Maximizing Energy Stability and Efficiency


This R+D project analyzes energy efficiency strategies, barriers and successes of all-electric, zero net energy (ZNE)-ready, affordable multifamily housing projects across three climate zones in California. Prompted by the pioneering success of five Mithun-designed Bay Area projects achieving ambitious EUI (sub 20 kBTU/SF/year), this research investigates holistic design strategies and systems approaches to create energy stability and resilience for building owners and residents.

The building sector accounts for 40% of global greenhouse gas emissions (GHGs), the majority of which is from energy use in building operations. Amidst the compounding climate crisis and a lack of housing affordability, this research analyzes the holistic outcomes of all-electric, ZNE-ready design. As power grids rapidly decarbonize in many regions, building electrification, rather than NZE building design, proves the fastest pathway to reducing GHGs and achieving zero carbon. Local jurisdictions across the nation are rapidly adopting all-electric reach codes, and designers and developers have found a gap in understanding first costs, building performance and system operations. This research aims to address that knowledge gap, helping to advance electrification.


During the first phase the team led the creation of a design-practitioner assessment tool in collaboration with Integral Group, aiming to optimize packages of energy efficiency strategies to achieve zero net energy for the multifamily residential sector, as well as easily enable users to compare energy performance, Title 24 code compliance and LEED implications across different construction types and packages of design decisions. During this phase the team further examined the limitations of ZNE within certain multifamily typologies, resulting in a more detailed study of all-electric strategies and implications in phase two.

In phase two, the team analyzed the implications of all-electric, energy efficient design in terms of first cost, annual utility cost and operational carbon. Through five project case studies, the team studied an all-electric versus an electric and gas alternate design, and compared the relative impacts. Additionally, the relationship between energy consumption, energy efficiency metrics and occupant density were explored at a high level, comparing energy use intensity (EUI)—measured per area—to energy use per capita.

Looking Forward

The study’s findings include evidence for all-electric first cost savings, an anticipated average operational energy savings of 32% and a significant average operational carbon reduction of 77%. This research has garnered significant local and state level policy interest with its implications for carbon reductions, healthy communities and long-term climate resilience. The Mithun R+D team has presented findings locally and nationally, at forums that include San Francisco Department of the Environment, the San Francisco Mayor’s Office on Housing and Community Development, the Getting to Zero National Forum and the Net Zero Annual conference, among others. The team has submitted eighteen letters of support for all-electric reach codes in local jurisdictions, and research team members serve in advisory roles on task forces dedicated to electrification, including the San Francisco Carbon Emissions Task Force, the Decarbonization Guide Working Group and the City of San Jose Reach Codes Advisory Group.

Through illustrating the social, environmental, and economic benefits to all-electric multifamily affordable housing design, this research aims to continue to advance electrification across the building industry.

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