pervious concrete grotto
Principle Investigator - Alex Timmer
University of Wisconsin - Milwaukee
Milwaukee, WI
2019 - 2021
The wall is composed of modular precast elements made from pervious concrete, a material engineered to allow water and air to pass through its porous structure. Each unit is designed with a geometry that enables flexible assembly: when mirrored, the elements align to form a continuous, linear wall; when repeated in the same orientation, they induce angular shifts, causing the wall to bend and articulate. This stacking strategy introduces spatial variation, generating alcoves and pockets that break the monotony of a flat façade.
These smaller, recessed spaces are not merely aesthetic—they serve a critical environmental function. By shaping the wall to include voids and turns, the design enhances its ability to moderate microclimatic conditions. Rainwater, instead of running off, is absorbed into the depth of the wall through the pervious concrete, saturating its mass. As ambient wind and natural ventilation move through and around the structure, the moisture within the wall begins to evaporate. This process draws heat from the concrete, lowering its temperature and cooling the surrounding air.
The result is a localized microclimate—an area with noticeably cooler conditions than its surroundings. This passive cooling effect is especially pronounced in the smaller cavities formed by the wall’s geometry, where airflow is concentrated and evaporation is more efficient. However, the extent of this cooling is inherently tied to environmental factors: higher air temperatures and lower relative humidity enhance evaporation, while cooler or more humid conditions reduce it. Thus, the wall operates as a responsive system, adapting its thermal behavior to the climate in real time.