An energy efficient house should be warm and it should not lose heat. One of the best ways to prevent heat loss is insulating the walls and the roof. The walls lose 15-20% of total heat loss and the roof loses 10-15%. It is important to minimise these losses.

Types of insulation materials

Insulation materials are a significant element of the envelope of a modern building. They assure thermal and acoustic insulation.

Energy efficiency of insulation materials is measured by thermal conductivity coefficient λ which is calculated in Watts per metre per Kelvin degree [W/mK]. In general, a lower λ value indicates a more energy efficient material. The overall heat transfer coefficient (U-value) of the insulation depends on both the thermal conductivity of the material (λ) and its thickness. The U-value characterises the entire insulation. It is measured in Watts per square metre per Kelvin degree W/m2K. Well insulated walls have U = 0,25 and lower, well insulated roofs have a U of less than 0,20.

A wide range of insulation materials is available on the market:

The infographics below present the use of most common insulation materials on individual elements of the house.

How much does it cost and how much can you save? A case study.


  • lnitial state

  • Solution

  • Results

Thermal insulation

  • Basic information
  • A 50 year old detached brick house with a a living area of 115 m2 is heated with a gas boiler. lts walls are 45 cm thick and have no insulation. Uninsulated walls and roof are responsible for huge heat losses in the autumn - winter period.
  • The owner of the house contacted PolREFF engineers and decided:
    1. to insulate external walls with styrofoam panels of 14 cm thickness and a thermal conductivity coefficient of 0,038 W/m2 K.
    2. to insulate ceiling with a 30 cm thick layer of minerał ool and thermal conductivity coefficient of 0,052 W/m2 K.
  • The investment will enable the owner and his family to enjoy amore comfortable home thanks to significantly reduced heat losses and to save zł 2.200 annually on energy costs.

Thermal insulation

  • Kluczowe liczby
  • Annual costs of heating

    7600 zł

  • Cost of external walls insulation

    18 000 zł

    Cost of ceiling insulation

    9000 zł

  • Annual savings due to ower energy consumption

    2200 zł


Brochure „Save energy and the environment”, FEWE