21/04/2026
When we talk about supply air (also commonly known as make up air), we’re referring to the new air that is delivered into a home.
Supply air is really important to consider when you’re looking at ventilation systems, as no system/strategy is complete without it.
Without a steady supply of new air entering the home, your extraction fans can create negative pressure.
When negative pressure builds up, the home results in drawing air in through gaps and cracks, or just not at all.
This can cause health issues including headaches and nausea, irritation of the eyes, nose, and throat, dry and itchy skin, and respiratory problems such as coughing and wheezing.
Alongside this, negative pressure can cause damage inside the home to things like wooden furniture, fixtures and fittings.
As homes become more airtight to meet energy efficiency targets, ensuring a proper supply of new air is more important than ever!
Without it, we risk trapping moisture and pollutants inside, leading to condensation, discomfort, and health concerns.
All homes need air both in and out. Which sounds simple, but the moment one side of the equation is off, things stop working…
If you’re an installer, a wholesaler, or a landlord, it’s important to ensure that you have both sides covered for a balanced home.
👉 Are you calculating the supply rate properly?
👉 Do the doors have enough gap to allow free movement of air?
👉 Are trickle vents in place if using extract only fans?
