 Building Science at UC Berkeley: Research
Alternatives to Compressive Cooling in California Transition Zones--Development of Advanced Prototype Controls for California Residences Using Alternatives to Compressor Cooling Edward Arens, Department of
Architecture & Director, CEDR California Institute for Energy Efficiency In this multi-institution project, CEDR is collaborating with researchers from the Davis Energy Group, UC Davis, Lawrence Berkeley National Laboratory, Berkeley Solar Group, and Taylor Engineering. Phases I and II conducted background research on alternative cooling with a focus on California transition climates. The knowledge gained has been used in the development of a compressorless house design capable of providing thermal comfort in California transition climates and intended for implementation by the production building industry. There is one necessary major component of the prototype house that is not yet available: alternative cooling system controls capable of being used by the initial and subsequent occupants and serviced by the existing industry. Development of such a control, first in the form of a specially configured version of existing off-the-shelf equipment (for immediate use) and later as an optimized commercializable version, is the remaining major technical problem for this project. During the current phase of work, CEDR has been working with the research team to develop (1) a complete specification for a turn-key configuration of existing equipment that will successfully control the alternative cooling systems in a planned pilot subdivision, and (2) a complete concept (capability description) for cost/capability optimized alternative cooling system controller with advanced user interface and multi-configurability for various night cooling options. In support of this effort, CEDR has conducted an extensive review of relevant research literature and commercially available controls products for HVAC and home systems. Based on the above review, the research team has selected the SmartVent Model SV10, manufactured by ZTECH, as the interim control option. The SmartVent controller is designed to be connected to an existing residential HVAC system and to automatically circulate fresh, filtered, outside air throughout the home. In its off-the-shelf configuration, the SmartVent system includes a power transformer, vent thermostat, indoor and outdoor thermostats, and motorized damper(s). We are now working to modify the SmartVent control capabilities to enable it to handle more advanced strategies such as nighttime ventilation. In this scenario, the SmartVent would ventilate the house with cool nighttime air to allow the structural mass of the house (largely gypboard walls and concrete floor slab) to be cooled down to a preset level in the morning. The cool thermal mass would then absorb heat from the surrounding space to offset rising temperatures during the peak cooling periods of the afternoons. Optimally, this nighttime precooling strategy is sufficient to eliminate the need for compressor-based cooling during peak cooling periods. During the coming year, we will be conducting a field study of five houses in the Sacramento area that are equipped with the SmartVent. The field study should provide for a better understanding of occupant satisfaction with an alternative cooling system whose controls resemble a portion of the proposed control package from this project. The homeowners will be interviewed prior to the beginning of the test and will also fill out a background survey to provide information on their understanding and opinions about the SmartVent system. They will also complete a daily environmental conditions log to characterize their daily interactions and observations about the SmartVent. Over the same test period (2-3 week) instrumentation will be installed to continuously monitor temperatures, system control performance, and power consumption. One-time measurements (air flow, pressure) will be taken to assess how well the SmartVent system is working. This project provided support for one Masters student.
|
