Page 115 - Zero Net Energy Case Study Buildings-Volume 1

SCIENCE & ENGINEERING BUILDING I
software issues, but since the migration of the lighting control programs to the Web this has be- come easier to coordinate for the facilities staff.
It should be noted that building design specifications for lighting controls only describe features required for these systems and necessarily do not deal with optimal operation strategies. This is the task of the building owner and operator, which should be undertaken as part of the overall commissioning process. For UC Merced, this is an evolving task, the results of which are show- ing continued progress in energy use reduction.
Setting the lights to be turned on and off according to a strict schedule, as valuable as that is for energy reduction, is only half of the story of opportunities for lower energy use by reducing light- ing load. UC Merced staff realized that by such non-interactive scheduling, people are removed from the possibility of controlling the lights to match their actual needs and use patterns. The result is that there is a sizable amount of time when lights are turned on in unoccupied spaces.
The staff therefore worked to involve the laboratory users to set a controls program that suited their needs rather than set up something that they would constantly override and cause the user- involved program to become counter-productive. Combined with infra-red and motion-detection occupancy sensors, UC Merced staff are evolving a highly efficient lighting controls program.
The lighting control logic that was established for the building starts with lighting control zones that are based on general room use or, in the case of individual rooms, occupant’s request. Each lighting zone is part of a “scheduling area”, which includes the HVAC equipment components related to the same space or room. In this way, the lighting and HVAC are linked by the control system and operate together to serve the space.
There are three possible lighting operations for interior spaces set by the control system:
1. Lighting is strictly scheduled on and off. This is a basic approach in public spaces such as hallways and lobbies. Local manual switches are overridden to be inactive during the scheduled occupied period.
2. Lighting is scheduled occupied, but not turned on. The lights only turn on if someone enters the zone and uses a manual light switch. The lights then remain on until the end of the scheduled period, when all lights turn off. This is a typical operation in private zones such as laboratories where users have complete control of the lights. Manual light switches can also override the unoccupied schedule for one-hour increments; the link to the HVAC system signals a ramp-up of space conditioning for the override period.
3. Lighting is scheduled to turn on at sunset and off when the schedule expires. This type of schedule is used in zones at the building perimeter with a large amount of daylight. Manual light switches can override the schedule for one-hour increments.
Exterior lighting is set to operate on a sunset-to-sunrise schedule. The time at which each of these events occurs is updated daily.
New Methods of Lighting Control and Efficiency of Use
While this scheduling logic for lighting control has been very effective in lowering electrical en- ergy use, UC Merced staff are exploring some additional methods to shave lighting energy use even further.
The staff continue to work closely with building users to establish both lighting and connected HVAC schedules that support rather than potentially inhibit transparent environmental system operation. Regular meetings with the users lead to a schedule that has user buy-in. If ongoing experiments have specific requirements for airflow, these can be programmed into the schedule also.
The staff are also evaluating use of “smart” occupancy sensors that are connected to the campus BMS and result in the system’s “learning” of occupancy patterns that can then be more closely built into the schedule.
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