# Insulation, thermal insulation and window tax credit

State aid and public subsidies: the tax credit in France for the purchase of insulation or thermal insulation materials.

Introduction and sizes

To choose an insulating product, it is important to know its thermal resistance R (ability of a material to slow down the propagation of the energy passing through it). It must appear on the product.

More R is important plus the product is insulating.

To get an idea of ​​the R, here is a document on Thermal Resistors recommended by RT2005

Ug, Uw: surface transmission coefficient. The thermal performance of a glazed wall depends on the nature of the joinery, the performance of the glazing and the quality of the installation of the window.

Uw is given for a complete chassis
Ug is given for a window

The quantity U is simply the inverse of the thermal resistance R, in other words: R = 1 / U or U = 1 / R.

Physically, U is the number of W lost per m² of window and per temperature difference (in ° C) between inside and outside.

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The smaller U is, the more windows or frames are insulating. In the place of U, we also often speak of K, they are strictly the same quantities.

Example: a good chassis has a U = K = 1.3.
It therefore has a thermal resistance of 1 / 1.3 = 0.78.

Thermally, it is therefore equivalent to approximately L = 0.78 * 0.04 = 0.03 = 3 cm of glass wool.

Insulation materials for walls, floors and water pipes

Features and performance:

a) Low floors on basement, on crawl space or on open passage: R> = 2,8 m² ° C / W

b) Facade or gable walls: R> = 2,8 m² ° C / W

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c) Roof terraces R> = 3 m² ° C / W

d) Attic floors, crawling roofs, attic ceilings: R> = 5 m² ° C / W

e) Insulation of all or part of an installation for the production or distribution of heat or domestic hot water R> = 1 m² ° C / W (ie 3,5cm minimum of radial insulation).

Chassis, windows and French doors

a) Windows or French windows, requirements for 01 / 01 / 2008:
- PVC: Uw 1,6 W / m² ° C
- Wood: Uw 1,8 W / m² ° C
- Metallic: Uw 2 W / m² ° C

b) Windows or French windows, requirements for 01 / 01 / 2009:
- PVC: Uw 1,4 W / m² ° C
- wood: Uw 1,6 W / m² ° C
- metallic: Uw 1,8 W / m² ° C

c) Reinforced insulation glazing (low emissivity glazing): Ug <= 1,5 W / m² ° C d) Double windows (second window on the bay) with reinforced double glazing: Ug <= 2 W / m² ° C . Safety shutters

a) Insulating shutters characterized by additional thermal resistance provided by the shutter-ventilated air knife assembly: R> 0,20 m² ° C / W.

For an isolated shutter with polyurethane foam of thermal transmittance of 0.035, this corresponds to a shutter insulation thickness of at least: 0,2 * 0.035 = 0.007 = 7 mm.