DPR Construction, a national commercial contractor, has developed four of their own offices as net-zero energy (NZE) properties since 2010. These include two new offices in San Diego and Phoenix, a deep energy retrofit in San Francisco, and most recently a deep energy retrofit of their Reston, Va., office. The Reston building posed a unique challenge for the company—a different climate than anything they had attempted before. Humidity concerns required DPR’s design team to rethink what they had learned to date and emphasized the importance of an engaged commissioning agent.
Through design-phase data-driven decision making, a selection of the mechanical system was made. The team wanted a system that could maintain thermal comfort consistently throughout the office as well as be efficient in the mid-Atlantic climate. Four different systems were proposed as possibilities and further analyzed for energy use intensity, cost, temperature, and humidity control and flexibility. The selected four-pipe system features a high-efficiency heat recovery chiller, cooling tower and a dedicated outdoor air system (DOAS).
Though meant for a larger space, and slightly more expensive, “the system is an example of what DPR thinks the future of mechanical systems will be, more efficient AND yielding healthier air,” said Chris Hoffman, DPR’s NZE renovation project manager. “It’s also really important that the commissioning agent is on board early because they understand what systems work and how they work,” Hoffman added.
In operations, data continues to drive management of the facility. Data is generated and monitored through a Honeywell controls system and Senseware sensors that measure energy usage from each of the components individually, as well as other energy users in the office such as lighting and plug loads and provides real-time analysis and monitoring. DPR developed a case study that chronicles their project including details about chosen technologies for their “living laboratory” such as the passive daylighting, LED lighting, Energy Star equipment, occupant plug load management, solar hot water heating, rooftop photovoltaic systems, and the controls that integrate everything.