External wall insulation in Annecy.

External wall insulation, or ITE, involves wrapping all the walls of your house in a continuous insulating layer, fixed to the outer face of the façade and then covered with render or cladding. The building is thus protected from both cold and heat from the outside, like a coat pulled on over the existing structure.

The key difference from internal wall insulation (ITI) lies in the principle: external insulation does not encroach on living space. You do not lose a single square metre inside, you do not have to move your furniture and you can stay in your home during the works. Above all, external insulation effectively eliminates thermal bridges — those areas where heat escapes at floors, corners and internal walls — which internal insulation deals with far less well.

In the alpine climate of the Annecy basin, with its cold winters between Lake Annecy, the Semnoz and the Aravis, this continuous treatment of the building envelope transforms comfort. Walls stay warm, the thermal mass of the building is preserved and heating bills fall for good. It is now one of the most effective and best-subsidised energy renovation solutions for a detached house or small apartment building in Annecy.

There are several ways of installing external insulation, and the choice depends on the architecture of your façade, the look you want and your budget. The most common technique is rendered external insulation: insulation boards (polystyrene, mineral wool or wood fibre) are bonded and mechanically fixed to the wall, then covered with a mesh-reinforced base coat and a finishing render. The result looks like a conventional rendered façade, in the colour of your choice.

Clad EWI, on the other hand, relies on a frame fixed to the façade, which holds the insulation and then a ventilated facing: timber cladding, composite cladding, metal or mineral materials. This solution provides a very durable ventilated air gap and a wide choice of looks, and blends perfectly with the mountain character of the chalets and Haute-Savoie houses around the lake. Finally, insulated facing systems and ready-to-fit insulating panels allow fast works in certain configurations.

The right choice is made case by case: a very flat, regular façade lends itself well to render; a façade you want to clad in timber, or one that is uneven, will be better served by cladding. We work out the insulation thickness required, the treatment of details (window sills, roof overhangs, downpipes) and the constraints of the Grand Annecy inter-municipal local plan (PLU) before recommending the most suitable technique.

One of the great advantages of external insulation is that it combines naturally with façade restoration. If your façade is looking tired — cracked render, dirt, flaking paint — and restoration is needed anyway, it is the ideal time to insulate. Rather than simply freshening up an uninsulated wall, you share the cost of scaffolding and labour to carry out two projects in one.

The benefit is twofold: you improve energy performance while giving your house a complete aesthetic makeover. New render colours, contemporary timber cladding, redesigned mouldings: EWI is an opportunity to modernise the look of your property and increase its value. For a small apartment building in Annecy-le-Vieux, Seynod or Cran-Gevrier, it is also a chance to harmonise the whole façade in a single co-ownership operation.

Atelier NovAlp coordinates the entire operation: survey of the existing building, choice of materials, submission of the prior declaration (déclaration préalable) of works, façade treatment if needed, fitting the insulation and finishing. You have a single point of contact from design through to handover.

External wall insulation is among the best-supported measures under public schemes. As an RGE CertiRénov-certified company (no. CR-2026-73-0095), Atelier NovAlp enables you to use MaPrimeRénov', Energy Savings Certificates (CEE) and the zero-interest eco-loan to finance your external insulation. These grants, which can be combined subject to conditions, greatly reduce your out-of-pocket cost and make the project affordable.

In terms of performance, walls account for up to 25% of heat loss in a poorly insulated house. By treating this surface continuously, EWI delivers immediate heating savings and improves the home's energy rating (DPE) — a decisive advantage in Annecy's tight property market, whether you sell or let. Summer comfort also improves, as the walls act as a shield against the heat, a valuable asset during heatwaves in the valley floor.

To go further, EWI fits ideally into an overall energy renovation project in Annecy: combined with loft insulation, new windows and doors and a heat pump, it can achieve spectacular gains. Find out more about our approach and guarantees on our RGE energy renovation page.