Determining Architecture's Footprint: Preliminary Methods for Measuring the True Environmental Impact of Buildings

Introduction

Current approaches to designing sustainable buildings are inadequate for meeting environmental goals. Despite the progress made by green certification programs such as BREEAM, LEED, and Green Globes, climate change continues to accelerate and human societies remain incapable of meeting shared carbon reduction targets. Buildings continue to consume nearly half of all resources, and architects, engineers, and contractors remain complicit in their deficient environmental performance—as well as the consequential global overshoot of resource consumption.

The problem is not the lack of intent, but the absence of a methodology based on definitive measures. The green building programs and checklists used by AEC professionals today are problematic in that they deliver a false sense of accomplishment. They are relative models that estimate environmental improvements over standard building practices. Such changes are measurable at a local, incremental level—such as improved insulating capacity or reduced use of VOCs—and the architects who attain green certification for their buildings gain a sense of accomplishment. Yet such accreditation is meaningless in the absence of absolute measures of building performance based on global environmental objectives.

For example, a building might be awarded “LEED Silver” certification yet still contribute significantly to carbon emissions, thus exacerbating the challenge of meeting greenhouse gas reduction targets. Indeed, is there a calculable link between “LEED Silver,” “Three Green Globes,” “Living Building Challenge Certification,” or any other environmental building labels and allowable CO₂ emission levels worldwide? Using these platforms, is it possible to say with any confidence that a building is utilizing no more than its fair share of the Earth’s resources? The answer is no. In fact, the possibility exists that even if all new buildings were designed and constructed to “LEED Platinum” standards (or their equivalent), they might exacerbate current climate goals.

The green rating systems in frequent use today are relative models. They are motley collections of best practices that are primarily atypical, aggregated into point-based checklists. For example, reducing nighttime light pollution, minimizing stormwater run-off, or providing bike storage facilities are not standard building design strategies. Indeed, one can argue that each of these approaches enhances the environmental responsibility of a project. Yet how is this responsibility measured? Although green rating systems offer individual points that culminate in a total score, the points are arbitrary. Can one argue, based on scientific evidence, that the provision of bike racks is equal to the minimization of stormwater run-off in terms of environmental performance? Absolutely not. In all likelihood, the point systems are so inherently skewed and internally inconsistent as to be unreliable, particularly given the complex nature of assessing ecological impact.

It is imperative that the AEC industry pursue an alternative approach based on measurable outcomes. Such a strategy would connect building design decisions with global implications, enabling architects to calculate environmental impacts authentically. The most appropriate existing model is the Ecological Footprint (EF) method devised by Mathis Wackernagel and William Rees at the University of British Columbia in the early 1990s (Wackernagel & Rees, 1996). EF quantifies the human demand on the environment in terms of both resources and waste, translating these impacts into land area equivalents. EF is typically calculated in terms of individual or national resource consumption. The outcome is simple and readily comprehensible: the number of Earths required to sustain present demand. If a country is using its fair share of one planet’s worth of resources or less, environmental objectives are met. If not, the use pattern is by definition unsustainable. No “silver” or “gold” labels are required: one is either sustaining the Earth’s healthy functioning or not.

Wackernagel and Rees have written little about EF related to individual buildings, and the AEC industry does not utilize the EF approach. Nevertheless, it is possible to make credible links between EF and life cycle assessment (LCA), the comprehensive method of environmental impact accounting that is being adopted within the construction industry. The key is to determine the land area-equivalency of LCA midpoint impacts, which can be accomplished at various scales including a building, an assembly, or a material unit.