Page 39 - Zero Net Energy Case Study Buildings-Volume 1

PACKARD FOUNDATION HEADQUARTERS BUILDING
only in summer and is not needed during the swing seasons or winter.
Post-Occupancy: Natural Ventilation
Over the course of 2013, the building users used the natural ventilation features as planned and it was discovered that the occupants availed themselves of outdoor air even when it was at relatively high temperatures. The system initially signaled the occupants using the monitor alert system described above to close windows when the outdoor air temperature exceeded 65°F, admittedly a conservative setpoint. As the occupants experienced the system over time, the building engineer adjusted this setpoint to higher temperatures. There are now days when the outside air temperature is 70°-75°F and the office spaces are fully naturally ventilated and the mechanical cooling system is turned off.
Post-Occupancy: Lighting
Initially, there was a post-occupancy commissioning issue with the daylight sensors. The light fix- tures in the office spaces were dimming up and down over short periods, creating an annoyance to users. The cause was the direction of the daylight-detecting photocells associated with the light fixtures, which were incorrectly aimed at wall surfaces that brighten when lights were turned on and darken again when lights are turned off. The cycling of the lights resulted from this cycling change in wall brightness. By aiming the photocells where only daylight would be perceived, the cycling of the lights was eliminated.
The design engineer found that the instructions for directing the photocells were not included in the shop drawings for installation. A contributing factor was the change in third-party pre- occupancy commissioning agent for the lighting in the middle of the process and a failure to communicate the issue properly.
Post-Occupancy: Energy Metering Systems
After the first three months of operation, the metering system installed in the Packard building was found to be missing data. For energy use, there is an overall energy use meter and sub- metering for each circuit at the panel boards. PG&E’s meter at the point of service entry is very accurate and it was known that the individual metering of the solar photovoltaic panels was also accurate. The difference between the two should have equaled the total recorded by the building circuit meters. However, about 5% of the data appeared to be missing.
The issue was determined to be incorrect sizing of the current transformers (CT), which were too large for a building with such low electric loads. Replacing the CT’s allowed the meters to detect all of the lower levels of current and the readings were confirmed to be correct. As a result, however, several months of performance data had to be abandoned. With the end of 2013, the building was able to confirm one year of good energy data for reporting.
Post-Occupancy: Plug Load
At the time of move-in, the Packard Foundation IT staff introduced virtual server software (VM- Ware®) to the building network, which reduced the number of servers required for the system. This in turn made the pre-purchased UPS system oversized for the actual server load. The IT staff noted that about 1/3 of the capacity of the UPS was not being utilized, though the equip- ment had to be fully charged. As an example of creative load reduction, the IT staff tapped into the available unused power for use with audio-visual equipment. Load reduction can be fixing a wasteful problem, but it can also be squeezing more energy out of a system in creative ways.
Post-Occupancy: General
Measurement and reporting of energy use is essential to tune the building’s operation and to reduce energy use. This metering and reporting delivers a large amount of data that needs to be processed by the client’s building management staff. Well-conceived building management soft- ware similar to that developed specifically for this project will make this task significantly easier and lead to more efficient operation of ZNE buildings. This particularly successful aspect is one of several that are helping to shape the state-of-the-art of ZNE buildings.
CASE STUDY NO. 1
Zero Net Energy Case Study Buildings: Volume 1
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