Sacramento Municipal Utility District (SMUD) Customer Service Center

Portions of the building not covered by the underfloor air system are cooled by a Large Temperature Differential (LTD) chilled water storage system coupled to a continually resettable VAV system.  The TES system operates with a 30°F chilled water temperature differential, which reduced the TES tank size by 50% compared to “normal” 15°F temperature differential systems.

These VAV systems serve large areas of the facility with widely varying loads.  On top of the typical VAV system design issues, Mr. David Freeman, CEO of SMUD at the time of the project, wanted operable windows integrated into the design wherever possible.

We were initially very reluctant to incorporate operable windows into the HVAC system, but Mr. Freeman can be very persuasive, thus design strategies were incorporated that would shut off the mechanical cooling system to the spaces served by a zone terminal that had a window opened up.  When the window was closed, mechanical cooling would then be re-admitted to the space.  

In this manner, we were able to meet the needs of the client, minimize energy losses through the open windows, thus preserving the over 80% margin to Title 24 required for this project to meet its objectives.

Low Termperature Air | Mixed Mode Ventilation | Thermal Energy Storage | Underfloor