Written by Francesca Desmarais / Architecture 2030
The 2030 Palette is a set of distinct actions – or Swatches – for the planning and design of environmentally responsible and resilient buildings and communities worldwide. Our case studies illustrate how a unique palette of Swatches can be applied to create buildings and communities that consume fewer fossil fuels, compliment and preserve sensitive ecosystems, access site renewable energy resources, and can adapt to climatic changes.
The Bullitt Center, currently regarded as one of the greenest office buildings in the world, is an exemplary case study illustrating how a palette of design strategies can result in truly dramatic performance outcomes. Located in in the city of Seattle, this six-story office building is on track to be the largest certified Living Building in the world, achieving energy and water self-sufficiency while creating a healthy, net zero carbon, and beautiful built environment.
To achieve a high level of performance, the design team had to push beyond traditional practices to an integrative, performance-based process. The architects, engineers, contractors, developers, and consultants all worked collaboratively from the very beginning to meet the ambitious sustainability goals established by the Bullitt Foundation, the owner. The result was a building in which building elements and holistic, interconnected systems have multiple functions and perform across a variety of scales.
Much more than an isolated building, the Bullitt Center was designed to connect with the fabric of the neighborhood. The site was partly chosen to increase commercial activity within the surrounding, largely residential, area. The building fits many of the development goals of the neighborhood including sensitive infill development and the creation of interesting urban spaces. As part of the project, McGilvra Park — a pocket park located to the south of the building — was revitalized leading to talks with City of Seattle Department of Parks and Recreation and the Seattle Parks Foundation on how best to create a vibrant public space.
The site was also chosen because of its accessibility to alternative, low-carbon public transit options. Twenty-one public bus routes can be accessed within a 1/2 mile of the Bullitt Center and proposed light rail stations will be within walking distance as well. Sidewalk plantings protect pedestrians from vehicles and make the walking experience more enjoyable. The building has no car parking, but does have indoor “parking” for bicycles and showers for commuters.
At the site scale, stormwater is a chief concern in the wet climate of Seattle and non-point source pollution from surface runoff can flow into the Puget Sound. To minimize and treat surface runoff, all stormwater is collected and managed on site. Rainwater that falls on the expansive roof is collected in a 56,000 underground cistern and then treated through a system of filters and UV light disinfection. The system is currently undergoing testing, but the plan is to reuse the treated water throughout the Bullitt Center — in sinks, water fountains, and showers — so that 100% of water demand is met onsite.
Any additional rainwater not captured is directed through pervious pavement and landscaping located along pedestrian sidewalks. These natural drainage systems filer the water and allow it to infiltrate the soil, reducing surface runoff.
Greywater from the sinks and showers is also treated onsite; it is pre-filtered and then passes through a constructed wetland located on a strip of roof on the second floor. This green roof not only helps break down the organic components in the grey water but also aids with stormwater management. The resulting, treated water is used to irrigate landscaping on the site.
In addition, composting foam flush toilets are located on each of the six floors, making the Bullitt Center the tallest building in the world to use composting toilets. The resulting compost will be treated and then reused as fertilizer. All told, these innovative water strategies and the use of low-flow, efficient fixtures help the Bullitt Center achieve an 80% reduction in its water footprint.
At the building scale, the incorporation of passive lighting, heating, and cooling techniques were critical in meeting the net zero energy goals of the client. Given the small footprint of the site, there was limited potential for on-site renewable energy generation and the design team minimized the energy loads of the building through the use of natural systems, high-efficiency mechanical systems, and tenant engagement. The Bullitt Center achieves an impressive Energy Use Intensity (EUI) of 16 kBtu – an 83% reduction in energy use when compared to a typical Seattle office building.
Natural daylighting is maximized throughout the Bullitt Center. Extensive side daylighting is integrated at each level and high floor-to-ceiling windows admit as much of the Seattle sun and daylight as possible. Open floor plans and light interior finishes help distribute this daylight evenly across the spaces. Skylights on the sixth floor (punched through the photovoltaic array) admit additional top daylighting to the space below.
In winter and on cooler days, the glazing on the southern façade admits direct sunlight and heat, passively heating interior spaces. The heat is absorbed by the concrete floors which store some of the excess daytime heat and maintain stable, comfortable interior temperatures.
Automated blinds on the exterior of the building control unwanted heat gain and glare, balancing daylighting and passive heating systems. These shading devices are deployed only when needed and adjust to block unwanted sunlight during warm periods. They create an animated and layered façade, a visual expression of the building’s response to the climatic conditions of the day or season.
Operable, parallel projection windows on each floor pop-out from the building envelope to facilitate cross ventilation and natural cooling. These windows are not only automated by the building’s energy management system to optimize comfort and energy efficiency, but can also be adjusted by tenants. At night, the windows open to flush out heat and cool the masonry concrete floors in summer.
The image above also depicts the orange liquid-air-barrier, specially commissioned for this project without hormone-imbalancing phthalates. Meeting a hallmark requirement of the Living Building Challenge, none of the materials or building products used in the Bullitt Center contain toxins forbidden under the challenge’s ‘Red List’. Prosoco, the company that spent months researching and developing the phthalate-free liquid air barrier, plans to reformulate its entire product line to reflect this new, healthier alternative.
All of the electricity needs of this high-performance building are produced on site by the 264,000 kwh/yr photovoltaic array located on the roof of the building. The array extends dramatically over the building like a hat, reflecting traditional roof overhangs of Northwest architecture. The panels generate excess electricity to the grid during summer which is then offset by winter electricity consumption, resulting in a net zero energy building. Additional energy for heating and cooling is produced by ground source heat pumps and then circulated through radiant heating/cooling systems in the thermal mass floors. A 65% effective heat recovery system further minimizes heat loss (it also recovers heat from the compost digesters).
As one of the most aggressively sustainable office building of its size, the Bullitt Center is a living laboratory in which the tenants play an important role. How occupants use the building impacts both water and energy consumption and, in fact, Living Building certification hinges on how the building performs over its first year of operation. To ensure low energy and water use, tenants have energy budgets they must meet or pay extra, computers are required to be 80% laptops and only 20% desktops, office cleaning takes place during the daytime, an “irresistible stair” encourages tenants to walk rather than use the elevator, and a large dashboard tracks occupant energy and water use throughout the building.
The Bullitt Center takes sustainability to the next level. Through an integrative and performance-based process, a comprehensive palette of design strategies has been beautifully combined into an elegant, low-carbon, and low-impact structure.
Register for the 2030 Palette to explore the Swatches featured in this project: Urban Infill, Parks, Sustainable Sites, Water Catchment and Storage, Constructed Wetland, Green Roof, Form for Daylighting, Side Daylighting, Side Daylighting Controls, Top Daylighting, Daylighting from Multiple Sides, Direct Gain: Glazing, Direct Gain: Heat Storage, Cross Ventilation, Shading Devices, and Solar Shading.