Question about what the humidity should be in a modern home.

[problem_solving]

Hello everyone

I understand that humidity changes, however I have no doubt that there is a standard. It’s this that I am looking for.

As the new builds from what I have been told are vacuumed sealed and air is put in under pressure to find any minor air leaks. 

So on such a build as this, when there’s nobody living in the building there will be a humidity that that building will be at. At the very least there will be a range.

So then when we look into the older builds there are some key differences, from the new builds. I’m now looking into the hows and whys.

As I find it interesting that the new builds have a humidity that super dry that your throat hurts, and yet in some buildings that this is not the case. 

After all there are not to many differences. 

So I would be grateful of any advice. 

Thank you all in advance.

[Adsibob]

It’s all to do with the level of ventilation vs the level of human occupation. If humans (and animals) live in a property they produce humidity. If the property is very well ventilated, the ventilation will help counter act the humidity. If the property is not well ventilated, then the humidity caused by the occupants will create damp. It is more complicated than this, but that’sa quick summary.

 Old properties are usually pooorly insulated and ventilation is mixed (some have better ventilation than others). New builds have very good insulation and very good ventilation.

You want to aim for about 35% to 55% relative humidity. Within that range it shouldn’t be too dry (which is what causes a dry throat) or too moist. It will naturally fluctuate, but within that range you will be fine. If you have something like MVHR it will be more stable. Here is a graph of my bathroom’s ambient conditions.

 

 

You will see it is pretty stable between 45% and 55% except for a peak where it almost reached 80%. That was when I was showering and so it peaked very quickly, but because we have MVHR it cleared the humidity very quickly.

Edited December 3, 2022 by Adsibob

[JohnMo]

To add to the above, if you have a prolonged cold period outside, such as central Europe experiences, and MVHR, then as you heat the incoming air with out going air, you can do reduce the relative humidity.

 

A big house with only one person in it with sub zero temps for quite a few days could experience well below normal humidity levels.  But not sure it's that likely in the UK.

 

Our house today is sitting at 42% RH and 20 degrees inside, 6 degs outside and 77% RH outside.