Opinion - 29/July/2020

The quest for carbon-neutral cities

A development being planned in Sacramento, California, could provide a blueprint to tomorrow’s cities. Many of the answers are already here, but some research remains, says Geeti Silwal from design firm Perkins and Will

The views expressed are those of the author and do not necessarily reflect the position of FORESIGHT Climate & Energy

Low-carbon construction and car-free zones only gets us so far to achieving greener cities

The pursuit of carbon neutrality is, at its heart, a clarion call for a culture change—one that heeds our delicate relationship with nature and gives back to the environment more than it takes. As we grapple with a global public health crisis and issues of social equity and climate change, cities are waking up to their responsibility for a much-needed shift in city planning values.

City infrastructure—be it utility, transportation, or food—determines people’s choices, behaviour, health, and community culture. A mixed-use, high density, transit-reliant community enables an active and healthy lifestyle, while a sprawled city, like Los Angeles, instills a culture of car-dependency.

According to a 2019 report by the UN Environment Programme and the International Energy Agency, transportation accounts for 23% of greenhouse gas emissions worldwide. Achieving low-carbon cities requires a deep commitment to sustainability on a holistic scale, reducing car-dependency, and shifting toward renewable energy sources. As city designers, it is incumbent upon us to understand the impact of our plans and building designs on the health of people, the city, and the environment.


One project that’s leading the charge toward carbon neutrality is the Sacramento Valley Station Master Plan. This 13.5-hectare parcel in the heart of the City of Sacramento, California, is set to become one of the first public agency-led Living Community Challenge Master Plans. Developed by the International Living Futures Institute, the accreditation is inspired by a philosophy of regeneration in addition to sustainability. Certification may only be achieved by demonstrating a project’s performance over at least a year after completion.

Perkins & Will's proposed design for the Sacramento Valley Station Master Plan

Perkins & Will’s proposed Sacramento Valley Station Master Plan

The project aims to achieve net-zero carbon emissions from building operations, and net-positive energy and water. Designed to connect the users closely with nature, through intentional biophilic design moves, the project will also serve as a model for how a district can achieve resource efficiency and cost-effectiveness, quality of life and environmental benefit, as well as historic preservation. Once completed, the Sacramento Valley Station will be a regional intermodal transportation hub within a connected, walkable community where people — not cars — take centre stage.

The plan seeks to develop mixed-use projects and strengthen the connections between Old Sacramento, Downtown Sacramento, and the emerging Railyards District to the north. The finished site will include a new station concourse, light-rail station, regenerative utility centre for district energy and water treatment, parks, robust pedestrian and bike network, as well as mixed-income housing, offices, and other amenities for a complete transit-oriented community. Convenient access to a multitude of mobility options will allow individuals to rely on sustainable modes of transportation instead of single-occupancy vehicles. As a result, this new district will substantially reduce greenhouse gas emissions.

The carbon-neutral principles that underpin the Sacramento Valley Station are also coming into fruition at Market Street—one of San Francisco’s most historic and busiest thoroughfares but is now a car-free boulevard through the heart of the city.

The aim of this decade-long project was to revitalise a 3.5-kilometre stretch of Market Street by banning the use of private vehicles, creating safe bike lanes, and dedicating lanes for public transit and enabling spaces for public life to unfold. Today, Market Street is a hub that supports a diversity of social, cultural, and economic activities and contributes to lowering carbon emissions.



These projects are a start, but we need more than just low-carbon modes of mobility and decarbonisation of the construction industry to create clean cities. My research on what I call the Resource Infinity Loop discusses a solution for a closed-loop water and nutrient infrastructure within our cities.

Much like the way systems in nature flow to create and restore life, cities can similarly operate in an endless cycle of reuse and regeneration. It starts with treating used water locally and reclaiming nutrient-rich wastewater for urban farming. With the help of compost as a natural fertiliser, these farms can grow fresh fruits and vegetables for community consumption. From there, the cycle repeats.

Additionally, the gas that is released from fresh organic matter — such as organic waste and sewage — is actually bio-methane, a renewable energy source. Harnessing this energy and implementing wastewater treatment plants would help catalyse a shift toward self-sustaining and resilient cities.

The International Living Futures Institute is inspiring the architecture, engineering, and construction industries to take responsibility. To achieve the institute’s Living Building and Living Community certifications, a completed project must generate its own energy, recycle all its water, and process all its waste.



We are currently on the path toward carbon neutrality through projects like the Sacramento Valley Station Master Plan. But we also need to invest in research, like the Resource Infinity Loop. These are all interconnected parts of a greater goal—designing carbon-neutral cities that are resilient and regenerative and slow the rate of climate change.

As a global design community, we must do it now, together, to preserve our planet for future generations.

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