As urbanization sweeps across Asia, vertical cities— characterized by high-density and mixed-use development—have emerged as a potential solution its challenges (Yeh and Yuen 2011). This shift is not only an architectural choice but a strategic necessity in response to land constraints. Integrating residential, commercial, and recreational spaces within high-rise developments can help optimize the use of limited urban land, promote accessibility, and maximize agglomeration benefits.
Innovative Plot Ratio Regulation: Balancing Rapid Growth with Urban Sustainability
Plot ratio control—the ratio of a building’s total permissible floor area to its land area—is a key planning tool for managing high-density development. It plays a crucial role in land use policy, regulating building intensity to ensure efficient space utilization.
However, in rapidly growing city centers with high population densities, plot ratio restrictions often need to be relaxed to accommodate expansion, allowing for more floor area on a given plot. This raises a critical question: If vertical urbanism is a solution, how can we determine the right plot ratio to maximize benefits while ensuring a community-oriented and sustainable approach?
The challenge is to prevent buildings from being too low, which would underutilize development potential, or excessively tall, which could disrupt urban aesthetics and livability. Striking this balance remains a priority for many Asian cities striving to accommodate expansion while maintaining quality of life.
Hong Kong, China and Singapore, recognized as pioneers in vertical urbanism (Lau et al., 2015), have successfully managed this challenge by implementing three innovative plot ratio regulation mechanisms: exempted gross floor area (GFA), bonus GFA, and transferable GFA.
Exempted GFA: Encouraging Green Building Features for Urban Heat Mitigation
Exempted GFA allows developers to exclude certain features from their GFA calculations, incentivizing sustainable design elements that enhance environmental quality (Azhann 2024).
In Hong Kong, China, the Building Authority grants GFA concessions for design elements such as balconies and designated green spaces under Section 42(1) of the Buildings Ordinance (Cap. 123). Private developers can receive a maximum 10% GFA concession for integrating these features. In Singapore, the Urban Redevelopment Authority (URA) offers GFA exemptions for green features such as sky terraces, communal planter boxes, and sun-shading devices (URA 2018; Cossé 2011).
These exemptions encourage developers to integrate eco-friendly elements into their projects, particularly in dense urban areas where space constraints and high land costs limit options for incorporating rooftop greenery and ventilation corridors. Such mechanisms enhance air circulation, reduce the urban heat island effect, and improve overall urban livability (Cooper 2015; Chousein 2014).
Bonus GFA: Incentivizing Community-Oriented Urban Infrastructure
Bonus GFA allows developers to gain additional floor area by incorporating features that serve the public interest (BCA 2021), which fosters a more community-centered urban environment. In Hong Kong, China, under Regulation 22 of the Building (Planning) Regulations, developers may be granted bonus GFA for dedicating public passageways or spaces for street widening. The bonus GFA granted can be up to 5 times the dedicated area but is capped at 20% of the permissible plot ratio as compensation for private land contributions to the public domain. In Singapore, the Urban Redevelopment Authority grants bonus GFA for providing public amenities such as sports facilities, community centers, and elder care facilities within developments. It also offers bonus GFA in designated districts to promote walkability and public space integration.
This mechanism ensures that private developers prioritize both economic returns and the broader public good. By promoting vibrant, community-oriented spaces and enhancing public services, cities become more functional and connected.
Transferable GFA: Facilitating Strategic Urban Redevelopment
Transferable GFA enables developers, including public authorities, to relocate unused or excess floor area entitlements from one site to another within the same area to support strategic urban regeneration. In Hong Kong, China, the Town Planning Board introduced TPB PG-No 42, Guidelines for Application for Transfer of Plot Ratio under Section 16 of the Town Planning Ordinance. These guidelines permit up to 30% of permissible GFA to be transferred from sending sites to receiving sites within the same Outline Zoning Plan.
By shifting GFA from areas with low development potential to more suitable locations, this mechanism supports the revitalization of aging districts, optimizes land use efficiency, and contributes to dynamic urban renewal.
Strategic Densification: Lessons for Urban Asia
With rapid urbanization across developing Asia, cities are increasingly densifying near their centers, making vertical development more relevant than ever. Hong Kong, China, and Singapore, which have undergone significant urban transformations over the past century, showcase how innovative plot ratio control mechanisms can support sustainable growth.
Key questions remain: Can policymakers in developing Asia adopt similar mechanisms? How should planning control codes and laws be revised to ensure effectiveness? While increasing plot ratios, how can cities ensure long-term sustainability and avoid unintended distortions? What principles and regulations should be established to balance urban growth and livability?
Although lessons can be drawn from these case studies, their application must be context-specific. Each city has unique economic, social, and environmental challenges, shaped by distinct geographical features and development timelines. To successfully navigate urban densification, governments must assess their cities’ conditions, plan strategically, and balance development with sustainability—ensuring livable, resilient, and well-planned urban environments for all.
References
Azhann. 2024. Gross Floor Area (GFA). https://www.99.co/singapore/glossary/gross-floor-area-gfa-a-comprehensive-guide/
BCA. 2021. Circular to Professional Institutes. https://www.corenet.gov.sg/media/2330759/-bca-webpage-bca-ura-joint-circular-built-environment-transformation-gfa-incentive-scheme_24112021_r3.pdf
Chousein, B. C. 2014. Rethinking Urbanism Through Vertical Cities. World Architecture Community. https://worldarchitecture.org/architecture-news/pmhmf/rethinking-urbanism-through-vertical-cities.html
Colliers. 2023. Trial Plan Allows Developers to Transfer GFA Between Sites. https://www.colliers.com/en-hk/news/cvas-trial-plan-allows-developers-to-transfer-gfa-between-sites#:~:text=The%20Plot%20Ratio%20Transfer%20Pilot%20Scheme%20allows%20the%20transfer%20of,GFA%20permitted%20for%20the%20RS
Cooper, M. 2015. Asia’s Vertical Cities: Will They Translate to Other Continents? https://urbanland.uli.org/planning-design/asias-vertical-cities-will-translate-continents
Cossé, V. 2011. A Practical Approach: Incentives for Skyrise Greenery. https://www.nparks.gov.sg/-/media/cuge/ebook/citygreen/cg2/cg2_01.pdf
Lau, S., and Q. Zhang. 2015. Genesis of a Vertical City in Hong Kong. Original Publication: International Journal of High-Rise, Buildings 2: 117–125. https://global.ctbuh.org/resources/papers/download/2356-genesis-of-a-vertical-city-in-hong-kong.pdf
URA. 2018. Guidelines at a Glance: Gross Floor Area. https://www.ura.gov.sg/-/media/Corporate/Guidelines/Development-control/GFA/Summary_GFA.pdf
Yeh, A. G. O., and B. Yuen. 2011. Introduction: High-Rise Living in Asian Cities. High-Rise Living in Asian Cities: 1–8. Springer Netherlands. https://doi.org/10.1007/978-90-481-9738-5_1
No comments yet.