The main problems that homeowners face in winter is condensation on windows. You may have noticed moisture or fog building on your windows. It can be frustrating and if left unchecked can lead to damage. In this guide, we will look at the reasons behind window condensation in winter, and the solutions to these problems and how moisture can become a health or energy developer issue. If we understand the factors behind condensation, will enable us to enjoy a more comfortable and healthy home this winter.
Why do windows sweat in the winter?
For homeowners, winter means dealing with window condensation, but why does this happen? When warm air inside the house comes in contact with the outside cold window, the air cools down and loses its moisture, potentially creating condensation. This process is when the air reaches the dew point, a point where the air fully loses its moisture. The outer surface of the windows cools the air inside the house to its dew point which means the air is losing moisture to the windows surfaces.
This process involves two concepts which are the indoor humidity and the dew point which represents the air moisture level. The higher the humidity inside a house means the higher chances of condensation on the windows surface.
Are condensation on windows a sign of worries or totally normal?
During winter, a few droplets of moisture building up on windows are normal as condensation occurs. If moisture retention continues, it indicates other underlying problems of the home. Moisture retention on windows is a sign of poor ventilation or insulation problems in the home.
Also, it’s a good practice to start learning the difference between the condensation inside the home and that from the outside. The condensation from outside of the home occurs when the air from inside the home meets the colder outside air and the moisture in the air freezes. This is considered a sign of normal minor worries and is a part of nature. It is the condensation on the inside windows of the home that indicates a possible insufficiency in the home ventilation, humidity regulation or insulation, and these are the big worries.
Condensation and Indoor Humidity
The key to managing window moisture in the winter is understanding relative humidity. An important factor in the process of condensation is relative humidity (RH). The greater the humidity contained in the air within your home, the greater the possibility of condensation occurring on your windows. This is especially critical in the winter, when the air outside is dry and we use thermal devices that potentially aggravate the moisture levels in our home.
What is Relative Humidity?
Relative humidity, is the amount of water vapor present in air, expressed as a percentage of the total that the air can hold at that temperature. Because the air is warmer when you heat your home in the winter, it can hold more moisture, so when your windows are cold, condensation is more likely.
Recommended Indoor Humidity Levels in Winter
Consider the following chart for recommended Indoor Humidity Levels for the Winter based on the Outdoor Temperatures.
| Outdoor Temperature | Recommended Indoor Humidity |
|---|---|
| 20°F to 40°F | 35–40% |
| 0°F to 20°F | 30–35% |
| Below 0°F | 25–30% |
Maintaining the recommended Indoor Humidity Levels increases your comfort levels, energy efficiency, and reliability.
Common Causes of Excess Window Moisture
Moisture fogging the inside of your windows can be blamed on a few things.
High Indoor Humidity
The more on the go your household is the more indoor humidity levels are raised. Modern society incorporates increased levels of Indoor Humidity into their lifestyles from cooking, to drying laundry, to upgrading their shower to include steam and even showering in them!
Poor Ventilation
Let us talk about ventilation. Moisture can be trapped in your home due to poor ventilation. This can be especially pronounced in bathrooms, kitchens, and laundry rooms. If your absoultely no ventilation systems your home can become even more prone to window fogging due to increased levels of moisture trapped inside.
Windows That are Cold or Poorly Insulated
Windows that are cold, especially those that are poorly insulated, are more likely to develop significant condensation. Since there is poor insulation, heat that is generated in the home escapes, and the surface of the window becomes cooler, resulting in moisture build up.
Air Leaks Around the Windows
Even the smallest of imperfections around windows can allow moisture to come into contract with the cold surface of the glass, resulting in condensation. The leaks around windows contribute to window moisture and diminish the overall energy efficiency of your home, and increases the effort needed to maintain a comfortable indoor temperature.
Cause–Effect–Solution Matrix
Understanding the causes of window moisture is only the first step. The matrix below gives guidance on what works to fix the problems.
| Cause | Why It Happens | Effective Fix |
|---|---|---|
| High humidity | Moist indoor air | Use dehumidifier |
| Poor ventilation | Moisture trapped in the air | Use exhaust fans |
| Cold glass | Heat loss through windows | Upgrade insulation |
| Air leaks | Drafts and gaps | Seal gaps and use weatherstripping |
Addressing the above problems with the right solutions will reduce moisture build up on windows during winter months.
Moisture Management in Windows During Winter
Control Humidity in the House
Using a hygrometer, manage the moisture in your home, while keeping it in the recommended range. The active use of a dehumidifier is suggested if the humidity in your home is too high.
Keep in mind to not oversaturate the humidity in the bathrooms and kitchens, since it is already high in those areas.
Improve Ventilation
Improved ventilation is crucial in keeping window moisture in control. Make sure you have exhaust fans in your bathrooms and kitchens and use them while doing moisture-triggering activities like showering and cooking. If conditions allow, open windows a bit in order to let moist air out.
Increase the Temperature of the Window Surface
Keeping the windows warmer is a good way of preventing condensation. Use insulated window covers or thermal curtains to keep the heat in. Another way is to keep blinds open during the day so sunlight can warm the windows.
Seal and Insulate Windows
Weatherstripping and caulking gaps should seal the window to eliminate drafts and reduce the cold glass contact. If your windows are old or poorly insulated, consider replacing them with double or triple-pane ones.
What NOT to Do (Common Mistakes)
People make several common mistakes and attempt to avoid window moisture.
- Wiping moisture: If the cause of condensation is not addressed, wiping the moisture off the window is only a temporary solution. Always reduce the humidity indoors and improve ventilation.
- Using humidifiers: If a humidifier is used to defrost the glass in the winter, and it is used too often, the moisture in the air will worsen the condensation.
- Neglecting condensation: If humidity is kept under control but condensation persists, it may mean the insulation and ventilation are worth looking at again.
Condensation Raising Mold Risk
Some condensation on windows is normal and rarely causes issues, but continued dampness can lead to mold growing on surfaces. Noticing mold on your windows, a musty smell around the windows, or damage to the window frame can indicate condensation is a serious problem, as mold can create serious health issues, including respiratory challenges and allergies.
Addressing any visible mold must be a priority and the reason for condensation must be resolved, as there is no way to remove the mold without resolving the cause of the condensation.
Window Upgrades Considerations
After trying to manage humidity and improve ventilation, if condensation is a constant challenge, window upgrades should be considered. If windows are drafty, single-pane, and have poor insulating values, condensation and heat loss will be an issue. Upgrading to energy-efficient windows will improve comfort, energy efficiency, and reduce condensation in the home.
Summary: A Healthier Home is a Home with Dry Windows
Windows Drying is an important factor to consider to maintain a comfort and healthy living space in the home. By reducing the condensation and the damages to the home, the humidity and insulation levels can be controlled, coupled with an increase in the ventilation. Foster a healthier home, free from mold and costly repairs with improved efficiency all winter long.
