C33 -- A Holistic Approach to Decarbonizing a High-Rise Multi-Family Residential Tower through Design, Construction, and Leveraging Water-Energy Nexus PDF

This paper intends to show case a decarbonization approach implemented for a 15-story, 112-unit net positive energy multi-family residential tower located in Belltown neighborhood of Seattle. The building is designed to meet the City of Seattle’s Climate Action Plan (CAP), which targets reaching net zero greenhouse gas (GHG) emissions by 2050. We designed the tower under Seattle’s Living Building Pilot Program, with the intention to achieve the Living Building Energy and Water Petal certification. This certification required our team to perform a 100-year whole building lifecycle assessment (LCA) to holistically assess embodied carbon, operational carbon, and water use associated with the building design. Our analysis shows that overall lifecycle carbon associated with the design amounts to approximately 1,622 tonnes of carbon dioxide equivalent (CO₂e). The building is designed to be net positive energy, generating a 9% surplus clean renewable electricity through a combination of on-site and off-site solar panels on an annual basis. Hence, there are no operational carbon emissions associated with the design. Implementation of surplus clean electricity generation allows the building design to avoid 2,054 tonnes of CO₂e from using grid electricity over the building lifecycle. The embodied carbon in the new design amounts to 3,572 tonnes of CO₂e achieving a 15% reduction from the reference design. This paper details the strategies our group employed to reduce embodied carbon emissions, operational energy use and associated carbon emissions, and how the design leveraged water systems to reduce energy use and integrate HVAC and plumbing systems in the design to improve overall performance eliminating the need for fossil fuels in the project.