An Efficiency Leader In the San Francisco Bay Area

Delta Electronics is the Taiwan-based company you may never have heard of, but whose products are all around you.  Founded by Bruce C.H. Cheng, Delta has excelled in the fields of electric power switching, solar photovoltaic inversion, uninterruptible power supply, industrial automation, EV charging, LED lighting, medical devices, telecom networking, graphic displays, image projection, and many more.

CaliforniaGeo is bringing you this feature not only because it may be the most outstanding commercial building, utilizing a marriage between earth and sky (geothermal heat pumps and solar photovoltaics) but because it incorporates many applicable Delta-manufactured products inside this LEED Platinum-rated facility.

Dedicated in October, 2015, the 175,000 square foot Delta Americas building is located at the eastern edge of the San Francisco Bay’s Silicon Valley in Fremont, California.  It serves as Delta Americas Headquarters, providing office space, display and demonstration facilities, and warehousing for product distribution.

We were fortunate to visit Delta Americas in April of 2018, as three of our Association’s members were part of the geothermal system’s ground loop heat exchanger (GHEX).  Our board member Terry Proffer of Major Geothermal designed the GHEX that was horizontally bored and placed by Eric Hanson of Precision Directional Boring, with looping and headers to the mechanical room by Gerard Maloney of EarthHeat.  Underground conducting pipe at an average 22-foot depth (under the building and some of it’s parking lots) totals just over 12 miles in length and serves the building’s 580 tons of dominant cooling load.

This building is currently rated as LEED Platinum but is headed for carbonless Zero Net Energy when its current 616 KW of solar PV is joined by another 400 KW, suspended in carport configuration over current parking.  There are no cooling towers or fossil-fired equipment on the site. 

While the EUI (Energy Utilization Index) of the average LEED Building exceeds 50,000 BTU per square foot per year, Delta’s comes in at 70% less (only 15,500).  This is a ratio that can only improve when the future solar addition is completed.  Beneficial electrification is definitely at play here, and there is no friendlier partner to the electric utility company (Pacific Gas & Electric) than Delta Americas.

Employees enjoy a pleasant and comfortable working environment via advanced climate controls, lots of natural lighting, and generous fresh air.  Their conditioned space performs well, even in this region’s 114° heat during the summer of 2017.  This workforce can “boost their green footprint” at work by tapping one of Delta’s own EV charging stations located about the building.  On the day we visited, there were both full electric and electric plug-in hybrid cars attached for a charge, helping to reduce California’s dreaded “duck curve” (a renewable electricity challenge to the grid).

 How the system works

Delta Americas uses a combination of solar electricity and a circulating closed water loop heat exchanger (from underground) to serve several large (chiller style) heat pumps that produce warm and cool water loops that circulate throughout the building.  All occupied zones in the building are controlled by thermostats.  These will adjust air temperature by using fan coils and ductwork that convert those fluid loops into distributed air flow, warming or cooling the interior.

Thermal energy in the underground, geothermal heat exchanger (GHEX) allows the heat pumps to perform their “miracle” of concentrating and transferring heat in either of two directions—adding or subtracting heat from the inside of this building.  Heat transfer through the walls of GHEX piping that connects to the earth by conduction is what gives the heat pumps access to a heat source or heat sink, depending on whether energy needs to be imported or rejected.  This might be the least technical portion of the system, but it is the most beautiful.  It’s heat transfer that’s renewable, sustainable, and serves as a  permanent, on-site resource (without fossil combustion emissions).

Large buildings of this kind always require more cooling than heating (even in the Canadian far north of Edmonton, Alberta).  Therefore, especially in the mild climate of the Bay Area, the Delta Americas building is most often sending rejected heat underground for dissipation (after capturing some of it for hot water).  Consider the chilled water storage tanks on-site, and you can grasp that this building can make its cool water at night when off-peak power is cheaper.  Therefore, its solar collectors can send more exported electricity to the grid in daytime for a greater offset to its utility bill.

Geo heat pump systems like Delta’s face a significant up-front expense represented by the GHEX’s 12 miles of underground pipe, but that expense is recaptured by significant reduction in operating expense over time for a technology that will far outlive any alternative.  Since Delta has long been committed to efficiency in their products and their thinking, it was an obvious choice that their 21st green-rated building would incorporate a mix of state-of-the-art solar and geothermal heat pump renewables.