Loyola University Chicago
SOLOMON CORDWELL BUENZ Chicago
SIEBEN ENERGY ASSOCIATES Chicago
HALVORSON AND PARTNERS Chicago
ELARA ENERGY SERVICES Hillside IL
TRANSSOLAR CLIMATE ENGINEERING
POWER CONSTRUCTION COMPANY Chicago
ESCHE & LEE MASON CONTRACTORS
BMI | BRICK INC | CLEVELAND MARBLE
COLD SPRING GRANITE | DOW
HECKMANN BUILDING PRODUCTS
HOHMANN & BARNARD | INTERSTATE BRICK
LANCE CONSTRUCTION SUPPLIES | JP LARSEN
NORTHFIELD | YORK MANUFACTURING
Total Square Feet 72,000 SF
Completion Date JULY 2012
Upon reading the article you will be able to:
- Summarize masonry characteristics that contribute to an energy efficient building envelope
- Identify LEED points to which masonry materials and/or wall systems may contribute
- Describe systems that may be incorporated into passive heating/cooling strategies
- List materials present in an insulated masonry cavity wall
From the beginning of the design process of Loyola University Chicago’s Cuneo Hall, there were two main project goals. First, the new facility was to complete the inner campus quad, consistent with the early-1900s master plan. The new building was to seamlessly match the context of the existing campus architecture and details were developed based on neighboring historic buildings.
Secondly, the project was to provide an advanced, high-performance, energy efficient classroom and faculty office building that would quantify energy usage through a sophisticated, automated system. Masonry was an obvious choice to help achieve both of these goals.
Use of modular brick, cast stone, a granite base and clay roof tiles for the envelope tied the new building into the contextual surroundings. The bronze brick, in two finishes, is a campus staple and reddish mortar provided the desired monolithic appearance. Neighboring buildings were photographed so that details could be developed replicating the scale and proportions from adjacent Dumbach Hall built in 1908. While not as ornate as Dumbach, cast stone arches and window surrounds allow Cuneo to blend seamlessly with the existing aesthetics and fabric of campus. After Cuneo Hall was completed, one of the best compliments received was from a passer by who indicated that he thought the building had been there for many years.
The 72,000 sf four-story structure is comprised of perimeter and interior loadbearing masonry walls supporting precast concrete floor planks with a concrete topping slab.
Design team for Cuneo Hall, right, drew inspiration from neighboring buildings on the campus’ Inner Quad.
Thermal mass of the stone-clad atrium wall provides a vertical path for air circulation as a passive heating/cooling strategy utilized for maximum efficiency.
This system was chosen over steel and composite decking and cast-in-place concrete for cost effectiveness, the ability to improve thermal performance and streamline design detailing, removing need for shelf angles (and subsequent thermal bridging) at each floor.
When the design of the interior spaces began, partition loadbearing concrete masonry unit (CMU) walls were located not only to define the seminar rooms and classrooms but were laid out to accommodate economical spans for the precast concrete planks. These interior loadbearing walls provide acoustical isolation, cutting down on any noises transmitting from one classroom to the next. They also provide fire separation around all elevator shafts, egress stairways and corridors. CMU walls easily achieve required fire ratings and as detailed, fully grouted, allowed elevator guide- or handrails to be anchored into the wall without any special reinforcing.
Thermal Performance Exceeds R24
Per the University’s directive, a LEED Gold certification was targeted. The energy goal was a 47% reduction in usage over the base building energy model performed utilizing eQUEST software. Masonry as a structural element contributed significantly to these aggressive energy goals. The structure is of high thermal mass material, providing a passive system for radiating heat and cooling into the building. The use of the thermal mass helped the project receive points under the Optimize Energy Performance Credit 1 of the Energy and Atmosphere category of LEED v2.2. In all, Cuneo Hall achieved 9 of 10 possible points for that credit.
High mass masonry walls, exposed concrete slabs and suspended radiant panels, or clouds, to radiate heat and cooling, improve the thermal comfort of the classroom and office environments, which contributed to an additional point for Indoor Environmental Quality Credit 7.1.
Passive night cooling was achieved by drawing air through the atrium and across a massive stone wall on one side of the central atrium. The air moved naturally through open vertical paths within the building (stack affect), or was supplemented with fans through operable vents at the top and intake grills at the bottom.
The principle behind the high thermal mass storage is simple. During summer days, reinforced masonry walls and concrete slab absorb the sun’s heat. At night, the cooler air is drawn over the warmed surfaces to extract heat built up in the mass. During the winter, the temperature-or energy-is held in the material and, since indoor temperatures are controlled and maintained constant, stored heat in the mass radiates back into the spaces. Thermal mass helps provide both heating and cooling, along with the other systems designed to condition the spaces with minimal amount of air.
At the perimeter enclosure wall, the overall U-factor is a 0.041. Utilizing an R1.28 for the 10″ CMU and R0.36 for the standard brick, 3″ of continuous foil-faced polyisocyanurate insulation in the cavity accounted for an R19.00 and along with an air/vapor barrier, cavity air space, interior and exterior air films and the isolated finished metal stud and gypsum interior finishes (R1.6), the total prescriptive R-value for the wall is 24.29, or a reciprocal U-factor of 0.041. With the addition of a moisture/air barrier on the exterior face of the structural loadbearing concrete block backup and concentrating on maintaining the continuity of this air and moisture barrier at window openings, an air tight envelope is created. The masonry wall is highly insulated and both air and water tight. Focusing on maintaining the continuity of the thermal barrier, the air and moisture barrier components of the wall ensured a reduction in energy usage as uncontrolled heat loss and air infiltration was minimized. Air, thermal and moisture barriers located on the exterior side of the CMU wall limit potential damage from uncontrolled condensation.
To further enhance this perimeter wall’s performance, thermally-broken masonry anchors were used to laterally support the standard face brick back to the load bearing CMU. Masonry ties used a single screw with a special washer system that sealed tight to the insulation and the moisture air barrier. This fastener anchored back into the reinforced concrete block wall was fitted with a plastic wing nut to accept a stainless steel masonry hook tie. The plastic wing nut creates the thermal break. The use of stainless steel provided a corrosion resistant anchor with low thermal conductivity. This type of anchor also allowed for adjustability.
Reinforced cast stone lintels were used above openings, eliminating the need for steel shelf angles. By not using steel shelf angles tied back to the structural wall, thermal bridging was reduced and the transfer of cold into warmer areas of the wall construction was eliminated.
When this envelope enclosure wall is combined with proper site orientation, along with selection of high performance glazing types and glazing orientation, higher energy savings can be achieved by rejecting unwanted heat gains, yet cutting back on heating or cooling by retaining the desired temperatures within the building.
Since this was a four-story loadbearing structure, one challenge was locating required CMU control joints and brick expansion joints. Wall movement becomes visual in joints around windows with larger movement at the top. To accommodate, joints were ¾” at the base and widened to 1½” at higher floors. Lateral anchors allow for movement. Vertical control joints were integrated with movement joints. Dynamics of how the wall would move over the course of a Chicago season were established to masonry standards by the structural engineer.
Loyola University wanted to use the building as an educational tool to make occupants aware of efficient energy usage and design. Students and faculty are direct participants in energy savings awareness through their ability to control natural ventilation by operable windows. Display lights in each classroom signal occupants when weather conditions are appropriate for opening windows. When conditions allow, HVAC systems shut down. Light in each classroom signals occupants to open windows. One step in developing energy efficiency dialogue between building and occupants.
All energy usage at Cuneo Hall is measured (btu meters for hot and chilled water supply and electric sub-meters for lighting, plug loads, mechanical systems and miscellaneous loads). Actual energy usage measurements are monitored.
After four months of full data (July- October 2012) and after normalizing for the weather influenced portion of energy, Cuneo Hall is performing almost 58% better than the design model predicted. The model predicted the building would utilize 46% less energy than ASHRAE 90.1. Actual energy is 78% lower. On a kbtu/sf/year basis, the building model predicted annual energy use would be 59. It is currently on target to achieve 29 kbtu/sf/year.
Masonry contributed to additional LEED points under the Material and Resource section. Credits 2.1 and 2.2 Construction Waste Management were earned, as brick, CMU, mortar, grout and stone waste can be reused or recycled into new products. CMU contains as much as 70% recycled content, contributing to Credit 4 Recycled Content. It is locally sourced and produced, contributing to Credit 5 Regional Material. Cuneo Hall earned 40 points and a Gold LEED certification.
Cuneo Hall is performing 58% better than the design model predicted
Jody Buell, AIA, LEED AP BD+C, associate at Solomon Cordwell Buenz, brings a strong sense of technical and management expertise to the design and construction of recreation, institutional and residential projects. She leads projects in all aspects of technical oversight, management, client and staff communication. As a project manager, she is in charge of the business and contractual relationship between the client and the project team. She holds a Bachelor of Science in Architectural Studies and Masters of Architecture from University of Illinois at Urbana Champaign. [email protected] 312.896.1231
Scott R Marker, RA, LEED Green Associate, associate principal at Solomon Cordwell Buenz, has more than 35 years of experience in the practice of technical architecture, project assurance and quality control. He is responsible for monitoring and facilitating project development, streamlining teams to produce stellar documents and assuring code compliance. He is also currently serving as the chair to the Chicago Committee on High Rise Buildings. Marker received his Bachelor of Science in Architectural Studies from the University of Illinois at Urbana Champaign and Masters of Architecture from University of Illinois at Chicago. [email protected] 312.896.1192