Advancing Urban Sustainability


Advancing Urban Sustainability

Learn more about our Phoebe work and services by emailing us at [email protected]. Follow the conversation on twitter: @TerrapinBG | #PhoebeFramework

This post is part of an ongoing series discussing the foundations and theory of Terrapin’s Framework for an Ecological Built Environment (Phoebe). Phoebe is a suite of tools that use ecosystem-based assessment to evaluate and improve the built environment. Phoebe merges sustainable design with environmental planning, industrial ecology, and restoration ecology. Its aspiration is to reconcile ecosystem dynamics and contemporary environmental pressures with human-dominated environments. These articles explore the ways these fields interact within the context of the thought process and goals of Phoebe.


The more our world looks and functions like this natural world, the more likely we are to be accepted on this home that is ours, but not ours alone.”

– Janine Benyus

The ambition to live in harmony with nature has preoccupied many environmental thinkers and conscious developers of the built environment. In recent years, green building standards have attempted to codify this concept into widely applicable standards that resonate with cross market environmental problems. However, when constructing a set of performance standards, it is equally important to begin with the ecological and environmental narratives of place. The diversity of context necessitates an unconstrained set of metrics and open-ended questions: How is this site currently connected to existing ecosystems? How does the operation of a site depend on services found on and off-site? What functions in local ecosystems can be mimicked to improve the functionality and resiliency of communities?

Terrapin is developing a framework for ecosystem-based standards for the built environment we call the Framework for an Ecological Built Environment (“Phoebe”). Phoebe is a framework for evaluating human development against ecosystem patterns and processes. It merges the fields of sustainable design, environmental planning, industrial ecology, and restoration ecology by creating a standard of performance grounded in the ecology of a site.

Phoebe has three primary goals:

  1. Connect Humans to Natural Systems
  2. Establish Ecological Functions and Processes On-site and Align The Built Environment To Regional Ecosystems
  3. Integrate Larger Ecosystem Impacts Into Planning and Decision Making

Phoebe is both a thought provoking exercise that reframes the goal of design and a set of tools for design decision-making and project evaluation. The goal of this framework is to reconcile increasing human domestication of global ecosystems with the structure and function of unmanaged ecological communities.

Universal Applicability to System-centered Productivity

Phoebe aspires to be a next step in contemporary sustainability practices for the built environment grounded in an understanding of place. Current environmental evaluation tools are typically structured to be universally applicable across a range of building configurations and settings. However, achieving broad applicability limits place-based discussions of sustainability. Phoebe shifts the objective from broadly applicable best-practice goals to system-centered, place-based goals. They consider projects relative to the provisional capacity of ecosystems and infrastructure and frame impacts from the perspective of an ecosystem.

The value of this framework goes beyond its potential to support ecosystems. Phoebe has the opportunity to help building owners and operators save money through reduced resource consumption and improve health and productivity in several ways.

First, by identifying the resources beyond the project site that are necessary for the long-term functionality of a project, Phoebe allows for the protection and stewardship of those resources.

Second, the ecosystem approach of Phoebe is fundamentally a risk mitigation tool. By understanding the interconnections between a community and its ecosystem, the community can understand the risks to be managed to ensure the health of the community. This requires an evaluation of the services required by the community: Are they reliable? Are they efficient? Do we have the ability to manage them in an emergency? Do they follow our code of ethics? This kind of conversation elucidates structural risks and leads to the creation of resilient systems.

Finally, by grounding performance in the environmental narrative of place, a project aligns its goals with the goals of a community, reducing conflicts and reinforcing positive results.

Phoebe’s evaluation of historic and contextual site ecology also provides unique value. Understanding ecosystem change over time allows us to think more holistically about the future potential of urban-ecosystem interactions and imagine future conditions more effectively. For example, the extent of flooding caused by Hurricane Sandy so closely approximated the edges of the pre-development shoreline-in some cases more accurately than FEMA maps— demonstrating that understanding this history is valuable to understanding flood vulnerability.

Phoebe as an Aspirational Goal

Phoebe is aspirational for a few reasons. Our understanding of the relationship between human engineered and natural systems is continuously evolving. Phoebe pushes us to deeply consider humanity’s stewardship of ecosystems and that means working within the uncertainty of ecological dynamics.

Phoebe reframes the discussion of built environment in terms beyond the bounds of building operation. This reframing may challenge an architect, engineer or building operator but it also opens up the discussion. For instance, proscribing a 15% reduction in energy-use will likely result in an established set of energy efficiency solutions that deal with energy consumption, not production. If we change this proscription to a Phoebe goal that a site sequester more carbon dioxide than it generates, not only do we get to the heart of the problem –climate change associated with Greenhouse Gases (GHG)—we also are asking an open ended question with more pathways to a solution.

Phoebe is aspirational because in many ways, they may be impossible to achieve with current practices in the built environment. For instance, consider what is required to support the occupants of a midtown Manhattan block in 2014. Many services must be outsourced to the region and globe. How could we affect this footprint such that all the outsourced services are reconciling their operations with local ecosystems? This is a revolutionary act that will require a fundamental rethinking of how we provide and consume resources at all levels of society.

We are more likely to break the molds of standard practice by striving for the impossible. This shift in language for designers and managers encourages engagement with the science and conversation around an environmental issue. However we also confront the many uncertainties and data limitations presented by scientific literature. How do we resolve these uncertainties so that they are relevant to the day to day operations of buildings and sites? Developing systems with channels for feedback and analysis are critical. There is a need to be experimental and flexible when it comes to the evaluation of poorly understood interactions.

The well-known mantra, “what gets measured, gets done” is often repeated in the facilities management world. There is clearly a need for monitoring, measuring, and documenting actions to ensure operational engagement and continual improvement. However, it is equally important not to exclude criteria that do not have tools yet. Phoebe is used to establish aspirational targets and to define evaluation metrics; it is also used to define new metrics, many of which are currently unmeasured.

Historical Context

It is critical that we understand the larger context of ecological and architectural thought, and how they have influenced each other and the discipline of urban planning over the years. Ecological theory has moved from regarding nature as static, to a closed cycle at equilibrium, to a dynamic and constantly changing ecosystem.

The built environment and the environment within which it is built have a complex relationship that began almost as soon as architecture and the natural sciences were conceived.

Understanding the relationships between human and natural history has become critical with the interconnected nature of global sustainability issues today.  Ecosystem restoration today covers a multitude of aims – from pure scientific purposes of replicating a historical state, to restoring a degraded landscape for production reasons. Acknowledging that human action can also create or support a healthy ecosystem also opens up the possibilities for restoration methods beyond conservation.

With this context we will delve deeper into each of the goals for Phoebe:

  1. Connect Humans to Natural Systems
  2. Establish Ecological Functions and Processes On-site and Align The Built Environment To Regional Ecosystems
  3. Integrate Larger Ecosystem Impacts Into Planning and Decision Making

Connect Humans to Natural Systems

The goal of “connecting humans to natural systems” is biased toward individuals. In part, this goal follows the biophilia hypothesis that there is “an innately emotional affiliation of human beings to other living organisms.” Phoebe implies that our interaction with “natural systems” may be assertive and engaged; not only do we benefit from our relationship to nature, we understand our actions as an essential component of the ecosystem.

Many activities can bridge the connection between natural systems and us. Sometimes these subtle habits reconnect us in surprising ways. In the offices of Terrapin Bright Green and CookFox architects, a green roof was installed as a building feature; a visual amenity that managed rainwater. It wasn’t until kestrels began using the site as hunting grounds that the employees began to see the roof as part of a larger landscape of habitats. The green roof has become an integral part of the office culture and has expanded to include an apiary, a test garden for clients, and an onsite laboratory for understanding native specie adaptation to rooftops. At the same time the roof is also a habitat, thermal regulator and part of the city’s hydrological cycle. We are recognizing that designing with awareness of ecosystems has real, tangible economic and social value.

Re-establish Ecological Functions and Processes On-Site and Align The Built Environment To Regional Ecosystems

Development often comes at a cost to local ecosystems. At greenfield sites, habitat is cleared and rarely replaced by environments of equal value to an ecosystem or by the corresponding ecosystem services. Contemporary urban systems do not replicate most of the functions of intact ecosystems.

At the scale of a neighborhood or eco-district, Phoebe aims to integrate natural systems back into the urban context and mimick these ecological functions. The Phoebe will ideally improve the robustness of urban ecosystems, improve the comfort of human spaces, expand the ecosystem services found within the community, and increase the disaster resilience of human settlements.

The goal of restoring function to an ecosystem at a single site in a dense urban area like New York City may seem daunting. But a new system that learns from and engages the larger ecosystem will be more cost effective and resilient to changing cultural shifts and adaptive to climate change.

We will need to go beyond simply integrating ecosystems back into our communities, we will have to redesign our engineered systems to mimic ecosystem functions and processes in order to provide services and characteristics to meet the scale of human needs.

In nature, systems with high levels of resilience are characterized as having diversity, openness, reserves, tight feedback loops, modularity and redundancy.

A resilient forest is one that can grow back to the same kind of forest after a pest outbreak. A resilient business is one that can absorb a market shock and return to profitability. A city can bounce back from shocks as well. In these examples, the basic identity of the system stays the same though each system is changing all the time – by changing, the system enhances resilience.

Integrate Larger Ecosystem Impacts into Planning and Decision Making

The third goal of the Phoebe is to integrate off-site ecosystem impacts into planning and decision-making in the built environment. These ‘outsourced’ or ‘embodied’ impacts are environmental impacts associated with activities upstream or downstream of the site. Awareness of these embodied impacts is important to in order to inform our decisions at the building level.

With industrialization and urbanization comes the reshaping of global economy, where the number of individuals who have a direct relationship with landscapes has greatly diminished. In cities, the food we eat, the water we drink, the tools we use are nearly all connected to sites that we have little to no knowledge of. It is this decoupling of most humans from ecosystems that has rendered the flows of material and energy through contemporary society abstract to much of society.

For instance, most people understand that energy is linked to carbon emissions, but few associate their energy use with its other impacts: degraded mining land, polluted water bodies, and diminished water resources. In translating inputs and outputs to impacts, Phoebe represents a significant step in connecting the consumption of resources to their production and associated place-based impacts.

Tracing the services demanded by the built environment reveals a vast ‘ecology’ of interrelationships that connect a built site to the city, region, and globe.


The concept of an ecosystem reference standard sets aspirational targets and creates a sustainability framework that provides new strategies and evaluation tools. To that end, the Phoebe at Terrapin is developing into a comprehensive strategy that not only suggests target results; it also alters the framework for traditional approaches and suggests entirely new solutions.

Rather than categorize topics by building operation values (eg. energy, water, waste) we re-frame the categories by the impacts we are most concerned with such as climate change, land-use change, and freshwater resource loss. Many of the classic metrics of ecologists describe impacts of human development relevant to building sustainability performance measures. Additionally, employing the frameworks of ecology suggests a new set of variables may become indicator metrics for the built environment.

The goal of Phoebe is to ground the evaluation of sustainability of the built environment to the dynamic interactions of ecosystems. The motivation for this is the mental reconnection of landscapes and natural systems that is lost when we abstract sustainability metrics to incremental reductions in input and outputs. The past is a guidepost, not only for describing the limits of ecosystems, but also for understanding how humans interacted with local environments before modern engineered systems decontextualized the built environment. Reference standards describe what we choose to value and how we judge ourselves against those values. If we are serious about learning to live in congruity with nature, evaluating ourselves on the terms of our local ecosystems is an important first step.

Next Steps

We are currently working with colleagues and clients to develop these ideas in a more formalized fashion in order to broaden the discussion and begin the larger challenge of implementation.



NOTE: The previous name “BERS” was changed to “Phoebe”.
*Header and feature image courtesy of Chris Garvin

Chris is a senior project manager and researcher at Terrapin. He has a multi-disciplinary background, combining the skills of an architect with knowledge from the environmental sciences. In addition to his work on green buildings, waste, energy, and food systems, Chris teaches and writes about ecological design.