Page 10 - Designing for Zero Carbon-Volume 2_Case Studies of All-Electric Multifamily Residential Buildings

DESIGNING FOR ZERO CARBON, VOL. 2 INTRODUCTION
Introduction
This book of case studies is the second volume of the sub-series1, Designing for Zero Carbon. This sub-series focuses on the electrification of buildings, a current aspect of California state government policy to combat climate change and its effects. Volume 1, published in March 2022, considered case studies of recent projects that were non-residential, both new buildings and renovations. This Volume 2 continues the narrative of zero-carbon buildings, but focuses on the important category of multifamily residential projects.
Energy efficiency remains an important goal, as reflected in the steady tightening of California’s Title-24 energy code requirements, and the role of on-site renewable energy sources continues to grow. But, as discussed in the Introduction to Volume 1, full decarbonization of the building sector will only be realized when the use of carbon sources of energy in buildings such as natural gas is eliminated and the electric power grid is itself fully decarbonized. The latter goal is man- dated2 to be achieved in 2045.
The transition to all-electric operation of buildings, both new and existing, is the formidable task that lies ahead for the building industry. As usual, California’s Title-24 energy code sets the direc- tion for the industry to follow, but much can be done outside of code requirements to advance the state of the art in this regard, both technically and in a cost-feasible manner.
The challenge to building developers, owners and design professionals, then, is to find the op- portunities to utilize electric energy systems in place of gas systems while striving for cost-effi- ciency and quality design. In this Volume 2, multifamily residential buildings take center stage, featuring many successful projects that achieved this goal.
The Multifamily Residential Challenge
The category of building labeled “multifamily” is quite broad and actually includes many types of structures and uses. There are code definitions of types of multifamily structures with slight differences (California Building Code and California Energy Code), but this book will use the simple definition of a multifamily building as one with three or more dwelling units for permanent residents. Consistent with the 2023 California Energy Code, the multifamily buildings discussed in this volume are both low-rise (three or fewer habitable levels) and high-rise (four or more hab- itable levels); that is, buildings of any height. Furthermore, groupings of attached townhouses (three or more) will also be the subject of discussion in this volume, as well as buildings of mixed- use housing and commercial.
The appropriate design of the energy systems in this range of structures will vary significantly, so each type of multifamily building and occupancy will be discussed in this regard. Further, the design and its associated cost will also be a significant factor in the choice of system, usually dependent on whether the dwelling units are to be rented or sold. Adding yet one more facet to this set of factors in the case of rental housing, if the multifamily building is designated as “afford-
1 The full series of seven case study books, which were published about a year apart start- ing in 2014, covers an expansive range of building types to support the adoption of energy-
efficient, low-carbon building design practices in California. These books can be found and downloaded for free from https://calbem.ibpsa.us/resources/case-study-books/. They are also available on Amazon in softcover print form at: https://www.amazon.com/s?k=zero+net+energy +case+study+buildings&i=stripbooks&ref=nb_sb_noss.
2 Governor’s 2018 Executive Order B-55-18 and SB-100, the state law passed that same
year. See also: March 2021 Joint Agency Report Summary, “Achieving 100% Clean Energy in California”, https://www.energy.ca.gov/publications/2021/2021-sb-100-joint-agency-report- achieving-100-percent-clean-electricity.
viii
Case Studies of All-Electric Multifamily Residential Buildings