Passivhaus buildings are designed to be almost completely airtight, with no unsealed gaps in the exterior of the building. While a typical home might struggle to achieve that, there are ways to reduce unwanted draughts and heat loss. Continuing our series of Passivhaus hacks, Kate Jacobs asks our panel of experts to share their airtight ideas.

Let’s start with the staggeringly simple: just closing internal doors during cold weather will generally reduce the draughts circulating around a house, while in summer, opening them all will improve air flow. Thinking about more ambitious measures, William Gottelier of Becoming X advises homeowners to consider “internal draught exclusion around windows and sealing the various services going in and out of house such as wastewater pipes and electrical connections, using lime render to achieve an airtight layer, it’s an old, low-impact technology now experiencing a return.”

Within most homes, there are common ‘usual suspects’ when it comes to draughts. “It’s crucial to block major sources of draughts, such as chimneys and letterboxes. Installing both an external and internal letterbox can prevent significant heat loss,” says Fergus Knox of Knox Bhavan. To block unused chimneys in older buildings, Gottelier suggests a sustainable Chimney Sheep, made from naturally breathable felted wool, while for pet owners, he recommends the Petflap draughtproof door.

Well-sealed shutters and high-quality curtains can make a surprising difference to draught levels. Use curtains with thick thermal lining or interlining for maximum effect and, when hanging curtains, make sure that they extend well above and to the sides of the window opening. Consider a ceiling-mounted pole or track to help to reduce draughts over the top of the curtains, while floor length curtains will also help to retain more heat. If you have radiators located beneath windows, use short curtains and fit a simple shelf above the radiator to avoid the heat passing behind the curtains, or tuck the curtains carefully behind the radiator. External doors can also be protected with a curtain – pivoting portiere curtain rods are a good option in this situation. A classic ‘sausage’ draught excluder will reduce under-door draughts, too. If you’re still struggling with hard-to-locate draughts, turn detective with a draught detection kit.  

For our full series of Passivhaus hacks see:

The Green Series #1: an insiders’ guide to insulation

The Green Series #2: how to control heat and draught-proof your home

The Green Series #4: how to make your home breathable and thermal-bridge free