From the Lab to the Field
Contributing Author: Alex Haynor
You may remember from our virtual tour that the new Innovation Exchange office has a research lab... but how do our staff use it?
Research Technician Alex Haynor is building a “bypass” relay system to flip between old controls and optimized controls for CEE's Advanced Rooftop HVAC Unit Controls Pilot.
To gauge whether or not the optimized control systems save energy cost-effectively, our research team needs to compare their performance against that of the existing systems. Data loggers on the RTUs record return air temperature and power consumption in five-minute intervals. Similar projects may collect a year of data from the existing system, then install new controls and record a second year of data to perform a “before and after” comparison. But heating and cooling needs are not consistent year to year: outside temperature and humidity affect HVAC energy demand.
To account for variations in weather, our RTU pilot will “flip-flop” between the old controls and the new, optimized control system weekly. Inside the building there are two thermostats side by side: one hooked to the old control system, and one hooked to the optimized control system. Because the project “flip-flops” between the two, only the thermostat attached to the active controls system is adjustable. Here’s an example from our downtown office, where we’re testing two different optimized control systems on our own building’s roof:
Our research team will record the heating element of the process, but expects that the optimized control system will achieve most of its energy savings when the RTU is cooling. The project is also monitoring space temperature and relative humidity: these indoor conditions help gauge occupant comfort. Another benefit of “flip-flop” testing? If the optimization package is not working properly, we can remotely connect to our logger and tell it to change back to standard mode. This switches back to standard controls, ensuring occupant comfort throughout each stage of the project.
Most of CEE’s research happens outside the office, but the lab helps prepare for those experiments. In addition to wiring up bypass systems, Alex and other researches use it to build field measurement devices, calibrate and test equipment, and pull field data for analysis. They also take advantage of the writable walls to track project progress!
* This research is supported in part by a grant from the Minnesota Department of Commerce, Division of Energy Resources through the Conservation Applied Research and Development (CARD) program. And with co-funding by CEE in support of its nonprofit mission to advance research, knowledge dissemination, and program design in the field of energy efficiency.
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