Pleasant Hill Library

2024 Design Awards Merit Recipient

Engaged by Pleasant Hill to create its first civic building in many years, we were asked to design a 21st century library, where all ages would feel welcome and encouraged to learn, create, and explore. The City wanted an inclusive community destination and a “signature building” with a timeless, flexible design. The library was conceived alongside three adjacent projects partially located within the Grayson Creek 100-year floodplain, including roadwork improvements, a new multifamily housing development, and future sports fields. Together, the project team mitigated flood concerns, while knitting sites together with bike and pedestrian pathways.

Pleasant Hill Library is an exemplary response to numerous Framework measures, including Equitable Communities, Wellbeing, Ecosystem, Economy, and Change. The project’s all-electric, highly energy-efficient design is targeting net zero energy, and includes radiant heating and cooling, natural ventilation with night-flush operability, and a rooftop PV solar array. Its free span central hall provides ample capacity for diverse offerings and allows easy reconfiguration of stacks should programmatic needs evolve. Movable furniture subtly delineates zones tailored to youth, teens, and adults, while bringing pops of color to the interior. A clerestory and large skylights allow natural light to flood the interior. Pavilions off the main hall house a ‘messy makerspace’, ‘story lab’, and a quiet reading ‘retreat.’

Since opening, Pleasant Hill Library has become a vibrant community hub, with nearly 30% more checkouts than the next county branch in its first full year of operation. The library has also hosted nearly 51,000 participants across 548 events.

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This project got a lot for a little. A beautiful children’s library. The way the building brings daylight in and modulates with these special rooms makes it an exceptional space. There is also a strong sustainability program and landscape design—really strong.

//framework for design excellence measures

Measure 1: Design for Integration

Pleasant Hill Library is an exemplary response to numerous Framework measures, including Equitable Communities, Wellbeing, Ecosystem, Economy, and Change. A thoughtful interweaving of architecture and landscape, the project stretches along the site’s east-west axis, allowing the Grayson Creek riparian corridor room to expand and providing optimized solar orientation. In concert, flood mitigation studies validated site placement, allowing grading adjustments to mitigate stormwater by directing flow around the library. Prevailing southwest breezes are also harnessed for natural ventilation.

Pleasant Hill Library is all-electric and targeting net zero energy through the incorporation of passive and active strategies. The primary roof pitches upward to the south, bringing indirect daylight into the main hall through a continuous clerestory. Solar panel arrays are clipped directly to the standing seam metal roof, while large glass windows and curtain walls frame views of native shade trees and drought-tolerant plantings.

A radiant concrete slab leverages the regional climate’s large diurnal swing as the primary heating and cooling system. In summer, the slab’s thermal mass naturally cools overnight and provides passive cooling the next day. The slab gradually heats or cools during off hours in advance of forecasted temperatures. The design also integrates a natural ventilation system with night-flush cooling.

Measure 2: Design for Equitable Communities

The project team coordinated and led extensive programming and community engagement processes with stakeholder groups of all ages through meetings, focus groups, and charrettes to guide the library’s diverse spaces. Out of this process, a consensus was reached to organize the library around an open hall that could function as a community ‘living room’. The decision was made to plan the library as a single-story building to prioritize universal access and ease of circulation to library patrons of all ages. Community engagement also informed the placement of the Story Lab, a flexible gathering and event space.

Measure 3: Design for Ecosystems

Natural light and views connect occupants to their surroundings. This is particularly evident in the community living room, which looks onto the new bioretention areas and the Grayson Creek landscape. By providing this habitat buffer zone along the Creek, the ecological health of the area has been improved with an expanded riparian corridor. Native oak tree plantings were introduced, along with larger Valley oaks, to blend with the existing creek landscape. Winding pathways bring the public closer to this wonderful resource. Two-thirds of species are locally adapted, drought tolerant native plants that tolerate the recycled water used for irrigation.

Measure 4: Design for Water

Library site design involved extensive flood mitigation in coordination with adjacent projects. This included raising the finished grades of the library site by an average of 4’, lowering the sports field to accept floodwater, and creating bioretention basins between the library and creek. These basins naturally filter and treat all stormwater runoff from the site – including roof, parking lot, and hardscape – while retaining floodwaters when Grayson Creek overflows. Basins were tested with strong atmospheric rivers during the 2022-23 winter and provided the necessary volume for water infiltration and delay, improving the performance of the local watershed.

Measure 5: Design for Economy

City and Library desired a flexible space that could adapt to changing needs and provide lasting value. While the new library is smaller than Pleasant Hill’s former facility, it provides a significantly greater diversity of programs. Balancing first costs against long-term benefits, square footage was carefully managed by right-sizing spaces with staff and maximizing use through blended, multi-use arrangements – each space is tasked with supporting multiple functions. Mechanical and electrical systems prioritized long-term value and efficient performance. An in-floor hydronic radiant slab, the primary means of heating and cooling, minimized overhead equipment and ductwork, reducing long-term maintenance costs.

Measure 6: Design for Energy

The library is currently targeting Net Zero Energy. During the first full 12 months of operation, measured use indicated a positive KWH delta. Ongoing conversations with our client and energy consultant indicate possible explanations including many more people than anticipated using the library as a daily workspace and that the rooftop PV array may not be performing as intended. We continue to work with staff to monitor energy use and resolve performance issues to help the project achieve net zero energy.

Measure 7: Design for Well-Being

The library’s natural ventilation system provides fresh air throughout. During wildfire events, all operable windows close, and the active mechanical system, equipped with MERV-13 filters, will provide code-minimum air exchanges. Local controls for ceiling fans, lighting, and window shades allow adjustments by staff. Building and landscape design encourage a healthy lifestyle, with a protected Activity Yard and tree-lined promenade linking Monticello Avenue through the entry plaza to a new creek trail, establishing the library as a trailhead for bike and walking paths extending to the middle school and downtown. Low-emitting materials and paints comply with CALGreen VOC limits.

Measure 8: Design for Resources

With a lifespan goal of 100 years, the decision was made to invest in an architecturally exposed structural steel frame. Durable exterior materials improve lifespan, including cedar siding, precast concrete panels, and aluminum framed glass curtain wall and windows. A cast-in-slab radiant flooring system will last the building lifetime, reducing need for mechanical upgrades. Fly ash and slag were used as replacements for cement in concrete mixes. Structural members have high demand ratios to reduce material size and quantity. Many materials, including the standing seam roof, western red cedar siding, and Activity Yard sculptures, were produced and sourced locally.

Measure 9: Design for Change

The Library offers daily flexibility and continued innovation in services over time. Its free span central hall, pavilions, and flexible furniture create easily adaptive environments that can be used in different ways. Over the long term, the column-free space allows library staff to re-program as needs evolve. Wireless internet and a distributed layout of electrical floor boxes were provided throughout to ‘future-proof’ against likely changes. To address future risks from environmental change, the all-electric building features a rooftop solar PV array, and the library plans to install an integrated battery system that stores its solar energy for backup protection.

Measure 10: Design for Discovery

We worked with library and city staff to transition from a dated facility to a state-of-the-art building, together commissioning the radiant mechanical system, fans, LED controls, and motorized window and shade systems. We hosted a 2023 AIA Conference tour to share lessons learned with the profession. Client, architect, and energy consultant continue to monitor performance and adjust use, such as turning lights off during the day, to help the project achieve net zero energy. In 2023, the library saw 271,520 visitors, with 359,270 checkouts (not including ebooks or renewals), 30% more than the next busiest county branch.