Building control system with feedback and feedforward total energy flow compensation
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Solution Overview
Problem
HVAC systems react to temperature deviations after they occur, leading to delayed comfort adjustments for occupants, and existing control methods may not accurately account for heat flows from various sources within a building space.
Innovation Solution
A system that uses multiple sensors to estimate disturbance heat flows from sources like people, computers, and solar radiation, combining these estimates with feedback temperature measurements to control HVAC equipment proactively and maintain a consistent temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If HVAC systems use traditional feedback control based on temperature sensor measurements, then the system can react to temperature deviations, but the response is delayed because the temperature sensor is located at one position in the space and lag time exists between heat flow at different areas and temperature change at the sensor
Solution Approach 1:
The system performs preliminary action by estimating disturbance heat flows (from occupants, equipment, solar radiation, etc.) before they cause temperature deviations. The feedforward controller uses sensor data to predict heat gains/losses and adjusts HVAC output proactively, eliminating the lag inherent in traditional feedback-only systems that wait for temperature changes to occur.
Solution Approach 2:
The system introduces an intermediary estimation process that translates sensor measurements (occupancy, equipment status, weather) into predicted heat flow values. This intermediary layer bridges the gap between indirect sensor measurements and actual thermal conditions, providing more accurate and timely control signals than direct temperature measurement alone.
2Device complexity
If HVAC systems use a single temperature sensor for feedback control, then the control system is simple, but it cannot accurately account for heat flows from various sources within the building space
Solution Approach 1:
The system segments the total heat flow into distinct components (occupant heat gain, equipment heat gain, solar radiation, transmission heat loss, etc.), each estimated by specific sensors or algorithms. This segmentation allows accurate accounting of individual heat sources while maintaining modular, manageable control logic that doesn't require excessive system complexity.
Solution Approach 2:
The control system achieves multi-functionality by using a single integrated controller that performs both feedforward disturbance estimation and feedback temperature regulation. Multiple sensors (occupancy, weather, equipment status) serve multiple purposes: they provide data for heat flow estimation while also enabling predictive control, eliminating the need for separate complex subsystems.
Data Source
AI summary
A system for controlling air quality of a building space includes HVAC equipment configured to serve the building space, sensors configured to measure a plurality of parameters relating to the building space, and a control system. The control system is configured to receive data from the sensors, determine a feedforward air quality contribution, determine a feedback air quality contribution based on a measured air quality and an air quality setpoint for the building space, combine the feedforward air quality contribution and the feedback air quality contribution to determine a target amount of ventilation or filtration to be provided to the building space by the HVAC equipment, and control the HVAC equipment to provide the target amount of ventilation or filtration.