Adaptive Thermostat Fan Control During Utility Load Events
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Solution Overview
Problem
Existing load-control systems for HVAC systems fail to consider the role of circulation fans during load-control events, leading to compromised occupant comfort and potential dropout from utility-driven load-control programs.
Innovation Solution
An adaptive-fan-control (AFC) communicating thermostat that overrides fan operation based on occupant-selected settings, facility conditions, and utility-managed load-control factors to maximize comfort during load-control events, using a controller with a transceiver to receive load-control messages and adjust fan operation dynamically.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the circulation fan is turned off during load-control events to save energy, then energy consumption is reduced, but occupant comfort deteriorates due to poor air circulation
Solution Approach 1:
The system dynamically adjusts fan operation based on real-time conditions during load-control events. The controller monitors temperature, humidity, and air quality sensors to determine when fan operation is necessary for maintaining comfort, rather than using a fixed on/off schedule. This allows the system to optimize energy savings while preserving comfort when needed.
Solution Approach 2:
The system changes operational parameters of the circulation fan during load-control events, such as reducing fan speed rather than completely shutting it off. This partial operation maintains sufficient air circulation for comfort while consuming less energy than full-speed operation would require.
2Ease of operation
If the circulation fan continues to operate during load-control events to maintain comfort, then occupant comfort is preserved, but energy consumption increases
Solution Approach 1:
The system uses feedback from temperature, humidity, and air quality sensors to continuously monitor comfort conditions during load-control events. Based on this feedback, the controller intelligently adjusts fan operation to maintain comfort only when sensor readings indicate it is necessary, thereby avoiding unnecessary energy consumption during periods when comfort is already satisfied.
Solution Approach 2:
Instead of maintaining full fan operation throughout the entire load-control event, the system applies partial action by operating the fan only during specific intervals or at reduced capacity when comfort parameters warrant it. This selective operation achieves sufficient comfort maintenance while reducing overall energy consumption compared to continuous full-speed operation.
3Loss of energy
If utility companies implement stricter load-control measures to increase energy reduction, then energy savings are maximized, but occupant comfort deteriorates leading to program dropout
Solution Approach 1:
The system performs preliminary cooling or heating of the space before load-control events begin, storing thermal energy in the building's thermal mass. This pre-conditioning allows the system to withstand longer or more stringent load-control periods without compromising comfort, thereby enabling greater energy savings while maintaining program retention.
Solution Approach 2:
The system dynamically adjusts multiple operational parameters during load-control events, including fan speed, temperature setpoints, and humidity control levels. By optimizing these parameters in real-time based on environmental conditions and comfort thresholds, the system achieves maximum energy reduction while maintaining comfort within acceptable ranges to prevent program dropout.
Data Source
AI summary
An adaptive-fan-control (AFC) communicating thermostat for controlling an electrical load and controlling an HVAC circulation fan during a load control event. The thermostat interrupts and overrides an occupant-selected fan setting of the thermostat. The AFC communicating thermostat includes a controller in communication with a temperature sensor and the occupant-selectable fan control.