Utilizing Latent Building Thermal Mass for Dehumidification

Traditionally, attic space in buildings is perceived as a source of nuisance. In winter, moisture condensation on the attic ceiling encourages mildew growth. In summer, the heat buildup in the attic space increases the cooling load. However, if the attic is integrated in a holistic design and control strategy, it can function as a solar energy collector, a heat exchanger, and a desiccant. This research investigates energy saving by optimizing direct and indirect ventilation through the attic to precool buildings and to reduce humidity. The proposed energy saving strategies are examined in a double story house with an attic. The house is located in a moderate-humid climate. The built-up heat in the attic space and outside air ventilation is used to dry up roof construction materials during the day. When outside air cools down during the night but maintains high humidity, the indoor air is circulated through the attic space. The attic construction materials absorb moisture from the indoor air. Thus, indoor air loses both heat and moisture. EnergyPlus Simulation software was used to simulate these cooling and dehumidification strategies. The simulation results show a significant passive cooling and dehumidification in the building.