Home Ventilation

During the colder months of the year and with rising energy prices, we all seek to eliminate draughts for home comfort and to reduce expenses. It is, however, also important to consider the ventilation of your property during this time. Often overlooked, insufficient ventilation can lead to the warm, humid air trapped within the property, condensing upon colder surfaces (such as around window openings and to external facing walls). If this is allowed to persist, it can lead to damp, mould growth and poor internal air qaulity.

Recently, the risk to health of damp and mould have been well publicised; the NHS website states: if you have damp and mould in your home you’re more likely to have respiratory problems, respiratory infections, allergies or asthma. Damp and mould can also affect the immune system.

In addition, to the risk to health, condensation and poor ventilation can also lead to damage of the internal decorations of a property (dark patches on walls/peeling paper/bubbling paint) as well as a failure of plaster, early decay to timber fittings and, in severe cases, the timber structure of the building itself (such as timber floor and roof structures). Whilst it is possible to redecorate in the case of minor humidity issues, improved ventilation will help to safeguard against the onset of more serious problems.

How can you ventilate your property in the winter months?

A number of measures can be taken to reduce humidity levels within a property and we have outlined a few ideas below:

Ventilate rooms such as bathrooms, shower rooms, kitchens, utility spaces and laundry areas effectively as these areas will naturally produce higher amounts of humidity.

When in use, ensure that the doors to these spaces are closed to reduce the spread of humidity throughout the home.

Any windows should also be left open for a suitable amount of time after showering/bathing to allow for warm, humid air to exit. Ideally, all windows should feature trickle vents and these should also be left in the open position to provide background ventilation throughout the dwelling.

Try to limit the amount of moisture production within the home - drying clothes indoors, for example, will introduce additional humidity into the dwelling. If clothes are being dried indoors, close the door to the room and ensure the space is sufficiently ventilated. Any tumble dryers should also be suitably vented. It is important to highlight that condenser dryers will still emit humidity into the air.

Cooking and sleeping are also key culprits of humidity - one person sleeping in a room can emit up to 500ml of water into the air (often leading to an inner mist on the windows during colder mornings). Using a towel to dry moisture from the surface of windows in the morning will prevent the reproduction of humidity when these surfaces heat up.

During the day, we recommend that internal doors within the home are left open to allow air to circulate within the property (please note that fire doors should be closed at night to ensure the fire safety of the dwelling).

Consider investing in a humidity monitor – these items can be purchased for under £30. Ideally, humidity within your home should be at 50-55% to prevent mould growth. It is worth noting that mould is much more likely to occur where the humidity level is at 70% or more for sustained periods of time.

Though many of us are cutting back on the use of heating, allowing your home to repeatedly heat and cool will increase the production of condensation. Suitable insulation will also help to minimise the cold entering your home and keep internal walls warmer. In this way, these surfaces will not be as susceptible to condensation forming upon them (as well as saving you money in the longer term). See our Blog on improving the energy efficiency of your home here: https://www.calsurv.co.uk/surveyorsnotes/2022/4/18/how-to-improve-your-energy-efficiency-and-reduce-the-effect-of-rising-energy-prices

Where possible, ventilation systems should be installed in rooms susceptible to higher humidity to allow for excess moisture to be removed from the air. We have outlined some ventilation systems below:

• Standard mechanical ventilation. This type of ventilation uses an extractor fan to remove air. To operate effectively, this should be left on for a suitable amount of time to allow for humid air to fully disperse. As many of us tend to turn such items off when leaving a room, this type of ventilation can prove ineffective.

• Humidity activated ventilation. This type of system, as stated, is activated by the presence of humidity. Humidity activated ventilation is more effective than mechanical ventilation as the extraction function will continue to operate until a safe level of humidity is restored. These cost of these items ranges from around £50 - £200 (excluding the cost of installation).

• Single room heat recovery. This type of unit continuously extracts moist air, keeping room temperatures more consistent and, therefore, conserving energy and warmth within the home. These units are typically sourced at a cost of around £400 - £700 (excluding installation).

• Where ventilation systems can not be readily installed (for instance if you are renting a dwelling) consider the use of a dehumidifier to reduce internal humidity. A good quality dehumidifier can be purchased for around £300 and can be taken with you when you move on.

Don’t forget floor and loft spaces…

It may seem counterintuitive; however, the roof and sub floor voids (present within timber framed properties) require ventilation. If these areas are not adequately ventilated, humidity can become trapped within the voids and this can lead to the degradation of the structure of the building (as well as giving rise to the risk of wood boring beetle infestation). If you are seeking to insulate the roof structure, remember to ensure that any insulation does not seal the roof coverings but is of a sufficient level to preserve heat within the living areas. In addition, it is important that any floor vents are not obstructed or sealed and that there are adequate vents in place to provide a cross flow of air to the floor structure.

In summary, it may feel wasteful to allow heat and humid air to escape a property, however, the risks to health and the building fabric from high humidity levels are clear. Simple measures can be employed to help improve ventilation, however, if humidity issues persist, then we recommend specialist advice is sought to offer specific recommendations for treatment.