Landscape and Urban Planning 63 (2003) 197–211 Green plot ratio: an ecological measure for architecture and urban planning Boon Lay Ong ∗ Department of Architecture, School of Design and Environment, National University of Singapore, 4 Architecture Drive, Singapore 117566, Singapore Received 8 January 2002; received in revised form 23 August 2002; accepted 25 August 2002 Abstract Current research on sustainability of cities has favoured the implementation and conservation of greenery in the urban context. The benefits of plants are not just environmental but recreational, aesthetic and emotional. The full benefits of plants and the role they play in the ecology of cities remain to be mapped out but the general significance of plants appears to be uncontested. This paper proposes a new architectural and planning metric for greenery in cities and buildings. This new metric, the green plot ratio (GPR), is based on a common biological parameter called the leaf area index (LAI), which is defined as the single-side leaf area per unit ground area. The green plot ratio is simply the average LAI of the greenery on site and is presented as a ratio that is similar to the building plot ratio (BPR) currently in use in many cities to control maximum allowable built-up floor area in a building development. GPR allows more precise regulation of greenery on site without excluding a corresponding portion of the site from building development. It provides flexibility to the designer while simultaneously protecting the green quota in the design. This concept has been applied in a number of design competitions in which the author has collaborated with colleagues and various architectural practices. It has also been adopted as a planning requirement by the client authority for one of the competitions for which the author has entered. While seen as a fundamental and important metric, GPR is not in itself an indicator for all the ecological relationships between plants and cities. A larger set of related metrics need to be developed. © 2002 Elsevier Science B.V. All rights reserved. Keywords: Green plot ratio; Leaf area index; Ecological masterplanning; Plants; Urban landscape 1. Introduction One of the key components in the planning of sus- tainable cities, according to current research, is plants and planted spaces. Whitford et al., 2001 (abstract), in developing indicators for the ecological performance of urban areas in the UK noted that “the greatest in- fluence on ecological performance was the percentage of green space, particularly of trees.” The fields of ∗ Tel.: +65-874-3536; fax: +65-779-3078. E-mail address: akiongbl@nus.edu.sg (B.L. Ong). landscape ecology and urban ecology have emerged from research to become the primary advocates of ecological design in cities. While a considerable body of research has been gathered, problems of integration and common standards remain to be resolved. Leitao and Ahern (2002), for example, noted that there are “literally hundreds of metrics developed” and that these metrics are “frequently strongly correlated, and may be confounded” (p. 74). They suggested a reduced list of 7–9 metrics categorised under two aspects of landscape planning—composition and con- figuration. According to Pauliet and Duhme (2000), 0169-2046/02/$20.00 © 2002 Elsevier Science B.V. All rights reserved. PII:S0169-2046(02)00191-3