An Industrial Ecology Approach to Sustainable Highrise Construction

Introduction

The aim of this article is to put into context the challenges of infrastructure development in cities arising from increasing urbanisation. We will introduce the emerging field of industrial ecology which is a new approach to dealing with the sustainable development of cities. Furthermore, we will discuss how achieving sustainable highrise is only possible when the bottom line impacts are considered across the various ecologies and systems of the city.

Industrial Ecology (IE)

The aim of Industrial Ecology is to achieve a balance between human activity and its impact on the environment. Its techniques look at how human systems can integrate the natural systems, in a sustainable manner by minimising resource (materials and energy) consumption. Allenby (1992)1 proposed the following definition for Industrial Ecology;

"..The means by which a state of sustainable development is approached and maintained. It consists of a systems view of human economic activity and its inter-relationship with fundamental biological, chemical and physical systems with the goal of establishing and maintaining the human species at levels that can be sustained indefinitely given continued economic, cultural and technological evolution."

By human systems, we mean cities and the process of achieving equilibrium with the natural system of earth which can be considered to be a definition of "sustainable development". The balance required is the flow of materials and energy between the two systems in urbanising cities that are sustainable.

IE defines a "system" as an interconnected group of objects that exhibit high level behavior namely, adaptation, resilience and self regulation. As such, a sustainable city is one that can adapt to change, proves resilient to social and environmental changes and is self-regulated.

In order for an urbanising city that wishes to develop sustainably, the three main strategies associated with these behaviors are: Production, Consumption and Planning. These operate at differing spatial and temporal scales impacting a changing profile of stakeholders.

The city as a system is not a new concept, but it is valuable as it allows us to introduce spatial and temporal scales across the triple bottom line. When combined with the classic construction paradigm of cost, time and quality we have the basis of a pragmatic framework as proposed by Augebone-Pearce (1998)² and illustrated in Figure 1.

Figure 1 contains five triangles. The first two are the triple bottom line (Economics, Environment, Social) and the construction paradigm (cost, time, quality).

The latter three triangles define the strategies of Production, Consumption and Planning and gives us the Davis Langdon Industrial Ecology model³:

Production / Adaptation: (Design & engineering of the city)

• Economic Change = Environmental Quality & Social Cost Consumption / Self Regulation: (Behavior of individuals and groups within the city)
• Social Quality = Environmental Change & Economic Cost Planning / Resilience: (The city impact on the planet)
• Environmental Cost = Social Change & Economic Quality

A related concept of IE is the consideration of impact across temporal and spatial scales and as suggested earlier, differing stakeholders. This is illustrated in figure 2⁴:

This illustrates the sequence of the strategies defined earlier and the concept of urban metabolism which is the flow of resources through the activity of the city system. It also clarifies how planning serves as the "feedback loop" that helps cities to build resilience in their response to environmental change.

The purpose of the IE based framework is to highlight the considerations involved in sustainable development. Furthermore, any response to increasing urbanisation needs to adapt to changes to the city (either through social drivers e.g., growth of the population and / or environmental drivers e.g. legislation / climate change) and require design and engineering activities of the system in order to allow it to support the increased consumption whilst minimising its environmental impact through planning.

Cities as focal points:

The United Nations forecasts that the majority of population growth will be in cities in emerging regions such as Africa, Asia and Latin America. Cities in these regions are designated "mega cities" based on the fact that they have populations of 10 million plus. These mega cities represent areas of significant urban growth and hence increasing use of natural resources in creating an environment that supports the human activities therein.

In developed nations, there are mega cities too but the population isn't the key driver for their urban growth. It has more to do with the activities conducted therein and this is represented by the designation of "global cities" 1 where these cities represent global / regional hubs of commerce, transport and cultural activities.

In both scenarios, cities are locus of human activity representing very dense production and consumption behaviors per square mile. As such, their environmental impact on the region's (i.e. country) natural resources far outweighs that of the rest of the country's land mass.

Furthermore, cities represent focal points of population and affluence that are key components of the IPAT equation introduced earlier.

The drivers of this increasing urbanisation are:

• Firstly, globalisation - there is only one market
• Secondly, the focus of the global banking system in key cities where exchanges are located and secondary cities that support wealth creation through trade and production
• Thirdly, migrants seeking higher incomes are drawn to cities due to the diversity of opportunity.

These drivers also influence an emerging trend of inter city competition globally to attract the best talent, the richest companies and the most creative minds to locate within their boundaries.

The rest of this article will look at how a city like Delhi, which is at once a mega city and was ranked 41 in the global cities index² of 2008, can utilise key the three strategies of adaptability, self-regulation and resilience to not only support its growth rate but also to do it in a manner that is sustainable.

City Development

Cities by their very nature consume to create and produce. They are a collection of "hard systems" driven by the needs of the "soft systems". This is illustrated below1: "Soft Systems" are defined by the Political, Economic, Social, Technological, Legal and Environmental (PESTLE) factors that determine the need for the region (country) and the city. These need to be balanced against the triple bottom line resources available that influence the city's growth. Combined, these formulate the strategy that will define the hard system requirements of the city. "Hard systems" are defined as transport, communications, energy, water and built environment infrastructure that support the city and the human activities therein.

In case of Delhi, a planned city with its hub and spoke arrangement of roadways interconnected by arterial roads, the capacity of established hard systems are clearly straining to cope with the increased urbanisation and wealth of the populace as evidenced by the near constant grid lock of its roads. Furthermore, its architectural heritage and the associated zoning are an additional complexity to any new development of its urban framework.

Another element that contributes to the architectural fabric of Delhi are the 900 slums or shanty towns. These informal communities are a result of the rural migration and urbanisation mentioned earlier, provide evidence that the growth rate of the population of the city has far exceeded that of the development of the hard systems of the city.

In this context, the case for highrise buildings appears to be simple. Increasing population density per metre square by building taller implies a more efficient land use. Additionally, highrise buildings serve a multitude of purposes for the city. They act as landmarks in defining areas of the city, they act as focal points or nodes for various infrastructure systems and they provide an efficient means of creating "urban capacity" i.e. a built environment that supports the population in terms of housing and commercial activity.


However, highrise are very large energy and material sinks that are capable of generating a disproportionate of waste that goes to landfill for the actual area of land they occupy. Also, in order to support the increased population that can be accommodated in a high-rise, the development needs to incorporate upgrades to the capacity of the surrounding hard systems infrastructure. This issue is compounded when highrise is grouped together in one area or "clustered".

Planning – building A Resilient City

The implications for a city such as Delhi to expand its urban capacity through high-rise, is that coordinated planning strategies operating at the right scale levels need to be developed. This is illustrated below:
As detailed earlier, the aim of planning is to create a resilient urban framework that supports growth on a city wide level.

The social change that occurs for residents within the tower can either be a reaffirmation of their improved status arising from an increase in economic quality or they can serve to accelerate the degeneration of the community. The former scenario represents a positive social change whilst the latter represents a negative change. This is closely correlated with the degree of economic quality placed into the development of the urban framework. The negative scenario represents a significant environmental cost to the city in the form of built capacity and inefficient hard system infrastructure that does not support the increasing urbanisation.

For Delhi, the urban framework planned needs to adopt a portfolio perspective by providing guidance on "clusters" where the accommodation requirements meet that of the surrounding community currently and in the future. Moreover, the framework should focus on infrastructure installation and upgrade built with over capacity to accommodate forecast levels of growth in population.

This infrastructure framework allows the identification of zones for differing activities ranging from commerce, education, cultural and heritage. In defining uses permitted to certain areas and encouraging them through planning policy and / or tax incentives, the city is able to take a pro-active approach to the growth of the city.

In terms of funding such investments, Delhi could consider examples from around the world such as municipal bonds which can be tax exempt and pay a fixed rate of interest, with additional support from government offering rebates on the interest costs. The risk is that Delhi experiences falling tax revenues combined with increasing interests costs leading to the city defaulting. Another alternative albeit riskier since it relies on future tax revenue generated from the asset, is tax incremental finance (TIF). The risk here is that the municipality is liable for any shortfall in revenue leading to tax rises and hence Delhi losing its competitiveness as a city globally.

Consumption Considerations– supporting Self– regulatory Behavior

The aim of a masterplan is to support self-regulatory behavior that effects an improvement in social quality through environmental change at an economical cost.

This is in essence what it means to "place make" when masterplanning a new area of the city which has a highrise element. The social quality dimension is related to the behaviors that the new masterplan influences on the city's response to it. This is dependant on the environmental change that occurs as a result of the new masterplan. An illustration of this is how vortex shading related to highrise architecture impacts on the public realm of the masterplan at ground level. This can be mitigated either through adaptation to the architectural form or through wind breaks at ground level such as trees and /or structural forms.

Clearly in creating the masterplan and highrise, a large amount of inputs will be consumed, however once operational its consumption of resources can be self-regulated. This is achieved by providing in the masterplan, multiple modes of transport access to the development. This is evidenced by trend to locate highrise buildings on infrastructure hubs such as the tower proposed on Mumbai's new bus terminal as well as, the BREEAM rating system of masterplans that heavily weights in favour of multiple transport modes. Additionally, the mix of uses incorporated into the development can encourage end users to stay on site and walk around instead of using transport infrastructure to get to other parts of the city.

We are not advocating gated communities since these have a negative impact on the social quality of the surrounding area. Indeed, the "porosity" of a masterplan, meaning the accessibility of the entire area development is a key factor in integrating the new development successfully into the city.

An emerging and interesting aspect of self regulating consumption of the masterplanning process is the use of online consultation in stakeholder management. This form of social inclusion seeks to poll the widest community and how they would consume the proposed masterplan.

Additionally, the power of computing is being used to model the complex interactions of the various hard systems and how they integrate with the existing context. One of the most innovative approaches to this "computational" method is being led by Aedas Architects R&D team who's system of digital masterplanning uses urban design coding at its principle driver in generating masterplan solutions. This provides immediate visual feedback as options are investigated with evidence being provided by end user models based on behavioural algorithms interacting with the proposed design.

With regards the complex inter¬relationships of high rise construction and sustainably, Davis Langdon and Aedas Architect's R&D team along with Arup and Hilson Moran have developed an early stage parametric modelling tool that seeks to visualise the form factor, calculate the quantum of material required, and qualify the energy consumption and lifecycle aspects of the proposed skyscraper⁸.

Production Considerations– engineering Adaptability

In terms of economic resources, high rise buildings are a product of cheap debt. They can be considered the harbingers of economic change. This is reinforced by the skyscraper index1 which links the opening of the worlds tallest building with that of economic collapses. Furthermore, high rise do take longer to build and represent a high environmental cost during construction. As such they represent a social cost to the city during development as it has to adapt to the intrusion of construction activities and the impact on traffic flow.

Environmental quality with relation to "iconic architecture" and high rise development contributes to the city across scale and over time. These icons not only provide a statement of the city's aspirations to be a global city but also provide the city inhabitants with reference points for way finding. Additionally they can be "markers" or catalysts for major urban regeneration initiatives in a bid to create a destination for a new area of the city. Alternatively, environmental quality can relate to a diversity of uses incorporated into the high rise. This invariably leads to a taller building, but the combination of uses implies that the land use efficiency is greater.

In terms of producing a high rise building in a sustainable manner, the Design for Environment (DfE) concept provides key areas of focus in adopting a DfE approach to construction are:

Manufacturing – understanding the environmental impact of the manufacturing process required to produce the materials used in construction. As suggested earlier, high rise do consume a larger amount of material but this can be off set if the next aspect of DfE is incorporated in the design.

Materials Innovation – the use of alternative materials / techniques who's production impacts less on the environment than that of steel production represent a sustainable approach and is supported by the LEED sustainable rating. This is evidenced by the LEED Platinum rate Bank of America building in New York that used the waste produced in steel manufacture in the composition of the concrete used. This introduces the next aspect of DfE namely recyclability.

Disposal and Recycling – seeks to minimise the waste in construction by incorporating designing buildings that when are disposed allow the materials to be re-used. A more practical and traditional approach is to recycle the building stock through re-use. This can be incorporated into the design by ensuring the "space" created by the building is sufficiently flexible for it to be reconfigured and / or repurposed. This is clearly a lot more difficult in a high rise building since the core dimension and the HVAC system specification are fixed for the initial use. However, flexibility and extension of the life of the building can be achieved by altering the occupational density to respond to the needs of the city at that time.

Lifecycle Analysis – is the final technique related to DfE which affords the architect and engineer the ability to understand the flows of materials and energy during the development of the high rise.

Conclusions

Mega cities located in developing countries consume a greater quantity of resources as their urbanisation expands with high rise and denser buildings consuming much more in terms of resource per square metre. However, they have a less efficient metabolism in that they consume the majority of inputs than export to the region. Additionally these cities generate far more waste streams resulting in ever larger landfills. Both landfills and the built environment represent "sinks" of material and both are major contributors to the generation of GHG.

If we add energy as an input into our consideration of cities urban metabolism, the difference between megacities and global cities is even more marked. Whilst the former are expanding at a quicker rate and hence consuming more, the latter has much higher rates of consumption i.e. their metabolim is far more efficient but they are no longer growing in terms of scale.

This does not imply that global cities have a lesser impact on the environment than that of mega cities, indeed, it could be said that global cities have become more efficient in off loading their environmental impact to not only other areas within its region, but to other regions globally.

All of which serve to illustrate the point that sustainable development of cities are a focal point for a nation's desire to reduce its environmental impact. Pro-active planning is required to ensure the right balance of energy, materials and waste flows whilst reducing the overall environmental impact.

With regards the creating of a sustainable built environment infrastructure, embracing approaches such as design for environment represent a good start as well as specifying a suitably high award in one of the globally recognised green rating systems, namely BREEAM or LEED.

In the case of whether high rise can be sustainable, the impact they have on the city in terms of spatial and temporal dimensions suggest that to assess them as standalone products is not the correct approach. The approach implied here involves a degree of complexity and sophistication that hitherto is not yet industry standard practice. This is particularly the case in the context of iconic high rise buildings.

In order to improve the probability of successful implementation of a sustainable high rise development, the considerations of the city, its past, present and future as well as its people need to be balanced with that of the resources afforded to us by mother nature.

Steve Watts is a Partner of Davis Langdon and is head of the Tall Buildings group. He is also head of the finance and economics special interest group with the Council of Tall Buildings and Urban Habitat. He has authored a number of articles on tall building development and is involved in a number of high profile iconic skyscrapers both in London and globally.

Neal Kalita is an Associate of Davis Langdon in their Banking & Finance team. His current role is renewable energy investment and integration with the real estate asset class to catalyse development and reduce environmental impact. He has authored a number of articles on global sourcing strategies, construction costs and methodologies and a number focussed on tall buildings and the urban environment.

References

1. Braden Allenby, "Achieving Sustainable Development Through Industrial Ecology," International Environmental Affairs 4, no.1 (1992).
2. G.Augenbroe, Annie R. Pearce "Sustainable Construction in the United States of America – A perspective to the year 2010" Georgia Institute of Technology, June 1998
3. Davis Langdon / Fakton 2010
4. Watts, S and Kalita, N, 2010
5. GaWC, Loughborough University
6. AT Kearney "The 2008 Global Cities Index", Foreign Policy Magazine , 2008
7. Davis Langdon / Fakton 2010
8. Watts, Kimpian et al (2009), "Sustainably Tall: Investment, Energy, Lifecycle" ACADIA Conference Paper 2009
9. Lawrence, Andrew (1999). The Skyscraper Index: Faulty Towers. Property Report. Dresdner Kleinwort Wasserstein Research, January 15, 1999.