Systems and methods for ventilating a building
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Solution Overview
Problem
HVAC systems face challenges in accurately determining and managing ventilation airflow rates, leading to inefficiencies in air quality control and energy usage, particularly in rooftop units where outdoor and return air interactions are complex.
Innovation Solution
The implementation of a controller system that utilizes sensors and actuators to calculate and adjust ventilation airflow rates based on feedback data, including pressure differences and economizer damper positions, using pre-measured economizer ventilation data and flow coefficient tables to ensure optimal airflow according to desired ventilation standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional HVAC systems use fixed damper positions and simple airflow estimation, then the system is easier to operate and less complex, but ventilation airflow rate determination becomes inaccurate leading to poor air quality control and energy inefficiency
Solution Approach 1:
The system implements feedback control by continuously measuring actual airflow using differential pressure sensors and comparing it against target airflow rates. The controller adjusts damper positions based on this feedback to maintain accurate ventilation airflow rates, resolving the contradiction between measurement precision and system complexity through closed-loop control.
Solution Approach 2:
The patent replaces simple mechanical airflow estimation methods with electronic sensing and computational algorithms. Differential pressure sensors, flow coefficient tables, and controller-based calculations substitute for traditional mechanical airflow measurement devices, achieving high measurement precision without proportionally increasing mechanical system complexity.
2Reliability
If the outdoor damper is opened to allow fresh air into the building to meet ventilation requirements, then indoor air quality improves, but energy consumption increases due to conditioning additional outdoor air
Solution Approach 1:
The system dynamically adjusts the outdoor damper position based on real-time conditions including outdoor air quality, indoor air quality requirements, and current ventilation airflow rates. This dynamic control ensures the minimum required fresh air intake for air quality while minimizing excess outdoor air that would require conditioning, thus resolving the contradiction between reliability and energy consumption.
Solution Approach 2:
The controller changes operational parameters (damper positions, airflow rates) based on varying conditions such as occupancy levels, outdoor air quality, and temperature differences. By adjusting these parameters dynamically, the system maintains adequate ventilation for air quality while optimizing energy consumption through reduced conditioning loads.
3Loss of energy
If the system accurately measures and controls ventilation airflow rates using sensors and actuators, then energy efficiency improves, but the device complexity and initial cost increase
Solution Approach 1:
The system achieves self-service by using the existing HVAC infrastructure (ducts, dampers, blowers) combined with minimal additional sensing. The differential pressure sensors leverage the existing airflow paths to derive ventilation rates without requiring separate complex measurement systems, reducing overall device complexity while maintaining energy efficiency.
Solution Approach 2:
The controller system performs multiple functions: it measures airflow, calculates ventilation rates, adjusts damper positions, and optimizes energy consumption. This multi-functionality consolidates what could be multiple separate complex systems into a single integrated controller, achieving energy efficiency without proportionally increasing device complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enables precise control of ventilation airflow, improving indoor air quality and energy efficiency by accurately determining and adjusting ventilation rates, thereby meeting ventilation requirements while minimizing energy consumption and maintaining compliance with standards like ASHRAE 62.1.
Implementation Method 1
A known relationship of the pressure differential to an amount of flow through the barometric relief damper is employed to determine the amount of outdoor air entering through the exhaust opening
Data Source
AI summary
Systems and methods are disclosed for ventilating a building using a rooftop heating ventilating and air conditioning system that in one instance involve determining a first outdoor airflow into the system through a barometric relief damper; subtracting the first outdoor airflow from a minimum required outdoor airflow rate to arrive at second outdoor airflow; and setting an outdoor damper to provide an outdoor airflow through the outdoor damper that is greater than or substantially equal to the second outdoor airflow. Other systems and methods are disclosed.