Controlled Ventilation Using Dew Point Limits to Prevent Mildew

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Solution Overview

Problem

Existing methods for controlling ventilation in buildings, particularly in old buildings undergoing renovation, often fail to effectively manage moisture levels, leading to mold growth and moisture damage due to inadequate consideration of ventilation adjustments alongside thermal insulation improvements.

Innovation Solution

A method and device for controlled ventilation that determine the minimum surface temperature, measure indoor and outdoor temperatures and humidity, calculate a maximum allowable relative humidity to prevent condensation, and initiate ventilation only when necessary to maintain this humidity level, ensuring moisture condensation is avoided while minimizing energy usage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If ventilation is increased to reduce moisture and prevent mold growth, then the risk of moisture damage is reduced, but energy consumption increases due to excessive ventilation

Engineering Contradiction:
Improvemoisture damage preventionVSAvoidenergy consumption
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The system dynamically adjusts ventilation parameters (air exchange rate, timing, duration) based on real-time measurements of indoor/outdoor temperature, humidity, and calculated dew point conditions. Ventilation is initiated only when specific parameter thresholds are met (indoor relative humidity exceeds maximum permissible value and minimum achievable relative humidity through ventilation is below maximum permissible value), optimizing energy usage while preventing moisture damage.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The system continuously monitors indoor and outdoor environmental parameters (temperature, relative humidity) and uses this feedback to calculate the maximum permissible relative humidity and minimum achievable relative humidity. Based on this feedback loop, the system intelligently controls when to initiate and terminate ventilation processes, ensuring moisture prevention without unnecessary energy consumption.

Inventive Principle:
Principle #23Feedback

2Use of energy by stationary object

If thermal insulation is improved in renovated buildings, then energy efficiency increases, but moisture condensation risk increases due to reduced ventilation adaptation

Engineering Contradiction:
Improveenergy efficiencyVSAvoidmoisture condensation risk
Core Design Contradiction:
Use of energy by stationary objectVSObject-affected harmful factors

Solution Approach 1:

The system proactively calculates the maximum permissible relative humidity based on current thermal conditions and outdoor parameters before condensation occurs. By monitoring trends in temperature and humidity and calculating the minimum achievable relative humidity through ventilation, the system initiates preventive ventilation actions in advance, addressing moisture risks before they materialize into condensation problems on thermally insulated surfaces.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system dynamically adapts ventilation control to changing thermal insulation conditions and environmental parameters. Rather than using fixed ventilation schedules, the system continuously recalculates maximum permissible and minimum achievable relative humidity based on real-time measurements of indoor/outdoor temperatures, relative humidity, and thermal insulation characteristics, enabling flexible response to varying condensation risks in renovated buildings.

Inventive Principle:
Principle #15Dynamics

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 effectively reduces the risk of moisture damage and mold growth while optimizing energy consumption by ensuring ventilation occurs only when necessary, thus preventing excessive energy waste.

Implementation Method 1

calculating a maximum permissible relative humidity inside the room as a function of the minimum surface temperature and the temperature inside the room in order to avoid condensation of moisture inside the room

Methodology Applied
Scientific EffectCondensation: Condensation

Implementation Method 2

measuring the temperature inside and outside the room and the relative humidity inside and outside the room with a measuring unit

Methodology Applied
Scientific EffectTemperature measurement:

Implementation Method 3

ventilation takes place when either the partial pressure inside is greater than the partial pressure outside or when the dew point temperature of the inside air is greater than the surface temperature of the area at risk of mold growth

Methodology Applied
Scientific EffectDiffusion: Diffusion

Data Source

PatentEP1878979B1Method and device for controlled ventilation against mildew
Publication Date: 2010.08.11 PENNING JOSEF
  • EP1878979B1 patent drawingFigure 1
  • EP1878979B1 patent drawingFigure 2
  • EP1878979B1 patent drawingFigure 3

AI summary

The method involves determining minimum upper surface temperature of a room. The temperature and relative air humidity, outside and inside the room, are measured. The relative air humidity is determined depending on the minimum surface temperature and the internal temperature of the room, for preventing humidity in the room. The minimum obtainable relative air humidity is calculated depending on the outer temperature, internal temperature, and relative humidity outside the room. An independent claim is also included for a device for controlling air of a room, which comprises a temperature measuring unit, a humidity measuring unit, a carbon dioxide measuring unit, and a control unit.