We have all experienced it: sitting by the window on a cold winter evening and feeling a chill radiating into the room, even though the window is hermetically closed. Or, worse, waking up in the morning to find the window frames "sweating", with water running down to the floor and mould appearing in the corners.
This was the harsh reality of old aluminium frames from the 1980s and 1990s. Today, however, things have changed dramatically. The keyword that has transformed the construction industry in Greece is one: Thermal Break.
Let us look in simple terms at what this technology really is, how it works and why choosing it is no longer merely a "luxury" but is now required by law.
Aluminium is an excellent construction material: it is lightweight, never rusts, is incredibly robust and offers top security. However, it has one huge disadvantage by nature: it is an excellent conductor of heat.
Think of old, plain aluminium (known as "cold") as an open highway connecting inside to outside. In winter, it "pulls" the precious warmth from your radiator and throws it outside. In summer, it does exactly the opposite: it channels the blazing Greek sun straight into your living room.
Engineers call this phenomenon a thermal bridge. These are points in the structure where heat escapes or enters unimpeded, dramatically increasing energy bills and creating moisture problems.
To cut that "bridge" and stop energy leakage, the industry found a brilliant solution. It took the aluminium profile and "cut" it in half (one piece for the exterior of the house and one for the interior).
Between the two aluminium pieces, a special, ultra-resistant plastic material called polyamide was inserted. Polyamide, unlike metal, is a terrible conductor of heat.
The result is a "sandwich" of materials. When winter cold hits the outer aluminium, it stops at the polyamide. It cannot cross the profile and reach the inner aluminium inside your room. The temperature has just been "broken".
Choosing thermal-break systems is no longer a matter of preference. It is a necessity for three very important reasons:
The degree to which a material allows heat to pass through is measured by the U-value (specifically Uf for the frame). The lower this number, the better the insulation. Old cold aluminium had a huge Uf (around 7.0). Modern thermal-break systems bring this number below 2.0 (or even below 1.5 for premium systems). Practically, this means you turn the thermostat down much sooner and save hundreds of euros every year on electricity, heating oil or natural gas.
Remember the water we mentioned earlier? It forms when the warm air in your home touches the ice-cold metal of old aluminium. Because the thermal break keeps the interior part of the window warm (at room temperature), the air does not condense. Thus, you permanently say goodbye to black mould stains around your windows and improve the air quality your family breathes.
In Greece, the Building Energy Performance Regulation (KENAK) now prohibits the installation of "cold" aluminium in heated residential spaces. If you are building a new home or carrying out a major renovation, you are legally obliged to install thermal-break systems. Naturally, no subsidy programme (such as "Exoikonomo") funds simple aluminium, as it offers no energy upgrade to the property.
Not all thermal breaks are the same. When you receive a quote from a manufacturer, check one very simple number: the polyamide width.
A polyamide of 16 mm or 20 mm is considered a basic, satisfactory choice for most applications in Greece.
As we go higher (e.g. 24 mm, 34 mm or even 38 mm), insulation soars, making the window ideal for extreme weather conditions or for Passive Houses.
Aluminium windows with thermal break combine the best of both worlds: the unmatched durability, security and aesthetics of metal, with the top thermal-insulation properties demanded by the modern era. It is an investment that pays for itself quickly through energy savings and immediately upgrades the quality of life in your home.
💡 Key Takeaway: A thermal break is not a luxury - it is a legal requirement (KENAK), an economic necessity (lower bills) and a health safeguard (no more mould). Always check the polyamide width before you sign.
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