice versa in winter. The results also reveal that higher wind speed provides good thermal comfort in summer but poor thermal comfort in winter. The wind comfort level at typhoon days at communal sky gardens would be in the category of ‘uncomfortable’ or ‘very uncomfortable’. Finally, limitations of CFD simulation and its complimentary application with wind tunnel tests are briefly discussed.

Sustainable community and environment in tropical Singapore high-rise housing: the case of Bedok Court condominium

Is it possible to create successful ‘sky gardens’ – spaces which encourage outdoor living and communal interaction – as part of high-rise high-density apartment developments?

Posts and Telecommunications Building, Xiamen, China

The aesthetic design for the sixty-six storey Posts and Telecommunications Building in Xiamen, China, is inspired by carrier waves, the fundamental building block of modern computer telecommunications. The design physically merges the concept of spiral frequency waves with the celebrated traditions of Xiamen as a garden city of arts and commerce through the introduction of three-storey-tall “sky gardens” which form a helical pattern along the cylindrical tower shaft. The functional and cost-effective design for the tower form is completed by a classic reinforced concrete perimeter framed-tube structural system that is particularly suited to the aggressive wind and seismic environment in this part of the world.