Page 10 - Designing for Zero Carbon - Case Studies of All-Electric Buildings

DESIGNING FOR ZERO CARBON INTRODUCTION
(Right) Illustration of energy storage applied to the typical 24-hour demand profile for the California statewide electric grid (called the Duck Curve). Energy stored during the af- ternoon hours from excess solar energy and discharged during the evening to prevent the sharp peak load that would occur at that time. (Courtesy of Michael Burnett)
Burnett, M., “Energy Stor- age and the California Duck Curve”, Stanford University (2015).
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Designing for Zero Carbon: Volume 1
Embodied Carbon
Embodied carbon is a parallel consideration in the design of these buildings that is becoming an important factor. Carbon emissions result from the construction process itself, the manufacture of building materials and the transportation of those materials to the building site. At the present time, these processes result in substantial carbon emissions and are in addition to the carbon emissions produced in building operations over the life of the building. Even reuse of the sal- vaged materials from the building’s ultimate demolition is part of this embodied carbon discus- sion.
As the electric grid is gradually decarbonized and more processes in the manufacturing and transportation sectors are electrified, the embodied carbon factor will gradually diminish. Until that general economy-wide decarbonization occurs, however, any thorough analysis of energy use and carbon emissions for a project should include that of embodied carbon, especially since that general decarbonization is likely to lag behind complete decarbonization of the electrical grid in 2045.
Such an embodied carbon analysis can point the way for design decisions about alternate ma- terials, building structural systems and even renovation versus new building. (Case Study No. 4 in this book, Robert Redford Conservancy, includes an example of such an embodied carbon analysis.)
Grid Harmonization
With the shift to all-electric buildings utilizing solar photovoltaic systems, the statewide electric grid will be facing even more of a challenge of where to put all the excess renewable energy generated by these buildings during the middle of the day and how to meet the increased peak power demand created by these buildings on overcast days and in the evening. Referred to as “The Duck Curve Conundrum”, this issue is discussed at length in the Introduction to Zero Net Energy Case Study Buildings, Volume 3.
The solution pathway to this challenge lies primarily with energy storage, which would allow the growing peak demand in the evening to be reduced by shifting the midday excess energy to that time period. It lies as well with incentive structures for load shifting and demand response, which reinforce and enhance this effect. The nature and design of these necessary components of the electric energy system is now under discussion at the state and local levels.