Page 12 - Zero Net Energy Case Study Buildings-Volume 3

ZERO NET ENERGY CASE STUDY BUILDINGS, VOL. 3 INTRODUCTION
perhaps more economically, on the part of the individual building owner. As can be seen in the conceptual chart on the facing page, energy can be stored in the middle of the day and then accessed in the evening to eliminate the problem areas of the demand curve and synchronize the utilities’ power plant operations with the solar PV component provided largely by all building owners in the state.
The exact nature and design of this necessary component of the electric energy system is now being debated and discussed. Should energy storage be mandated as an integral part of the renewable energy supply system in buildings, when such systems become required by code? Should this storage be accessible for use by the public utility providing the backup energy for the ZNE building in the same way that excess solar energy is harvested from the building?
The prototype case study buildings in this Volume 3 begin to offer answers to these questions and related larger issues posed by the large-scale development of ZNE buildings.
Roadmaps and Mandates for ZNE Buildings - Update
In the two years since Volume 2 was published (2016) there has been a continuing develop- ment in the various roadmaps to statewide adoption of mandated goals for ZNE, as well as the recent (2018) mandate by the California Energy Commission (CEC) to require by code in 2020 (as planned for many years) the installation of enough solar PV on new low-rise residential construction so that such dwellings are capable of performing at ZNE. (These actions, and the unexpected affordability of solar PV systems, have accelerated the phenomenon of the Duck Curve, described in the section above.)
As noted in the Preface, since the publication of Volume 2, the California Public Utilities Com- mission (CPUC) has released the Commercial Buildings ZNE Action Plan, aiming at 2030 for its adoption just as the CEC has recently enacted for 2020 the Residential ZNE Action Plan for low-rise buildings. Given the time required for building projects from design through occupancy, the opportunity of the shared experiences rendered by these case studies of ZNE buildings is vital.
Smart Building Technologies - Update
There has also been a continuing improvement in the past two years in building technologies available for adapting ZNE design strategies more seamlessly. Volume 2 revealed the preva- lence of a common problem affecting the performance of ZNE buildings: the sub-optimal—even dysfunctional—operation caused by the absence of the proper integration of control systems in these “smart” buildings. (See Introduction and Observations in Volume 2.) While still an issue, there has been improvement due in part to various studies4 and actions by the control systems industry.
Related to this, the proper collection of performance data from installed metering systems con- tinues to be a challenge. While not essential to ZNE building design, these systems provide verification of the effectiveness of various design strategies and the ability to troubleshoot any irregular performance.
The case study buildings of this Volume 3 show advances with both issues, but still with the possibility of improvement.
4 Zero Net Energy Building Controls—Characteristics, Energy Impacts and Lessons, New Buildings Institute (NBI), Research Report for Continental Automated Buildings Association (CABA), 2015.
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Zero Net Energy Case Study Buildings: Volume 3