Proper insulation saves money

According to “SwissEnergy”, the Confederation’s subsidy programme, over 1 million buildings in Switzerland urgently need energy-saving renovations. Primarily, this includes effective thermal insulation, which can save up to 60 percent of heating costs. Using an example house, energieheld.de calculated how much heat is lost and from where (proportions of overall heat loss): 1 percent of all heat loss is through the roof, 30 percent through the facade, 11 percent through the cellar and 12 percent through the windows. A further 26 percent of heat is lost through ventilation and inefficient heating.

Heat loss from a house

There’s a great deal of potential for energy savings in the building envelope, and there are so many possibilities tap into. Here is an overview of insulation methods and materials.

Which insulation methods are there?

Depending on the building part and/or construction type, you have different options to choose from:

Facade

• External wall insulation system (EWIS): EWIS is the most common and cost-effective method. Insulation panels are applied to the facade from the outside and then rendered.
• Rear-ventilated curtain wall: this method is more elaborate and expensive. The insulation is covered with an additional layer, which opens up greater design freedom than EWIS. Instead of just paint, wood and other materials can be used as cover panels.
• Cavity wall insulation / blown-in insulation: cavity wall insulation is an option for buildings with a double-leaf outer wall. Blown-in insulation is the simplest, fastest and most cost-effective variant. The insulation is simply blown into the hollow space, right into the otherwise unreachable corners and the holes are then sealed.

Facade insulation can also be applied from the inside, which can be necessary, particularly with a listed property. But internal insulation is somewhat more problematic with regard to moisture damage and thermal bridges. It also makes the living space smaller. In any case, you should always consult a specialist about internal facade insulation.

Roof/upper floor

The following methods are offered:

For pitched roofs

• On-rafter insulation: insulation panels are mounted onto the rafters from the outside. This method is worthwhile only as part of a full roof renovation.
• Inter-rafter insulation: insulation panels are mounted between the rafters. This is a popular, simple and relatively cost-effective method.
• Under-rafter insulation: insulation panels are mounted on the rafters from the inside, frequently in addition to inter-rafter insulation.
• Insulation of the uppermost floor: as a cost-effective alternative to rafter insulation, the ceiling of the uppermost floor can be insulated. This can also be implemented as a variant that can be walked on.

For flat roofs

• Cold roof: in this case, there is a hollow space between the insulation and the roof covering so that air can circulate. This variant offers good heat protection in summer.
• Warm roof: in this case, there is no hollow space between insulation and roof covering, so no ventilation.

The two variants have similar insulation capacity.

Cellar

In existing buildings, the cellar (if present) is usually insulated from the inside – with the disadvantages already mentioned. When cellar rooms are not to be used as living space, insulating the cellar ceiling is sufficient. In new builds, the cellar is usually underlaid with a damp course and furnished with exterior insulation.

What insulation materials are there?

Besides the various insulation methods, there are also many different insulation products. There are three basic groups:

• Synthetic products made from fossil resources: these include the widely used polystyrene hard foam (EPS, XPS) and polyisocyanurate hard foam (PIR). These products have an excellent insulation value, which means that a relatively small amount of material strength is sufficient to maintain the required insulation capacity.
• Mineral products: these include mineral wool, glass wool, mineral foams and foam glass.
• Organic products from renewable resources: these include wood fibres, hemp and cellulose.

Most products are available in different formats for different installation methods – for example, as panels for classic external insulation or as flakes, granulate or foam for blown-in insulation.

What costs should be considered?

The expense of thermal insulation depends on many factors. Which building parts are to be insulated? How large is the area? Which methods and what type of insulation will be used? Not all methods can be applied to all buildings and building parts. For example, the relatively cheap blown-in insulation requires a double-layered exterior wall with a hollow space.

The fundamental rule is:

• The insulation method is the factor that determines the cost. The insulation material you choose plays a relatively small role in terms of cost.
• A large part of the cost is due to installation (including scaffolding erection)

Here is an overview of the average costs for various insulation types 

Apply for subsidies!

The Confederation and the cantons subsidize energy-saving renovations and construction methods, including thermal insulation, because they make a vital contribution to minimizing the greenhouse gas emissions from buildings. The subsidies are significant and can amount to up to one third of the costs.

Find out whether you can receive a subsidy for your project and how much at Energie Franken. Just enter the postcode of your place of residence to get detailed information about the subsidized measures.

GEAK provides guidance

If you’re not sure whether new insulation is worthwhile or how you should go about it, the cantonal energy certificate for buildings (GEAK) can offer valuable guidance. Trained specialists undertake a comprehensive energy assessment of your house and give recommendations for any energy-saving renovations.

More on the subject