Occupancy-Based HVAC Control for Energy-Efficient Comfort
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Solution Overview
Problem
HVAC systems in buildings face inefficiencies due to poor design and operation, leading to significant energy wastage, with traditional control methods relying on design occupancy or complex algorithms that are costly and limited in adaptability.
Innovation Solution
Implementing a control system that uses real-time occupancy measurements to adjust HVAC inputs, including supply air temperature, flow rate, and return air ratio, without requiring complex algorithms, thereby improving energy efficiency while maintaining indoor air quality and comfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If traditional control methods using design occupancy or complex algorithms are used, then HVAC systems can operate, but energy efficiency is poor and costs are high
Solution Approach 1:
The patent implements feedback control by continuously measuring actual occupancy using CO2 sensors and adjusting HVAC operations based on real-time occupancy data. The controller compares measured CO2 levels against thresholds and dynamically adjusts supply air flow rate and temperature, creating a closed-loop system that responds to actual conditions rather than relying on predetermined schedules or complex algorithms.
Solution Approach 2:
The HVAC system performs self-adjustment by automatically modifying its operation based on occupancy measurements. The controller autonomously determines when to adjust supply air parameters by monitoring CO2 levels and comparing them to predefined thresholds, enabling the system to self-regulate without requiring complex external control algorithms or manual intervention.
2Use of energy by moving object
If high efficiency HVAC equipment is retrofitted, then energy efficiency improves, but substantial investment is required
Solution Approach 1:
The patent achieves energy efficiency improvements by changing operational parameters (supply air flow rate, supply air temperature, return air ratio) rather than changing physical equipment. The controller adjusts these parameters based on occupancy measurements, allowing existing HVAC equipment to operate more efficiently without requiring costly retrofits or new high-efficiency equipment.
3Productivity
If occupancy-based control is implemented, then energy savings are achieved, but measurement and detection complexity increases
Solution Approach 1:
The patent uses CO2 concentration as an intermediary parameter to infer occupancy levels. Instead of directly counting occupants or using complex occupancy detection systems, the controller measures CO2 levels in the zone and uses these measurements as a proxy for occupancy, simplifying the detection process while still enabling effective occupancy-based control.
Data Source
AI summary
A system for controlling at least one heating, ventilation, and/or air conditioning unit to increase efficiency while maintaining comfort. The system comprises at least one computer. The at least one computer is configured to receive an indication of measured occupant load. The at least one computer is further configured to send a control signal to the at least one heating, ventilation, and/or air conditioning unit. The at least one computer may receive the indication of the measured occupant load by receiving from at least one sensor node at least a zone occupant quantity and a zone temperature. The at least one computer may send the control signal to the at least one heating, ventilation, and/or air conditioning unit by sending a signal that controls at least one variable air volume box to set a supply air flow rate and a supply air temperature based on the measured occupant load.