THE NATURAL STEP AS AN ASSESSMENT TOOL FOR THE BUILT ENVIRONMENT Jennifer R. DuBose, Interface Research Corporation Annie R. Pearce, Georgia Institute of Technology ABSTRACT The Architecture/Engineering/Construction industry has begun to show an increased interest in the concept of sustainability as a way of improving the performance of facilities throughout their life cycle, in terms of indoor and outdoor environment, economics, and other criteria. Decision makers in the A/E/C industry, along with facility owners and users who are interested in increasing the sustainability of their facilities, need a tool with which to evaluate their buildings in terms of the critical variables of sustainability. Because there has been little agreement over the precise composition of sustainability and the essential elements of a sustainable building, different sets of sustainable building indicators have been developed to satisfy the various schools of thought. One of the more promising recent approaches to achieving sustainability is The Natural Step (TNS). Many people seem to like the approach of TNS, since its four system conditions are relatively easy to understand and accept and its tenor is non-judgmental. While the system conditions of TNS provide a useful starting point for evaluation, their application to specific technologies such as buildings is difficult because of the complexity of the technologies and the indeterminate nature of the system conditions. This paper seeks to answer the following question: “How can TNS be applied to built facilities, and what does it mean for how we build buildings?” Using TNS as a framework, we have developed a matrix evaluation tool which categorizes building-related indicators according to the four system conditions. INTRODUCTION Sustainability offers a way of interacting with our world which reconciles the ubiquitous human desire for a high quality of life with the realities of our global context. It calls for unique solutions for improving our welfare that do not come at the cost of degrading the environment or impinging on the well-being of other people. Although there is no general agreement regarding the precise meaning of sustainability beyond respect for the quality of life of future generations, most interpretations of the term “sustainable” refer to the viability of natural resources and ecosystems over time, and to the maintenance of human living standards and economic development [1].The Natural Step Approach One of the more useful frameworks for thinking about sustainability is The Natural Step (TNS). This approach is an attempt to simplify the language and distill sustainability down to critical issues. This framework was developed by Dr. Karl-Henrik Robèrt in 1989 in Sweden. As an oncologist, Dr. Robèrt began noticing an increase in cancer rates among children. In an attempt to understand the cause of this phenomenon he concluded that children were being impacted by something pervasive in the environment, as opposed to a lifestyle choice which might lead to cancer in adults. This led him to the conception of “molecular garbage” -- the detritus that has accumulated in the environment and is found at the molecular level. We have unearthed persistent metals and unleashed them into the terrestrial environment. We have also created synthetic toxics that can not be broken down by nature. All of these persistent materials linger in the environment and make their way it into the molecular structure of living things, including humans. Dr. Robèrt was aware that there are very clear parameters which prescribe the conditions a cell must have to live and wondered if a similar set of clear rules could be developed for our environment. He drafted a document outlining potential parameters and after 21 iterations among 50 scientists, the final product was a list of four system conditions that must be met for sustainability to be achieved. While most environmental frameworks have focused on type and quantity of materials consumed, The Natural Step looks at waste generated as the primary limiting factor. In a speech to Monsanto, Paul Hawken refers to a high school science experiment with bacteria in a petri dish. He points out that the bacteria do not die from lack of food, but are poisoned by their own waste products [2]. The Earth is a closed system just like the petri dish, and our wastes are threatening to poison us: Our resources are being rapidly transformed into useless garbage, some of which is obvious to the naked eye, but most of which escapes awareness. The smaller portion can be seen in garbage dumps and other visible waste. By far the larger portion can be thought of as ‘molecular garbage’ - consisting of the vast quantities of tiny particles that are daily spewed out into the earth’s air, water and soil. [3]Basic Principles of The Natural Step The four conditions shown in Table 1 were the result of the consensus process undertaken by Robèrt. These parameters are seen as non-negotiable conditions required for a sustainable system. 1) Substances from the Earth’s crust must not systematically increase in the biosphere. 2) Substances produced by society must not systematically increase in the biosphere. 3) The physical basis for the productivity and diversity of nature must not be systematically deteriorated. 4) In order to meet the previous three system conditions, there must be a fair and efficient use of resources with respect to meeting human needs. Table 1: Natural Step System Conditions [4] Although TNS cannot tell us what materials to use, nor how to design, construct, operate, or deconstruct buildings, it can be helpful in the field of the built environment. It can be instrumental in framing our thinking, and can serve as a guide to evaluating the sustainability of a building. TNS does not judge or tell us what to do, but it does guide us in the right direction. METHODOLOGY The primary objective of this work was to transform the operational system conditions of TNS into an evaluation tool which could be used to assess the sustainability of built facilities. The methodology consisted of interpreting the TNS system conditions and finding building-specific indicators which represented each condition over the critical phases of the facility life, resulting in a life-cycle assessment matrix. Developing a Matrix of Sustainability from The Natural Step Indicators
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