HVAC Setback Control Based on Target Recovery Time
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Solution Overview
Problem
Conventional HVAC systems lack the ability for operators to directly control the recovery time, making it difficult to balance comfort and energy savings, as the recovery time is dependent on the difference between setback and setpoint temperatures.
Innovation Solution
An HVAC controller that calculates a setback temperature as a function of a predetermined recovery time, allowing for independent control of the recovery time and thereby enabling operators to set a desired temperature within a specific time period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the setback temperature is adjusted to achieve desired recovery time, then the recovery time control is improved, but the system complexity increases due to the need for dynamic calculation and adaptation
Solution Approach 1:
The patent implements dynamic adaptation by continuously monitoring actual recovery time and adjusting the setback temperature accordingly. The controller modifies the setback temperature based on the difference between actual and desired recovery times, creating a dynamic control system that adapts to changing conditions rather than using fixed temperature settings.
Solution Approach 2:
The patent employs feedback control by measuring the actual recovery time and using this information to adjust future setback temperatures. The controller compares the actual recovery time with the desired recovery time and modifies the setback temperature to minimize the difference, creating a closed-loop control system that continuously optimizes performance.
2Loss of energy
If the setback temperature is increased to reduce energy consumption, then energy savings are improved, but the recovery time increases making it difficult to meet comfort requirements
Solution Approach 1:
The patent changes the setback temperature parameter dynamically based on the desired recovery time and actual system performance. Rather than using a fixed high setback temperature for energy savings, the controller adjusts the setback temperature to achieve the optimal balance between energy consumption and recovery time, modifying this critical parameter in response to system conditions.
Solution Approach 2:
The system dynamically adjusts the setback temperature to balance energy savings with recovery time requirements. The controller modifies the setback temperature based on real-time performance data, allowing the system to achieve energy efficiency without compromising the ability to recover to the setpoint temperature within the desired time frame.
3Speed
If the setback temperature is decreased to ensure faster recovery to setpoint, then recovery speed is improved, but energy consumption increases
Solution Approach 1:
The patent dynamically changes the setback temperature parameter to optimize the balance between recovery speed and energy consumption. The controller adjusts this parameter based on desired recovery time and actual system performance, preventing both excessive energy use and insufficient recovery speed by finding the optimal setback temperature for each operating condition.
Solution Approach 2:
The system uses feedback control to adjust the setback temperature based on actual recovery performance. By monitoring whether the system recovers to the setpoint within the desired time, the controller modifies the setback temperature to achieve the optimal balance between recovery speed and energy consumption, preventing both wasteful energy use and inadequate recovery performance.
4Ease of operation
If fixed setback and setpoint temperatures are used, then the control system is simple to operate, but the recovery time cannot be directly controlled or optimized
Solution Approach 1:
The patent inverts the traditional control approach by allowing the user to specify the desired recovery time directly, rather than specifying a setback temperature and having the recovery time be a dependent variable. The controller then calculates the appropriate setback temperature to achieve the user-specified recovery time, reversing the cause-effect relationship to put recovery time control in the user's hands.
Solution Approach 2:
The system changes the control parameter from setback temperature to desired recovery time. Instead of requiring users to understand and adjust setback temperatures to indirectly control recovery time, the patent allows direct specification of recovery time and automatically calculates the necessary setback temperature, making the system more intuitive and easier to operate.
Data Source
AI summary
A system controller of a heating, ventilation and air-conditioning system is configured to control the operation of a demand unit to maintain a comfort characteristic setpoint of a conditioned space. The controller includes a setback calculation module that is configured to calculate a setback value of the setpoint as a function of a recovery time from the setback value to the setpoint.