HVAC Schedule Off Periods for Unoccupied Energy Savings
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Solution Overview
Problem
Current HVAC controllers lack an efficient way to manage energy consumption by not being able to completely shut off the HVAC system during unoccupied periods, leading to continued energy usage despite setback temperatures.
Innovation Solution
An HVAC controller with a programmable schedule that includes an HVAC-off control mode, allowing users to manually associate this mode with specific time periods, ensuring the system remains off regardless of indoor temperature during those times, thereby minimizing energy use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If setback temperatures are used during unoccupied periods, then energy consumption is reduced, but the HVAC system continues to cycle on and off consuming unnecessary energy
Solution Approach 1:
The control schedule is segmented into distinct time periods with different control modes. The system divides the day into occupied and unoccupied periods, allowing different HVAC control strategies for each segment. During unoccupied periods, the system can completely shut off the HVAC unit rather than merely adjusting temperatures, eliminating wasteful cycling while maintaining comfort during occupied periods.
Solution Approach 2:
The system changes the control parameter from temperature-based cycling to on/off based control mode during unoccupied periods. By switching to an HVAC-off control mode where the system remains completely off regardless of temperature deviations, the patent eliminates unnecessary energy consumption while still providing comfort during occupied periods through normal temperature control.
2Reliability
If the HVAC system operates continuously to maintain temperature, then comfort is ensured, but energy consumption increases during unoccupied periods
Solution Approach 1:
The HVAC control system dynamically adjusts its operation based on the time of day and occupancy status. The programmable schedule allows the system to transition between different control modes - maintaining temperature during occupied periods for comfort, and shutting off during unoccupied periods to save energy. This dynamic adaptation resolves the contradiction by making the system responsive to actual needs rather than operating continuously.
Solution Approach 2:
The system implements periodic on/off control based on a programmable schedule that alternates between occupied and unoccupied periods. During unoccupied periods, the HVAC unit is shut off completely, and during occupied periods, it operates to maintain comfort. This periodic action pattern allows the system to balance comfort requirements with energy conservation by matching operation to actual occupancy needs.
3Use of energy by moving object
If setback temperatures are programmed, then energy savings are achieved, but the system lacks complete shutdown capability during unoccupied periods
Solution Approach 1:
The HVAC controller is designed with multi-functionality, supporting both traditional setback temperature control and complete shutdown control modes. The programmable schedule can associate different control modes with different time periods, including an HVAC-off control mode that enables complete shutdown. This universality allows the system to adapt to various occupancy patterns and maximize energy savings while maintaining the option for temperature control when needed.
Data Source
AI summary
An HVAC controller may include a user interface, along with a memory for storing a recurring programmable schedule having two or more time periods. The user interface may be configured to allow manual modification by a user of the recurring schedule stored in the memory, wherein the user can associate an HVAC-off control mode with any of the two or more time periods. In the HVAC-off control mode, the HVAC controller may not cycle the HVAC unit on regardless of the temperature of the air in the inside space. The HVAC controller further may include an output that is configured to issue operational commands to the HVAC unit in accordance with the programmable schedule.