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ConstructionWhat is thermal insulation and why it matters
Thermal insulation reduces heat loss in winter and overheating in summer, lowering heating and cooling costs, improving living comfort, and reducing a building's environmental footprint.
Thermal conductivity (λ, lambda)
Every insulation material has a thermal conductivity coefficient — a value indicating how well it conducts heat (measured in W/(m·K)). The lower the coefficient, the better the insulating properties, and the thinner the insulation layer needed for the same effect.
Recommended thickness by surface type
- Roof: requires the thickest insulation layer, since warm air naturally rises and the roof is where the most heat is lost.
- Walls: moderate thickness, balancing efficiency with preserving usable room space.
- Floor: usually the least thickness among the three, especially for upper floors.
Material comparison
- Mineral wool: affordable, good fire resistance, breathable.
- EPS foam: lightweight, inexpensive, easy to install, but flammable.
- Extruded polystyrene (XPS): higher density and moisture resistance, suitable for foundations.
- PUR/PIR boards: best insulating properties (lowest λ), allow the thinnest layer, but more expensive.
The calculation provides an estimated thickness based on a simplified model. For precise insulation design of a specific building, consulting a thermal engineer who accounts for climate zone, building codes, and structural details is recommended.
FAQ
What is thermal conductivity?
It's a value (λ, lambda) that indicates how well a material conducts heat. The lower the coefficient, the better the material's insulating properties.
Why do different parts of a building need different insulation thickness?
The roof loses the most heat (warm air rises), so it needs the thickest insulation layer. Walls and floors have lower requirements.
Can you insulate too much?
Excessive insulation thickness gives diminishing returns in efficiency while increasing cost, so there's an optimal thickness beyond which extra spending doesn't pay off in heating savings.