Using estimated schedules and analysis of zone temperature to control airflow
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Solution Overview
Problem
Traditional ventilation systems in buildings rely on maximum occupancy values, leading to over-ventilation when spaces are not at capacity, causing unnecessary energy consumption and equipment wear, and require costly CO2 and occupancy sensors for accurate control.
Innovation Solution
Implementing a demand control ventilation system that uses a combination of scheduling and environmental sensors to estimate the number of occupants and adjust airflow based on actual occupancy, temperature settings, and external weather conditions, reducing the need for CO2 and occupancy sensors and optimizing energy use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If maximum occupancy values are used to control ventilation, then ventilation capacity is ensured, but energy consumption increases and equipment life decreases
Solution Approach 1:
The ventilation system dynamically adjusts airflow based on real-time temperature measurements and occupancy estimates rather than operating at fixed maximum capacity. The controller modulates the ventilation system to provide adequate ventilation only when and where needed, reducing energy consumption while maintaining reliability.
Solution Approach 2:
The patent replaces mechanical occupancy detection systems (sensors, counters) with a thermal field-based detection method using temperature sensors. By measuring temperature changes caused by occupants and estimating occupancy thermally, the system avoids complex mechanical sensing while achieving accurate demand-controlled ventilation.
2Measurement precision
If CO2 sensors and occupancy sensors are installed, then accurate ventilation control is achieved, but initial setup cost and maintenance cost increase
Solution Approach 1:
The temperature sensor serves multiple functions: it detects occupancy through temperature changes, monitors environmental conditions for comfort, and provides data for ventilation control decisions. This multi-functionality eliminates the need for separate CO2 sensors and occupancy sensors, reducing initial setup cost and maintenance requirements.
Solution Approach 2:
The patent uses temperature as an intermediary parameter to indirectly detect occupancy. Instead of directly measuring CO2 levels or occupancy presence, the system measures the thermal effect of occupants on the environment and uses this intermediate measurement to infer occupancy and control ventilation accordingly.
3Measurement precision
If CO2 sensors are used to determine total CO2, then ventilation control accuracy improves, but hardware cost and maintenance overhead increase
Solution Approach 1:
The patent employs inexpensive temperature sensors that can be easily replaced if needed, rather than expensive CO2 sensors that require periodic calibration and maintenance. The temperature-based approach achieves sufficient measurement precision for ventilation control at a fraction of the hardware cost.
Solution Approach 2:
The patent substitutes chemical sensing (CO2 detection) with thermal sensing (temperature measurement). This replacement eliminates the need for complex CO2 sensor hardware and its associated maintenance overhead while achieving effective occupancy-based ventilation control through thermal field measurements.
Data Source
AI summary
A facility providing systems and methods for demand control ventilation for a building, or a portion/portions thereof, using a combination of scheduling and environment sensors for fallback is disclosed. The facility for demand control ventilation modulates the volume exchange of outside air into an enclosed space (i.e., air that is external to the enclosed space) by mechanical air conditioning equipment or ventilation system, such as a fan, a Heating, Ventilation, and Air Conditioning (HVAC) system, and so on. Demand control ventilation is used not only to ensure that people within buildings have an allotted amount of fresh air but also to provide a cost savings to users, as a lower amount of airflow can reduce energy use and, therefore, energy costs.