Exposed chilled sails for an architectual application. Photo courtesy of Price Industries

A USGBC LEED Silver designation for the building was targeted from the outset of the design process, with the design team specifying a cutting-edge hybrid HVAC system that incorporates both underfloor air distribution and chilled sails—the first of its kind in a U.S. college. Close collaboration between the design team, mechanical contractors, and the manufacturer was key to achieving core objectives of an HVAC system that would reduce operating costs, provide maximum comfort for students, and afford future flexibility as the utilization of the space evolved—all within a new building that fit with the historic feel of the 153-year-old campus.

A hybrid underfloor air distribution and chilled sail solution was specified. Architectural firm Meyer, Scherer & Rockcastle, Ltd, (MS&R) and mechanical engineering firm Karges-Faulconbridge, Inc. (KFI) had successful experiences with underfloor air distribution systems in the past, and were intrigued by the additional benefits of incorporating chilled sails into a hybrid solution.

The underfloor component of the hybrid system ventilates the building with fresh air, while the chilled sail component delivers radiant heating and cooling to classrooms, offices, and the auditorium. Underfloor air distribution is renowned for the flexibility it brings to evolving spaces, as it uses an easily reconfigured raised floor tile system and underfloor air plenum. The underfloor displacement diffusers deliver high indoor air quality, as air in the space is thermally stratified and contaminants move up and out of the breathing zone, rather than being recirculated. Chilled sails, which provide both a radiant and convective component, use water to efficiently condition the space. Convection currents are created when warm air is cooled as it passes over the surface of the sail. This cooled air then naturally falls into the occupied zone, forcing warm air to rise.

The underfloor component of the hybrid system ventilates the building with fresh air, while the chilled sail component delivers radiant heating and cooling to the Liberal Arts Building at Upper Iowa University. Photo courtesy of Price Industries

Chilled sails rely on the underfloor air distribution system to provide fresh air for ventilation, which greatly reduces the supply air volume requirement and makes the system extremely energy efficient. Due to their aesthetically pleasing appearance, chilled sails also fit extremely well into the architect’s design vision for the building, making them both an architectural element and an HVAC system component.

The raised-floor plenum used in the underfloor air distribution system is substantially smaller than the suspended ceiling necessary for an overhead system. This reduced construction costs and ensured a floor-to-floor height that was in line with other facilities on campus.

Executive Director of Facilities, Bryan Jolley, states that the building has already played an important role in illustrating design concepts and demonstrating to prospective students the ways in which sustainable design goals on the campus are being met.

In the new Calgary Science Centre, which doubles the capacity of the existing facility, and hosts up to 500,000 visitors each year, Calgary design firm DIALOG specified an innovative mechanical system that has achieved an energy savings of 44 percent lower than the ASHRAE 90.1-1999 baseline.

In addition to a high-performance building envelope designed to reduce mechanical ventilation system operating cost, space cooling and heating requirements were decoupled from the ventilation system, yielding enhanced energy performance, thermal comfort, and indoor air quality.

Generally all areas are ventilated, and partially cooled, by a displacement ventilation system, which introduces supply air at or near the floor level, at a low velocity, and at a temperature only slightly below the desired room temperature. The cooler supply air “displaces” the warmer room air, creating a zone of fresh cool air at the occupied level. Heat, moisture, and contaminants produced by activities in the space rise with the air to the ceiling level and are exhausted from the space.

Perimeter radiant heating panels were used to manage glazing loads and envelope losses throughout the perimeter spaces. Radiant cooling panels were incorporated into the majority of occupied spaces to augment cooling from the demand controlled displacement ventilation system. In the various galleries, floating clouds of perforated radiant cooling panels create a well-integrated, finished acoustic ceiling plane. Office areas utilize perforated acoustic panels in a lay-in acoustic ceiling. Finally, the central atrium uses radiant chilled/heated slabs and displacement ventilation, creating a mechanical system which is inconspicuous but highly effective.

In operation, the hybrid mechanical system has proven its energy-saving ability, its draft-free thermal comfort, greater ventilation effectiveness, and superior acoustics. The building received the Alberta Construction Magazine Top Award, Institutional Category and the Canadian Institute of Steel Construction 2013 Alberta Steel Design, Architecture Award of Excellence.

At TELUS Spark, there are radiant panels on the ceilings, and the silver floor-to-ceiling columns have architecturally integrated displacement diffusers embedded into the base. Fire protection is integrated into the panels, with sprinkler heads that pop out when required. Photo courtesy of Price Industries