HVAC Away-Mode Dewpoint Control for Unoccupied Spaces
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Solution Overview
Problem
In unoccupied spaces, especially in hot and humid climates, there is a challenge in maintaining indoor air quality by preventing mold and mildew growth while conserving energy, as existing HVAC systems often require complex configurations and may lead to either insufficient humidity control or excessive energy consumption due to the tradeoff between dehumidification and temperature settings.
Innovation Solution
A controller with an 'away mode' that operates HVAC system components to maintain humidity and temperature levels, including the option to overcool when necessary, using a dehumidifier or air conditioner, and compensating for temperature differences within the space, even without a humidity sensor, to ensure effective dehumidification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the temperature is lowered to reduce humidity levels, then dehumidification is improved, but energy consumption increases and may cause moisture buildup when dewpoint exceeds room temperature
Solution Approach 1:
The system changes the control parameter from temperature setpoint to dewpoint setpoint. By directly controlling the dewpoint temperature rather than the room temperature, the system achieves effective dehumidification without unnecessarily lowering the room temperature, thus reducing energy consumption while preventing moisture buildup issues
Solution Approach 2:
The system uses feedback from humidity sensors and dewpoint calculations to automatically adjust the air conditioner operation. The controller continuously monitors indoor humidity levels and adjusts the cooling setpoint based on the calculated dewpoint, ensuring optimal dehumidification without excessive energy use
2Reliability
If the air conditioner is used for dehumidification, then humidity control is improved, but temperature may drop below dewpoint causing moisture buildup
Solution Approach 1:
The system implements feedback control by continuously monitoring indoor humidity and calculating dewpoint temperature. The controller uses this feedback to adjust the air conditioner setpoint dynamically, ensuring the temperature remains above the dewpoint while achieving adequate dehumidification, thus preventing moisture buildup on walls and surfaces
Solution Approach 2:
The system performs preliminary calculation of the dewpoint temperature based on measured humidity levels before adjusting the air conditioner setpoint. This preliminary action allows the system to proactively set the temperature to a level that guarantees dehumidification effectiveness while preventing the temperature from dropping below the dewpoint
3Measurement precision
If thermostat and humidistat are configured separately, then control precision is improved, but system complexity and difficulty of operation increase
Solution Approach 1:
The system merges the thermostat and humidistat functions into a single integrated controller. The controller simultaneously manages both temperature and humidity control by calculating dewpoint and adjusting the air conditioner setpoint accordingly, eliminating the need for separate devices and their complex coordination while maintaining precise humidity control
Solution Approach 2:
The controller is designed as a universal device that performs multiple functions: it acts as both a thermostat for temperature control and a humidistat for humidity control. By integrating these functions and using dewpoint-based control logic, the system achieves precise humidity management without requiring separate configuration of multiple devices
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively prevents mold and mildew growth while conserving energy by automatically adjusting HVAC settings to maintain optimal humidity levels, even in the absence of a humidity sensor, ensuring indoor air quality and reducing energy bills.
Implementation Method 1
When operated as a dehumidifier, air flowing past the air-conditioning coils results in condensation on the coils, which removes water from the air and reduces the humidity levels within the space
Data Source
AI summary
Methods of providing dehumidification control in unoccupied spaces are disclosed. An illustrative method can include the steps of providing a controller having an away mode of operation adapted to provide dehumidification within the interior space of a building or room, providing one or more system components adapted to control the humidity and/or temperature within the interior space, initiating the away mode of operation within the controller, and operating the one or more system components for at least one cycle to reduce the humidity within the interior space.