The report, which analyzes the potential impact that structural thermal breaks have in reducing the overall heating energy consumption and raising interior surface temperatures, shows structural thermal breaks can reduce overall heating energy consumption from 7 to 14% and raise interior surface temperatures by roughly 13ºF, versus conventional concrete slabs. The complete Morrison Hershfield (MH) report, Thermal and Whole Building Energy Performance of Thermal Break Technology for Concrete Balconies in High-Rise Multi-unit Residential Buildings, is available at www.schock-us.com/MHReport .
"This study is timely and relevant to high-rise residential buildings in cold climates and jurisdictions where industry is adjusting to more stringent energy standards but is looking to minimize costs, minimize changes to construction methods and limit constraints on architecture. The report provides guidance regarding questions that builders and designers are asking about the impact of thermal breaks for cantilevered balconies." said Patrick Roppel, Building Science Specialist from Morrison Hershfield.
MH utilized a whole building energy model, Energy Plus, to analyze a common multi-unit residential high-rise building – a 32-floor, 422-unit structure, with 356,608 sq.ft. of floor area, 163,321 sq.ft. wall area with roughly 40% "vision glass" (windows, glass doors), and 3.5% of exposed cantilevered concrete slab area (balconies).
The study analyzed the impact of thermal bridging (energy loss, condensation risk and thermal comfort) regularly caused by penetrating a building envelope with a balcony slab, for three concrete balcony scenarios:
Findings show Schöck Isokorb surpasses others
The goals of the study were to 1) thermally analyze the balcony detail, determine the U-value, a measure of heat transmission through a building part, and assess the difference in interior surface temperature and 2) determine the impact on whole heating energy consumption for the three balcony slab scenarios.
The study found that Schöck Isokorb delivers an effective thermally broken slab. The U-value, and therefore the heat transmission, is reduced by implementing Schöck Isokorb thermal break. Schöck's solution cuts heat flow through or around the slab by 75% compared to a conventional continuous balcony. In contrast, the slab with intermittent concrete connections provides only a 21% improvement over the conventional balcony slab.
The study reports that "a principal benefit of the Schöck solution is that the floor is much warmer in the winter than with the other construction methods. The floor slab at the perimeter is warmer, thus providing benefits for condensation resistance and thermal comfort, and the heat loss through the balcony area is greatly reduced."
From a whole building perspective, the Schöck solution reduced overall heating energy consumption from 7% to as high as 14% when using Isokorb in conjunction with higher performance assemblies compared to a building with conventional balcony slabs. The study noted that the Schöck solution also can help meet Building Code requirements, without requiring investment in other costly improvements related to the building envelope.
"Modern buildings require high quality and durable solutions," noted Dieter Hardock, product manager, Schӧck. "Tenants and owners of new apartments expect high standards, good thermal comfort and energy efficient buildings. The MH study shows that Schöck Isokorb not only helps to fulfill these immediate expectations, but is also an investment in performance and quality that will stand the test of time."