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Damp toolbox 2: Tips to reduce moisture getting into the air in the first place

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The headlines

The previous article in this series explains:

  • Why we have damp issues in UK homes.

  • The many problems it causes and costs it affects.

This article addresses the main causes of damp in homes, US!


It gives you:

  • A thorough understanding of all the daily activities in a home that generate damp air (and specifically how much in some cases).

  • Practical tips on how you can reduce the amount of water you put into the air in your daily activities.

The air in a typical home is able to hold around 2 litres of water vapour.


However, showering, cooking and a wide range of other activities adds to that all the time. It is estimated that each adult adds between 2 and 4 litres of additional water into the air in a home every day.


Reducing this amount by any way you can is a really powerful way of reducing damp and condensation issues.

 

Quick links to sections below:

Showering

Baths

Cooking

Washing

Laundry drying indoors

Other sources of humidity and tips

Links to my other articles on damp

 

Why it's worth the effort to reduce the water you put into the air

Every drop of water you can keep out of the air gives immediate benefits:

  1. Reduces the need to put the heating on or turn it up.

  2. Less need to own or use a dehumidifier.

  3. A reduced (but not eliminated) need for ventilation.

  4. A more comfortable home.

  5. Reduced mould growth and a reduction in some indoor pollutants.

There are only up sides and no down sides trying to reduce the amount of moisture you generate in a home.

 

Sources of damp explained, with practical tips on how to reduce it entering the air in a home

Some of the tips below can have a big impact on reducing humidity levels.

Other tips have small benefits and sound a bit geeky. I am listing them all anyway to highlight how many different sources of damp air there are in a home.

If you have any other tips, please do let me know and I'll add them.

Keep in mind these figures when reading the next sections: The air in a home already holds around 2 litres of water. At the very most it can hold is 3 litres. A home with 3 litres of air in it would feel very unpleasant.

 

Showering and bathing

The average person uses around 50 litres of hot water per day. Some as much as 100 litres a day. A large proportion of this is due to shower and bath use.

Showering and bathing both put a lot of moisture into the air which is why I am covering them first.


Showering

Sadly, warm fine jets of water from a showerhead are one of the best ways to put water into the air. We see the effect of this as 'streaming up' of mirrors. and glass.

Tips to reduce this:

  • Close the door to the shower / bathroom. This will then prevent the moist air from spreading into the rest of your home.

  • Reduce the water flow rate - A powerful flow of water will put much more water into the air than a gentle shower. Most shower controls will allow you to reduce the flow rate.

  • Reduce shower time - More minutes means more fine water droplets are absorbed by the air.

  • A hot "steamy" shower - Puts a lot more water into the air than a lower temperature shower.

  • Shower using the 'caravanner' method - This is where you run the shower briefly to wet yourself. You then turn the shower off to apply soap and shampoo, and then turn the shower on a second time to rinse off.

  • During (or at least after) the shower open a window an inch or two to ventilate the room. The aim is to completely replace the damp air in the room. Ensure the door to the shower room remains closed when you leave the room. Ideally leave the room like this, with the window open and door closed, until all wet surfaces are dry.

  • Use an extractor fan if there is one. Leave it on for some ten minutes or so after a shower if it doesn't have an automatic timer.

  • If you’re thinking of installing or replacing an extractor fan, consider one with a humidity sensor. This will ensure the extractor continues to run until the humidity level in the bathroom has been sufficiently lowered.

  • REALLY IMPORTANT. Wipe down surfaces. The wet surfaces after a shower all add up to around 200ml or 0.2 litres of water, almost half a pint. If you don't wipe away this water it will dry off, and that water will go into the surrounding air.

  • A towel will absorb around 100ml or 0.1 litres of water when you dry off after a shower or bath. That water will dry off into the air in the home during the day. There is little you can do to avoid this. But if there are several people showering each day this all adds up to a big addition to the 2 litres or water that will already be in the air in the home.

  • If you use a flannel or a wiping cloth for wiping surfaces down, squeeze out as much water as you can down the plug hole. Don't just let it sit there full of water as it will just evaporate into the air.

  • Alternatively, wipe the water from shower surfaces and bathtubs into the drain using one of these.

  • The most effective solution is to use a window vac on any wet surfaces such as one of these. It captures the water so you can pour it directly away. They range in price from £13 (Aldi) to £40.

 

Baths

The tips above for showers mostly apply to bath time as well, but here are some bath specific tips.


Baths increase the humidity in a home because they expose a big area of hot 'steamy' water to the air.

  • If bathing small children use a kids plastic bath inside the main bath. This reduces the amount of water exposed to the air during the bath, as well as using less water and energy.

  • Just as longer showers put more moisture into the air, the same is true of longer baths.

 

Cooking

Cooking with hot water, and heating food by any method releases water into the air. This is the case even when cooking food in an enclosed space such as an oven, air fryer or heating a pizza under a grill.

  • If possible, keep the internal kitchen door closed and open a window a little during cooking. This will trap the moist air in the kitchen while it's being replaced by fresher air from the window.

  • If boiling – vegetables, pasta, rice, etc. - keep the lid on the pan as much as possible. As well as reducing humidity it will also save a decent amount of energy too. Boiling a pan of potatoes puts over 100ml of water into the air if you leave the lid off the pan. And, once boiling is complete, if you delay taking the lid off the pan by a few seconds you’ll avoid the steamy plume.

  • Covering items being reheated in a microwave will reduce the amount of water released into the air.

  • Use the extractor fan if it extracts air out of the building. If the extractor hood is one that just recirculates the air inside the room (as some do) all the hood will do is chuck the damp air from cooking back into the room.

  • Even use an extractor when cooking in a frying pan. Foods such as bacon, mushrooms, or eggs for example all release water when being cooked.


  • Try to avoid simmering at a high temperature. Most boiled foods will cook on a gentle simmer with a lid on.

  • Even if you use an extractor, a kitchen may feel humid or stuffy when you’ve finished cooking. There might also be condensation on the windows. Leave a window open, extractor on and door closed for a few minutes until it clears.

 

Washing dishes

  • Washing up in a sink in super steamy hot water is only generally needed for greasy items in my experience. Washing in a sink with lower temperature water will reduce the amount of water going into the air (also saving you energy).

  • Washing up in a plastic bowl as opposed to the sink will reduce the amount of water exposed to the air.

  • Pour away the water when it is no longer needed. Even luke-warm water sitting in the bowl will create moist air.

  • Wipe down surfaces and squeeze as much water as you can out of dishcloths directly down the plug hole.

  • Dishwashers are great at keeping moisture out of the air when running. But avoid creating the 'steam rush' you see in the photo below. Once the machine has completed its wash cycle, wait for it to cool down. On my own dishwasher this means leaving it to cool for a good half hour.

Opening the door early releases lots of water into the air
Wait for it to cool before opening the door
  • Avoid opening a dishwasher part way through its cycle as this can often mean a steam rush too.

 

Laundry drying indoors

A 2019 survey found that 81% of homes dry laundry indoors during the winter months.

A laundry wash load can contain anywhere between 0.7 and 3 litres of water. I know this from geeky measurements I've made 🙄, accurately weighing laundry before and after a washing and drying. Sad fella I am!

Laundry drying indoors is one of the most common and significant contributors to damp air in a home, especially in busy households with many laundry loads each week.

When drying laundry indoors it doesn't matter whether you dry it quickly or slowly, or whether you are drying it somewhere cool or warm.... ALL that water goes into the air in the home.

The Energy Savings Trust and other independent experts recommend that drying laundry indoors should be done in a room with the door closed and the window open. It only needs to be open a crack, even in cool weather. This will allow fresh air from outside to replace the humid air that exists around the laundry.


There are also ways to reduce the amount of laundry that needs to be dried which will help:

  • Use smaller towels. Towels which are half the size will hold half the moisture. Drying them will put less water into the air than large ones. Smaller towels also take up less space in the washing machine, so you may be able to do fewer washes.

  • Challenge yourself on how often you wash towels. I know someone who washes them after just one use.

  • Dry laundry outdoors if you are able to. Even in winter you can expect 70-80% of moisture to be removed, especially if there is a breeze of any sort. See my other article here with creative ways to dry laundry outdoors including a weather forecasting tool focussed on laundry drying outside.

  • Plan ahead. Wash items that absorb a lot of water, like towels and jeans, on days which are the forecast to be dry and breezy.


Giving laundry a second spin in the machine?

  • I've done experiments measuring how much water a second spin cycle actually gets rid of.

  • The best results I had were with adult cotton 'towel' dressing gowns. Each dressing gown held around 700ml water at the end of the first 1400 spin. An extra spin only reduced this by around 50ml, which is about 3 tablespoons of water. Not much!

  • I really don't think doing a second spin is worth it given that spinning is one of the most stressful things a washing machine does.

Super high speed spin dryers

There are dedicated spin dryer products on the market that can spin up to 2800RPM such as this one. I've seen one Facebook user reporting great success in using one of these to extract EVEN MORE water from laundry. This is a significant cost and space investment but might be attractive to some people.



Other tips on laundry:

  • If your tumble dryer is the vented type, never vent it into the home. It might seem attractive to have all that vented air warming the place up. But, that air is holding a whole heap of water. This warm humid air might feel nice at first. But it will soon cool down to create a clammy-feeling humid air and be let loose to cause damp problems 'somewhere' in the home.

  • Some people dry laundry by hanging items in a warm airing cupboard, or over radiators. These methods dry laundry really quickly, BUT, they will also put all that moisture into the air over a short space of time. Ventilation is particularly important when drying laundry this way, even though the air might not feel damp near the laundry.

  • Challenge yourself as to why you need to wash some laundry items as often as you do. Items like trousers and jumpers can be worn (in my opinion!) many times before needing a wash.

 

Other sources of indoor humidity and tips

  • Using a window vac to remove condensation on windows is a great help. If you do this, this will prevent all that water from entering the home again.

  • Breathing - Humans themselves are a significant source of humidity in the home. Adult men generate around 400ml in 24 hours just by breathing. We are all familiar with the "steam" in our breath when we are outside in very cold weather. We breathe this moist air out all the time including indoors of course.

  • Sleeping - open a window at night. Around 30% of people do this. This is partly to get rid of the humid air that accumulates in the bedroom as we breathe, but have shown it improves sleep quality and alertness the following day.

  • Perspiration - I know this sounds like a lot...but adults give off up to 400ml per day of water in the form of perspiration. This will be higher if you exercise. If you use a treadmill at home for example, consider keeping the door closed and opening a window a little in the room.

  • Steam mops - The tank in these normally holds around 250ml of water. All of that water goes into the air when you mop. At the end of steaming damp mop head also holds around 100ml of water at the end, so it you just let it air dry in the home that water will just go into the air. Try to dry it outside if you can.

Damp steam cloth mop water content
A damp steam clothe will hold around 100ml of water
  • Steam irons - The water tank in our iron holds 300ml. That water will all go into the air in the room when ironing. Ironing damp clothes will of course also contribute to indoor humidity. If it's possible to, ventilate the room in which the ironing is done.

  • Carpet shampooing - A vax carpet cleaner has a 2.7 litre clean tank and a 1.5 litre dirty tank. This suggests that 1.2 litres of water will be absorbed into the carpet during shampooing. Cleaning carpets in this way is best done during the warmer months when doors and windows can be opened.

  • Kettle boiling, hot mugs of drink, hot tea bags left out by the sink....all create moisture in the air. Every time you boil a kettle it puts between 10 and 20ml of water into the air (roughly a tablespoon full). That doesn't sound a lot but if you are big tea drinkers or use the kettle a lot it all adds up. (These numbers are from geeky measurements I've made btw 😁.)

  • Wet umbrellas, wet anoraks, wet or sweaty running gear or gym kit will all add to internal moisture if they are air dried indoors. Shake off what moisture you can outdoors.

  • Portable indoor gas heaters give off significant amounts of water. They produce roughly 1 litre of water for every litre of gas burnt so ventilation is essential when using them.

  • If you have a fish tank or aquarium, cover the top. This will be especially important if the tank water is heated. The warmer the water, the more quickly it will evaporate into the air.

  • Our dog is like a sponge if we walk him in the rain. If you have a damp dog after a walk, give pooch a dry down with a towel before it comes back into the house. But.....there is wicked catch (haha...); the towel now holds the water that was on the dog!

 

Quick links to the other main articles on this subject.

Other supporting articles on damp:

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Thanks.


Mark Thompson


Get Energy Savvy - simple practical home energy efficiency information

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