Ben Franklin Elementary School
The primary and fundamental goal of the design team was to create
synergies among consultants, ensuring that all elements of the
building would work together to respond to seasonal changes in
weather and occupancy. Implementing the concepts of year-round
natural ventilation, daylighting, and eliminating mechanical comfort
cooling required close coordination of all disciplines.
Using the concepts of thermal buoyancy and pressure differentials,
thermal chimneys create a stack effect in the building, drawing
fresh air through low-level perimeter windows and louvers and
venting it at high level. Extensive computational analysis was
performed to perfect the geometry of openings through each classroom.
Whole-building natural-ventilation design techniques, affecting
building orientation, windows, shading, construction materials,
daylighting, and ventilation openings, were employed to allow
for passive cooling throughout the building during occupied seasons.
In heating mode, the air passes over fin-tube water heating elements
located at the perimeter louvers before it is introduced into
the classroom spaces.
Occupancy sensors and automatic dimming controls were installed
on light fixtures in all classrooms. Daylighting models of the
classrooms, activity areas, library, gym, and commons were analyzed
to ensure that the spaces would meet optimal design criteria and
achieve a 2% outside illumination baseline. Automatic dimming
controls adjust light levels in the classrooms to maximize the
energy efficiency benefit of the daylighting. Daylight harvesting
is expected to reduce lighting energy usage by 25% in these areas.
Mechanical systems were designed to avoid unnecessary redundancy.
Instead of "doubling up" on equipment to ensure complete
backups or relying on large safety factors the design team used
the ASHRAE design criteria for the heating systems. Each condensing
boiler was sized for 60% of the total capacity rather than 100%.