Page 141 - Zero Net Energy Case Study Buildings-Volume 2

The Exploratorium recognizes that the controls and monitoring systems need an integrative overhaul and must include the data monitoring system so that energy use trending can be readily observed and tracked in all pertinent categories. Once this is completed, a truly informative en- ergy dashboard for public education purposes can be programmed to provide the real-time en- vironmental story of the facility itself. It is the latter opportunity that motivates the Exploratorium to make this systems overhaul a high priority now that the move-in period is coming to an end.
Post Occupancy: HVAC and Commissioning
As noted, the complexity and uniqueness of the HVAC system posed challenges during the early post-occupancy period, which were met during the commissioning period. Some of these chal- lenges were of the standard type, others were not.
An example of the unexpected challenge is the initial failure of the vertical turbine pumps used to pump the seawater from San Francisco Bay up to the heat exchange equipment at pier deck level. These industrial-grade inline pumps were placed at the top of the vertical tubes that extend below the pier into the water. Similar to the design at the Seattle Aquarium, this type of instal- lation allows ready access to the pumps for maintenance above the water. In the case of the Exploratorium plant, however, the turbine bearings burned out immediately on start-up. This has been attributed to the length of tube segments required at this installation and the unfortunate resonance of these segments with the pump motor vibration. This amplified the vibrating motion and, combined with the unexpectedly corrosive conditions of the relatively still water in the Bay, caused the bearings to fail.
The design was changed to submersible pumps located at the bottom of the vertical tubes. The submersible pumps are standard equipment and can be serviced by the Exploratorium staff us- ing a winch system to allow for monthly maintenance and inspection. The industrial-grade vertical turbine pumps required outside specialists for maintenance. The final solution is actually more suitable to the Exploratorium’s general “hands-on” approach to design and problem-solving.
Beyond the start-up and commissioning issues, both small and large, the operation of the uncon- ventional HVAC system has been relatively trouble-free.
Post Occupancy: Lighting
The very low level of ambient lighting as designed to supplement the exhibit lighting, namely 0.5 watts per sq. ft., is working well and has contributed to the low overall lighting energy use. The building staff would prefer a more robust lighting control system, however, that has more flex- ibility in the time controls and could respond to daylight conditions.
Post Occupancy: Occupant Behavior
One noticeable (but predictable) occupant response to a ZNE design feature occurred at the staff office space, which is set on a second level within the high volume of the building. This location raised the office area close to the roof monitor, where direct sunlight can penetrate and create a severe glare problem at computers and general work surfaces.
In general, however, the Exploratorium staff are very conscious of the ZNE performance goal for the building and have responded accordingly. Since the performance over the 2014-2015 settling-in period has fallen short of this goal, though improving over time, the staff are focusing more on behaviors and system adjustments to bring the building to that level of performance.
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THE EXPLORATORIUM
CASE STUDY NO. 11
PHOTO: BRUCE DAMONTE