Page 12 - Zero Net Energy Case Study Buildings-Volume 2

ZERO NET ENERGY CASE STUDY BUILDINGS, VOL. 2 INTRODUCTION
proprietary system; all three experienced good operational results. (See Case Study Nos. 7, 8 and 9.) The remaining two case study buildings, without the inclusion of a master control system, experienced operational difficulties in one case (Case Study No. 10) and data access and collection issues in both cases (Case Study Nos. 10 and 11).
A side benefit of integrating the control system communications is that the system can also be programmed to provide ready access to recorded data, including information beyond simple energy use data. With the proper energy metering setup, energy performance monitoring is simply done and typically accessible via an online dashboard. There are obvious advantages in having this information with regard to improved energy efficiency of operations during occupancy and communication of performance successes to the building occupants.
The case study buildings documented in Volume 2 have benefited from the advance in control system technologies and point the way for future projects with respect to essential ZNE building sub-systems and design strategies.
• Financial Models for Decision-Making in the Design of Zero Net Energy Buildings
With few exceptions, every project has cost constraints that drive decision-making in the design of new buildings or renovations. A ZNE building is generally assumed to have a higher initial cost—after all, an entire renewable energy system is usually installed—which is offset over time with the large savings in energy cost. The questions often asked are about how much higher the construction budget must be compared to a “standard” building and how much time before this extra investment is paid back.
Both the questions and the answers are actually more nuanced than this. On the question side, for example, the construction budget is derived from many aspects of the building’s makeup and a prioritization of expenditure could affect the allocation toward ZNE as a base item. Or some features may have energy-efficiency implications as well as other types of design benefits for the occupants, such as daylighting elements—how would this cost be allocated in a financial analysis for determining ZNE “feasibility” if there are parallel benefits. As another example of the complexity of the question, it has also been shown that a strong passive design approach to a building results in such smaller climate control equipment, that the result is actually a much less expensive HVAC plant for a ZNE building employing those strategies.
On the answer side, the “right” financial analysis process may not be clear. Aside from the discussion among financial analysts about the appropriate metric to use for life cycle cost analysis or LCCA (payback period, return on investment or ROI, and others) as well as interest rate and energy cost inflation rate, the client needs to consider the types of “investment” in a ZNE building project appropriate to its situation. For a client that is not holding the building for any length of time, these metrics will be different than for a client that has a specified time period (say a lease period) or for a client that will own the building for long, undetermined period of time. The criteria for design decisions will be quite different in each case.
The case studies documented in Volume 2 each elaborate on this issue of cost constraints and the financial criteria used for design decisions. The differences in each case are clear and demonstrate the complexity of the issue. Case Study No. 10, the West Berkeley Branch Library, is an example of a public project with a fixed budget, which required all ZNE design features to be treated like every other aspect of the project. In such public projects, there is typically no mechanism of providing additional funds that can be “paid back” from future cost savings due to the ZNE features.
In Case Study No. 7, the DPR Construction Office Building, the client chose its 10-year lease as the restriction controlling the payback period for any ZNE design feature installed as part of the tenant improvements in this renovation project. The most interesting example, however, is Case Study No. 9, the Speculative Office Building at 435 Indio Way, which was subject to a meticulous financial investment model that proved that the ZNE building design would actually be more profitable as an investment than a standard building design. The financial argument is sufficiently compelling that it is included as a separate sidebar discussion of the topic.
Ultimately, when ZNE building design is the standard and required for all new buildings, the financial analysis of alternative design features and strategies will also become standard and similar to the process used today by project designers to meet project budgets and provide the best product for their clients.
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Zero Net Energy Case Study Buildings: Volume 2