Green Plot Ratio
The Green Plot Ratio is part of a number of related ideas that began when I started to think about architecture as an ecosystem. At the time when I first started working on this, ecologists know little about architecture and architects know nothing about ecology. Yet, it was clear, when you think about it, that the built environment is an ecosystem no less than any other natural ecosystem. It may not be a very beneficial ecosystem but, precisely because it is an ecosystem and part of the earth's ecosystem, we are reaping the results of our narrow mindedness. Over the years, I worked on a number of concepts that have helped me understand better what this central theme (that the built environment is an ecosystem) means.
Paradise Paradigm (1996)
Cities are to architecture what forests are to trees. Where architecture signifies the place (home) of an individual (person or unit), the city signifies the place of human society, and is indeed the centre of a nation. The capital of a country is almost always a city, not a forest nor a plot of farmland. The defence of these places — cities, homes, etc. — is paramount. Armies are kept constantly on the alert in case of war, and war is primarily about the acquisition and defence of places. lf we accept that civilization is about places, about finding places, possessing them and protecting them, then it is important to understand how and why place is so important to us. The paradise paradigm hypothesis offered here suggests that its basis is ecology.
Contrary to popular belief, our ecological record, in the early years of human civilisation, was not good. We did not live in harmony with nature but destroyed it wherever we went. Human intervention led to the extinction of the mastodon and the mammoths in Africa and South East Asia some 40,000 years ago, and in Australia and North Eurasia 13,000 years ago. In the Americas, about 11,000 years ago, there were giant bison (with a 2m horn spread), casteroides, camels, ground slothes, stag moose, large cats, mastodons and mammoths, and wild horses. Less than a thousand years later, nearly all were extinct as a result of human activity. Horses had to be reintroduced to the Americas in the 16th century AD.
Considering the technological capabilities demonstrated by the earliest cities — the Pyramids of Giza at around 2500 BC, the Great Wall of China at around 200 BC, the Hanging Gardens of Babylon at around 600 BC, and the Mayan city at Yucatan at around 400 BC — it is hard to imagine that such technological knowledge can emerge quite so suddenly.
Cities were never clean nor hygienic. J.D. Hughes wrotc of the cities of Mesoporamia (Wall, I994, pp. 33-34):
The earliest cities seemed to have shared some of the problems which have become as annoying in their modem counterparts The evidence
of narrow streets and small rooms in houses huddled within the compass of defensible walls tell us that overcrowding in ancient cities were
extreme. Garbage accumulated in the houses. where the dirt floors were continually being raised by the debris, and human wastes were rarely
carried further than the nearest street. The water supply... was likely to be polluted. Life expectancy was short Flies, rodents and cockroaches
were constant pests. Even air pollution was not absent. In addition to dust and offensive odors, the atmosphere filled with smoke on calm days.
Our forefathers were intelligent enough to invent tools. They were capable of art and war. They formed societies and developed a distinctive culture in each. They were certainly clever enough to recognise a basic fact of ecology — that not all parts of the environment were equally hostile nor equally advantageous. Certain places, particularly those that were near water bodies, are especially propitious. Here, in such places, they had easy access to plant food and water. Small animals that came to drink and feed there were easy prey. The humans had only to protect themselves from attack from predatory animals or other human tribes and their future would be ensured. Here, in such places, they did not have to find sustenance, the environment supported them. Such places were paradise.
References
Ong, B. L. (1996). Place and Plants in Architecture: An Investigation Into the Phenomenon of Place, the Thermal Environment and the Significant Role of Plants. Unpublished PhD Thesis, University of Cambridge, Chap 8.
Ong, B. L. (1999). The Paradise Paradigm: An Ecological Account of the Development of Human Civilization. In A. F. Foo & B. Yuen (Eds.), Sustainable Cities in the 21st Century (pp. 163-180). Singapore: NUS Press (jointly with World Scientific).
Wall, Derek (1994) Green History Routledge, London.
Leaf Area Index (LAI)
An explanation of LAI and why it is important from the original paper on Green Plot Ratio:
In the literature reviewed, the primary metric for greenery is land cover. This metric is sometimes further delineated into lawns and shrubs-and-trees. The present paper proposes that a more scientific and accurate metric be adopted. Most, if not all, of the benefits gained from plants result from plant metabolic processes. These processes include photosynthesis,
evapotranspiration, respiration and uptake of minerals from the air and ground. The extent to which plants engage in these processes is directly related to the amount of green matter, usually found in the leaves of the plant (see Jones, 1992, for example, for a detailed account of plant metabolism). Even dry deposition of pollutants and particulates depend on the total leaf area of the plant and its leaf characteristics.
The total leaf area of a plant is indicated, in biological science, by the LAI. The present paper provides a summarised account of LAI in current application and proposes an equivalent planning metric called the green plot ratio (GPR), for urban planning. GPR is defined as the average LAI of the greenery on site.
LAI is related to a range of ecological processes like photosynthesis, transpiration and metabolism. These plant processes in tum enable the prediction of net primary production, rates of energy exchange between plants and the atmosphere, rates of future growth and yield, and the monitoring of changes in canopy structure due to pollution and climate change. The ability to estimate LAI is therefore a valuable tool in modelling the ecological processes occurring within a forest and in predicting ecosystem responses.
Actual plant productivity is dependent on chlorophyll concentration, stomatal density and other physiological and environmental factors.
References
Jones, H.G., 1992. Plants and Microclimate (2nd ed). Cambridge University Press, Cambridge, UK.
Ong, B. L., 2002, Green Plot Ratio: An ecological measure for architecture and urban planning, Journal of Landscape and Urban Planning, 965, p1-15
Green Plot Ratio (2002)
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.
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 guidelines need to be developed.
It should be noted that the benefits (and disadvantages) of plants are dependent primarily on the extent of leaves or leaf area. In current literature, the exact species of the plant (with the notable exception of biogenic emitting plants studied by Karlik and Winer, 2001) and the nature of the landscape (whether it is a nature reserve or an artificially maintained landscape, even agricultural) are generally less critical than the extent of greenery available. For the purposes of urban ecological planning, it would appear that “farmland has much in common with natural ecosystems (Whitford et al., 2001, p. 91).” Such generalisations, while patently untrue, are however necessary and valid when a larger context like cities are being studied.
References
Karlik, J.F., Winer, A.M., 2001. Plant species composition, calculated leaf masses and estimated biogenic emissions of urban landscape types from a field survey in Phoenix, Arizona. Landsc. Urban Plann. 53, 123—134.
Ong, B. L., 2002, Green Plot Ratio: An ecological measure for architecture and urban planning, Journal of Landscape and Urban Planning, 965, p1-15
Ong, B. L., Ho, A., & Ho, D. K. H. (2012). Green Plot Ratio - Past, Present & Future. Paper presented at the iNTA2012 - Tropics 2050, Singapore.
Whitford, V., Ennos, A.R., Handley, J.F., 2001. ‘City form and natural process—indicators for the ecological performance of urban areas and their application to Mcrseyside, UK. Landsc. Urban Plann. 57, 91—103.
Nurtured Landscapes (2004)
Two emerging ecological planning approaches, landscape ecology and industrial ecology, are applied here to look at alternative ways of planning industrial parks. As an emerging field, landscape ecology provides different viewpoints from the traditional approach of natural conservation, which mainly focuses on the protection of nature. The approach of landscape ecology regards the environment as a land mosaic, a mixture of natural and urban environment, which concerns a manageable human—scale environment across one or two human generations. Industrial evology, on the other hand, goes beyond the traditional “end of pipe” idea of pollution control and learns from the ecosystem concept. If raw materials, energy and by-products are more easily replaced or reused by technology and management, then research on industrial ecology and related knowledge will be crucial for developing natural resource substitution by innovative technology and new ways of environmental management. Where it is difficult to substitute natural resources, the skills of planning and managing natural resources will take priority over other strategies. In this situation, the knowledge of landscape ecology needs to be applied to the prediction, design and evaluation of ecologically optimum resource uses, patterns and processes in the mixture of natural, urban and industrial environment.
A new concept, “nurtured landscape”, is proposed for mediating between the natural ecosystem and the urban/industrial environment. The nurtured landscenige provides a basis for the development of new ecological technology using landscape to ameliorate the polluting ellects of the urban/industrial neighbourhood. The planning of Singapore’s Jurong Island industrial park provides a test of applying the principles of landscape ecology and industrial ecology to the possible transformation of an industrial area.
Reference
Yang, P., & Ong, B. L. (2004). Applying ecosystem concepts to the planning of industrial areas: a case study of Singapore’s Jurong Island. Journal of Cleaner Production, 12(8-10), 1011-1023.
Thermal Aesthetics (2012)
Perhaps more than any other sense, heat imparts an emotional if not aesthetic overlay on perception. Colors can be hot, warm, cool or cold. Other senses like smell, sound, taste and touch are also often similarly described in adjectives of heat. The aesthetic enjoyment of food, in particular, is enhanced when consumed at the right temperature. Not only does food taste different at different temperatures, heat is critical in drawing out its appetizing smells. Music, dance, poetry and other aeft forms as well are viewed in terms of heat — tango is hot, jazz is cool, poetry warms the heart.
We have two kinds of aesthetic analysis (and experience). The first is visual and analytical. It deconstructs the painting and hypothesizes on the formal aspects of the painting that make it beautiful. The second seeks to evoke an aesthetic empathy in the reader. This is achieved through describing the ambiance of the picture — the light from above imparts to the philosopher thoughts on "higher things and eternai truths", while the light of the hearth is of "the material and temporal things of life". Throughout, there is the undercurrent and premise of heat — the food for the mind is counterbalanced against the food for the body. This aesthetic experience is what I mean when I suggest that the aesthetics of ambiance is in fact an ecological phenomenon best understood in terms of the heat. The power of Rembrandt's painting comes into its own when we locate it within the argument presented here — that heat is the currency of ecology and that life is enacted through the dynamics of heat.
It is conventional wisdom that vernacular architecture responds to local climate. This response is modified by available material, building technology, site, economics and even religion. While these other factors — available materials, existing technology, religion, etc. — are more commonly regarded as external to climate, it is also possible to argue that in fact, these factors of technologv, construction, religion and so on contribute to what we may call human ecology.
Modern aesthetics has been dominated by the principle of disinterestedness ~ where aesthetic considerations must be isolated from other considerations in order to be truly aesthetic. This isolation has made it difficult to discuss aesthetics in a subjectively meaningful way. Climate change and natural calamities in recent years have lent weight to
the argument that we need to be more concerned with the environment we live in. Translated into aesthetics, this concern with the environment is an aesthetic of ambiance. The
proposal presented here is that an understanding of ambiance aesthetics is best characterized in terms of an ecology of heat. Thermal aesthetics is not simply a matter of temperature but an understanding of the energetics of heat. Or, put in another way, heat is the sensual manifestation of energy.
From an entirely scientific and engineering viewpoint, getting the right approach to thermal comfort will result in significant savings in the energy consumption of buildings. There is aiso research that suggest that access to the external climate results in better health and less abrupt adaptation and lower stress. The success of vernacular architecture is because it is both a socio-cultural as well as technological response to climate. The dominance of visual aesthetics has objectified architecture and given us a distanced experience of ambiance. Embracing the aesthetics of heat will regain for us an architecture that is re-humanized.
References
Ong, B. L. (2012a). Ecology and the aesthetics of heat. Paper presented at the Ambiances 2012, Montreal.
Ong, B. L. (2012b). Warming up to heat. Senses & Society, 7(1), 5-21.
Ong, B. L. (Ed.). (2013). Beyond Environmental Comfort. London: Taylor and Francis.
Ong, B. L., & Hawkes, D. U. (1997). The Sense of Beauty - Role of Aesthetics in Environmental Science. In D. Clements-Croome (Ed.), Naturally Ventilated Buildings: Buildings for the senses, the economy and society. London: E & FN Spon.1-16