Preventing Condensation on Windows

Droplets of condensation appearing on bedroom windows in the morning is a common sight around the UK and is caused when warm moist air that builds up overnight comes into contact with the cold glass surface.  Condensation on your windows is not a problem in itself, but it can be both a signal that there is a wider problem with moisture levels and ventilation in your home, and if left untreated, can cause damage to surrounding walls and causse wooden window frames to rot over time.

What Causes Condensation on Windows?

Condensation can appear on any surface in your home that is cooler than the ambient air.  At any given pressure and temperature, air has the capacity to carry a specific amount of water vapour.  When the air comes into contact with cooler surfaces such as windows or walls, the amount of moisture that the air can hold falls, and that water is deposited onto the surface.

Condensation can appear almost anywhere in your home but is often most noticeable on bedroom windows when you wake up in the morning.

Many household activities contribute to the amount of moisture that is in the air including cooking, cleaning, and bathing, In the case of condensation appearing on bedroom windows in the morning, the main culprit will be night-time breathing. 

Most people do not run their heating at full blast overnight and tend to close their bedroom door to prevent any noises from the rest of the house disturbing sleep.  In these conditions, the temperature in the air of the room can gradually drop over time, and the water vapour exhaled by residents can build up.

According to ISSE (The Institute of Specialist Surveyors and Engineers), the average person exhales about 40g of water per hour when sleeping.  Over the course of 8 hours of sleep, a couple in a room can exhale a total of 640g of moisture.  This amount, coupled with the cooler temperatures at night is the main cause of window condensation in the morning.

Is Condensation on Windows a Problem?

The condensation on your windows is not a problem itself, although you should wipe it away in the morning to prevent it standing.  The problem with condensation is that if it is allowed to soak into porous surfaces such as plaster or wood, it can become damp, which provides a good environment for moulds to grow that can be damaging to your health.

How to Prevent Condensation on Windows

Poor night-time airflow in bedrooms is the main reason why you will see condensation in the morning.  Moisture rich air that we breathe out at night cannot escape from a bedroom with the doors and windows closed, so the humidity gradually increases.

The most effective way of ensuring that air flow remains steady throughout the day is to install a whole house ventilation system that will gradually feed fresh air from outdoors into each room of your home over the course of the day.

Positive Input Ventilation systems are cost effective and energy efficient.  They feature a centrally mounted unit – usually in your loft – which is connected to vents throughout the home where fresh air is released.  This constant gentle flow of air keeps humidity constant and prevents condensation from forming as a result.

Find out More

For more information about how positive input ventilation systems work, and to get advice about preventing condensation and the damp problems that it can cause, please contact us today to book a free home survey from your local ventilation specialist.  They will be able to assess your needs and recommend the best solution for your home