was 13. 35 kBtu/ft2 (including the
restaurants). The net zero target was
originally established by assessing
the maximum amount of PV energy
that could generated with high efficiency panels installed only on the
roof of Pier 15.
The original goal was to offset all
of the building’s operations with the
exception of the tenant-designed
and operated restaurants, which pay
their own energy bills. The original net zero goal also requires the
Exploratorium to cut plug loads by a
more substantial 50% as described
in Plug Load Performance. Many
of the measures to accomplish this
plug load reduction have not yet
been adopted, but there are specific
phased plans to make this a reality.
Predicted solar production in
Figure 3 is based on typical year
insolation data for San Francisco.
Actual production is reported
from the PV utility meter. Actual
annual production was 3% less
than expected for a typical year.
However, prior data from the first
year showed that based on the number of sunny days the panels should
have produced even more.
In the first year (February 2013
through January 2014), total production was only 86% of that expected
based on rooftop measured insolation
values. According to the installer and
service provider, the PV panels have
produced less than their potential due
to infrequent cleaning and because
the Exploratorium was pressured
by neighbors to turn off a rooftop
loudspeaker system that imitated the
screeching of hawks to prevent marine
birds from nesting on the panels.
The Exploratorium is in the process
of installing fishing line across the
panels to prevent nesting and have
also agreed to increase the frequency
of panel washing from twice annually
to quarterly. Both of these measures
should bring the PV energy output
10% reduction in overall plug loads
compared to the baseline building.
Its restaurants are consuming nearly
twice as much energy as anticipated
in the baseline model.
The systems’ performance
(Figure 2) resulted in an annual
energy use intensity (EUI) of 50.05
kBtu/ft2 (including the restaurants).
This energy use represents an overall energy savings of 40% compared
to the Standard 90.1-2007 baseline.
However, the Exploratorium has not
yet met its original net zero energy
target; its annual net EUI (after PV)
Type Wood framed, exterior rigid
Overall R-value R- 28
Type Metal/wood framed
Overall R-value R- 9 for existing walls,
R- 19 for new construction
Glazing Percentage 42%
Slab Edge Insulation R-value R-10
Effective Under-Slab Insulation R-value
Effective U-factor for Assembly 0.6
Solar Heat Gain Coefficient
Visual Transmittance 0.5
Latitude 37° 48’ 3.08” N
FIGURE 2 ENERGY USE, 2013–2014
Fujiko Nakaya’s “Fog Bridge” stretches
across the 150 ft pedestrian bridge that
spans the water between Piers 15 and 17.
More than 800 high-pressure nozzles lining
the bridge create an immersive environment
that shrouds participants in mist. The installation also illustrates how fog is affected by
minute shifts in the local environment.