A Case Study of the Conrad N. Hilton Foundation Headquarters - Deep Data for Uncharted Territory
As the quest for viable zero-net-energy buildings expands, advanced natural ventilation and other advanced HVAC design techniques are becoming more and more prevalent. The headquarters of the Conrad N. Hilton Foundation in Agoura Hills, CA, is at the leading edge of this quest for zero, leveraging a novel design that incorporates solar photovoltaic and thermal energy systems, hot water thermal storage, buoyancy-driven fanless heating ventilation and air conditioning system and cooling, automatic exterior shades, and advanced lighting controls.
Among the most prominent components of the building design is the buoyancy-driven ventilation system (pictured). Air is supplied to the spaces using “chimneys” that are capped by a cooling coil with air intake louvers at the top perimeter of the building. The cold air in the shaft is intended to drive ventilation, heating, and cooling of the space.
Given the complexity of the building and reliance on fanless ventilation systems it became evident that the typical new construction commissioning process alone would not deliver a truly optimized building. Therefore, at the project’s initial inception, a detailed trending and analytics platform – SkySpark by SkyFoundry – was employed to assist in commissioning and to serve as an on-going data management platform for the building automation system and energy metering.
The key to achieving performance for this advanced design relies in the functionality of the building automation controls system. During the design and construction phases, detailed controls coordination meetings were conducted with all of the key stakeholders – engineer, controls contractor, mechanical contractor, owner, commissioning agent, and general contractor – to work to define optimized and implementable sequences backed up with all of the necessary hardware and sensors.
However, even with this deep investment in planning and hardware for the controls and metering system, it became clear shortly after building occupancy that enhancements to control sequences were needed to ensure the buoyancy system was operating at peak performance. Throughout the first year of occupancy, many incremental and reactive changes were made in an attempt to address issues with comfort and ventilation controls, resulting in a building that wasn’t meeting the full design potential.
To remedy performance issues, a data-driven re-commissioning effort was launched. This effort was underpinned with the data from SkySpark, which served as the “flight data recorder” for all building systems during all of the seasons and changes during the first year of operations. Using this data, the team was able to quickly analyze the correlation of ventilation and comfort performance to various conditions. Combined with detailed analytics on thousands of trend points, the project team was able to systematically identify, analyze, and implement changes to the system to improve performance, while getting real time feedback on the systems response to verify the outcomes.
Most building performance issues are not caused by one or two big problems, but rather the culmination of many small items that lead to significant problems in terms of both occupant comfort and energy performance. To efficiently and effectively address performance throughout the entire facility, the Hilton Foundation Headquarters project sought a comprehensive solution. Fortunately, the big data platforms installed and commissioned during construction, along with diligent field work, provided the answers.
Some of the key issues the project team uncovered and fixed include:
Unlocking the Cooling Systems
Diving into the data, the chiller was identified as a source of trouble. It was found that the chilled water valves at the water coils were not appropriately enabled before occupancy, causing the chiller to trip on low load. This was corrected and the pre-cool sequence functioned as intended.
The project team also observed that the shafts were unable to control their temperature until the “occupied period” started. A deep dive into the data revealed that the relief dampers on the building did not operate until occupancy, hence the building - even with intake dampers opened - was airlocked and unable to cool until the relief dampers were opened. Programming was corrected to operate relief dampers in all cooling modes and the pre-cooling cycle of the building began to work as intended.
Reversing the Flow
Early in the project, it was observed that the buoyancy system would sometimes reverse, and warm air from the building would flow out of the intakes instead of through the space, resulting in cold air pooling in through the middle of the building.
The data showed that shutting off coils that were intended to temper the air eliminated the conditions that caused the flow reversal. Updated sequences allowed these coils to be re-enabled after a time delay, and analytics proved that the flow reversal condition did not reoccur by monitoring key parameters.
Importance of a Blended Forensic and Data-Driven Approach
The data systems were the cornerstone of making the Hilton Foundation Headquarters building work, but many of these issues could not be identified or corrected without physical testing guided by the data results. Understanding multiple systems, how they interact, and how they trend over time, while validating data points and what they really mean, is critical to the troubleshooting complex and high performance buildings. In other words, technology can enable performance improvements, but will never substitute for the imperative that building operators need to be actively engaged in their facilities.
Progressing Toward Zero-Net Energy Goals
As a result of this ongoing process, the Hilton Foundation Headquarters building is living up to its advanced design potential, delivering excellent occupant comfort and indoor environmental quality, and nearly achieving true zero-net-energy status. Data systems that provided the Foundation for achievement are continuing to play a key role in the on-going quest for zero, both for the Foundation and for many projects to come.
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There are many different opinions on the definition of a smart, intelligent, connected, high-performance building. Energy conservation, operational efficiency and occupant experience are the three fundamental pillars of a smart building. While some take the path of first exploring the technology options, others find greater value in studying completed projects that have incorporated the technology. Case studies provide the opportunity to review the technology decisions as well as the organizational issues and planning processes involved in creating a next generation project. This webinar will present the most successful and notable smart building projects in the world. Project leaders will share their vision, successes and challenges!