Control for a passive-ventilation system of a building
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Solution Overview
Problem
The challenge is to increase energy efficiency in building ventilation while maintaining a thermally comfortable internal environment.
Innovation Solution
A method for controlling a passive-ventilation system in a building involves determining outdoor and indoor air temperatures, calculating a temperature difference, and adjusting the state of passive-ventilation devices such as windows or vents based on predefined setpoints and temperature limits to optimize natural ventilation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If passive-ventilation devices are opened to increase natural ventilation, then energy efficiency is improved, but thermal comfort may deteriorate when outdoor temperature is higher than indoor temperature
Solution Approach 1:
The control system continuously monitors outdoor and indoor temperatures and adjusts the opening state of passive-ventilation devices based on real-time temperature differences. When outdoor temperature is lower than indoor temperature, devices are opened to maximize ventilation; when outdoor temperature exceeds indoor temperature by more than a threshold, devices are closed to maintain thermal comfort, thus resolving the contradiction between energy efficiency and thermal comfort
Solution Approach 2:
The system dynamically adjusts the opening fraction of passive-ventilation devices based on varying temperature conditions throughout the day and season. The opening state is not fixed but changes continuously according to the temperature difference between indoor and outdoor environments, allowing the system to optimize both energy efficiency and thermal comfort under different operating conditions
2Productivity
If passive-ventilation devices are fully opened to maximize ventilation, then air exchange is improved, but control precision deteriorates due to lack of modulation
Solution Approach 1:
The system replaces binary open/closed control with continuous modulation of the opening fraction. The passive-ventilation devices can be positioned at any opening fraction between fully closed and fully open, allowing precise control of ventilation rate. This dynamic positioning capability enables the system to achieve both high air exchange when needed and precise modulation for optimal performance
Solution Approach 2:
The control system changes the opening fraction parameter continuously based on temperature difference and other environmental conditions. By modulating this single parameter, the system can precisely control the ventilation rate to match the building's thermal needs, achieving both high productivity and precise control
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 approach results in a controlled and energy-efficient passive-ventilation system that maintains thermal comfort, reducing reliance on active mechanical systems and lowering energy consumption.
Implementation Method 1
passive-ventilation system that utilizes temperature difference for air circulation and heat transfer between the indoor and outdoor environment
Data Source
Figure 1
AI summary
The invention relates to a method for controlling a passive-ventilation system of a building, comprising determining an outdoor air temperature (Tout) of air in an environment of the building; determining an indoor air temperature (Tint) of at least one zone inside the building; calculating a temperature difference (ΔT) by subtracting the determined outside air temperature (Tout) from the determined indoor air temperature (Tint); and, if the calculated temperature difference (ΔT) is greater than zero: Control a state of at least one passive-ventilation device of the passive-ventilation system to be in any of: a closed state, an open state, one of one or more intermediate states between closed and open state, where each of the states corresponds to one value of an opening fraction value (OF) of the at least one zone inside the building varying between 0 and 1, the opening fraction value (OF) being set to an upper fraction limit equal 1, if the calculated temperature difference (ΔT) is equal or below a pre-set lower temperature difference limit (k), to a lower fraction limit (I) equal or greater 0 and less than 1, if the calculated temperature difference (ΔT) is equal to or above a pre-set upper temperature difference limit (m), to a value of a passive-ventilation function of the calculated temperature difference (ΔT) otherwise, the passive-ventilation function monotonically decreasing with increasing calculated temperature difference (ΔT) in order to increase energy efficiency in the ventilation of a building while maintaining a thermal comfortable internal environment.