The “Tea Cosy” Problem: How to Solve Mould & Damp in Older Insulated Properties

When we aim to reduce energy and carbon in our older homes, we often pop a ‘tea cosy’ over it with EWI and/or IWI to trap the heat inside. This results in a warm home, but moisture builds up, and mould and stale air become an even worse issue. The problem is that it’s too cold to open windows, which defeats the purpose of the insulation, but daily life still creates steam and moisture that has nowhere to escape bringing mould and damp in older properties

insulating traps stale air and moisture

 

 

 

 

 

 

 

 

 

 

Understanding the Science of Mould & Condensation

The warm air circulates, and its molecules, swollen with water, bounce off colder surfaces like a window or an external wall. The air molecule immediately shrinks and spills its contents, which leeches into the plasterwork. This creates the perfect environment for mould spores, which are dragged in on our clothes and shoes or via pets, to germinate and spread. In desperation, walls are bleached, which merely masks the issue, and windows are opened, allowing more spores and moisture in along with pollutants.

Air molecules carry moisture that condenses on cold surfaces, aiding the germination of mould spores.

 

 

 

 

 

 

 

 

 

Solution 1: Low-Temp Surface Heating

Instead of heating the air, there is a solution that heats surfaces first. When used at the correct frequency on the ceiling and over a large surface area, this “light” heats the surfaces without immediately warming the air. The air molecules remain restricted and simply bounce off the warmer walls. The “light” also penetrates deep into the walls to dry out any damp within them. As the walls retain the heat energy, they continue to warm the room even when the “light” is switched off. For stubborn areas, the light can even be emitted from within the wall itself, keeping the surface above the “dew point” and drying out any moisture.

Thermal image showing infrared heating radiating into the room from the ceiling

 

 

 

 

 

Solution 2:  Preventing condensation in old buildings with Mechanical Ventilation Systems

Daily activities still create moisture that builds up. A traditional centralized MVHR (Mechanical Ventilation with Heat Recovery) system would extract this and send it out of the roof, retaining the heat and then bringing in fresh, filtered and warmed air back in. Unfortunately, these systems are expensive, take up a lot of space, and require extensive ducting to be run throughout the home to collect the ‘bad’ air. This is not so bad in a new build, even though many house builders still refuse to fit them, but very hard to retrofit into older properties.

Centralized MVHR unit taking up space in a cupboard.

 

 

 

 

 

 

 

 

 

 

 

Instead of sending the stale air upwards, a more compact solution sends it outwards. These “through-wall” units consist of carefully positioned 200mm to 300mm long ducts that are placed through external walls. Each duct has a high-density ceramic core and two reversible fans that work silently and continuously. These units use just 2 watts of power and recover around 98% of the heat. Each unit also has a sensor that monitors moist air and foul air and can let a central hub know if the room needs to be purged.

The Complete Solution to Damp & Mould in older properties

Moisture control through ventilation and low-temperature surface heating is our bread and butter, thanks to German engineering and over 60 years of experience in the European sector. To find out more about our energy-efficient surface heating and ventilation solutions, please get in touch.