Carbon Reduction Strategies

Building Reuse

“The most sustainable building is the one that is already built,” a refrain you have probably heard! Building reuse, sometimes called “adaptive reuse” when the building use changes, is effective for reducing embodied carbon because they minimize the need for new materials and construction processes. By repurposing existing structures, we save the energy and resources that would otherwise be spent on producing and transporting new materials. This approach also reduces waste and extends the life of buildings, making it a more sustainable option overall.

Renovating an existing building typically saves 50% to 75% of the embodied carbon that would be emitted by constructing a similar new building.4 Simple studies evaluating reuse and new construction can be completed using the Care Tool. 

Additionally, in California, the decision to renovate is often driven by a need for seismic retrofit. This also makes campuses more resilient while preserving cultural heritage.

The risks of reuse often come from project unknowns that can lead to cost or schedule inflation. Operational carbon should also be considered and building performance also considered for retrofit.

Learn from UC San Diego’s Marine Conservation and Technology Facility​ about and adaptive reuse research laboratory facility that was transformed from a 1963 fishery building.

Learn from UC Davis’s Walker Hall Renewal​ about how the historic 95-year old graduate center building’s life was extended by a seismic retrofit.

Mass Timber

Mass timber projects offer an alternative to steel or concrete for large commercial buildings. In addition to being a lower-carbon manufacturing process, timber products offer the potential for biogenic carbon storage for the life of the project. This means that carbon removed from the atmosphere from tree growth remains outside of the atmosphere for the life of the product.

The benefit of mass timber is contingent on healthy forests and tree growth. For this reason, it is important to understand where lumber is sourced from to ensure no deforestation is occurring and practices such as clear cutting are avoided. At a national level, US forestry practices are sustainable, but practices vary by location.

Currently, there are no mass timber manufacturing facilities in California. Because of potentially long distances, it is important to consider transportation emissions (A4) in decision making studies. 

The risks associated with mass timber have generally been cost and insurance. However, there is potential to mitigate concerns when considering potentially shorter schedule and eliminated cost of finishes when mass timber is exposed. The insurance industry also continues to adapt to price risk on these projects.

Learn from UC Berkeley’s ASRB​ about how the first mass timber building on campus and overcame logistic challenges to achieve significant carbon reductions.

Low Carbon Concrete

All new construction will have concrete on the job—either as topping on CLT or metal deck or as the building foundation. Low-carbon concrete is an entry point for decarbonization on every project. Through collaboration with general contractors and ready-mix suppliers there is always potential for optimization and carbon reduction.

Concrete emissions are primarily the result of cement production. Cement is production requires heating limestone to high temperatures using fossil fuel sources while also emitting CO2 as a biproduct of the calcination process. The most common way of reducing cement is the use of supplementary cementitious materials (SCM) like fly ash or slag. Performance based concrete specifications are the mechanism for requiring carbon reduction and should be established in collaboration with the structural engineer.

Lightweight concrete requires more cement content than normal weight concrete due to the aggregate is not as strong and manufactured aggregates are also processed at high temperature. Natural lightweight aggregates, like pumice or scoria, can be a means of mitigating emissions.

Generally, carbon reductions on the magnitude of 15-30% are possible without impact to cost. Greater reduction is possible but may result in cost or schedule impacts. It is important to consult your contractor.

• Learn from UC San Francisco’s Helen Diller Hospital and Bayfront Medical Building about how early communication and goal setting led to low-carbon concrete procurement.

Mechanical Equipment and Refrigerant Leakage

MEP systems are often overlooked from whole life carbon perspective (energy and embodied carbon). However, these systems can be a blind spot both for material embodied carbon of equipment (e.g. metal ducts, pipes, and heavy machinery), but also high global warming potential refrigerant leakage. MEP embodied carbon is currently underestimated due to lack of information (EPDs) and often lack of modelled data in BIM, but industry initiatives like MEP 2040 are shedding light on the importance of tracking these systems. 

• Learn from UC Santa Barbara’s Henley Hall​ about how incorporating passive solutions to reduce operational carbon also had a positive impact on MEP embodied carbon.

Interiors

The majority of campus building stock is and will be existing buildings between now and 2030 or even 2050. While the impacts of new construction can be significant, the repeated consumption and emissions from elements that are frequently replaced, such as FF&E and finish materials, accumulate over the life of a building—contributing as much or more as the initial construction.

The carbon problem is integrally linked with our campus waste problem. The built environment uses almost half of the world’s extracted materials and generates as much as 2.2 billion tons of Construction and Demolition (C&D) waste globally each year by 2025. Transitioning to circular economy, an economic model where materials and products retain their value through their useful service life, being refurbished or remade into equal or higher quality products after their service life, offers a framework for mitigating both carbon pollution and waste, among other societal benefits.  

The building industry must pivot quickly to develop marketplaces, material selection criteria, and design strategies to be able to create beautiful, healthy environments with minimized carbon impacts.

• Learn from UCLA’s Surplus Stop​ about how student and department donations can find new life and avoid costly, economically and environmentally, impact of new products.

Hospitals

Hospital projects have their own challenges to meet requirements set by OSHPD. Well intended requirements that are meant to ensure safety can lead to onerous limitations that potentially do not improve safety as intended. Performance criteria can prove safety while also enabling more sustainable solutions.

• Learn from UC San Francisco’s Helen Diller Hospital​ about how alternative means of compliance (AMC) were used to make carbon reductions possible in its concrete mix designs.

Laboratories

Lab projects, similar to hospitals, often have unique and high-performance requirements, such as sensitive vibration criteria or HVAC requirements. Each project offers opportunities for innovation and supporting the transition to decarbonize our built environment.

• Learn from UC San Diego’s Marine Conservation and Technology Facility​ about how building reuse can reimagine a high-performance building.
• Learn from UC Santa Barbara’s Henley Hall​ about how pioneering building sustainability goes beyond energy efficiency.