|GREENING EAST CAMPUS|
|“What gets measured gets managed.”
Sir John Browne, Chief Executive Officer, British Petroleum, 1997
Financial costs and benefits of buildings are generally well understood and effective quantitative methods are available to assess building expenditures and investments. However, many architectural decisions have effects far deeper than the easily recognized factors of cost, function, and aesthetics. Even though such a statement may be widely agreed upon, designers and other decision makers currently lack the frameworks necessary to consider the broader implications of their decisions, such as the sustainability issues of building occupant wellness, production and construction worker safety, and environmental impact. Traditional economic cost-benefit analysis cannot fully embody the sustainability vector of a decision, as many of the health and environmental components are difficult, if not impossible, to value monetarily, let alone discount in today’s market context. In this section, a tool is presented that aids decision-making around the non-monetary attributes of a sustainable building system. Case study analyses of the East Campus Project at the Massachusetts Institute of Technology using this framework are presented as follows:
The most comprehensive evaluation of non-monetary impacts of a construction project starts by viewing the project as a process occurring from “cradle to grave:” construction, use, demolition, and reuse. Each life cycle stage consumes resources, releases wastes to the environment, and produces benefits and services for users. Inputs include building materials, labor, energy, and maintenance supplies over the lifetime of the building as well as many others too numerous to list exhaustively. Wastes include construction waste, used consumable supplies for building operation, emissions from energy production used to heat and light the building, and other residuals of construction and use. Identification of benefits is a subjective exercise that largely depends on functionality of a built structure, but some basic benefits include shelter, specialized work facilities, social interaction, and cultural qualities.
Various design features can affect the types and amounts of inputs required, wastes produced, and benefits gained. However, these features do not act alone, and their effects are not simply additive. The performance of each depends on its interaction with the rest of the building’s design and its surrounding environment. Figure 1 demonstrates this dynamic. The goal of sustainability entails minimizing the inputs to and outputs from the life cycle of a building (or product or service). This can be achieved without sacrificing benefits and, in many cases, can contribute to them. However, given the varying natures of the different inputs and outputs, as well as the complex interaction of various design features, it is difficult for designers and project managers to determine how best to meet the goal of sustainability within the constraints of sites, budgets and engineering realities.
Such difficulty arises from the fact that sustainability issues are based on various levels of scale, affecting varied physical and social phenomena. While most of these effects can be measured with one or another set of units, converting these measures into a common unit (either money or some sort of composite index) in order to sum them along a common dimension, involves subjective valuation of the relative importance of each issue or phenomenon. Is reduction of CO2 emissions more significant than reduction of dioxin releases or improving stormwater retention? Answers to this question depend on whether global warming, toxins in the environment, or water resources and flood control are the serious problem and for whom the impacts are to be accrued. Our present level of understanding of the world allows us to make subjective judgements on these questions, but does not allow us to answer them using objective and defensible technical methods. Therefore, these types of composite analyses, by definition, involve subjective evaluation, which is generally presented in varying degrees of transparency.
Today in the United States, the most widely known tool for improving the environmental performance of a building is the Leadership in Energy and Environmental Design (LEED) green building rating system, developed by the U.S. Green Building Council. LEED provides a “shopping list” of design and engineering options to improve the environmental performance of a building or site along with a certification system to reward compliant buildings. This system essentially gives equal weight to most environmental benefits and produces a composite “score” for the sum of all measured sustainability criteria. It does not provide for the weighting of various impacts based on personal judgment, nor does it include an underlying framework to comparatively assess design options.
Current methods to assess alternative design scenarios and design tradeoffs primarily consist of first-cost minimization and increasingly include Life Cycle Cost Assessment (LCCA), where operating costs are estimated to determine payback periods for initial investments in improvements such as energy efficient equipment. Research is well underway in Europe and has a strong foothold in the U.S. to make use of Environmental Life Cycle Assessment (LCA) and to incorporate LCCA into the LCA methodology . Overall, today’s most widely practiced methods for making sustainable building decisions consist of LEED’s point system and some type of cost analysis. A methodological framework to assess non-monetary impacts and multi-purpose design decisions is lacking.
|Comprehensive Decision Making and Life Cycle Assessment|