Demand Ventilation Fallback Control for Occupancy Sensor Failure
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Solution Overview
Problem
Demand control ventilation systems face energy wastage due to sensor failure, which causes them to default to full ventilation mode, leading to excessive energy consumption when occupancy levels are inaccurately indicated.
Innovation Solution
A method to monitor occupancy indicators, such as carbon dioxide sensors and motion sensors, to adjust the ventilation damper position and provide a set amount of fresh air, ensuring energy conservation by partially opening or closing the damper based on maximum occupancy levels or historical data, even if the sensor reading is erroneous.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If demand control ventilation systems default to full ventilation mode upon sensor failure, then ventilation reliability is improved, but energy consumption increases
Solution Approach 1:
The system applies partial action by providing a predetermined set amount of fresh air (less than maximum) when sensor failure is detected, rather than maintaining full ventilation mode. This resolves the contradiction by providing adequate but not excessive ventilation, reducing energy consumption while maintaining reliability through the fallback protocol.
Solution Approach 2:
The system changes the ventilation parameter from maximum fresh air provision to a predetermined set amount when sensor failure is detected. This parameter change allows the system to maintain reliable operation while reducing energy consumption by adjusting the ventilation level appropriate to the failure condition.
2Productivity
If sensors are used to indicate building occupancy levels, then ventilation efficiency is improved, but sensor failure risk increases
Solution Approach 1:
The system prepares for sensor failure by establishing a fallback protocol that activates when sensor readings become erroneous. This beforehand cushioning allows the system to maintain ventilation efficiency during normal operation while having a predetermined response ready to handle sensor failures, preventing complete system collapse.
Solution Approach 2:
The system monitors sensor readings for errors and activates a fallback protocol when failures are detected. This feedback mechanism allows the system to respond to sensor reliability issues by switching to a predetermined ventilation mode, maintaining operational reliability while preserving ventilation efficiency through automated detection and response.
3Object-affected harmful factors
If full ventilation mode is maintained after sensor failure, then indoor air quality is improved, but energy wastage increases
Solution Approach 1:
The system provides a predetermined set amount of fresh air (partial action) rather than maintaining full ventilation mode after sensor failure. This approach maintains adequate indoor air quality by continuing to provide fresh air while avoiding the energy wastage of excessive ventilation, resolving the contradiction between air quality and energy consumption.
Data Source
AI summary
Demand ventilation protocols can address the issue of sensor failure while still providing desirable levels of energy conservation. An occupancy indicator such as a sensor can be monitored. If the sensor reading is determined to be incorrect, unexpected or otherwise erroneous, the ventilation system can provide an amount of fresh air sufficient for adequate ventilation without over-ventilating the building.