Causes and Prevention
Condensation on windows is something most people have experienced at some point in their lives. It can appear virtually anywhere in your home if the conditions are right. In this article, we will explore why it appears on our windows. You may have seen it inside your kitchen or bedroom, between your glass panes, or even on the outside of your windows. But how does it form? And what can you do to prevent it?
Understanding the Invisible Water Around Us
Water is all around us, in the air in vapor form. It's not visible to the human eye, but we can certainly feel it on humid days. The scientific definition of condensation is the process by which a gas or vapor changes into a liquid. Air can hold a limited amount of water; this changes as the temperature rises and falls. As the air temperature rises, it can hold more water. Once the air reaches its water capacity, it is considered saturated.
If a surface is cooler than the saturated air, then the moisture is pulled from the air and gathers as droplets, in our case, on the glass. Condensation can gather on different areas of the window for different reasons, but it always occurs when air with a high moisture content comes into contact with a cold surface. It is often assumed there is a fault with the window or double glazing, but with the exception of one instance, it is not.
Understanding Window Condensation: Internal, Between Panes, and External
Inside the window on the glass (internal condensation):
This mostly occurs when we have too much moisture inside our home. The glass can look foggy and droplets appear in the lower corners of the glass units. Extreme cases will see water running down the windows and pooling on the internal window boards; this can look like a window is leaking.
Inside the unit between the glass panes:
Water can form between the panes of glass. This can spoil our view and look unsightly.
Outside the window on the glass (external condensation):
This can occur on new energy-efficient windows and often happens on a still damp morning. Condensation can form on the outside of the glass and obscure our view.
Understanding and Managing Condensation in Your Home
Condensation in our homes can be a serious problem. Modern energy-efficient windows make our rooms warmer. The downside to these improvements is less ventilation and fewer air cycles. This results in higher levels of humidity within our homes created by us living our everyday lives. The moisture we create via breathing, making a cup of tea, showering, cooking, and laundry (the list goes on) has nowhere to escape.
As the humidity of a room increases, the moisture, which has nowhere to go, will begin to form on the coldest surface first. This is usually the glass on your windows. Homes with excessively high water content in the atmosphere can experience damage to paintwork, curtains, wallpaper, and window fittings. Sometimes it will look like the window is leaking in extreme circumstances. The question is, how do you solve these issues without compromising your comfort?
The four main factors which contribute to condensation on double and triple glazed windows are:
Water vapor content of the air
Inside room temperature
Outside temperature
Variation between the inside room temperature, the outside temperature, and the glazing
Points 1 and 2 are the only factors we can control. Making the right changes to these will reduce internal condensation.
The Importance of Moisture Control in Home Ventilation
Simply living and breathing inside our homes releases moisture into our atmosphere. There are various ways to control the level of moisture in the air inside our homes with different types of ventilation like kitchen and bathroom extractor fans, background ventilation via trickle vents with our windows, or by using purge ventilation, e.g., opening a window while generating excess moisture like cooking and washing, for example. Some new homes don't require window trickle vents and are built with a HVAC system which controls the air within your home. These are excellent for controlling your air but can be very expensive or sometimes impossible to retrofit to existing properties.
Sometimes our living habits and activities can be the cause of condensation. For example, drying clothes indoors can contribute to high moisture levels. Consider using an outdoor washing line or a tumble dryer. In serious cases that require immediate results, a portable dehumidifier can be very effective.
Preventing Condensation on Windows: Tips for a Warmer, Drier Home
Upgrading to energy-efficient double or triple-glazed windows is a very effective way of increasing room temperature due to them being a big cause of heat loss. The higher surface temperature of the glass within the room makes the air in the room warmer, which allows it to hold more water vapor, reducing condensation. Chances of condensation are generally reduced when more energy-efficient glazing replaces older glazing.
People often believe that double-glazed or triple-glazed windows should never condensate unless faulty. However, it is important to remember that while energy-efficient windows are warmer, they cannot control the level of moisture in the air. If the moisture in the atmosphere becomes too high, it will begin to condensate, starting with the coldest surface in the room, which naturally is the glass on your windows.
High water content in the air and a low glass surface temperature are the key factors leading to condensation on your windows. To prevent these problems from occurring, it is important to remove excess moisture and lower the water content of the atmosphere by ventilating rooms.
Here is a list of steps you can take to help reduce condensation forming on your windows:
Provide your rooms with natural ventilation by opening a window, through a trickle vent, or through an airbrick.
If you have airbricks, be sure they are not blocked or obstructed, reducing airflow.
Open a window in every room for a short part of each day to allow an air cycle to take place, replacing old air with new fresh air.
Use extractors in bathrooms and kitchens when in use.
Be sure your home is draught-proof, particularly bathrooms and kitchens.
Try to keep bathroom and kitchen doors closed where possible to reduce the amount of air with high water content traveling around your home.
Increase the air temperature of rooms which are more susceptible to condensation; sometimes 1 or 2 degrees can make all the difference.
Understanding Condensation in Double and Triple-Glazed Units
Condensation occurs between two panes of glass when the hermetic seal has failed. Double-glazed and triple-glazed units are airtight. Air from outside the unit can leak in when the hermetic seal fails, bringing in moisture with it. Over time, the water content will increase within the unit, and when the temperature is right, it will condense on the inside of the panes.
Once a unit loses its seal and begins to break down, it will need replacing. Depending on its age, your unit may still be under warranty with your installer, meaning a replacement could be free of charge. However, if your unit is out of warranty, we can provide you with a free, no-obligation quotation to replace it. Sometimes, all we need is a brief description or photograph with rough sizes to provide you with a price. This information can be sent to info@supreme-windows.com. If you accept or we need more information, our service engineer will arrange a site survey.
The Science Behind External Condensation on Modern Windows and Doors
Yes, you did read that correctly. You may be one of the few who has woken up with condensation on your windows and, on closer inspection, discovered it's on the outside. External condensation can occur in certain weather conditions due to recent technological advancements in double and triple glazing. Newer energy-efficient windows and doors tend to be more susceptible to external condensation as a result of better-performing glass. This is completely natural, and although not ideal, it is actually a great sign that your windows and doors are preventing heat loss. As we mentioned earlier, water begins to condensate on the coldest surface first.
Old, non-energy-efficient windows allow too much heat to escape through the glass. The external pane is warmed up as your heat passes through it to the outside. This means the external surface is too warm to condensate. New energy-efficient glazing has a special transparent coating. This coating reflects heat back into your home and helps prevent it from escaping and warming the external pane of glass. As less heat is passing through the external pane, it stays cooler and allows for condensation to gather in certain conditions, usually on still, cold mornings in spring and autumn.
External condensation is caused by external atmospheric conditions and, as a result, little can be done to combat it. It will naturally clear itself by evaporating as the air temperature rises. You can obviously remove it yourself with a squeegee if desired. External condensation on windows and doors is a result of thermally efficient glazing and shows that they are working as they should. It is not detrimental to the products and is not considered a fault.
