Page 9 - Zero Net Energy Case Study Buildings-Volume 2

INTRODUCTION ZERO NET ENERGY CASE STUDY BUILDINGS, VOL. 2
museum, public library. This volume provides an opportunity to examine the issues associated with building renovations—taking an older building and revamping it entirely to perform at a ZNE level. Four of the five projects in this volume are in fact renovations of existing structures. As such, cost issues were paramount with these projects and it is interesting to compare the cost basis of design decisions in each case.
Focus Issues for the Case Study Buildings of Volume 2
Certain problem issues were identified in the first generation of ZNE buildings, some of which turned out to be common to almost all of the case study buildings discussed in Volume 1. Not surprisingly, these issues were creating barriers to the ready adoption of the ZNE building design approach even for interested and willing owners.
Chief among these early issues was the general inadequacy of the several building control systems to communicate properly in order to optimize the coordinated operation of energy- efficient sub-systems, whether involving windows, shading, HVAC components, lighting or equipment. In the new generation of smart buildings designed to achieve ZNE performance, examples of which are included in Volume 2, a relatively sophisticated sequence of operations is usually employed, one that is highly responsive to varying outdoor conditions such as air temperature, solar intensity and wind conditions, and the indoor occupancy requirements. To accomplish this successfully and reliably, the various control systems need to have common communication protocols and be integrated with an overall master control system.
This understanding of the issue has led to both better control technologies and early engagement with the issue during the design phase of the project. The positive results can be seen in the new generation of ZNE buildings, five of which are documented here in Volume 2.
A second issue that emerged in the first wave of ZNE buildings was the matter of affordability. Once it was demonstrated that ZNE buildings could be realized in the normal built environment with the correct alignment of energy-efficient design and high-productivity renewable energy systems, the next task was to understand the most cost-effective ways of doing this. With the movement in California toward ZNE building code requirements in 2020 (residential) and 2030 (non-residential), and the interest in ZNE building design in general, the affordability of ZNE design features and systems has become a focus of discussion. The case study buildings of this Volume 2 provide a good opportunity to compare both design strategies and financial models for design decision-making.
• Control Systems for Zero Net Energy Buildings
The inadequacy of standard building control systems for the typical level of sophistication of the operation of ZNE buildings has been observed and lamented by many designers. Early ZNE projects were beset by problems of communication between building sub-systems that had different communication protocols built into them. The issue is derived from the lack of a universal communication software for all major building control system applications.
There have been attempts to create such a universal software, but these have devolved into three principal types that are not compatible with each other in integrated building applications: BACnet (a protocol developed by ASHRAE and published in 1995), Modbus (published by Schneider Electric in 1979 and now managed by Modbus Organization) and LonWorks (created by Echelon Corporation and accepted by ANSI in 1999). Manufacturers generally design equipment around one of these communication protocols and sometimes modify the software to improve the operation of their individual product, making integration of systems even more difficult.
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