Page 132 - Zero Net Energy Case Study Buildings-Volume 3

CASE STUDY NO. 16
LACCD HARBOR COLLEGE SCIENCE BUILDING
converting units to kWh). Therefore, the energy that must be provided by the campus PV system
is reasonably estimated to be 462,713 kWh, or roughly 463 MW. Using the PV-Watts calcula- tor1 for Long Beach weather data and this annual solar power generation needed to offset the gas use, the size of the solar PV component campus PV system that is required is 318 kW. This compares with the 264 kW system that is installed integral with the Science Building and 2,366 kW for the entire amount of solar PV arrays above the parking areas.
Based on this calculation, the solar PV arrays needed to be “assigned” to the Science Building are 13% of the total system installed above the parking areas, or roughly 120% of the size of the system integral with the building.
In addition, using PV-Watts, the electric energy provided by the PV system integral to the build- ing (264 kW) is approximately 414,000 kWh, which essentially zeroes out the electric energy use of the building. The total energy use for the building is therefore estimated to be 877,000 kWh or 877 MWh. This converts to an estimated EUI of 42.7. Although this is only an estimate based on the data recorded for the net electric energy use and an approximation using PV-Watts, it is a reasonable estimate that compares well with the modeled EUI.
Note that until the measured data for the Central Plant is recorded for one full year and the remaining data is updated accordingly, these calculations can be no more than a “reasonable estimate”. However, the order of magnitude of the portion of campus solar PV system (13%) that is required suggests that it is also reasonable to conclude that the Science Building is indeed achieving ZNE performance and the future recorded data will confirm that.
Post Occupancy: Observations and Conclusions
The Los Angeles Community College District, like many community college systems, set ambi- tious energy performance goals while being bound by required methods of procurement, con- struction contract type (design-build), first-cost price competition and limited M&O (maintenance and operation) budgets. These affected both design decisions and post-occupancy impacts, but the project nevertheless achieved most of the initial goals.
Post Occupancy: Controls and Monitoring
The carefully planned measurement and verification program was not continued into the post- occupancy period. Meters were installed to measure energy use in each relevant subsystem of the building but the BAS system failed to record the data properly. The District M&O staff did not detect this and a routine program of data verification had not been established. As noted above, nothing was installed at the Central Plant that would allow a separate measurement of energy used to provide heating and cooling for the Science Building.
Both of these situations have been corrected partly as a result of the inquiry for this case study publication and going forward the District plans regular data recording of all relevant system energy use.
Post Occupancy: Natural Ventilation
The compromise made during the design phase by changing the system from automatic control and operation to one of only occupant control has led to likely imperfect system operation. How- ever, this has not been studied in a post-occupancy evaluation and no data has been available to do so.
Post Occupancy: Occupant Behavior
The basic design decision to eliminate corridors and similar connecting circulation spaces was posited on the assumption that energy use in those conditioned spaces would also be elimi- nated. Teaching staff reports, however, that they frequently find the doors to classrooms ajar so that conditioned air escapes directly to the outside. Maintenance staff are charged with ensuring proper operation of the doors and windows, but staff often are not viewing the central monitoring system.
The building requires some occupant involvement in the proper operation of systems and features. There were faculty complaints that some of the staff missed the training sessions that were set up to explain these aspects. As a result, knowledge of these user-controlled and user- impacted systems was not transferred to some of the occupants, so it is reported that there has been some confusion and lack of buy-in by the staff.
12 http://pvwatts.nrel.gov/
2
(Opposite Page) A class meets on the roof deck space to discuss the details of the solar PV system as part of the regular curriculum.
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Zero Net Energy Case Study Buildings: Volume 3