Natural ventilation: boost indoor comfort

Natural ventilation has been used for thousands of years to make homes more comfortable.

It uses wind pressure and thermal thrust to continually renew the air in your home.

Natural ventilation relies on two driving forces: wind pressure and thermal thrust. These natural events bring fresh air into your home and remove stale air to ensure constant air renewal.

• Wind pressure: when wind hits the walls of your home, it creates pressure differences that encourages air to rush into less pressurised rooms, resulting in natural ventilation.
• Thermal thrust: the heat that accumulates inside your home naturally rises and escapes through any upper openings. This movement of air facilitates air renewal.

There are five reasons to maintain good natural ventilation in your home:

1. Improved indoor air quality: some pollutants in your home can come from products used in your home, such as paints and cleaning products. Proper ventilation helps remove these pollutants, as well as allergens, carbon dioxide and other contaminants that can build up in poorly ventilated spaces.
2. Prevention of excess humidity: a damp home can cause mould to form and increase the risk of allergies¹. Natural ventilation helps control the humidity in your home and mould growth. It protects the structure of your home and the respiratory health of those who live in it.
3. Odour reduction: natural ventilation removes stale air and replaces it with fresh air from outside to keep your home smelling fresh.
4. Improve thermal comfort: natural ventilation helps regulate your indoor temperature by bringing in cooler air from outside when needed, especially during warmer months. 
5. Energy savings: good ventilation keeps your home cooler in the warmer months, reducing your reliance on electric fans and other cooling systems.

Most importantly, a well-ventilated home should have a positive impact on your mental wellbeing and improve your overall mood².

Here are four natural ventilation strategies to optimise airflow throughout your home.

These methods can be combined and adapted according to the climate and the requirements of your home and the rooms within it.

Cross ventilation is where you open windows on opposite sides of your home to allow air to flow through it.

To be most effective, your home needs to be designed so that air can flow in through one window and pass through to the opposite window without being obstructed by walls or doors.

The success of cross ventilation depends on the orientation of your home in relation to the prevailing winds and the positioning of windows and doors to effectively capture and direct air flows.   

Unilateral ventilation involves ventilating through a single wall. This strategy is used when cross ventilation is not feasible, often due to your home’s configuration.

This system involves the entry and exit of air through openings on a single wall. It is less effective than cross ventilation, but you can improve unilateral ventilation in two ways:

• Making use of vertical pressure differences. This uses the natural tendency of warm air to rise - warm air leaves through a high window while cooler air comes in through a lower one. This works especially well in taller homes or apartments with windows stacked above each other.
• Use strategically placed openings to encourage the movement of air indoors. By opening internal doors and windows you make unilateral ventilation more effective at moving air through your home.

The stack ventilation process takes advantage of the difference in temperature between the interior and exterior of your home.

Lower openings, such as windows on your ground floor, allow fresh air to enter your home; warm, lighter air then rises to higher openings, such as roof windows, and creates vertical air movement that promotes natural ventilation.

Good to know: you can create a stack effect, even when your VELUX roof windows are closed, as they have a ventilation flap that, when open, continuously ventilates your room.

Wind-induced ventilation uses the force of the wind to move air through your home. Its effectiveness depends on the direction and speed of the wind and the design and orientation of your home.

Used over a short period when windy, it effectively eliminates odours and humidity.

Here are five ways you can optimise natural ventilation with roof windows:

Roof window positioning enables the stack effect, which occurs when warm air inside your home rises and cool air from outside comes in from below.

Opening a roof window allows this warm air to escape and creates a vacuum that draws cool air through lower openings, such as windows in walls.

This natural draught effect promotes a constant air flow and improves your home's ventilation.

When roof windows are used in combination with façade windows, they increase the effectiveness of cross ventilation.

Fresh air enters through side openings, passes through your living space and escapes through your roof windows with a draught that refreshes and renews your indoor air.

Roof windows help draw out excess moisture and indoor pollutants, such as carbon dioxide, volatile organic compounds (VOCs) found in paints and allergens.

By regularly opening your roof windows, especially after activities that generate humidity, such as cooking and showering, you help to maintain a healthier indoor environment.

Roof windows give you greater flexibility and direct control over your home ventilation. You can open and close them as needed to adjust your airflow.

If your VELUX roof windows are connected to the VELUX ACTIVE smart home solution they can be set to open and close automatically, refreshing the air in your home. 

Smart sensors monitor temperature, humidity, and CO₂ levels in your home, automatically adjusting VELUX products based on real-time conditions to create a healthier home.

Indoor spaces can quickly overheat, especially on very hot days.

One or more strategically placed roof windows allow hot air to escape and help stop your loft from getting too hot. They also improve the thermal comfort of your home and help keep your cooling bills down.

In addition to promoting air circulation, roof windows draw in additional natural light, which brightens up your interior and reduces the need for artificial lighting.

Expert tip: by incorporating roof windows into your home refurbishment or extension, you can significantly improve your indoor air quality and make your home more comfortable and energy efficient, while supporting sustainable construction.

Integrating natural ventilation from the design stage should make your home more comfortable, while reducing your energy consumption and avoiding problems with humidity, mould and unpleasant odours.