Wondering whether you should ventilate your home when it’s raining or keep the windows tightly shut? Here’s why it’s important to keep fresh air flowing in, and some simple tips for keeping your home healthy.
1. Don’t shut the air out
Proper ventilation is important in all weather. It’s beneficial for you and prevents condensation and mould.
2. Try doing it everyday
Open your windows several times a day for a few minutes. This could be when you’ve just woken up or before bed to get the air flowing in.
3. Roof windows make it easy
From integrated ventilation bars to rain sensors and smart systems that control windows based on humidity and temperature, VELUX roof windows make the most of fresh air.
Will opening windows during rain increase humidity?
Usually, no. Although the air outside might feel damp when it’s raining, cooler outdoor air can still help reduce excess moisture indoors once it enters your home and warms up.
Ventilation during rain is important for maintaining a healthy indoor climate, whatever the season or weather. The most effective way is to open your windows fully for a short time, a few times a day.
Without regular ventilation, indoor air can become stale, while pollutants, dust and moisture build up. And over time, higher humidity can increase the risk of condensation and mould. Opening the windows replaces any damp air with fresh air from outside.
How can I measure the humidity in my home?
Try using a hygrometer, a tool that measures the amount of humidity in your home and can be bought cheaply online. If you have a smart heating system, that may also display humidity levels, so it’s worth checking.
Ideally, indoor humidity should be between 40% and 60% depending on the season. Here are some tips for using your hygrometer to get your humidity levels right:
- If your hygrometer is portable, place it in rooms with the highest potential for humidity – your bathroom and kitchen during the day, and maybe even your bedroom at night.
- On rainy days, a hygrometer is really helpful for monitoring humidity and choosing the best times to ventilate.
- On cold winter days, use your hygrometer to check that humidity is below 45%. If you open a window, try reducing your heating to minimise heat loss.
- Opening a window or door is without a doubt the most effective way to get the air feeling fresh again. For the best results, create a draught by opening several windows at once.
- Avoid leaving windows on tilt or vent position; while this allows some air exchange, it cools surfaces in winter and wastes heating energy.
- After ventilating, wait a few minutes before checking humidity levels so the fresh air can reach room temperature. If humidity is still high, you can briefly increase your heating.
It's also worth balancing indoor and outdoor temperatures. If indoor air is much warmer than outdoor air, condensation can form on cold surfaces, increasing the risk of mould.
Ventilating during rain is essential to prevent condensation inside your home, such as on windowpanes.
What causes high humidity?
Indoor humidity can increase when there are lots of sources of moisture. These include:
- Cooking and boiling water: releasing steam into the air without using an extractor fan.
- Bathing and showering: taking long, hot showers that fill the room with water vapour.
- Drying clothes indoors: allowing wet laundry to evaporate moisture directly into living spaces.
What temperature should my house be?
The ideal indoor temperature is between 18°C and 22°C, with 20°C recommended for living rooms and bedrooms.
If your indoor temperature is too low, it can increase the risk of condensation and mould, so balancing heating with ventilation is super important in winter.
Watch out for excessively high temperatures, especially in bedrooms. If indoor air becomes too dry and the humidity drops below 30%, you might need to add some moisture back into the room. One way to do this is with houseplants: they’re a cheap and effective way of keeping your home at a balanced humidity level as they release moisture from their leaves.
How do you ventilate with VELUX roof windows when it’s raining?
Avoid opening roof windows during rain, as this could let it straight in. But there are ways you can get around it:
- VELUX roof windows have integrated ventilation bars. When it rains, you can set the bar to the ventilation position to ensure air comes in but your window stays closed.
- Electric and solar-powered VELUX roof windows have external rain sensors that automatically close the roof window when rain starts.
- VELUX ACTIVE smart systems use sensors to detect temperature, CO2 and humidity, opening and closing your roof windows automatically when needed.
If you have manual roof windows, you can always upgrade them with a solar conversion kit which is compatible with our VELUX ACTIVE smart systems.
All solar and electric VELUX roof windows come with a wall switch – one for each product – which means you don't need to be able to reach the roof window to open or close it. Just push a button on the wall instead – it’s that easy.
When rain begins, the sensor on electric and solar roof windows closes them automatically.
Types of automated roof windows
What are solar roof windows and how do they work?
Solar roof windows are powered by a solar panel mounted on the roof window. The panel captures sunlight and converts it into energy, which is then used to operate the window. These windows are ideal for areas without easy access to electrical wiring.
What are the benefits of electric and solar roof windows?
Electric and solar roof windows are great for allowing you to open and close them with the touch of a button or automatically through smart controls. They also improve ventilation and natural lighting, and can even be integrated into your smart home system for added functionality. Solar options provide the additional benefit of using solar power to operate your roof window.
Can electric and solar roof windows be installed in any type of roof?
Yes, electric and solar roof windows can be installed in most types of roofs, including pitched and flat roofs. It's important to choose the correct model for your specific roof type to ensure proper installation and performance.
Can I upgrade my existing manual roof window to an electric or solar version?
Yes, lots of manual roof windows can be upgraded to electric or solar versions using our conversion kits. These allow you to enjoy the benefits of an electric or solar roof window without needing to replace the entire unit.
What happens if the solar panel doesn’t get enough sunlight?
Solar roof windows are designed to store energy, allowing them to operate even on cloudy days. However, in areas with very low sunlight, their performance could be affected. We’d suggest ensuring the solar panel is installed in a location with good sun exposure.
How durable are electric and solar roof windows?
Electric and solar roof windows are built to withstand frequent use and harsh weather conditions. They are tested to be opened and closed thousands of times and are made from high-quality materials designed to last for years.
What should I do if my roof window stops working?
If you come across any problems with your electric or solar roof window, contact our customer service team as soon as you can. Our extended warranty covers most issues, and our technicians can guide you through troubleshooting steps or arrange for repairs.
To sum up
Here are our top tips to take away for ventilating your home when it rains:
- Use a hygrometer to monitor humidity
- Ventilate by opening windows several times a day for 6-10 minutes
- Reduce your heating when you ventilate and turn it back up afterwards
- Wipe away condensation from windows as soon as possible
- Keep room temperatures consistent, especially in winter
Frequently asked questions (FAQs)
What humidity level should trigger ventilation?
Keep indoor relative humidity between 40% and 60%, depending on season and the balance between indoor and outdoor temperatures. Ventilate when humidity rises above 45% or drops below 30%. If humidity drops below 30% if could cause dry skin or sore throats. If it gets too high (above 60%), that's when condensation happens and mould can form. A dehumidifier can help maintain a constant relative humidity, particularly if you dry your washing indoors.
Does humidity increase when it rains?
Yes, rain and snow can raise indoor humidity and encourage condensation. Ventilating regularly by opening windows for a few minutes several times a day helps keep humidity under control.
How much should you ventilate in the different seasons?
Spring is a great time to refresh indoor air. Try opening windows daily for 10-20 minutes in the morning and evening.
If it's a hot summer, the goal should be to try and keep your rooms comfortable for sleeping in overnight. Open windows in the early morning and late evening when its cooler, and keep your windows, curtains or blinds closed during the hottest part of the day to block out the heat. Also consider using fans to keep the air circulating.
In autumn, ventilate several times a day for 6-10 minutes with windows fully open. On days of continuous rain, morning and evening are the best times.
During winter, it's important to bring in fresh air and reduce condensation but without losing too much heat which can impact energy bills. The best way to do this is to ventilate briefly but effectively – open windows wide for 5 minutes, a few times a day. Avoid leaving windows slightly open all day as this doesn’t ventilate very well and can also waste energy. Also make use of your kitchen and bathroom extractor fans during cooking and washing to help prevent condensation.
Does opening windows during rain increase humidity?
Not necessarily. Although rainy outdoor air can have high relative humidity, bringing cooler air indoors and warming it can still help remove excess moisture from your home. Try opening windows or doors for shorter periods on exceptionally rainy days, rather than leaving them open all day.