Renovating for the Future: The Dominican Sisters of San Rafael's Pursuit of Sustainability and Resilience
by Henry Hundt
In San Rafael, California, the Dominican Sisters of San Rafael (DSSR) have been a steady presence, upholding faith, community, and tradition. Recently, they’ve taken additional steps towards sustainability, influenced by the teachings of St. Dominic and Pope Francis’ encyclical, “Laudato Si’.” In line with their Vision 2027 plan, the Sisters are thoughtfully integrating care for creation with contemporary renewable solutions.
The journey started with the decision to renovate and expand the existing, dated Dominican Convent building to improve the environment for the care of their sisters, while bringing the community together under one roof. Hoffman Planning, Design & Construction partnered with the Sisters, guiding the building planning and design while integrating a wholistic sustainability effort. Three core sustainability aspirations steered the project—eliminate green-house gas emissions, bolster the facility (and two adjoining smaller buildings) against grid outages and severe weather events, and ensure financial viability, minimizing long-term energy cost.
The planning phase was approached with care. The first step was to consider how the temperatures in San Rafael might change under climate change as the Sisters considered adding cooling to the Convent. This data guided the decision to electrify the HVAC (heating, ventilating, and air conditioning) systems using air source heat pumps that could provide the cooling and heating needs.
Electrifying the primary energy user—the HVAC system—was critical for their sustainability goals. Decarbonizing a building requires energy efficiency, electrification, and on-site renewable energy generation, once insulation and window standards are met. After optimizing design elements for energy efficiency, such as integrating LEDs and choosing appropriate skylight window glazing, the focus shifted to modeling the building’s future energy use. This determined the amount of solar photovoltaic (PV) panels required for a net-zero energy building.
Building energy modeling provides energy use and cost estimates. This aids in ensuring the facility’s efficiency and provides detailed energy use estimates essential for designing a solar PV system’s technical and economic performance. At this stage, available incentives and relevant utility rate structures are considered. Fortunately, during the DSSR planning process, the Inflation Reduction Act (IRA) was passed. This allowed nonprofits to directly access tax incentives as cash payments from the IRS, simplifying renewable energy incentives for the project.
The goal was audacious: deploy enough solar PV for a net energy positive facility. After examining the campus, a multi-array approach was chosen to preserve trees and avoid taking of any open space. The final design encompassed the Convent’s existing and new roof sections , complemented by a solar carport for additional solar panels, EV charging, and covered parking. This design ensured that most solar energy would be utilized onsite, minimizing grid sell-backs which would reduce the systems financial performance.
The sustainability goals, however, couldn’t compromise reliability. San Rafael faces grid outages most years due to high wind events, prompting utility power cutoffs to prevent wildfires. Historically, diesel or propane generators ensured resilience. However, this conflicted with DSSR’s sustainability vision. The solution was to use a battery energy storage system (BESS) combined with an integrated microgrid controller.
A microgrid functions independently, even during grid failures. For instance, should a grid outage occur at DSSR, the controller harmonizes the battery, building energy demand, and solar PV generation. Daytime energy needs are met primarily by PV, with excess energy stored in the battery. After the sun sets, the battery discharges to meet energy demands. This cycle repeats daily, with adjustments during reduced solar energy periods. Selecting the right technology partner is paramount. Symmetric Energies was chosen based on their track record and proximity, offering final electrical engineering design, installation expertise, and being based near the project.
The outcome is a dynamic system that achieves all three aspirations: sustainability, resilience, and financial efficacy. The comprehensive setup—comprising solar PV system, batteries, microgrid, and EV chargers—anticipates a 10-year payback with a net present value over $2 million. The final system uses 147 kW of PV and a 125kW, 440 kWh battery storage system that covers both the main convent building and an adjacent facility in the event of an outage. This initiative has positive and far-reaching effects. By reducing carbon emissions, the Sisters are making meaningful strides towards sustainability. The system they’ve put in place offers stability in uncertain times, both in terms of energy costs and availability. The efforts of Dominican Sisters of San Rafael show how organizations can align projects with their core values, and their journey provides a practical example for others to consider.
Henry Hundt is a sustainability leader with Hoffman who focuses on renewable energy design and planning as well as building performance. Henry can be reached at email@example.com.