KREC: Weather Responsive Ventilation for Residential Energy Efficiency and Indoor Air Quality

This proposal describes the research plan necessary to design and deploy a residential ventilation system that responds to weather conditions in order to optimize the amount of ventilation air relative to its energy liability while maintaining adequate indoor air quality. Historically, the air quality in residential buildings was maintained by natural forces bringing fresh outside air into homes to dilute indoor pollutants. Improved construction methods and concerns for energy efficiency are now making homes tighter and at risk of being underventilated. The conclusion shared by many researchers, building codes, and adopted by the national standard for residential ventilation in the U.S., ANSI/ASHRAE Standard 62.2, is that mechanical ventilation bringing in outdoor air is needed in homes to maintain acceptable indoor air quality. Standard 62.2 assumes a tight building envelope in a mild climate to prevent users avoiding mechanical ventilation by manipulating the building description input requirements. The assumption of a tight envelope is understandable given the lack of envelope testing, but the availability of local weather data precludes the need to assign a default climate. Inexpensive data communication devices and microcontroller applications have made real-time ventilation control a viable, cost effective option for residential homes. The goal of the research is to develop a weather responsive ventilation (WRV) control system to optimize the fan flow rate bringing in outdoor air as the conditions warrant increasing the flow when weather data suggests a small or even negative energy liability (or use) and decreasing the flow as the liability rises. Knowledge of past performance and anticipated behavior will ensure that minimum fresh air requirements are continually achieved. The research goal fits solidly in the research plans of the Department of Energy and the Energy Policy Act of 2005 which seek to make progress toward net zero-energy buildings by developing cost effective technologies that reduce energy consumption and create healthy indoor environments. The objectives necessary to achieve this goal are divided among four project areas: simulations, system calibration, test cell experiments, and field testing. Computer simulations will identify regional potential for energy savings by investigating how building parameters and local climate impact ventilation performance. Influential parameters found will be combined with different weather-sensitive optimization strategies to evaluate ventilation control algorithms for testing. The optimal algorithm found will be programmed into a microcontroller that will regulate the flow of a fan; and the response of the system to simulated weather conditions will be calibrated in a laboratory environment. The performance of the prototype system will then be evaluated on external test cells using a statistically designed experiment. Natural ventilation, weather responsive ventilation, and fixed-flow ventilation treatments will be compared. Lastly, the prototype system will be installed in a full-scale, highly instrumented residential test home at a national laboratory. The building air exchange and associated energy load will be monitored as the system alternates between fixed-flow and weather responsive ventilation modes. The project is expected to last 18 months and cost $152,861. The research will expand our understanding of economical ventilation control strategies and provide needed insight into our ability to control ventilation on a regional basis. Secondly, the research will produce a prototype device that will ensure a healthy indoor environment while using less energy than conventional ventilation strategies and thereby preserving Kentucky's internal and external environmental quality. Using this system to avoid '/4 to !Iz of the excess ventilation associated with a fixed-flow strategy could save approximately $5 to $10 billion annually in energy costs for the 107 million households in the United States or over $70 million annually in Kentucky.