Occupancy-Based Ventilation Control for Space-Level Fresh Air
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Solution Overview
Problem
Current building control systems inadequately correlate the need for fresh air with ventilation control, often mixing fresh air with heating or cooling air, leading to inefficient temperature management and unnecessary fresh air distribution.
Innovation Solution
Implementing MEMS sensors to measure CO2 levels and determine occupancy, allowing for separate control of fresh air and heating/cooling ventilation in each space, enabling more precise ventilation and temperature management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If additional supply air is admitted to the room for the purpose of providing fresh air, then the ventilation need is met, but the temperature may become lower than desired
Solution Approach 1:
The system segments the ventilation control by space, using occupancy sensors in each room to independently control fresh air supply to that specific space. This allows fresh air to be directed only to occupied rooms rather than uniformly to all spaces, preventing temperature drops in unoccupied areas while meeting ventilation needs in occupied areas.
Solution Approach 2:
The system applies local quality control by adjusting fresh air supply based on local occupancy conditions in each room. Occupancy sensors detect presence locally, and the control system adjusts ventilation dampers room-by-room, ensuring that fresh air is supplied only where needed rather than uniformly throughout the building, thus avoiding unnecessary temperature changes in unoccupied spaces.
2Temperature
If a particular room requires additional cooling, but does not require further ventilation, then fresh air is unnecessarily directed to spaces in which humans derive no benefit from the fresh air
Solution Approach 1:
The system segments the control of fresh air and cooling functions, allowing independent adjustment of ventilation dampers based on occupancy rather than uniformly applying cooling to all spaces. This enables cooling to be targeted at occupied areas while preventing unnecessary fresh air distribution to unoccupied spaces where it would not benefit anyone.
Solution Approach 2:
The system implements local quality control by using occupancy sensors to determine which specific rooms require fresh air supply. The control system adjusts ventilation dampers on a room-by-room basis, ensuring that fresh air is directed only to spaces with detected occupancy, thereby avoiding waste in unoccupied areas while still meeting cooling demands where needed.
3Quantity of substance
If the mixture of fresh air is controlled based on measurements taken in the return air, then the overall building ventilation is managed, but the needs of individual spaces are not addressed
Solution Approach 1:
The system segments the ventilation measurement and control function from a centralized return air approach to distributed occupancy-based sensing in each space. Instead of measuring CO2 in return air and controlling fresh air mixture at the building level, occupancy sensors in each room provide localized input that enables independent damper control for each space, addressing both overall building ventilation and individual space needs.
Solution Approach 2:
The system transitions from uniform building-level ventilation control based on return air measurements to localized space-level control based on occupancy detection. Each room's occupancy status independently influences its fresh air supply through dedicated dampers, enabling the system to meet both aggregate building ventilation requirements and individual space ventilation needs simultaneously.
4Adaptability or versatility
If the amount of fresh air is preset and keyed to the time of day, then ventilation is provided based on expected occupancy, but actual occupancy conditions are not considered
Solution Approach 1:
The system replaces open-loop time-based ventilation scheduling with closed-loop occupancy-based control using feedback from occupancy sensors. Instead of preset schedules that assume occupancy patterns, the system continuously monitors actual occupancy conditions in each space and adjusts fresh air supply in real-time based on detected presence, ensuring ventilation matches actual needs rather than expectations.
Solution Approach 2:
The system changes the control parameter from time-of-day schedules to real-time occupancy detection. Instead of adjusting fresh air supply based on predetermined hours, the system uses occupancy sensors to detect actual presence and dynamically adjusts ventilation parameters accordingly, enabling precise adaptation to actual occupancy conditions rather than relying on temporal assumptions.
Data Source
AI summary
An arrangement for use in an occupancy-based ventilation system includes a plurality of CO2 sensors and a processing circuit. The plurality of CO2 sensors are disbursed throughout a plurality of spaces in a building. The processing circuit is operably coupled to receive information representative of CO2 measurements generated by the plurality of CO2 sensors. The processing circuit is operable to determine a value corresponding to occupancy, based on information from the CO2 sensors, and to control the flow of fresh supply air into the building ventilation system based on the determined value.