heating and ventilation

whatnots2015

I live in a rented property and have recently become aware of black spots possibly of mildew appearing inside the house on the external walls and there has always been black mould around a window where the double glazing unit has blown, meaning that there is condensation between the panes. My landlord simply said that I should open the windows more often! Yet last winter I couldn't get the indoor temperature above 15 degrees centigrade even after the heating had been on for several hours. The person who serviced the boiler said that it didn't have a very high output. I suppose my question is, given that the heating system cannot heat the house adequately, will opening windows more often thereby making the house even colder make the mould and mildew even worse? I keep the bathroom and kitchen windows open a fraction all the time and often cook with the back door open as there are no trickle vents or extractor fans or cooker hoods in the property. Any thoughts would be much appreciated.

tacpot12

You need to report the situation to your local authority. They will have a team that deals with repair issues in private rented accommodation. 

If the heating system cannot heat the house above 15 degrees centigrade this is not enough to avoid mould and other health problems. The team at the local authority can serve an improvement notice on your landlord to:

• install extractor fans in the kitchen and bathroom,
• install more radiators and an uprated boiler (and a thermostat if the system doesn't have one),
• fix the failed double glazing unit.

RelievedSheff

How often and for how long do you heat the house?

It takes a long time to heat a house through from stone cold. You have to heat the whole fabric of the building. It may be that if you have your heating on for longer then the heating will raise the temperature in the house further as the building warms through which will discourage the mould growth.

There is no getting round the fact that you need adequate ventilation as well and if you don't have trickle vents and extractor fans then that means opening the windows to air the building through.

Mickey666

tacpot12 said:

You need to report the situation to your local authority. They will have a team that deals with repair issues in private rented accommodation. 

If the heating system cannot heat the house above 15 degrees centigrade this is not enough to avoid mould and other health problems. The team at the local authority can serve an improvement notice on your landlord to:

• install extractor fans in the kitchen and bathroom,
• install more radiators and an uprated boiler (and a thermostat if the system doesn't have one),
• fix the failed double glazing unit.

Mould is not temperature-related.  I have some rooms in my house that have no heating and are therefore pretty cold in winter yet none of them have any mould.
Mould is far more likely to be a ventilation issue.  Poor ventilation causes a build-up of humidity and the warmer the air the more moisture it can hold so the worse the condensation when it occurs, leading to mould growth.

tacpot12

In my experience, mould is temperature related. If the property is heated properly, condensation does not form because the walls and ceilings are above the dewpoint, even at very high levels of RH.

I would agree that you need ventilation to cure the problem, hence the expectation that extractor fans will be needed, but heating the property correctly is necessary to allow the humid air to be exhausted before the water can condense on cold surfaces. Correct heating lowers the RH and prevents condensation, which is the root cause of the mould.
 
I forgot to mention that the extractor fans should be controlled by a humidistat, not by a human. Humans are unreliable. Positive Pressure Ventilation is another solution, but this requires trickle vents and might require boosting when humidistat in the kitchen or bathroom senses a high RH. 

Mickey666

I agree that mould can be temperature-related, but my point was that it's not a simple relationship, as evidenced by my unheated rooms having no mould or damp problems (not all are unheated, I hasten to add!).

Unfortunately, our energy-conscious times have led us towards hermetically sealed houses leading to poorly ventilated homes.  I suspect this is a contributory factor towards the increasing prevalence of asthma and other respiratory and allergy conditions in children today as compared to the 'good old days'.  There's a lot to be said for fresh air and wearing wooly jumpers in winter instead of shorts and tee-shirts all year around.

Yes, I know, silly old fogie

Doozergirl

Mickey666 said:

tacpot12 said:

You need to report the situation to your local authority. They will have a team that deals with repair issues in private rented accommodation. 

If the heating system cannot heat the house above 15 degrees centigrade this is not enough to avoid mould and other health problems. The team at the local authority can serve an improvement notice on your landlord to:

• install extractor fans in the kitchen and bathroom,
• install more radiators and an uprated boiler (and a thermostat if the system doesn't have one),
• fix the failed double glazing unit.

Mould is not temperature-related.  I have some rooms in my house that have no heating and are therefore pretty cold in winter yet none of them have any mould.
Mould is far more likely to be a ventilation issue.  Poor ventilation causes a build-up of humidity and the warmer the air the more moisture it can hold so the worse the condensation when it occurs, leading to mould growth.

If a wall is cold and the humidity high, the dew point on that wall is low.  Any cold spots will develop condensation.  Mould does go hand in hand with condensation.  

It is both a heat and ventilation issue.  Opening the windows will only serve to keep the walls cold and it won't help remove condensation.  

It is problem with the fabric of the building, but only being 15 degrees isn't going to help.  The OP should be speaking to the local authority as that is unacceptable.  It makes me so angry when landlords are only in it for themselves! 

Doozergirl

Mickey666 said:

I agree that mould can be temperature-related, but my point was that it's not a simple relationship, as evidenced by my unheated rooms having no mould or damp problems (not all are unheated, I hasten to add!).

Unfortunately, our energy-conscious times have led us towards hermetically sealed houses leading to poorly ventilated homes.  I suspect this is a contributory factor towards the increasing prevalence of asthma and other respiratory and allergy conditions in children today as compared to the 'good old days'.  There's a lot to be said for fresh air and wearing wooly jumpers in winter instead of shorts and tee-shirts all year around.

Yes, I know, silly old fogie

Energy consciousness still requires ventilation. It's ignorance, not by recommendation.  Windows still require trickle vents, wet rooms still require extraction.  People just don't get it.  

I now live in an otherwise hermetically sealed box by design, but we have *fresh*, warm air via mechanical heat recovery and ventilation.  

whatnots2015

Thank you for taking the time to reply! It's interesting to read about the relationship between temperature, ventilation and condensation.

We heat the house for 7 to 12 hours a day, 7 days a week. I remember one of my relatives' home developing mouldy furniture but think that this must have been as the house was empty for a few months.

We're currently keeping our community safe by self-isolating at home so scheduled to be in this cold prison for two weeks with no respite out at work full time or out anywhere except the outside yard. The thermometer says that the temperature is currently a balmy 19 degrees but I can feel the cold air blowing about from the open windows. And it's quite mild and still at the moment outside!

I have circulation problems so being cold is not really an option for me. I am currently wearing five layers including my woolly coat and had to stay elsewhere last winter as home was just too cold.