Uw, Uf & Ug Coefficients: A beginner's guide
Uf = frame, Ug = glass, Uw = whole window. Golden rule: the lower the number, the better the insulation.
Read moreEnergy Performance & Building Physics
A window is not simply an opening in the wall - it is the first line of defence against the elements. Understand energy coefficients (U-values), explore the physics of moisture and mould, and discover how bioclimatic design can eliminate heat loss.
Thermal Transmittance Coefficients & KENAK
The "dictionary" of thermal insulation. We translate engineering jargon into understandable selection criteria and explain what Greek regulation requires.
KENAK Requirements: What applies per climate zone
Maximum allowable Uw for Athens, Thessaloniki, the islands and mountainous areas - what the law mandates.
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Energy Performance Certificate (EPC): The upgrade value
How replacing old windows improves the energy class and increases property value.
Read moreLinear Thermal Bridges (Ψ-value): Hidden losses
The window-to-wall junction: proper sealing prevents "invisible" heat leakage.
Read moreSolar Heat Gain (g-value) vs Light Transmittance (Lt)
The sweet spot: glass that floods the room with daylight without turning it into an oven.
Read moreThe "100% Insulation" Myth: A realistic view
No window eliminates all losses - what to realistically expect from your energy bill.
Read moreAirtightness, Watertightness & Wind Resistance
The performance triad. How does your window behave in a storm? Certifications and lab tests that prove the durability and tightness of modern systems.
Airtightness (Classes 1–4): Why the house draughts
Class 4 is the gold standard. How EPDM gaskets seal every gap in the window frame.
Read moreWatertightness: Will water leak in the next downpour?
Resistance classes (e.g. 9A) and the critical role of drainage slots in removing water under pressure.
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Wind Resistance: Islands and high floors
Structural adequacy classes C1–C5 ensuring the frame won't flex under 8+ Beaufort winds.
Read moreCE Marking & Declaration of Performance (DoP)
The window's "identity card" - which certificates the manufacturer must legally provide.
Read moreTest Chamber Trials: How they certify
Simulating hurricanes, torrential rain and extreme pressures in R&D labs to certify new systems.
Read moreBlower Door Test: The ultimate airtightness check
A specialist fan depressurises the house, revealing every hole around the window frame.
Read moreMoisture Physics & Thermal Comfort
We solve the number-one post-renovation problem: mould. Understand air behaviour and learn to manage temperature and humidity correctly.
Why do new windows "sweat" (condensate)?
Dew point physics: condensation on glass means inadequate ventilation, not a window defect.
Read moreMould around the window: Eliminate it permanently
Relative humidity, cold plaster and thermal bridges - structural solutions, not just repainting.
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The "Cold Wall" Effect (Cold Draught)
Why you feel cold near the window without a draught - cold air cascading from a poor single-glazed pane.
Read moreProper Ventilation: The 5-minute rule
Forget continuous tilt. Shock ventilation: 5 minutes of cross-ventilation refreshes air without cooling walls.
Read moreTrickle Vents: Are they necessary?
Small vents built into the profile ensure minimal constant airflow without opening windows.
Read moreShading and Summer Thermal Comfort
Why curtains aren't enough: only external shading stops heat before it's trapped behind the glass.
Read moreBioclimatic Design & Passive House
The pinnacle of building performance. Strategic orientation and the strictest Passive House specifications create homes with near-zero energy demand.
Orientation: Which glass faces North and which South
Exploit winter solar gain on the south side while minimising losses on the north.
Read morePassive House: Window specs Uw < 0.8
Extreme specifications, Passivhaus Institut certification and complete elimination of thermal bridges.
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Stack Effect: Natural cooling by design
Strategic windows low (cool air in) and high (warm air out) = free summer cooling.
Read moreEnvelope Acoustics: When the wall is to blame
Flanking transmission: lateral sound transfer through brick, plaster or an uninsulated shutter box.
Read moreMechanical Ventilation with Heat Recovery (MVHR)
How airtight windows work with MVHR systems that "warm up" fresh air for free.
Read moreSmart Home & Window Automation
Sun, wind and rain sensors turn your windows into a self-protecting energy-saving system.
Read moreMain windows & doors guide
Return to the full guide covering frame materials, types, glazing, shading and economics.
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