Page 6 - Designing for Zero Carbon-Volume 2_Case Studies of All-Electric Multifamily Residential Buildings

DESIGNING FOR ZERO CARBON, VOL. 2 FOREWORD
Foreword
California is a long-recognized leader in clean energy, climate and building policy. Recent federal action presents a unique window of policy alignment that promises to amplify dramatically our progress toward the energy transition. California was the second state in the nation to legislate greenhouse gas emissions reduction requirements, and soon thereafter, requirements were en- acted to direct proceeds from cap and trade credits to disadvantaged communities. Address- ing energy supply, the state set a goal of zero-carbon electricity by 2045, and on the demand side, building energy codes are driving electrification, storage, and ever-deeper efficiency levels across the state. Federally, the U.S. Congress has legislated historic climate investments on the order of hundreds of billions of dollars, and to ensure that benefits accrue to justice communities, the Biden-Harris Administration has launched the Justice40 Initiative.
Equitably decarbonizing our buildings will require expanding efforts in the residential sector be- yond our historic emphasis on single-family homes. 42% of California’s low-income residents live in multifamily buildings (see figure on opposite page).
In just the last few years, we have seen a remarkable industry-wide shift to embrace zero and net-zero emission building performance as our collective “North Star”. We now understand that this means we have to clean the electricity supply, electrify, and continue improving efficiency – particularly in the envelopes of older buildings. There is also growing recognition that to increase system reliability and minimize costs, our buildings must also provide load flexibility to coordinate with a renewable grid.
The Clean Energy Act is already accelerating a clean energy supply, and the building code is driving solar photovoltaic (PV) systems, energy storage and electrification in the multifamily sec- tor. With this policy backdrop in place, today’s multifamily design and delivery professionals must focus on electrification done right, thereby setting the stage for all of our communities to benefit from our low-carbon transition.
Electrification done right means first getting the envelope right. In the zero-emission multifam- ily context, California’s building energy codes already require efficient thermal performance for windows and opaque facades. However, airtightness is not addressed and more attention is required to appropriately control flows between inside and outside, as well as internal flows. Both have impacts on energy and indoor air quality. These well-performing envelopes require more careful solar control to avoid overheating. Shading, orientation and glazing all become increas- ingly important if we are to avoid excess energy use for air conditioning in summer months.
With a well-designed envelope, space heating and cooling can be delivered more effectively. In multifamily buildings that offer unit-based electric heat pump systems, there are architectural and engineering challenges associated with locating the outdoor components. Accounting for both aesthetics and ease of installation/maintenance is important, particularly for high-rise buildings. Outdoor units are often sited on rooftops, requiring thought as to the location of vertical refrigera- tion lines and the large amount of refrigerant required for longer line sets. In addition, rooftop space is limited, and is also valuable for rooftop solar PV or solar water heating systems.
Water heating is often centralized in multifamily buildings, which can require creative design to overcome the lack of market-available heat pumps that have the capacity of large central boil- ers. Higher capacity may be achieved by leveraging thermal storage (including phase-change materials). This approach also has the advantage of limiting the peak power required for hot wa- ter. Other considerations include acoustic and installation issues. Many in-unit heat pump water heating devices are noisy, or do not come in form factors suitable for apartments. Improvements in water distribution design should also be considered, such as shorter, smaller diameter piping, and improved controls for circulation pumps.
iv Case Studies of All-Electric Multifamily Residential Buildings