© Nadine Post Photo 2: Lobby of Hearst headquarters showing thermally active floor (bottom center) and refrigerated water feature (bottom left corner). Avoiding Condensation Proper system design and layout and proper control sequences are crucial in avoiding the possibility of floor condensation. With proper design, condensation should never occur, even in the most humid climates. Condensation avoidance strategies should consider the actual usage and microclimate of the project, in addition to generic peak humidity design conditions. For example, the peak exterior dew-point condition for a project likely may occur when a thunderstorm inundates a hot asphalt parking lot outside the building’s entrance raising the local dew-point temperature above 80°F (26.7°C), much higher than the ASHRAE design condition. The peak internal latent gain may occur when someone holds open a door to February 2013 allow the entrance of a dozen drenched people. The generous safety factors recommended by this author are the result of this type of consideration. Below are some strategies to avoid condensation. The most important strategy for avoiding condensation on or within the floor is a supply chilled water temperature that is substantially higher than the dew-point temperature of the air in the space. The author’s projects are usually designed around an entering chilled water temperature of 61°F (16.1°C). The dewpoint, at sea level, of air at 75°F (23.9°C) and 50% relative humidity is 55.1°F (12.8°C). This 6°F (3.3°C) dew-point temperature safety factor allows significant interior microclimate variation before condensation can occur. Using a supply chilled wa- www.info.hotims.com/44629-46 ASHRAE Journal 43