# 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

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.

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Nature of the closures (shutters, blinds) is also involved in reducing losses, especially at night.

Amount of the tax credit

a) For all these thermal insulation materials, the tax credit rate is 25%. This rate is increased to 40% on the double condition that this equipment is installed in accommodation completed before 1/1/1977 and that their installation is carried out no later than December 31 of the second year following that of the acquisition of housing.

b) The tax credit applies to expenses paid between January 1, 2005 and December 31, 2009. For example, the expenses paid in 2007 must be declared when filing the income tax return for 2007. It is therefore in 2008 that these expenses must be declared.