The HVAC Factor: Systems Get A Break

By Robert Matthew Noblett, AIA, NCARB
From the November/December 2014 issue

The John and Frances Angelos Law Center at the University of Baltimore, which opened in April 2013, is a classroom, library, and faculty office building uniting the university’s entire law school program in a single structure with high ambitions for environmental sustainability. Recently certified LEED Platinum, the design of this 192,000 square foot building took as its point of departure the idea that sustainable design should not only be about how the building performs quantitatively, but it should also be about how the building’s appearance expresses a sustainable approach, and how it supports a sustainable view of learning, working, and interacting for its occupants.

University of Baltimore President, Robert Bogomolney, said of the law center: “As an educational institution, we envision a building whose design teaches critical lessons about how to create and sustain healthy urban environments.”
University of Baltimore President, Robert Bogomolney, said of the law center: “As an educational institution, we envision a building whose design teaches critical lessons about how to create and sustain healthy urban environments.” (Image: Behnisch Architekten.)

The central organizing element of the scheme is a narrow, slot-like “atrium” which rises up through all 13 levels of the building. This irregular, meandering stalk of space (see illustration on the right) opens up the interior of the building for daylight which enters from vertical glazing to the north and south, creates visual connectivity between the various levels of the building, contains the main vertical communicating stairs, and moves exhaust air from offices, classrooms, and the library up and out of the building.

All of the regularly occupied program spaces are contiguous with either the atrium or the building perimeter, ensuring that building occupants have direct access to natural light and outside views. Spaces that border the atrium are heavily glazed to allow maximum transmission of daylight through the depth of the floorplate, as well as to animate the atrium visually with the daily activities of working and learning spaces. The atrium itself is populated with a variety of informal seating and working areas that allow it to be inhabited on a constant basis by students and faculty who find themselves in between classes and meetings with a need to either work or meet casually with colleagues and friends.

The building is constructed of a thermally massive poured-in-place concrete frame intended to stabilize internal temperature swings. This structure, more or less fully exposed to the building interior, is integrated with a system of embedded plastic tubes that transform the concrete mass into the primary heating/cooling system for the building. The introduction of low temperature heated water and high temperature cooled water into these tubes allows the concrete surface temperature to remain nearly constant throughout the year, dramatically reducing the heating and cooling load on the building’s air handling systems. This approach is often referred to as a thermal active slab system.

Dropped ceilings were eliminated throughout the building, directly exposing occupants to the radiant surfaces, which have the added benefit of being virtually silent in operation and free of uncomfortable drafts typical with forced air systems. This energized, robust structure became the dominant motif of the building’s interior—punctuated with swaths of brightly colored paint applied directly to the concrete, influenced by the light within the building—as it subtly reinforces wayfinding.

This University of Baltimore facility includes 15 classrooms, 29 large- and small-group study spaces, a 32,000 square-foot library, and a 300 seat moot courtroom and event space.
This University of Baltimore facility includes 15 classrooms, 29 large- and small-group study spaces, a 32,000 square-foot library, and a 300 seat moot courtroom and event space. (Photo: Brad Feinknopf for Behnisch Architekten.)

This structural frame is clothed in a high performance façade that is designed to maximize protection from solar gains and heat loss while maintaining a high daylight factor and allowing for a full natural ventilation mode of operation. Exterior operable blinds can be automatically deployed and rotated to the appropriate position in order to block solar gain, and can be overridden by building occupants via internal controls. For natural ventilation, all of the occupied perimeter spaces have operable windows that can be opened by occupants when external conditions of temperature and humidity are favorable, as indicated by a green LED light located next to the window switch. Air that enters the building through the façade is transferred ultimately to the atrium via a series of transfer slots built into the interior walls that use an acoustically lined labyrinth to isolate sound between adjacent spaces. Ventilation can be supported by the natural stack effect of the atrium when outdoor conditions permit, or can be mechanically assisted by the atrium smoke exhaust fans at very low speed when exterior conditions are not conducive.

The John and Frances Angelos Law Center consolidates a number of strands of thinking that our office has developed over the course of the past several years, in which the technical approach to sustainable and energy conscious building is inextricably linked to the architectural approach. Passive heating and cooling systems, natural ventilation, daylighting, and solar control strategies require fundamentally new ways of thinking about the appearance, spatial character, and comfort in these buildings. At the University of Baltimore the massing, façade development, material selection, and interior fit-out have all been informed, to varying degrees, by these criteria in support of the sustainable goals of the project. This is the basis of what we would term an integrated design approach.

Noblett.
Noblett

Noblett, AIA, NCARB is the Partner in Charge of the Boston office of international architects Behnisch Architekten. He received his Bachelor of Science in Architectural Studies at the University of Illinois at Urbana-Champaign and a Master of Architecture at the Massachusetts Institute of Technology. In 2006 he joined Behnisch Architekten, Boston, where he has been executive partner since 2009. Noblett has taught at Boston institutions of higher education and currently lectures extensively worldwide on sustainable architecture and design excellence.