Page 142 - Designing for Zero Carbon-Volume 2_Case Studies of All-Electric Multifamily Residential Buildings

DESIGNING FOR ZERO CARBON, VOL. 2 OBSERVATIONS
Observations
The Transition Period for Multifamily Housing
As noted in the previous volume of Designing for Zero Carbon, building design has been in a period of transition from an emphasis on zero-net-energy (ZNE) buildings (with a focus on on- site renewable energy systems) to all-electric buildings. The goal to greatly reduce the building- caused greenhouse gas emissions that are contributing to climate change remains the same, but the path to this goal has been altered by recent plans to change the energy infrastructure supply- ing those buildings, namely to change the electricity grid in California to carbon-free production.
Now, projects will be able to operate with zero carbon emissions after 2045 without necessarily achieving ZNE performance, or to be designed with the size of solar PV system usually required for ZNE. Projects reflecting this change of emphasis have only recently been designed, and the case studies in this book (and the previous Volume 1) demonstrate the design issues that now need to be addressed.
So, specifically for the all-electric multifamily housing projects studied in this volume, what issues emerged requiring design strategies to produce buildings with the desired low-carbon emission profile?
Some Things Remain the Same
Even with the programmatic differences and project objectives of the multifamily housing cat- egory, there is a continuity of design strategies demonstrated by all five case study projects that effectively supports the emphasis on all-electric design solutions that result in zero carbon emis- sions when occupied.
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Case Studies of All-Electric Multifamily Residential Buildings
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Energy Efficiency
Energy efficiency for the individual project contributes to an overall energy efficiency for the building sector as a whole, putting less strain on the public utility grid and enabling renewable sources to supply the maximum share of the power required at an earlier date. Energy-efficient design is more cost-effective for the building owner as well.
Importance of Carbon-Free Renewable Energy
Whether it is sourced from on-site renewable systems at the building site or obtained from the public utility grid, renewable energy supply is clearly beneficial because, once installed, it produces no carbon emissions over the life of the system. For a building owner, the determination of which source is best will be purely a life-cycle cost evalua- tion.
For the case study projects in this book, which will have 20 years of life before the grid is completely decarbonized, the choice of on-site renewable energy systems was a result of cost-effectiveness calculations as well as indoor air quality and tenant health reasons.
Building Metering and Performance Verification
Because the transition period to the all-electric building design approach has only re- cently started, it is essential that the design strategies chosen for these projects be eval- uated and their success be confirmed in actual use of the buildings as designed. This can only be done through performance verification after occupancy, typically including actual energy use as metered over one year or more. When building commissioning is
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