Airing properly

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First of all, here’s the good news: airing rooms properly is not rocket science. With a few simple rules and a few minutes to spare, you can make sure every day that you are not sitting in a stuffy environment and prevent mould from spreading. Promise.

Let’s kick off our short course about how to air rooms properly with the fundamentals – the methods of guaranteeing an exchange of air:

Most effective: airing across rooms

We recommend airing across rooms to get the most out of airing: open all windows and doors in the room you want to air properly. Even better: do this in the entire property.


  • How long you should ventilate across rooms (windows and room door open):

    Winter: 2 to 4 minutes
    Summer: 12 to 20 minutes
    Spring and autumn: 4 to 10 minutes

However, please note: if you put the door ajar OR open window only slightly, exchanging the air will take considerably longer.

A great solution: opening all windows at once for a short space of time

Almost as effective as airing across rooms is opening all windows in the room and keeping the door to the room closed.

  • This is how long you should open all windows and keep the door closed for:

    Winter: 4 to 6 minutes
    Summer: 25 to 30 minutes
    Spring and autumn: 8 to 15 minutes

Be careful: you might have already guessed, but if you just open windows slightly, it will take much longer for the air in your room to be exchanged.

Not great: opening windows just slightly

If you open windows just slightly and keep the door to the room closed, you will not be doing things very effectively. In winter, you would have to do this for between 30 and 75 minutes until all the air in the room has been exchanged!

Brrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrr, by then your room will have completely cooled down, and you will have proverbially heated the outdoors. We don't have to mention the environmental impact with this airing method, do we?

Airing regularly – but why?

3 reasons to regularly air the property in a 4-person household

Imagine a family of four: parents and two children. Quite a lot of humidity. And this increased level of humidity is associated with an increased risk of mould forming!

Did you know...…

  • ...Just by being there, a family of four releases around 12 litres of humidity into the ambient air every day

    Yes, that’s correct: even when we sleep, we all generate between 40 and 50 grams of humidity an hour. And it doesn't even take vivid dreams for that to happen!

  • ... One hour of showering generates 2,600 grams of steam?

    Only 15 minutes of shower time per day for 4 people! Hopefully you don’t have teenagers living with you because then I can almost guarantee you this time frame will not be enough ;-)
  • ... 600 to 1,500 grams of humidity are released into the ambient air per hour of cooking?

    People wearing glasses will immediately notice this when they walk into a kitchen where someone is boiling pasta ... and you cook a lot in a household with children!

Wow, these examples clearly show how much humidity we humans produce in our homes every day. And that doesn’t even include drying laundry or your beloved plants.

But what can we do to help fight this much humidity in the ambient air? And what prevents mould from developing? Exactly: correct and consistent airing.

Airing properly – how many times a day?

In an ideal case, you open all doors and windows in your property at the same time and air the place across all rooms – or you open all windows and keep doors closed if you have no other option. And you adapt the airing time to the respective season, that’s a given.

But how often per day should you repeat this procedure? Science dictates:

three to four times a day.

Yes, that’s a lot. Yes, that’s a lot of work. It’s true, if people live in your household who are not at home during the day, you might also get away with opening all doors and windows twice a day on working days to prevent the formation of mould. In any other case, we recommend opening all windows and doors three to four times a day – for several minutes in winter and for up to half an hour in summer.

These airing recommendations apply to new and old buildings, to houses with new, energy-efficient windows and also to houses with older windows. One thing applies to all of them: opening all windows while keeping the doors closed for the right period of time depending on the season not only prevents mould from developing, but it also saves a lot of heating energy in every building – and is thus easy on your wallet.

Speaking of energy: how old are your windows?
With new, heat-insulating windows, you can save even more energy and therefore money!


EXTRA TIP: measure the humidity in your home

The optimum humidity level in rooms that are not bathrooms or kitchens is between 40 and 50% at a room temperature of approx. +20 degrees Celsius. Levels in kitchens and bathrooms can reach up to 60% or even over 70%. But in that case you should quickly air the room to prevent mould from developing in the first place!

We recommend buying hygrometers – one for each room. These small humidity measuring devices only cost a few quid. And make sure you always know exactly when the humidity in your rooms is too high and you are best advised to open all doors and windows across the property.

New windows – what to look out for

New windows add value to every building – they protect the environment and are easy on your wallet. But you should of course also like the new windows! They should also suit your lifestyle and your needs. So when seeking new windows, look closely at all the details and not just the U-value.

We have compiled the most important elements to look out for when purchasing new windows:

  • Brightness – let there be light!
    Do windows with large glass surfaces and a slim frame allow enough light to penetrate your living space?
  • Convenience and technology – already think about tomorrow today
    Have sturdy, high-tech materials been used to produce the windows? Do they have easy to clean folds? Is accessibility important to you?
  • Security – making life difficult for burglars
    Do the windows have sturdy profiles and fittings, lockable handles and special glass panes?
  • Design – windows as a design element
    Do modern windows match your building perfectly in terms of material and colour? Either by blending in or as a colourful contrast?
  • Smart homes – digital homes
    Dare to live in a smart, extremely convenient home? With programmable roller shutters, storm warnings and opening detectors on the windows?

If you consider these elements when buying your new windows, nothing can actually go wrong. As you can see: with new windows, you might not have to air less, but you can save a lot of energy and money while simultaneously and also automatically protecting the environment.

So? When will you start replacing the windows?

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