This webinar, Building America: Effect of Occupant Behavior and Air Conditioner Controls on Humidity in Typical and Low-Load Homes, was held on Wednesday, December 6, 2017.
Speakers were Jon Winkler and Jason Woods, both with the National Renewable Energy Laboratory, and Jeff Munk with Oak Ridge National Laboratory.
The discussion included an analysis investigating how occupant-related inputs impact indoor humidity predictions with a specific focus on internal generation rates, thermostat setpoint, moisture buffering of building materials, and air conditioner controls.
Increasing insulation levels and improved windows are reducing sensible cooling loads in high-efficiency homes. This trend raises concerns that the resulting shift in the balance of sensible and latent cooling loads may result in higher indoor humidity, occupant discomfort, and stunted adoption of high-efficiency homes. This study utilizes established moisture-buffering and air-conditioner latent degradation models in conjunction with an approach to stochastically model internal gains. Building loads and indoor humidity levels are compared for simulations of typical new construction and high-efficiency homes in 10 U.S. cities. The sensitivity of indoor humidity to changes in cooling set point, air-conditioner capacity, and blower control parameters are evaluated. The results show that high-efficiency homes in humid climates have cooling loads with a higher fraction of latent loads than the typical new construction home, resulting in higher indoor humidity. Reducing the cooling set point is the easiest method to reduce indoor humidity, but it is not energy efficient, and overcooling may lead to occupant discomfort. Eliminating the blower operation at the end of cooling cycles and reducing the cooling airflow rate also reduce indoor humidity and with a smaller impact on energy use and comfort.
The webinar recording is available.