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By Barbara Knecht

 

St. Meinrad Cathedral in Indianapolis, by Woollen Molzan Architects, features radiant heating and cooling in its granite floors. In this project and Pier One, Flack + Kurtz used computational fluid dynamics (CFD) analyses to design the systems for maximum energy efficiency and comfort. Screen grabs by flack + kurtz

Pier One, with the Ferry Building, is located at the symbolic center of San Francisco’s redeveloping waterfront. This grand space was recently renovated as a retail center by SMWM Architects of San Francisco and outfitted with a radiant-heated and -cooled floor. Besides its advantage of being located in a good climate, a space as large and high as this is an ideal candidate for a radiant system. Reaching a comfortable air temperature throughout such a space, blowing air from above and mixing it around to achieve a single, even air temperature that may or may not be comfortable to the occupants is a tough business. A radiant system heats and cools the surface and mass adjacent to the occupants, allowing air at the higher levels to heat up and be exhausted out.

By incorporating the thermal mass of the building into the conditioning system, the amount of heated or cooled water running through the mass is adjusted to maintain steady temperatures. Imagine a granite floor that receives a dose of solar heat during the day. With an air system, the sun heats the floor; the floor radiates that heat and warms up the air; the air system throws more cold air into the space, swirls it around, and tries to cool the occupants who are experiencing the radiated heat coming off the floor. With a radiant system, sensors detect the solar heat and adjust the amount and temperature of the water in the pipes running through the floor so that it prevents the mass from heating up in the first place.

 

Photography: © Bill Sheet’s Photography

In San Francisco, with its relatively low levels of humidity, the system is simple. An installation in Indianapolis illustrates how other controls are introduced to avoid the “puddling” effect. St. Meinrad is a 12,000-square-foot cathedral that was renovated in 1999 by Woollen Molzan Architects of Indianapolis. It features radiant heating and cooling in a granite mosaic floor. Since radiant systems supply only heating and cooling, there is also a mechanical ventilation system, which supplies air changes and makes adjustments in the humidity. The air is not delivered overhead but through displacement diffusers behind perforated plates located in the face of benches that line the exterior wall of the aisles on either side of the church nave.