Inside Docking State Office Building: Energy-Smart HVAC

The future, past, and sustainability come together in the historic preservation of the Docking State Office Building for the State of Kansas. Henderson Engineers partnered with PGAV Architects to honor the spirit of the original 1957 Docking State Office Building while designing a sustainable space built to last. Four new stories were built on top of the existing foundation, with many core building materials and features reused after the demolition of 14 original stories.  

Innovation and Sustainability in Civic Spaces 

Revitalizing historic civic buildings requires more than structural ingenuity, it demands a holistic approach to sustainability, performance, and occupant experience. As we continue to revitalize historic civic spaces, building for the future means designing and creating innovative sustainable building systems that deliver efficiency and project value. We developed hydronic and airside mechanical systems for the Docking State Office Building achieving energy performance that exceeds set energy goals. Executed under a competitive design-build process in partnership with Hutton Design+Build and PGAV Architects, Henderson brought to reality building systems and sustainable concepts identified in the bridging design led by project partners Clark Huesemann, Latimer Sommers & Associates, and Introba. 

Smarter Energy Systems for Lasting Impact 

Heating, ventilation, and air conditioning (HVAC) systems are often one of the largest energy users in a building. Two major contributing factors to HVAC system energy consumption are (1) conditioning the building against internal and external loads and (2) conditioning ventilation air. To reduce energy expenditure, the bridging team and construction team designed and executed a building that addresses both factors.  To reduce energy expenditure, the Docking State project utilizes energy efficient building assemblies and glazing systems to reduce overall building load and utilizes an energy-efficient ventilation system, while still providing a 30% increase above the ASHRAE ventilation baseline. 

The newly constructed Docking State Office Building features an atrium with an all-glass facade that provides a stunning visual connection to the Kansas State Capitol. While a three story all-glass space is not typically conducive to an energy efficient building, the atrium at the Docking State Building is the epicenter of energy saving architectural and engineering design.   

In order to reduce the solar load on such a space, electrochromic glazing was installed for the Atrium curtain wall. This glazing system helps provide passive solar heating in the winter and blocks over 90% of unwanted solar heat gain in the summer.  

From an engineering standpoint, the atrium serves as the lungs of the whole building as it is conditioned with 100% outdoor air. The excess outdoor air used to condition the atrium is then captured and used to provide ventilation to the entire office building at a rate 30% higher than is code required. The enhanced ventilation increases cognitive function while decreasing CO2 and VOC levels, improving indoor air quality. Multiple passive pretreatment methods are utilized to condition the outdoor air centrally, which results in significant energy savings. 

Pretreatment and Energy Savings 

The primary design element employed to pretreat the outdoor air for the Docking State Office Building is a thermal labyrinth. Traditionally built outside a building’s footprint below ground using concrete, this project’s thermal labyrinth was instead installed inside the building in an unused area of the basement. It utilizes concrete block and ground mass to exchange sensible heat with the air passing through it. Through heat exchange with the ground and mass walls, it pre-cools summer air and pre-heats winter air. This system cuts the building’s ventilation cooling load by 95% and the heating load by 77%. 

In the winter, transpired solar collectors are employed alone or in conjunction with the thermal labyrinth to preheat the outdoor air for the Docking State Office Building. Transpired solar collectors are perforated metal panels mounted to the exterior of the building.  Solar heat raises the temperature of the metal panel and the air across the panel surface. Outdoor air intakes installed behind the panels pull in the warmed outdoor air providing preheated outdoor air without expending additional energy. Outdoor air collected from the transpired solar collector in the winter feeds into the building’s thermal labyrinth or feeds directly into the air handling unit responsible for conditioning the Atrium.  

Through a complex damper and ductwork system, the building control system can source outdoor air from the labyrinth, transpired solar collector, or directly from the outdoors, to provide the best temperature air for the atrium. Finally, after passing through one or more passive pretreatment methods, all ventilation air flows through the atrium and is collected by another 100% outdoor unit. The ventilation air is then delivered to one side of dual duct boxes. Dual duct boxes distributed throughout the building combine ventilation air and conditioning air to condition all office, conference, and public spaces.  By decoupling ventilation air, fan energy is saved at times when less conditioning is required.  

By utilizing these various systems and design elements, the Docking State Office Building can benefit from significant energy savings and continue to meet their energy goals. 

Meeting Sustainability Objectives 

The design-build request for qualifications (RFQ) established an energy goal of 26kBtu/SF/yr. Our modeled performance outpaces the goal at 25.7 and significantly outperforms the 2003 CBECS architecture 2030 baseline of 134.

Graphic from Docking Building Performance Report

Sustainability isn’t just something we aim for, it’s how we work. Through advanced design and engineering strategies, we’ve helped bring to life a state office building that will serve its community for years to come and be a shining example of how to build sustainable environments. 

Partners to Achieve Your Goals 

We lead regenerative and innovative design to help our clients achieve better energy outcomes, superior performance, and lessen their environmental impact as we all work toward a brighter, clearer future. We’re here for you every step of the way to help you meet your climate and capital goals; from early in the design process with energy modeling and daylighting analysis, to developing an HVAC system that balances comfort, cost, and efficiency, to seeing through the life of the building.