Owner: Trustees of the Jones Library
Architect: Finegold Alexander Architects
Structural Engineer: RSE Associates

Project Overview:
The Jones Library in Amherst, MA was founded nearly a century ago. The collection’s permanent home was constructed in 1928; a residential-style building with stone walls, a gambrel slate roof, and an elaborately carved entablature. The interior has ornately detailed window and door surrounds, arched transoms and hand-carved stairs. An addition was added in the 1990s but is slated for demolition in the current renovation design. It will be replaced with a new 42,000 SF addition to meet the needs of a modern library. The project also includes the restoration and reuse of the structure, the envelope, and much of the interior woodwork of the historic 1920s building.

Sustainability has been a priority for the owner and project team since early design. The proposed project eliminates fossil fuels and will be all-electric and solar ready. The team had early conversations about reducing embodied carbon as well. The first strategy was to build less. The reuse of the historic structure and interior components contributed to this goal by capitalizing on the carbon already emitted in their construction. The addition was then designed to be highly efficient, flexible, and compact to limit the area needed in the new footprint. It is the smallest allowable size per the Massachusetts Board of Library Commissioners.

The next sustainability tactic was to build low carbon. The structure of the addition was designed for a hybrid mass timber and steel frame with CLT floor slabs. This was the most significant way to slash embodied carbon. Concrete foundations and footings were proposed with 30-35% fly ash for carbon reduction. Interior finishes were selected with long-term durability and cleanability to extend their useful life and avoid quick replacement in the future.

Replicability:
According to some estimates, there are over 300 billion square feet of existing buildings in the US. To best decarbonize the built environment, these existing structures should be utilized and renovated for greater energy efficiency. The Jones Library is an example of both reuse and new construction to reduce carbon emissions. The existing structure and envelope reuse account for roughly 30% of the completed project. Adding new square footage to it allows for better preservation of the old. The library addition solves accessibility issues with a new elevator and ramped access to two side wings in the original building that would otherwise not be accessible. The existing floor-to-floor heights are very low and inadequate for new mass timber beams and mechanical distribution. The new floors had to be taller than the original with ramps designed for smooth transitions. With the new addition carving out the space for accessibility and mechanical systems, it allows more of the history of the original portion to be preserved.

This project is also an example of incorporating a hybrid timber structure into a building typology with a high demand for quiet. Despite all the other benefits of timber and CLT, the inherent acoustics are simply not adequate for a library’s sound and impact isolation needs. The design team balanced the sustainability goals with the acoustic requirements and proposed a floor system consisting of a 6.75” CLT floor deck covered by 1.25” thick resilient mat and a 2” layer of gypcrete. This increases the mass and absorption of the floor system to raise STC levels without adding significant embodied carbon. Gypcrete is a lightweight concrete mix with a proposed 15% fly ash to further reduce the carbon impact.

Cost Effectiveness:
Building reuse and preserving historic components have value beyond just a dollar amount but, in this case, reuse also contributes to reduced construction cost since fewer new materials must be purchased. Based on our TallyLCA estimates, the proposed project prevents nearly 200,000 kg of mass from going to a landfill through reuse efforts. Much of that mass is the structure and envelope which are also high-cost items. Millwork reuse has fewer cost advantages, but duplicating the historic carvings would be costly. Instead, reuse preserves a unique creation and avoids extra embodied carbon.

As cost estimates have been completed in the various design stages, cost reduction efforts have been necessary. Even with a slight cost premium for the mass timber structural system, the owner has been adamant that it remains, and scope be removed elsewhere. Sustainability was never on the table for value engineering. The use of a wood structure does help reduce the cost of finishes that would otherwise be needed to cover a steel or concrete structure. The wood provides an inherently beautiful finish.

The roof was redesigned to lower both cost and embodied carbon. The initial sawtooth roof over the addition provided amble daylight to the core reading rooms, but was also expensive and utilized significant glass, metal framing, and roof flashing. Skylights are discouraged in libraries, so the team revised the design with a single roof pop up with windows on all sides. This building lantern allows natural daylight to brighten the inner spaces with less material and cost than the sawtooth roofline.

Innovativeness:
Some of the best innovations are a simplification from an otherwise cluttered process. There are three simple ways that the approaches in the Jones Library project are unique and innovative.

The design team’s greatest strategy to reduce embodied carbon was in having open discussions about carbon with the owners from the very beginning of design. Changing structure and materials is much harder later in the process. These early conversations embedded the sustainability goals into the design so they could be preserved through design and into construction later this year.

The natural beauty of wood in the timber structure and CLT floors are a key part of the design material palette in Jones Library. The floors required an acoustic topping to mitigate noise, eliminating the possibility of exposing them as finish floors. In spaces below the CLT slab the team found ways to achieve noise control while exposing the beauty of the wood structure. Rather than using acoustic ceiling tiles, a series of suspended acoustic fins were designed to absorb sound without obscuring views of the wood. Wood columns and beams were left exposed where possible.

Lastly, designing for flexibility is a “future-proofing” strategy to help avoid frequent renovations, and their associated carbon, down the road. The team found that adding extra storage (beyond what is typically included) in and near key spaces allows for greater flexibility. Greater storage allows the furniture to shift in and out as program changes within the same space. This flexibility and flex space also helped to reduce the overall square footage needed in the building, further reducing embodied carbon from what could have been a much larger building.

Client: University of Massachusetts Amherst & UMBA
Architect: Payette
Structural Engineer: LERA Consulting Structural Engineers
Contractor: Suffolk

Project Overview:
With the new 74,000 GSF Sustainable Engineering Laboratories (SEL), UMass Amherst is building a national hub to accelerate clean energy research and educate tomorrow’s sustainable engineering workforce. This cutting-edge living laboratory is designed to catalyze bold discoveries that can be replicated and scaled to deliver real-world solutions, with research concentrations in batteries, energy, transportation, and environmental technology. The SEL features flexible interdisciplinary workshops, shared specialty labs, instructional classroom spaces and a welcoming student learning commons. The flexible nature of the lab spaces future-proofs the building against obsolescence tied to the rapidly changing nature of academic research.

Total carbon reduction was a key project goal from the outset. Embodied carbon was studied in parallel with operational energy and other sustainability strategies, with anticipated certifications for LEED Platinum and ILFI Zero Carbon. The design team used early-phase, iterative analyses to compare options for the building structure, envelope and layout that informed key carbon reduction strategies. The mechanical systems were relocated from the basement to ground level and roof to reduce excavation costs and carbon-intensive foundation work. The structural grids were also optimized to reduce materials, also saving a significant amount of carbon.

Net program area is maximized relative to gross area and building volume via compact, efficient planning and a ‘skip stop’ sectional strategy that introduces three floors of offices (lower height requirements) into two floors of labs (taller requirements), thereby enclosing more program with less facade area and less structure.
Low-carbon materials and assemblies were prioritized throughout the project. In addition to the hybrid steel-timber structure, the concrete mixes were optimized to replace nearly 50% of the cement with low-carbon alternates. Other strategies included using polyisocyanurate roof insulation, timber curtainwalls and wood-framed windows throughout most of the building.

Replicability:
When designing the carbon reduction strategies for SEL, it was important to make sure that the strategies could be easily replicated. Basic, first-principles approaches to space planning yielded significant savings without relying on unique or proprietary systems or materials. Carbon intensive below-grade construction was minimized by moving mechanical and electrical services to the ground floor and rooftop. Reduction in gross area and façade area, while maintaining net program, delivered the same functionality with less building – another win for both cost and carbon (not reflected in the LCA due to ISO requirements for matching areas). Rigorous optimization of the structural grid to reduce column and beam quantities cut the total steel used in the building by over 20%. As a publicly-bid state project, SEL is required to use open specifications, ensuring that the majority of materials used in the project are widely available from multiple suppliers. This also suggests that the materials will be available for future projects.

The team was also careful to suggest material substitutions that were cost neutral. For example, specifying polyisocyanurate instead of XPS for the roof assembly yielded the most dramatic carbon savings of any one variable in the LCA comparison. This simple change to a specification section did not incur additional costs, loss of performance or aesthetic compromise.

SEL incorporates mass timber construction in a program type traditionally averse to this. The use of mass timber in lieu of steel and concrete structural systems has well-demonstrated benefits of reduced embodied carbon. However, laboratories have been much slower to adopt this innovation compared to other program typologies (such as office buildings) because the strenuous vibration criteria can make mass timber prohibitively expensive. The hybrid steel-timber system used for the SEL project offers a unique middle-ground: the carbon benefit of mass timber decking is integrated with the stiffness of steel framing.

Cost Effectiveness:
SEL is a state-funded project with a strict budget. Throughout the design phases, the cost and carbon analyses were completed in parallel. By comparing project budget estimates against early LCA studies, we developed a “cost per carbon reduction” method: a dollar value for every ton of carbon avoided or reduced through design. This method informed three key approaches to cost effectiveness.

First, we looked for optimizations to reduce both cost and carbon at the same time. This included minimizing below-grade construction, reductions in gross area and reductions in steel tonnage through structural grid optimization. These strategies cut nearly 5% out of the estimated construction cost, translating to $4 million in savings that were reallocated to other project priorities.

Next, we fine-tuned our specifications to include “low-premium” items that delivered carbon savings without impacting the budget. This included polyisocyanurate for the roof insulation and increased SCMs for the concrete mix design.

We recognized that some strategies, such as mass timber decks and timber curtainwall, may have initial large cost premiums. Therefore, we used an integrated systems approach to demonstrate the value of both strategies. The structural premium for timber was much lower when considering the added price of ceiling assemblies of similar acoustic and aesthetic quality that would be needed with a metal deck. The timber structural deck was about $50/sf more expensive than metal deck when looking at structure only, but a ceiling could add $25-85/sf. The timber decks also required fewer steel beams.

For the timber curtainwalls, we used Payette’s Glazing and Winter Comfort Tool to analyze the thermal performance of timber vs. aluminum mullions with the goal of improving thermal comfort for the building’s occupants. This eliminated the need for perimeter heating, which resulted in significant mechanical cost savings, which helped offset the increased façade costs.

Innovativeness:
The SEL design team used a variety of tools and iterative analysis to reduce embodied carbon throughout the project. Kaleidoscope, Payette’s embodied carbon tool, compares multiple envelope and interior assemblies to inform the selection of materials and façade systems. EPIC provided a coarse-grained analysis of operational and embodied carbon, predicting the total footprint of LCA scopes before the design was detailed enough to perform a Whole Building LCA using Revit plug-ins. Tally and EC3 were also consulted early in SD to compare design options.

LERA developed a matrix of 64 structural systems with steel, concrete, mass timber and hybrid assemblies. They were reviewed for embodied carbon, cost, depth, aesthetics and vibration. Ultimately, a hybrid steel and timber system was selected to meet the vibration requirements of the labs while delivering a significant carbon reduction against steel and concrete systems.

This iterative structural process also led to the steel beams being embedded into the depth of the composite timber deck, reducing overall structural depth while allowing a reduced floor-to-floor height. This reduced the total façade and interior wall area – saving both cost and embodied carbon.

Acoustical performance was analyzed throughout the process. Mass timber systems are generally criticized for their acoustic performance – partly because the sound-absorbing acoustic ceilings are often removed to display the beautiful timber decking. To mitigate this, SEL uses dowel-laminated timber (DLT) instead of the more common cross-laminated timber (CLT). DLT can be routed with grooves that accept acoustic foam – delivering a Noise Reduction Coefficient (NRC) of 0.70 from the structure itself. This acoustic DLT – despite having a slight material cost premium over CLT – delivered cost, carbon and aesthetic benefits. Without the need for acoustic ceilings or equivalent acoustic wall treatments, the construction fit-out schedule was accelerated, and more timber remains visible without compromise of the acoustic quality.

Project Overview:
PCA joined the Embodied Carbon Reduction Challenge to kick-start our efforts in understanding, measuring, and reducing embodied carbon. Leland House was our first test case.

PCA was privileged to team up with 2Life Communities and partners to design Leland House, an affordable senior living community. Designed to Passive House standards, Leland House brings improved health, economic, and environmental benefits to its residents and addresses the important objective of minimizing its carbon footprint.

Reducing embodied carbon was a primary goal of the project. However, without access to industry tools and resources, the team relied on estimations and intuition early in the design process. Since joining the Challenge, we’ve been able to measure the value of the project’s carbon reduction measures and educate the team on the carbon impacts of decisions made through construction.

Our carbon reduction strategies included low-carbon structural design solutions such as: mass timber columns and beams, wood-framed load-bearing walls, and wood trusses. Improved concrete mix designs included SCMs to reduce embodied carbon. Cellulose cavity insulation was used as a sustainable alternative to fiberglass insulation.

Additional project goals included specifying PVC free and Red List free interior finishes, while providing the community with an enhanced connection to nature through biophilic patterns, textures, and materials. Bio-based polyurethane resilient flooring provided an alternative to pervasive luxury vinyl tile. Low-carbon, alternative carpet tiles, plant-based acoustic ceiling tiles, wood veneer ceiling finishes, and exposed timber columns and beams contributed to the holistic design approach of the project.

Overall, Leland House demonstrated an 18% reduction in embodied carbon over baseline, including a: 15% reduction in the structure, 15% reduction in the enclosure, and 25% reduction in the interiors.

We found that Whole Building Life Cycle Assessment (WBLCA) provides us with the knowledge and data to reduce embodied carbon and help combat climate change.

Replicability:
Through the Challenge, we’ve gained access to the tools and training to perform life cycle assessments across various systems and scales. This in turn affords us the knowledge and data to impact design decisions on real-world projects.

Replicability was built into our process from the start. Upon joining the Challenge, one of PCA’s goals was to establish a workflow, understanding, and database that we could apply to the next project, so we could hit the ground running and target greater carbon savings. To this end, we created a Lesson Learned 2.0 Model to track carbon reduction measures that we might apply to the next project.

Selecting an affordable housing project, such as Leland House, was intentional, as it targets a highly replicable case study. The technologies we employed are common and well understood by the building industry at various scales and applications; wood-framed load-bearing walls and wood trusses provide cost-effective, low-carbon solutions to meet our most basic needs.

Concrete is a material we see on every project, and it was the largest contributor to embodied carbon emissions at Leland House. Here we learned a valuable lesson around providing performance-based specifications. Our specification allowed for up to 50% SCMs, but without specifying any minimum performance values, we wound up leaving another 35 metric tons of carbon on the table that could have been further reduced. We included these savings in our Lessons Learned 2.0 Model to demonstrate how to do better on the next project.

All the measures included in our proposed model successfully survived the VE process and are currently being constructed, further evidence of the replicability and cost-effectiveness of the strategies employed at Leland House. Design is inherently an iterative process, and the lessons we learned in our first WBLCA will form the foundation for the next project.

Cost Effectiveness:
LCA tools provide us with the knowledge and data to reduce embodied carbon and help combat climate change. The more we, as designers, request manufacturers’ EPDs and demand low-carbon alternatives for the most impactful materials, the more the costs will come down. In many cases, there are cost-effective, low-carbon solutions available to the marketplace.

WBLCA allows us to identify our most significant embodied carbon contributors (e.g., concrete, flooring products, steel, foam insulations, etc.) and focus our resources on targeting their reductions.

Furthermore, by taking a holistic design approach, we can identify synergies among project goals, such as eliminating PVC from the interiors and providing biophilic designs, while also reducing embodied carbon, all with a cost-competitive product. At Leland House, we used a bio-based polyurethane resilient flooring that provided a 42% reduction in carbon over ubiquitous LVT flooring. Resilient flooring was our second-highest contributor to embodied carbon. When high-impact design decisions can satisfy multiple project goals, they are more likely to remain part of the project, and LCA allows us to bring the carbon data to the table. Carbon tools and data help to illuminate these solutions.

Red List free composite alternative carpet tiles were priced competitively and saved the project 50% of the carbon of traditional carpet tiles. Similarly, plant-based ceiling tiles provided 1/3rd of the carbon of the typical ACT without an uptick in cost.

Gypsum board and paint were two of the larger contributing materials that we were unable to address in our study. In the case of gypsum board, our base spec already includes a low-carbon gypsum product and in the case of paint we were unable to find reliable data to give us the confidence to reduce. Further work is required in these categories and others to help steer the industry to lower carbon solutions.

Innovativeness:
Low-Carbon Affordable Housing 2.0 – Lesson Learned for the Next Project
Since we started the Challenge, we were mindful to track decisions we might have made differently had we had the benefit of quantifying carbon earlier in the design process. In addition to our Baseline and Proposed WBLCA models, we created a Lessons Learned 2.0 Model to track and quantify how we could improve our embodied carbon emissions on our next project. We reduced the embodied carbon in our Lesson Learned 2.0 by an additional 10%, or 28% total reduction over Baseline.

Early in design, we targeted an insulated foam glass aggregate for the under-slab insulation. At the time, we didn’t have the data to demonstrate the value of this approach. Had we known that XPS under-slab insulation was such a significant carbon contributor, we could have fought harder to keep the alternative insulated aggregate product and made a larger impact on our bottom line.

Additional strategies for deeper savings in our 2.0 Model included:
• Further improvement to the concrete mix design saved 27% over Baseline
• Low-carbon cementitious flooring underlayment saved 35%
• Mineral Wool Board insulation saved 22t CO2e, or 65% over Polyisocyanurate
• Balloon-framed parapets saved 1,700 kg CO2e
Total Carbon: Operational + Embodied Carbon
Leland House elected to use triple-pane, uPVC windows for improved occupant comfort and operational energy efficiency. We studied the total carbon impact of double vs. triple-pane windows. Based on today’s utility mix and assumption of a 35%, or 20t CO2e, increase in embodied carbon, we estimated the annual energy savings of 1.45% would lead to a “carbon payback period” of 2 to 5 years for triple-pane windows over double-panes. We believe this analysis can contribute to a larger discussion around tradeoffs between operational and embodied carbon. We present this innovative study for further discussion…

Owner: 2Life Communities;
Architect: Prellwitz Chilinski Associates, Inc.;
Civil/Landscape: Stantec;
Structural: B+AC;
MEP: Petersen Engineering;
Specifier: Kalin Associates, Inc.;
Contractor: Dellbrook | JKS