Application Scope of Insulation and Golden Rule

Where to Insulate

To obtain a thermally homogenous home and reduce heat losses properly, provide comfort in winter and summer, all surfaces in contact with the outside (roof, wall, loft) must be insulated.

The thermal performance of insulation must be very high in the roof. In winter and summer, strong thermal resistance in the loft is essential. In winter, losses are at their maximum through all opaque and glazed surfaces and structural links.

In the summer, direct sunlight on the walls and roofs - particularly exposed - can overheat the interior temperature. The same goes for windows which need outside shutters, blinds, awnings, etc to deflect direct sunlight from the house.

The specific case of old houses

Very old walls can be thick (about 1 metre). But despite their thickness, they do not provide sufficient insulation and comfort nor do they reduce energy consumption properly. They therefore need to be insulated. This is especially true for buildings erected after 1945 which often do have very thin concrete walls.

Thermal resistance and wall thickness

To obtain satisfactory performance with respect to current construction criteria (thermal resistance at R=3), the following wall thicknesses would be needed:

10.5 metres in granite
4.2 metres in concrete
and only 12 cm of insulation (λ =40)
In a home that is not properly insulated, heat escapes through

In a properly insulated home, heat transfers are reduced on all surfaces, both in summer and winter. Controlled mechanical ventilation optimises air renewal to keep losses down to a minimum.

Depending on the orientation, the size of windows and the occupiers’ lifestyle, free energy through sunlight can represent up to 20% of energy consumption and reduce the heating bill accordingly.

What are the Golden Rule of Insulation

The golden rule for good insulation is: 

High performance products within an insulation system including fitting accessories to ensure air-tightness of surfaces while respecting all professional guidelines and manufacturer recommendations as well as the implementation conditions set out in technical leaflets, taking particular care with all junctions.

Insulation performance

Effective home insulation requires a high performance insulation system complying with fitting rules to guarantee the home’s thermal continuity and reduce thermal bridges.

Air-tightness

Good air tightness is indispensable for an efficient insulation system: insulation that is not air-tight regardless of its insulation factor can represent energy consumption of 1 to kWh/m2.year i.e. 7 to 11% of the building’s consumption. Air tightness therefore needs to be taken on board right from the design stage of the building but also by strictly following professional guidelines during construction.

Measuring air tightness at the end of a building work is a means of checking the general quality of work. Here coordination is key and each profession should be aware that it can make a positive or negative impact. Doing things properly also saves time.

Controlled ventilation

The purpose of ventilation is to evacuate humidity, steam and pollution linked to the occupation of buildings, guaranteeing hygienic premises and healthy occupiers. Losses linked to air renewal can represent between 15 and 20% of a home’s total losses.

Quality fitting

Good fitting of insulation systems (including insulation material, accessories, breather membranes, joins, etc.) is essential to guarantee perfect draught proofing.