Thermostat Occupancy-Based Ventilation Control for Pathogen Reduction
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Solution Overview
Problem
Conventional thermostats lack advanced control mechanisms to manage ventilation and air quality based on occupancy schedules, leading to inefficiencies in energy usage and air quality management.
Innovation Solution
A multi-function thermostat that includes a processing circuit to receive occupancy schedules and user inputs, enabling pre-occupancy and post-occupancy purge modes to control HVAC equipment for enhanced ventilation and air quality management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional thermostats control HVAC systems by turning components on or off to maintain setpoint temperature, then temperature control is achieved, but air quality management and ventilation optimization based on occupancy are insufficient
Solution Approach 1:
The thermostat is enhanced to perform multiple functions beyond temperature control, including occupancy detection via sensors, air quality monitoring, and intelligent ventilation management. The device integrates temperature sensing, humidity sensing, CO2 sensing, and motion detection capabilities to comprehensively manage both thermal comfort and air quality in the space.
Solution Approach 2:
The system implements feedback mechanisms by continuously monitoring occupancy status, air quality parameters, and temperature conditions. Based on this feedback, the thermostat dynamically adjusts HVAC ventilation rates and operational modes to optimize air quality while maintaining energy efficiency.
2Stability of the object's composition
If HVAC equipment operates continuously to maintain temperature, then temperature stability is achieved, but energy consumption increases
Solution Approach 1:
The HVAC system transitions from static continuous operation to dynamic control based on real-time occupancy detection and environmental conditions. The thermostat modulates ventilation rates, heating, and cooling operations dynamically, reducing energy consumption during unoccupied periods while maintaining temperature stability when occupants are present.
Solution Approach 2:
The system implements periodic ventilation cycles and pre-occupancy purge modes that activate before scheduled occupancy periods. This periodic operation ensures fresh air supply and pathogen removal without requiring continuous HVAC operation, thereby reducing overall energy consumption.
3Object-affected harmful factors
If ventilation rate is increased to improve air quality and reduce pathogens, then air quality improves, but energy consumption increases
Solution Approach 1:
The system performs pre-occupancy purges by increasing ventilation rates before scheduled occupancy periods to remove accumulated pathogens and contaminants. This preliminary action ensures high air quality when occupants arrive without requiring sustained high ventilation rates throughout the day, thereby reducing overall energy loss.
Solution Approach 2:
The thermostat dynamically changes ventilation rate parameters based on occupancy status, air quality measurements, and outdoor conditions. During occupied periods, ventilation rates are optimized to maintain acceptable pathogen levels; during unoccupied periods, rates are reduced to minimize energy consumption while still providing periodic air exchange.
4Device complexity
If thermostat uses simple on/off control for HVAC components, then device complexity is low, but ventilation optimization based on occupancy schedules is insufficient
Solution Approach 1:
The thermostat system autonomously manages ventilation optimization by integrating occupancy sensors, air quality monitors, and HVAC control in one device. It automatically detects occupancy, schedules pre-occupancy purges, and adjusts ventilation rates without requiring external building management systems or complex external controls.
Data Source
AI summary
A controller for controlling HVAC equipment in a building includes a processing circuit configured to receive an occupancy schedule indicating at least one of a first occupied period or a last unoccupied period for a space in the building for a schedule period and receive a user input indicating the space should be purged based on occupancy. The controller selects, based on the user input, at least one of a pre-occupancy purge mode or a post-occupancy purge mode. The controller is further configured to control the HVAC equipment to ventilate the space for a purge duration prior to the beginning of the first occupied period in response to selecting a pre-occupancy purge mode, and ventilate the space for the purge duration at the beginning of the last unoccupied period in response to selecting a post-occupancy purge mode.