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©2016 This excerpt taken from the article of the same name which appeared in ASHRAE Journal, vol. 58, no. 8, August 2016

Dylan Connelly, P.E., Associate Member ASHRAE; Laura Fedoruk

About the Authors
Dylan Connelly, P.E., is an associate principal and Laura Fedoruk is a project engineer at Integral Group in Oakland, Calif.

DPR Construction’s retrofitted San Francisco headquarters building achieved approximately 20% net positive energy its first year of operation using efficient systems including HVAC, electrical and PV. And, in late 2015, it was certified as a net zero energy building.

The office building demonstrates the capabilities of integrated, innovative, and replicable design. And, it proves that sustainable buildings can reduce energy use and improve indoor environmental conditions, while being cost effective. It has become a hub for learning and collaborating on many sustainably minded design projects.


Building Description

The 20,010 ft2 (1858 m2) includes office space for 50 DPR employees, 20+ subtenant employees, conference rooms, a central atrium, break area, kitchen, and fitness center. With a large training room, and open-concept lobby for holding events, the DPR office is a social space that has been a part of multiple sustainability evenings, conferences, tours, and collaborations. The building has incorporated a publicly accessible building dashboard and a LEED dynamic plaque.



The DPR building team was faced with the challenge of retrofitting a building to net positive energy on a budget, within a tight schedule, and in a building surrounded by adjacent, taller buildings.

The integrated design process included rapid pricing and iterative spreadsheet energy models to do simple paybacks to determine the most cost-effective way to meet the energy target. The key technologies implemented included PV, VRF, roof insulation, tubular skylights, large ceiling fans and electrochromic glass skylights.

The design challenge was to achieve a replicable, net positive energy performance building on a reasonable budget ($200/ft2 [2153 m2]) within a tight schedule in an existing building in a downtown urban setting. The project team first set out to achieve net positive energy performance by reducing building loads to a target EUI, which could reasonably be offset by PV on the roof (24 kBtu/ft2·yr [272.6 MJ/m2·yr]). This firm goal was set and agreed upon by all stakeholders early on and enabled the team to find innovative strategies to overcome challenges while upholding the overall project goal. Being surrounded by other buildings on three sides prevented passive design strategies such as natural ventilation and full daylighting from being options.

Competing needs between roof space for photovoltaic panels and skylights, and the need to upgrade the structure to hold the additional weight of insulation and PV panels, were all challenges for achieving net zero energy design at non-premium construction costs. The project ended its first year with a EUI of 20.4 kBtu/ft2·yr (231.7 MJ/m2·yr), significantly lower than the code baseline of 49 kBtu/ft2·yr (556 MJ/m2·yr) determined using energy analysis software and less than the production on the roof of 24 kBtu/ft2·yr (272.6 MJ/m2·yr).


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