Load-based testing using a thermostat environment emulator

To test unitary residential cooling equipment with integrated controls and typical load responses, a load-based testing methodology has been developed where a virtual building model is used to emulate building-equipment dynamic interactions. With this approach, the temperature of an environmental chamber that simulates indoor conditions continuously tracks virtual room temperature setpoints that are adjusted based on outputs from the virtual building model. The test equipment thermostat senses the floating air temperature and communicates with the test equipment as if it were installed in the field. In order to achieve realistic dynamic behavior, it is important to properly emulate inlet flow conditions and inlet temperature dynamics provided to the thermostat that are representative of field conditions and that can be reproduced across different test facilities. The goal of the work described in this paper was to develop a thermostat environment emulator for use in load-based testing. The proposed emulator can dynamically control the thermostat inlet air temperature to the virtual room temperature setpoints using thermoelectric devices. Sample test results obtained using the emulator are presented in this paper to demonstrate its ability to track emulated building responses during load-based testing. A description of the design and control of the emulator is provided with sufficient detail to allow future researchers to reproduce it. Additionally, a two-dimensional dynamic model of the thermoelectric conditioning devices is presented that guided the overall design process. This emulator is a basis for a standardized solution for applying load-based testing that is reproducible across different facilities.