California Academy of Sciences - HVAC

Location: San Francisco, CA

Date: September 2008

The new headquarters for the California Academy of Sciences, located in Golden Gate Park, are unlike anything ever built before. With the goal of earning a rare Platinum LEED rating in mind, the new CA Academy of Sciences is designed to take environmental awareness to a whole new level.


The California Academy of Sciences sought to utilize an existing auditorium space to house the Extreme Mammals exhibit. Many of the exhibit items were open to the room environment around them, triggering requirements for tight temperature control of 69°F +/- 1°F, and humidity control of between 40-50% relative humidity.


Our design approach for achieving dehumidification within the space was to supply an increased number of room air changes with dry over-cooled air from the air handler, and offset the room’s latent loads.

In order to do this, colder than usual supply temperatures were needed to be achieved off of the cooling coil of the air handler. A new 8-row cooling coil was installed in the air handler to work in conjunction with a new dedicated glycol chiller to achieve off the coil air temperatures as low as 42°F. At temperatures this low, much of the moisture in the air was removed as condensation on the cooling coil, and a drier supply air condition was achieved.

Measures were taken to prevent overcooling of the auditorium with the installation of a new heating coil located downstream of the air handler, and new reheat coils in each of the auditoriums VAV boxes.

Additionally, the supply plenum of the air handler was retrofitted with an atomizing mist humidification system that prevented the auditorium from ever experiencing conditions that were too dry.

Finally a new control scheme with PID loop control was implemented to modulate both the discharge coil temperature and the air volume supplied to the auditorium in order to keep the room within spec. Optimization of these two control parameters, along with supplemental humidification when necessary allowed the auditorium to be maintained within design spec throughout the 5-month span of the exhibit.


Architect: Renzo Piano Building Workshop/Chong Partners
General Contractor: Webcor Builders
Mechanical Engineer: Ove Arup
Mechanical Contractor: ACCO Engineered Systems

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