Do Aluminium Double Glazed Windows Reduce Condensation and Mould? Here’s the Truth

Do Aluminium Double Glazed Windows Reduce Condensation and Mould? Here’s the Truth

Condensation on windows is one of the most common problems homeowners face, especially in colder months or in homes with poor ventilation. It often shows up as water droplets on glass in the morning, damp window sills, and in more serious cases, mould growth around frames and walls. For many homeowners, this raises a practical question: do aluminium double glazed windows actually solve this problem, or is it just a marketing claim?

The short answer is that thermally broken aluminium double glazed windows can significantly reduce condensation and mould, but only when installed correctly and combined with proper home ventilation. To understand why, it helps to look at what causes condensation in the first place and how double glazing changes the environment inside your home.

Why condensation happens inside homes

Condensation forms when warm, moist air comes into contact with a cold surface. In most homes, that cold surface is single glazed glass or poorly insulated aluminium frames.

Everyday activities create moisture indoors. Cooking, showering, drying clothes, and even breathing release water vapour into the air. When this moist air hits a cold window surface, it cools rapidly and turns into liquid water droplets which are visible on the glass.

This becomes more noticeable in winter because:

• The temperature difference between indoors and outdoors is greater

• Homes are often kept closed up to retain heat

• Heating allows warm air to hold more moisture

• Ventilation is reduced to keep warmth inside

Over time, repeated condensation leads to dampness, which creates the ideal conditions for mould growth.

The link between condensation and mould

Mould is not just a cosmetic issue. It grows in damp, poorly ventilated areas where moisture sits for long periods. Window frames, curtains, and wall edges are common problem zones.

Once mould starts growing, it can spread quickly. It releases spores into the air, which can trigger allergies, asthma symptoms, and general respiratory discomfort. In severe cases, it can even damage paint, plaster, and timber.

This is why reducing condensation is not just about comfort. It is also about maintaining a healthier indoor environment and protecting the structure of your home.

How aluminium double glazed windows work

To understand their impact, you need to understand the structure of a double glazed unit.

Double glazed windows consist of two panes of glass separated by a sealed air or gas-filled gap. This gap acts as an insulating barrier. Because air is a poor conductor of heat and (cold), it slows down the thermal transfer between the inside and outside of the home.

In practical terms, this means:

• The glass pane on the inside of the window stays warmer

• The cold outdoor air has less effect on the temperature of the indoor glass surface

• The temperature difference between the indoor glass surface and the inside of the home are reduced

This reduction in temperature difference across the interior glass surface is the key factor in lowering the risk of condensation.

When installed properly, thermally broken aluminium double glazed windows help maintain a more stable internal glass temperature, making it harder for moisture in the air to condense on the glass.

Do aluminium frames increase condensation risk?

A common concern is that aluminium frames conduct heat more easily than timber or uPVC. This is true for older, non-thermally broken aluminium systems.

However, modern aluminium double glazed window frames are designed with thermal breaks. A thermal break is an insulating barrier placed between the exterior and interior parts of the window frame to reduce thermal transfer.

By physically separating the external part of the frame from the part of the frame that sits inside the house, the thermal break prevents the transfer of cold from outside to in, thereby stopping the indoor portion of the frame from becoming excessively cold, which is often why and where condensation begins in older non-thermally broken aluminium window systems.

So while older single glazed non-thermally broken aluminium windows were prone to condensation, modern thermally broken systems with double glazed units perform very differently.

Why double glazing reduces the risk of condensation

The main reason thermally broken aluminium double glazed windows reduce the risk of condensation is simple physics.

Condensation forms on the coldest available surface. In single glazed windows, that surface is usually the glass itself, which quickly matches outdoor temperatures.

With double glazing:

• The inner glass pane stays closer to room temperature

• Heat loss is slowed down

• Cold surfaces inside the home are reduced

This means moisture in the air has fewer cold surfaces to condense on. As a result, you see less water droplets forming on windows and dripping onto sills.

In most homes, this leads to a noticeable reduction in morning condensation within days of installation.

Do thermally broken aluminium double glazed windows completely stop mould?

This is where expectations need to be set at a realistic level.

Thermally broken aluminium double glazed windows can significantly reduce mould risk, but they do not eliminate it entirely.

Mould growth depends on three main factors:

• Moisture

• Temperature

• Poor airflow

Double glazing mainly addresses surface temperature. It reduces cold surfaces that trigger condensation. However, if a home has persistent humidity problems or poor ventilation, moisture can still build up.

That means:

• Kitchens and bathrooms still need extractor fans

• Drying clothes indoors will still increase humidity

• Poor airflow in bedrooms can still create damp corners

So while double glazing and thermally broken frames can drive major improvements, they work best as part of a wider moisture control strategy.

The role of insulation and airtightness

Another important factor is overall home insulation.

Older homes in particular tend to leak heat and allow cold air infiltration. This creates uneven temperatures across rooms and surfaces. When some parts of a home are warm and others are cold, condensation becomes more likely in colder zones.

Thermally broken aluminium frames with double glazed windows helps by:

• Reducing heat loss through glass

• Creating more consistent indoor temperatures

• Reducing cold spots near windows

This improved thermal stability reduces the conditions that lead to condensation forming in the first place.

Ventilation still matters

Even with high-quality thermally broken aluminium double glazed windows, ventilation remains essential.

Without airflow, moisture has limited ways to escape. Over time, indoor humidity builds up again, and condensation can return even with improved glazing.

Good ventilation includes:

• Opening windows briefly each day

• Using extractor fans in wet areas

• Ensuring roof and subfloor ventilation is working properly

Homes that combine double glazing with proper ventilation see the best long-term results in controlling condensation and mould.

Common misconceptions about double glazing and mould

There are a few misunderstandings that often come up:

“Double glazing completely removes condensation”

It significantly reduces the risk of condensation forming, but it does not eliminate moisture created inside the home.

“Only heating fixes condensation”

Heating helps reduce cold surfaces, but without insulation and ventilation, moisture still builds up.

“All aluminium windows perform the same”

Older single glazed aluminium frames behave very differently from modern thermally broken systems.

Understanding these differences helps set realistic expectations.

When thermally broken aluminium double glazed windows make the biggest difference

You will notice the strongest improvement if your home currently has:

• Single glazed windows

• Old aluminium frames without thermal breaks

• Poor insulation in walls or ceilings

• High condensation on window surfaces every morning

• Visible mould forming around window edges

In these cases, upgrading to thermally broken aluminium double glazed windows often results in immediate improvement in indoor comfort and moisture control.

How dual GLAZE® helps reduce condensation issues

At dual GLAZE®, we work with homeowners who are dealing with condensation, mould, and cold homes every day. Our approach is focused on practical results, not just product installation.

We assess your existing aluminium or timber joinery to understand how heat is being lost and where moisture is forming. Our team then recommends tailored double glazing solutions that fit your home’s structure without unnecessary replacement work where it is not needed.

We install aluminium double glazed windows designed to improve thermal performance while reducing cold bridging in key problem areas. Our focus is on helping homes become warmer, drier, quieter and healthier through properly fitted glazing systems that work with New Zealand conditions.

We also guide homeowners on ventilation and insulation habits so the benefits of double glazing are fully realised. The goal is not just better windows, but better living conditions overall.

Final truth about thermally broken aluminium double glazed windows, condensation, and mould

Thermally broken aluminium double glazed windows do significantly reduce the risk of condensation by improving insulation and keeping internal glass surfaces warmer. This directly lowers the chance of moisture forming on windows, which in turn reduces the conditions that allow mould to grow over time.

However, they are not a standalone solution. Their effectiveness depends on proper installation, modern thermally broken aluminium frames, and good ventilation practices inside the home.

When these factors come together, homeowners typically see a clear reduction in dampness, fewer mould issues, and a noticeable improvement in indoor comfort.

In simple terms, thermally broken aluminium double glazed windows are one of the most effective long-term upgrades for controlling condensation, but they work best as part of a complete approach to home moisture management.

Frequently Asked Questions

1. Do thermally broken aluminium double glazed windows completely stop condensation?

No, they do not completely stop condensation. They significantly reduce the risk of it forming by keeping the inner glass surface warmer, but moisture can still form if indoor humidity is high or ventilation is poor.

2. Why does condensation happen more on aluminium windows?

Older non-thermally broken aluminium windows with single panes of glass conduct heat easily, which makes the frame and the glass cold. When warm indoor air hits these cold surfaces, moisture turns into water droplets. Modern thermally broken aluminium double glazed windows reduce this effect.

3. Can thermally broken aluminium double glazed windows prevent mould growth?

They can greatly reduce the risk of mould by lowering condensation levels. However, mould can still develop if a home has ongoing humidity issues, poor airflow, or excess indoor moisture.

4. Are thermally broken aluminium double glazed windows better than single glazing for damp homes?

Yes. Single glazing loses heat quickly, creating cold surfaces where condensation forms easily. Thermally broken aluminium frames with double glazing units improves insulation, which helps keep interior surfaces warmer and reduces damp conditions.

5. What else should I do along with installing thermally broken aluminium double glazed windows?

Good ventilation is essential. Use extractor fans in kitchens and bathrooms, allow fresh air circulation daily, and avoid excessive indoor moisture build-up. Combining these habits with double glazing gives the best results.