Page 71 - Zero Net Energy Case Study Buildings-Volume 1

IDeAs OFFICE BUILDING
comfortable space temperature would be reached at that time. On colder winter days, the time required would often mean that the radiant floor system would operate through the night. The net result as observed in the metered data was that the fresh air ventilation fan was providing outside air when there were no occupants in the building.
The immediate solution to this was to disconnect the ventilation fan operation from the radiant floor system operation and to use a time clock to schedule the fan operation. While this improved the energy efficiency of the operation, the best solution is to connect the ventilation fan to CO2 sensors in the occupied spaces; when the threshold CO2 level is detected, the fan will turn on and operate to provide the required amount of fresh air. Below this threshold, the fan will not operate. This approach is being planned for installation.
Post-Occupancy: Lighting
Metering data analysis revealed that the emergency lighting system battery ballasts were con- tinuously using a large amount of power, which amounted to an unexpected phantom load (that is, an energy use by equipment in standby operation even though the equipment is apparently not operating). The IDeAs staff is currently investigating possible alternative emergency lighting technology that is not characterized by such a high phantom load.
Post-Occupancy: Plug Load
The IT system for the building, considered part of the plug load for the building and by far the largest component of that category of energy load, originally included six servers located in the separate server room. (The design for the cooling of the server room is discussed in the system design section above.) After the building was occupied, VMware was installed on two of the servers and as a result four of the servers could be removed. This reduction to one-third of the number of server machines greatly reduced the total plug load.
In the future, as systems move to cloud servers, there would no longer be a need for on-site serv- ers and the server room. This is expected to have a significant impact on the reduction of plug load demand for individual buildings at the site boundary, although the load is effectively shifted to the off-site server facility. However, the intrinsic efficiencies of an off-site server facility will still make this an overall better option.
Network printers were originally planned to be continuously operational in a stand-by condition with a manual shut-off. In reviewing the metered data, the staff realized that the printers were not being turned off at close of business. The building controls were therefore modified so that the printer circuits would be turned off when the security alarm was set.
As part of the smart operation of the office computers, local occupancy sensors and sleep mode software put the workstation computer into a low energy demand mode in order to minimize phantom plug loads in the building. When the building is not occupied, the computers remain in sleep mode rather than being turned off so that system updates can be installed at night and also to provide off-site access to staff.
Post-Occupancy: General
This building is one of the earliest successful ZNE projects and provided much valuable experi- ence for the architects and engineers involved. As of this date (2014), the building has been in operation for seven years and has been a good proving facility for the design engineers, who still occupy the building as their own office. As an early adoption, the facility is a good illustration of the application of advanced design ideas using the technologies available at the time. It has contributed to the collective advancement of the understanding of the best approaches to ZNE design in general.
CASE STUDY NO. 3
Zero Net Energy Case Study Buildings: Volume 1
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