Page 11 - Designing for Zero Carbon-Volume 2_Case Studies of All-Electric Multifamily Residential Buildings

able housing” the choice of energy system may again be different if the costs are borne by the owner rather than the tenant.
Aside from the design of the energy system and the nature of the building structure itself (wood frame, heavy timber, concrete, steel), other related issues have become pressing in recent years, making the design of multifamily residential projects even more challenging.
Grid Harmonization and Resiliency — Energy Storage
In the Introduction to Volume 1 of Designing for Zero Carbon3, the issue of the statewide uneven demand for electric power throughout the day was discussed as a growing issue of concern. This “Duck Curve” phenomenon4 (the growing peak power demand in the evening hours and the decreasing lower demand in the midday period caused by increased use of on-site solar PV systems for buildings in California) suggests the use of energy storage to enable the public utility grid to moderate and manage the extremes of the daily energy demand.
The public utility companies already use time-of-use rates to help manage this growing demand fluctuation, charging significantly more for electric energy used during the afternoon and evening compared to much lower rates charged after midnight and in the early-morning hours. As elec- tric vehicles further penetrate the automobile market, this load shifting will become much more significant.
Energy storage will be introduced to some extent at the public utility level, but its primary applica- tion will be at the individual building level, installed by building owners in conjunction with their solar PV systems. On-site battery storage will enable building owners to store unused electric energy generated during the sunny daytime hours for use later in the evening when the utility rates are much higher. The ability to manage the electric power drawn from the utility grid in this manner will contribute to the overall cost effectiveness of the battery storage systems.
Another benefit of on-site energy storage for the individual building owner is the resiliency offered by such a feature during periods of utility power interruption such as California experienced re- cently during periods of wildfires and extreme weather events. The value of this resiliency feature is not measured in a standard cost-effectiveness evaluation, but nevertheless may be high in the estimation of the final users of the building.
In fact, for multifamily residential projects of four stories or more that are in the design and per- mitting phase, and for all such multifamily residential projects in the future in California, battery storage is now required along with a solar photovoltaic system.5
Embodied Carbon
Embodied carbon considerations are being included during the design phases as carbon re- duction for new buildings becomes more urgent in our societal effort toward the 2030 carbon reduction goals. Energy efficiency has been built into building projects for the past four decades in California and has been improved every code cycle. The move to all-electric buildings and the scheduled decarbonization of the public utility grid will eventually lead to a zero-carbon building sector from an operations perspective. A strong effort is therefore now being made by design professionals and others to reduce the embodied carbon in building materials that occurs due to
3 See p. viii of Volume 1.
4 Burnett, M., “Energy Storage and the California Duck Curve”, Stanford University (2015). 5 2022 California Energy Code, effective January 1, 2023.
INTRODUCTION DESIGNING FOR ZERO CARBON, VOL. 2
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