The risk of moisture damage at winter temperatures

With the electrical prices skyrocketing, the need to cut expenses this winter is higher than ever. A common way to save a few is to completely turn off the heat and electricity in summerhouses and other rarely visited properties. However, there is a great risk that moisture damage, mould growth and frost damage will occur, and the consequences can be very costly. With extensive experience in Temporary Climate Control, Polygon helps you manage the challenge.

With temperatures dropping swiftly in the northern hemisphere, it has become clear that colder days are ahead of us. In this season, many retreat back to the cities and leave summerhouses and garden houses unoccupied. Sometimes larger facilities, such as museums, cultural properties, community buildings and conference facilities, also decide to shut down during a period when fewer people visit. Leaving these properties without any heat or electricity to save some money this winter is a bad idea because the risk of water and moisture damage increases significantly. You could very well have to spend large amounts of money to restore the damages that occur.

Risks when the heat is reduced or switched off

"The first thing that happens is that the temperature drops indoors and approaches the outdoor air. There is then a great risk that water pipes and installations will freeze. Therefore, if a building is to be left unheated, pipeline systems and installations need to be emptied of water." says Kent Bergström, Development Manager for drying and measurement methods at Polygon Sweden.

"Another consequence is that the so-called relative humidity (RH) adjusts to the same level as the outdoor air. The concept of RH is, simply put, a measure of how much moisture there is in the air in relation to the temperature of the air," explains Kent. "This affects structures and materials such as wood, gypsum plasterboard, carpets, wallpaper and upholstered furniture. Here, the main risk is the high relative humidity created in new conditions indoors. If the humidity reaches about 90%, two things mainly happen", he says:

  • Material swells
  • Microbial growth

"During the coldest part of the winter, there is little risk of microbial growth because the temperature is low. But as spring arrives and the temperature of the outdoor air increases, you may face some surprises in your building," Kent says. "When the temperature increases indoors, the humidity also increases. The materials that have stood in spaces with too low temperatures are soon surrounded by about 90% RH, and microbial growth can take place in just a few weeks. If the electricity has been turned off completely during the winter and the property has been cold, it will be 10 times worse!", he expresses.

The risk is thus not during the winter when you turn off the electricity, but when the heat comes back. Materials that have then generated moisture are affected when the temperature increases.

How can damage be avoided?

There are two basic ways to keep the property healthy and sustainable. The first is to keep the heat source and ventilation at a "maintenance heat" of about 10-15 °C during the winter months. The second is to keep the relative humidity at <70-75% RH in the indoor environment.

In summerhouses, the advice is always to open taps, turn off the water, drain water pipes and have maintenance heating in the house. Power outages can always happen, so be observant of this in winter, but with low RH, the risk of freezing is small overall.

However, many properties and buildings are larger than the summer cottages. How can healthy energy saving, and minimization of future damage, take place while keeping the consequences of temperature reduction in check? Is it possible to avoid freezing, condensation, build-up and moisture damage?

"In order for a building such as a museum, a church, a manor or a community centre to keep healthy, with the risk of damage minimized year-round, some form of heating is needed. Even in larger spaces, maintenance heating is recommended, but it is of the utmost importance that automatic control of the relative humidity of the indoor air also takes place," says Kent. "This means that the relative humidity of the air is kept at a low level with dehumidifiers in place during the winter months. Different solutions are available, and Polygon can help you find the right one for your property," he states.

Polygon offers these kinds of Temporary Climate Solutions (TCS) in almost all our countries. Contact the Polygon team in your specific country if you are interested in TCS for your property.

Want to learn more about our services in Temporary Climate Solutions? Click HERE


Minimize the risk of moisture damage

  • Keep heat source on, as well as the ventilation system. 
  • Keep a maintenace heat of 10 - 15 °C.
  • Maintain the relative humidity at a level of <70 - 75% indoors. 

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