It’s the middle of winter. The heater’s on, your home is insulated and is Healthy Homes compliant.
So why are your windows covered in condensation each morning?
Both older and newer homes deal with condensation, especially in winter. That’s why ventilation matters. It’s not just about comfort, it’s also about keeping mould at bay.
Condensation Doesn’t Mean Something’s Wrong
If you’re wiping down your windows in the morning, it doesn’t mean your home has a problem. It means it’s holding heat, just like it should. The warm, moist air inside your home has to go somewhere, and when it touches cold glass or walls, condensation forms.
This is common in winter, especially when windows stay shut and curtains remain drawn all day
Where Does All This Moisture Come From?
Moisture is part of everyday life. A family of four can produce up to 8 litres of moisture per day through daily activities like:
- Showering
- Cooking
- Boiling the kettle
- Drying laundry indoors
- Even just breathing
Without enough ventilation, this moisture builds up. And it doesn’t matter if your home is brand new or 50 years old.
Older Homes: Built to Breathe, but Still Vulnerable
Older homes often have:
- Single-glazed windows or less efficient double glazing
- Timber frames and older insulation
- Areas that don’t heat evenly (cold spots)
Even when retrofitted to meet Healthy Homes Standards, they may still have:
- Drafty areas and inconsistent airflow
- Cold surfaces that attract condensation
- Corners where moisture lingers and air doesn’t circulate
So, despite ticking all the compliance boxes, an older home can still show signs of condensation – especially if windows stay closed and ventilation is minimal.
New Homes are Airtight and Efficient (But That Comes with a Catch)
Modern homes are designed to be energy-efficient, with tight seals, quality insulation, double glazing, and built-in heating.
While that’s great for warmth, it also means the home holds on to moisture. Without regular ventilation, that moisture has nowhere to go. And it builds up.
The result? Foggy windows, heavy air, and an increased risk of mould in hidden spots like behind curtains, wardrobes, or in room corners.
Even the warmest home can become damp and unhealthy without proper airflow.
The Risk: Mould
Condensation is more than just annoying; it’s a warning sign.
When moist air sits still for too long, it creates the perfect environment for mould to grow. Common places include:
- Bathroom ceilings
- Behind furniture
- Inside wardrobes
- Around window frames
You might already know that Mould affects your health. And this is especially true for babies, elderly people, and anyone with asthma or allergies. Not only that, it can damage your home over time.
Even a Healthy Homes-compliant property is at risk if it isn’t ventilated properly.
Why Ventilation Matters – Every Day, All Year
Yes, even in winter.
Cold air is usually dry air, and letting it in (even for a few minutes a day) helps flush out the damp, stale air inside. You’re not undoing your heating. What you’re actually doing is preventing damage.
Practical Daily Habits to Reduce Condensation and Prevent Mould
- 🪟 Open windows for 5–10 minutes each morning, even in winter
- 💨 Run extractor fans when cooking and showering, and leave them running after
- 🚪 Keep internal doors open during the day to help air move
- 🧽 Wipe windows and sills if you see moisture in the morning
- ☀️ Open curtains fully each morning to let in light and reduce cold air pockets
- 🌿 Consider a dehumidifier if your home stays damp even with ventilation
Open Curtains Daily
Keeping curtains closed traps cold air against the glass and prevents sunlight and airflow from drying things out.
When curtains stay closed all day:
- Air becomes stagnant and cool behind them
- Condensation forms on the windows
- Mould can grow in the folds of fabric and on frames
Letting light in helps warm the room, dry surfaces, and prevent mould from taking hold. But how you live in the home matters just as much.
Heating keeps your space warm, but ventilation keeps it dry.
If your windows are crying in the morning, it’s your home asking for a little fresh air. Let it breathe. You’ll enjoy a space that’s not just warm, but truly healthy.
Want help keeping your property dry, healthy, and compliant? Get in touch with our team for expert advice and support. Call us on: 09 630 2655 or drop us a line at office@renthub.nz.
