The moisture cycle — a loop that can break

Moisture moves through the home in a characteristic cycle. When part of the cycle fails, it builds up. This article goes into how the cycle works — and how data can reveal where it has broken.

Introduction

Moisture moves through the home in a characteristic cycle. It enters the indoor air through activities such as showering, cooking and breathing. It moves towards colder zones such as external walls and windows. It settles on surfaces or is absorbed by materials. And it is removed again through heating and ventilation.

When part of the cycle fails, moisture builds up. And that is where the problems start.

1. Moisture production is predictable

Moisture production in a home depends mainly on the number of residents and their activities. One person gives off around 40-80 grams of water vapour per hour during light activity and around 50 grams per hour while asleep. A shower can release 200-300 grams in a short time, and cooking several hundred grams. Drying laundry indoors can add several litres a day.

In a family of four the total moisture production can easily reach 10-15 litres a day. That sounds like a lot — and it is. If this moisture is not removed effectively, humidity in the home rises.

2. How moisture moves towards cold surfaces

Moisture moving towards cold surfaces is driven by the laws of physics and cannot be prevented — only managed. Warm air rises and takes the moisture with it. When the air meets cold surfaces it cools, and some of the moisture condenses.

This process is most pronounced in corners between external walls and ceilings, behind furniture placed against external walls, around windows and at thermal bridges at the base and between floors. These are the places where mould growth typically starts.

3. Where has the cycle broken?

IoT data makes it possible to understand the cycle in detail and see whether moisture build-up comes from the structure, such as thermal bridges or leaks, from technical systems such as faulty ventilation, or from behaviour such as insufficient airing out or drying laundry indoors.

• If humidity is high around the clock with no clear pattern, that points to ventilation or the structure.
• If humidity is mainly high at particular times, that points to behaviour.
• If humidity follows rainfall, that points to leaks.

This kind of diagnosis is only possible with continuous data.

4. Restore the cycle

Once you know where the cycle has broken, the effort can be targeted. Does the ventilation need repair? Does a thermal bridge need insulating? Does the resident's behaviour need to change? Often it is a combination — and data provides the basis for prioritising correctly.

Damp is not a random problem. It is a cycle.

When the cycle works, moisture is produced, transported and removed without problems. When it breaks, the build-up begins — and with it the risk. With data we can see where the cycle fails. Not guess. Not assume. But understand.

This is where we move from treating symptoms to targeted action. From uncertainty to precise measures.

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