Page 74 - Zero Net Energy Case Study Buildings-Volume 3

CASE STUDY NO. 13
LA ESCUELITA EDUCATION CENTER
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Zero Net Energy Case Study Buildings: Volume 3
that the thermal mass provides more radiant cooling effect than estimated during design. (Fans ceased night operation sooner than expected.)
The biggest issue concerns the large heating loads in midwinter that are offset by the conventional boiler plant. As the energy performance charts indicate, these account for 75% of the energy consumed by “The ZNE Group” of buildings and essentially cause it to fall short of ZNE performance. The building is still energy-efficient, as evidenced by its EUI = 29.9, so perhaps the large heating component is the result of the other systems being extraordinarily low by comparison.
There are other possible explanations, however, which the District may investigate. The first is a control system or component malfunction that operates the boiler at a level that is inefficient or wasteful. Another is that the users (students, teachers or maintenance personnel) are operating the controls or spaces incorrectly, generating the use of more heating during the winter months. These causes of use of extra heating energy are correctable.
There may also be a contributing factor of the structure of the building walls, which are basic 2X6 metal stud framing. There is a significant thermal bridging effect in such walls that do not have an added layer of continuous insulation to prevent heat transfer through the metal stud. It is estimated that the R-value of the wall assembly in such cases can be reduced by about 60% from the nominal value of the insulation. The decision to omit the layer of continuous insulation was based on cost, but nevertheless it resulted in a higher expenditure of energy for heating.
Post Occupancy: Occupant Behavior
The efficient operation of the unconventional systems in this project, particularly in the classrooms, requires some understanding of the design features and how they work. This effectively involves two groups of users: the teachers and the maintenance staff. When the building first opened, the maintenance staff received some training in system operations and the features of the controls.
One of the trained staff persons was assigned as liaison with the teachers, explaining the operation and controls as part of a teacher orientation at the start of the school year. However, this person was transferred and the replacement was not trained in the use of building. As a result, the teacher orientation was dropped, then discontinued. The only information available to a teacher is an instruction card posted on the classroom wall.
The result is a tendency for teachers to use the building like conventional one, often making operational errors. For example, as described in the section, Heating, Cooling and Ventilation, when the outside air is cool enough in the Swing Season to provide cooling with just fresh air from the package unit, the large room fan is automatically off. Yet teachers often override the fan’s controls and turn it on, not understanding that it is unnecessary. Similarly, when the outside air is warm and the large room fan is operating at full power (but not disrupting the classroom environment with noise or air “flutter”), teachers often open the classroom door or windows, which automatically shuts off the large room fan. This system behavior is counter-intuitive to the untrained teacher.
Lack of training or orientation to the operation of this building also resulted in observed behaviors such as overriding dimming controls when entering the classroom when light levels are sufficient for visual acuity, simply because the eyes have not immediately adjusted to the light difference with the exterior environment.
The building is currently close to ZNE operation and performance. Re-institution of a thorough orientation program for the teachers and training for the new maintenance staff may help close the gap and bring the building to Zero.