speaking ofsustainability

Good design is sustainable design. It adds social, economic, and environmental value to projects and communities, and it informs every aspect of Perkins Eastman’s work. The language of sustainability’s triple bottom line is critical to setting and achieving clear project goals. It is also continuously evolving. Many regulations, trends, and market standards have arisen out of the imperative to address climate change and create healthier communities, and the associated terminology is often unclear and ill-defined. This guide aims to bring a common understanding to several significant—and often misunderstood or misused—topics and terms. The goal of an aligned terminology is to more readily advance design performance and create better places for people and the planet.

Net Zero Energy

Simply put, net zero energy (NZE) is the ability of a project—a single building or an entire campus—to produce as much energy as it consumes on an annual basis. At Perkins Eastman, the NZE approach prioritizes reducing a project’s energy consumption through a deliberate design process that focuses first on reducing the energy needed by including all stakeholders and considering all energy uses. Energy use intensity (EUI) measures the total energy consumed by a building per square foot over the course of one year. Once the EUI has been lowered as much as possible, the remaining energy consumed is offset by renewable energy (typically photovoltaics) onsite when feasible.

Achieving NZE is often viewed as a technical or systems challenge. But the efficiency of a building’s design significantly impacts NZE goal achievement. Within an NZE framework, Perkins Eastman first employs passive design principles suitable for both current and future local climate conditions when shaping, sizing, and detailing a building. Once passive opportunities have been maximized, the next step is to include high-performance, all-electric systems to avoid the burning of fossil fuels and allow for a true offset of consumption to production. NZE is part of an encompassing approach to holistic wellness, and the wellness of people and planet should always be the ultimate goal.

Carbon Neutral

Like NZE, carbon neutral is an equation looking for a net-zero balance. Carbon neutrality requires absorbing and/or offsetting (through the purchase of offset credits that reduce greenhouse gas emissions) as much carbon from the atmosphere as is emitted. Since carbon emissions from human activities are driving global warming and climate change, the architectural profession has an imperative to work toward carbon-neutral or even carbon-positive outcomes that actively reduce greenhouse gas emissions.

As with an NZE approach, design plays a major role in achieving a carbon-neutral building. Design decisions impact both operational carbon (the carbon a building emits through energy usage across its lifetime) and embodied carbon (the greenhouse gas emissions associated with the life cycle of building materials, from extraction through manufacturing, transportation, installation, and end-of-life disposal, recycling, or reuse opportunities). Passive strategies and renewable technologies can reduce operational carbon, and reducing the quantity of new materials and selecting materials based on their life cycle can reduce embodied carbon.

However, designing carbon-neutral buildings is only one step toward achieving a carbon-neutral society. The larger goal is a cross-industry global challenge that involves transitioning transportation infrastructure and utility grids away from fossil fuels and toward green solutions; it also requires the reinvention of material pipelines. Today, carbon neutrality is not possible without carbon offsets, but with collaboration across industries, pulling carbon out of infrastructure systems altogether is possible.


Resilience is the enhanced capacity of buildings, systems, and communities to respond and adapt to, as well as recover from, adverse events such as natural disasters, climate change, and human-caused hazards both current and future. A resilient design maintains functionality and minimizes negative impacts; it contributes to the ability of broader socioecological systems to cope with change.

In design, the term resiliency is often used in reference to disaster response preparations. But resilience encompasses much more: the durability of built structures and the strength and vitality of their social, economic, and environmental context. A truly resilient design serves as a community asset in the face of varied challenges such as power and utility interruptions, extreme weather events, or changing populations.

The first step in designing for resilience is to proactively assess natural disaster risks and potential human-induced hazards, such as a utility disruption due to error or deliberate act, civil unrest, or technological failure. A resilient design process implements hazard-specific measures and prioritizes passive strategies to extend project functionality even when HVAC and other systems are down. Examples include a school that accommodates community use for emergencies or regularly occurring events, a hospital that remains functional after an earthquake, offices that can be repurposed into residential units, and renovations tailored to changing climate conditions.

Diversity, Equity & Inclusion

In the natural world, diversity is essential to the health of ecosystems. Similarly, diversity, equity, and inclusion (DE&I) are critical to the long-term sustainability of every community’s economic, social, and environmental fabric. A commitment to diverse, equitable, and inclusive practices and policies must be embedded in a firm’s culture and design process to create vibrant spaces and places that truly support people and communities.

There is much to learn from DE&I efforts both within and beyond the design world. For example, Gallaudet University, which educates deaf and hard of hearing students, is rethinking how the word “inclusion” is expressed in American Sign Language. The university believes that the sign, which involves one hand attempting to squeeze into a small hole formed by the other hand, suggests that one must adapt to fit a certain mold to be included. Its proposed alternative is a new sign that depicts one hand freely placing fingers onto the open palm of the other hand, representing the true meaning of inclusion. To achieve better design outcomes, a sustainable process deliberately invites all stakeholders to meaningfully contribute.

Circular Economy

A circular economy is a model that minimizes waste, maintains and extends the value of products and materials, and avoids extracting new resources. In a linear economy, buildings and materials are designed for one use, and significant waste is generated at the end of a project or material’s lifespan. Architects and designers contribute to a circular economy by designing for disassembly, deconstruction, reuse, future renovations, and adaptability for future uses.

The best way to move closer to a circular economy is to prioritize renovation and reuse projects that maintain buildings and materials of value and preserve the community fabric. Waste reduction can be as straightforward as limiting the number of new materials used in a project. For example, the recent design of Perkins Eastman’s Pittsburgh office streamlined materials by eliminating wall base and unnecessary bulkheads to reduce the quantity of materials used and enable more time to vet the final materials.

Indoor Environmental Quality

Indoor environmental quality (IEQ) refers to the conditions inside a building, such as air quality, daylight, acoustics, and thermal comfort. It encompasses how a building makes its occupants feel, and whether it positively or negatively contributes to their well-being and productivity. IEQ is fundamental to the firm’s “Human by Design” principles. Design impacts occupant experience and health.

With sleeves rolled up, the firm’s teams regularly go into the field to evaluate IEQ measures from pre-design to post-occupancy, and they use software tools throughout the design process to model IEQ parameters. The models and measurements are paired with on-site post-occupancy evaluations to assess the achievement of wellness and performance goals quantitatively and qualitatively, and the lessons of these data-based assessments are applied to future projects.

Healthier Materials

It is critical to holistically evaluate and specify materials for their impact on the health and well‑being of people, communities, and the planet. “Healthier materials” is a term often associated with the impacts of hazardous chemicals in building materials, but it encompasses a wider range of impacts. Perkins Eastman is a signatory of the AIA Architecture & Design Materials Pledge, which commits the firm to prioritizing materials that foster human health, social health and equity, ecosystem health, climate health, and a circular economy throughout their life cycle.

To assess a material’s impact, Perkins Eastman balances a variety of considerations and studies product disclosures and certifications:

  • Climate health: seek products that reduce or even sequester carbon emissions.
  • Human health: avoid products that include hazardous substances and materials that negatively impact the health of occupants and communities throughout their
    life cycles.
  • Ecosystem health: give preference to materials that support natural water, air, and biological cycles.
  • Circular economy: reuse buildings, select materials that can be repurposed, and minimize waste.
  • Social health and equity: look at the operations and supply chains of the manufacturers to ensure that they honor human rights.

The goal is to improve the quality of the air people breathe and the materials they touch, protect the health of communities affected by supply chains, and be responsible stewards of the environment. Every material specified should have a net-positive benefit throughout its life cycle.


Biophilia refers to humankind’s innate biological connection to nature: human health is inherently connected to the natural world. The term biophilia is rooted in psychology and biology, and built environment applications have been developed by research scientists and design practitioners. Biophilic design strategies are employed to improve cognitive function and performance as well as physiological and psychological health and well-being.

Biophilic design is more nuanced and layered than the inclusion of green walls or views of nature. The research-based biophilic strategies outlined in Terrapin Bright Green’s “14 Patterns of Biophilic Design: Improving Health and Well-Being in the Built Environment” are a good guide.¹ The environmental consultancy organizes its patterns into three categories:

  • “Nature in the Space” refers to the presence of natural elements (plants, water, breezes, scents, sounds) in a space; it seeks to address the five senses.
  • “Natural Analogues” include forms, patterns, textures, materials, and other sensory information that mimics and evokes connections with nature; it is often organized into a spatial hierarchy in which elements are highlighted or presented in multiple levels of visual detail.
  • “Nature of the Space” reflects relationships and spatial compositions found in nature that support the human desire to feel safe, overlook large expanses, experience risk, or discover new places; for example, humans seek places of prospect to survey an expansive area or refuge to withdraw into a protected space.

Perkins Eastman combines these strategies to create places to live and work that engage the senses, support joy, and facilitate wellness. N

1. Browning, W.D., Ryan, C.O., & Clancy, J.O. (2014). 14 Patterns of Biophilic Design. New York: Terrapin Bright Green, LLC. https://www.terrapinbrightgreen.com/report/14-patterns/

Recommended Reading

Braiding Sweetgrass: Indigenous Wisdom, Scientific Knowledge, and the Teachings of Plants by Robin Wall Kimmerer (Milkweed Editions, 2015)

Cradle to Cradle: Remaking the Way We Make Things by William McDonough and Michael Braungart (North Point Press, 2002)

Drawdown: The Most Comprehensive Plan Ever Proposed to Reverse Global Warming edited by Paul Hawken (Penguin Books, 2017)

Healthy Buildings: How Indoor Spaces Can Make You Sick—or Keep You Well by Joseph G. Allen and John D. Macomber (Harvard University Press, 2022)

The Shape of Green: Aesthetics, Ecology, and Design by Lance Hosey (Island Press, 2012)