Materials for insulating the house. Advantages and disadvantages, energy certificate

A while ago we were treating in an article natural materials that can be used to insulate the house. I said then that I would continue with the other types of materials in another article. It's time to keep my promise, especially as not long ago someone commenting on the article pointed out that I had forgotten about polyurethane foam. We will talk about polyurethane foam, basalt, polystyrene and other materials for insulating the house, as well as about the energy certificate and the best time to insulate the house.

Back to home insulation

Reducing energy consumption and protecting resources are now issues of concern to everyone from heads of state and government to apartment owners. Even if everyone sees the issues from a different perspective, the conclusion is clear: something must be done to reduce energy consumption. Studies made in various countries, including ours, have shown that a large part of the energy goes to domestic consumption, especially for heating and cooling homes. This is also the reason why European regulations on energy efficiency in homes and public buildings have emerged. These cover buildings to be constructed, but there is also a continuing concern to make old buildings more efficient.

To be energy efficient a building must not lose heat in winter and not let it in in summer. This is achieved through effective thermal insulation. Thermal insulation can be done on both the outside and inside of the house. For apartment blocks, insulation on the outside is recommended. In houses, in addition to the interior and exterior walls, the floor, ceiling, attic or loft must be insulated. Studies show that up to 35% of heat is lost through the walls and up to 25% through the roof. However, there is also 10-15% that is lost through doors, windows or floors. Therefore, in addition to insulation, for a high energy efficiency, window replacement is also recommended with double or triple glazed ones.

Insulating your home brings with it lower energy consumption which leads to lower maintenance costs and lower bills. But these are not the only advantages. Choosing the right materials and using them correctly will give you:

• reducing the risk of damage to the house due to damp;
• avoid mould formation;
• comfort, both in winter and summer;
• environmental protection as a result of reducing fossil fuel consumption.

When can houses be insulated

Thermal insulation of the house can be done during construction or after the house is built. Of course, it is best to deal with the thermal efficiency of the house during the construction phase. Because then you can choose building materials by analysing their properties, knowing that wood is a good thermal insulator and brick insulates better than concrete. What's more, from the design stage you can choose to make an energy-efficient house using prefabricated walls that already have insulating layers inside or even a passive house thus becoming energy independent.

Also during the construction phase, high-performance windows are chosen, their installation is done eliminating thermal bridges, the floor and roof are well insulated. Everything is simpler at this stage. The important thing is to take all aspects into account and think of the house and its insulation as a whole.

However, houses can also be insulated after they have been built. This is what happens now with blocks, even 40-50 year old ones. Insulating them properly greatly increases the comfort of the residents and reduces costs considerably. There are solutions for all kinds of buildings, even for very old ones. You just have to look at it closely and choose the one that fits best.

Energy certificate

A document that certifies how energy efficient a dwelling is is the energy performance certificate, in short energy certificate. For those selling or renting houses, this document has been mandatory since 2013. It can only be issued by authorised energy auditors or companies authorised by the Ministry of Regional Development and Public Administration (MDRAP). It is issued on the basis of documents received from the owner and following a visit to the house. The documents must contain information on the materials the house is made of, the date of commissioning, plans of the house with orientation to the cardinal points, data on annual energy consumption for heating. If these data do not exist, they can be reconstructed following an audit also carried out by authorised firms.

Depending on their energy performance, buildings can be classified into 7 classes. Class A is the most efficient, with the lowest energy consumption of up to 125 kWh/m²/year and class G the least efficient, with high energy consumption of over 820 kWh/m²/year. The energy certificate is valid for 10 years, unless work has been carried out in the meantime which has resulted in a change of classification.

In addition to the energy certificate for buildings, an energy audit can also be done. This, in addition to classifying the performance, determines the weak points in terms of energy losses and establishes what measures need to be taken to improve energy performance. The main recommendation is almost always to insulate the house.

Insulation materials; pluses and minuses

The choice of insulation materials is based on several criteria. Thermal conductivity and resistance, density, thermal diffusivity and vapour resistance have been discussed at length in previous articleso I won't insist. In addition to these criteria it is also important how easy they are to fit, how flexible they are, their water resistance, whether or not they are harmful to health, how environmentally friendly they are and, last but not least, the price.

About insulation with hemp, wool, jute, fibre and wood fibre panels, cork and cellulose we have already talked about. Next, about glass wool, basalt, polyurethane foam, polystyrene and aerogel.

Glass vase

It is, like basaltic wool, a mineral wool. It is made from recovered glass and sand heated to a very high temperature. It is a recommended insulation for interior use, for insulating partitions or loft. Next to polystyrene, it is one of the most widely used thermal insulations mainly because of its affordable price. It is more flexible than basalt and easier to install on walls with unusual shapes. It is also lighter, which is why it is recommended for old houses whose structure is not very solid. It is not flammable. It has a thermal conductivity between 0.031 and 0.044 W/mK.

Disadvantages:

• Less resistant to high temperatures than basaltic varnish,
• Inferior insulating properties of basaltic glass,
• Low moisture resistance. Not recommended for insulating areas with high humidity,
• If protective gloves and masks are not used during assembly, they cause allergies and irritation.

Basaltic vein

It is one of the best insulation materials. It is obtained from basalt - a natural volcanic rock - by heating at temperatures above 1600°C. Basalt veil has very good fire resistance. According to European standards, it is classified in class A1 reaction to fire, as non-combustible product that does not contribute to fire development.The basaltic veins last 2 hours at 1000°C before they start to melt.

It has very good dimensional stability, keeping its shape and dimensions unchanged regardless of conditions. Because of its heavy weight it is not recommended for insulating balconies or suspended terraces and houses with more fragile structures. It can be installed quickly using several fixing methods - adhesives, dowels, reinforcing mesh - or using mineral wool panels fixed to an adjustable metal structure. Thermal conductivity: 0.034-0.042 W/mK.

Advantage:

• high durability,
• fire resistance,
• vapour permeability,
• high sound insulation performance.

Disadvantages:

• high price
• high weight
• stiffness compared to glass wool.

Polyurethane foam

Until recently it was considered the most effective material for insulating the house. In the meantime, modern materials such as aerogel which we will deal with immediately. Polyurethane foam is a lightweight insulation recommended for insulating basements, floors, walls, roofs and terraces. It is highly effective in eliminating almost all heat loss and providing major energy savings. It provides protection against cold or hot air as well as moisture. It also provides sound protection by effectively reducing noise transfer.

The main disadvantage is that it has to be applied by a team of professionals. It is very durable, not changing its properties for over 50 years. It does not sustain fire and is not liked by rodents. There are 2 types of polyurethane foam insulation, closed cell and open cell. Open cell is cheaper but less effective. Thermal conductivity: o.022-0.028 W/mK. The thermal resistance is higher the thicker the layer. At 3 cm thickness, the resistance is 1.07 m²K/W, rising to 5.46 m²K/W at 14 cm thickness.

To recap, the advantages of polyurethane foam are:

• Instant and very good adhesion on almost any building material (concrete, wood, brick, etc.),
• Complete sealing - seamless application, closing all pores of the material to which it is applied,
• Reduced thickness and weight,
• Good sound insulation,
• It doesn't rot.

Disadvantages:

• High price,
• Toxic substances can be removed during application,
• Cannot be applied evenly,
• It needs application equipment and specialists.

Polystyrene

It is by far the most widely used material for insulating buildings due to its very affordable price and simple and easy installation. There are two types of polystyrene, expanded (EPS) and extruded (Expanded polystyrene is a porous material with good vapour permeability. Due to its properties it is usually used for external wall insulation, insulation of timber-framed roofs and terraces. The fact that it comes in the form of rigid panels is a disadvantage in the case of more specially shaped walls. The thermal conductivity of expanded polystyrene is between 0.030 and 0.040 W/mK.

Advantages of expanded polystyrene:

• Low cost,
• It's easy and doesn't clutter up the front of houses,
• Allows the circulation of accumulated vapours inside the house,
• Prevents the formation of mould and mildew,

Disadvantages:

• It can ignite in the event of a fire and sustain the fire (although it is also available in a flame retardant version),
• Synthetic material, pollutant,
• May attract rodents.

Extruded polystyrene has low vapour permeability (it does not allow vapour to escape which can lead to condensation and mould) and high mechanical strength. This is why extruded polystyrene is not used for cladding facades, but for foundations, floors, basements and terraces. Extruded polystyrene's resistance to moisture, combined with its hardness and elasticity, make it resistant to freeze/thaw cycles. Thermal conductivity: 0.029-0.039 W/mK. Thermal resistance is dependent on panel thickness, as with expanded polystyrene.

Advantage:

• Higher density than expanded polystyrene,
• Better thermal insulation than expanded polystyrene,
• Resistant to all types of wear and tear,
• Good for foundation and basement insulation.

Disadvantages:

• does not allow vapour to circulate, which leads to moisture build-up between the wall and the insulation and the appearance of damp and mould.

There is a new polystyrene variant - graphite polystyrene - which has started, timidly, to be used in our country. It is also an expanded polystyrene, to which graphite powder has been added to improve the thermal coefficient by about 15%-20%. The advantage is that the same insulation performance is achieved at lower thicknesses. This means more space in the home. Graphite polystyrene also provides a cooler environment in the summer due to its increased ability to reflect heat radiation.

In some countries (Germany, Canada) polystyrene is no longer used because it is considered dangerous to health.

Aerogel

A very modern material developed by NASA. So far it is the product with the best thermal coefficient - 0.0131 W/mK - lower than that of air (0.023-0.024 W/mK). It is made from silicon oxide and contains 99.8% of air. It is durable, does not mould and does not harm the environment. It can be used for thermal insulation of masonry, foundations, roofing, windows or lightweight structures.

The aerogel is waterproof, it repels liquid water but allows moisture to pass through. It is quick and easy to fit and requires no special tools or devices. It is available in two thicknesses, 5 or 10 mm, and widths of about 1.5 m. Its great advantage is its very high efficiency at low thicknesses, which makes it suitable for indoor insulation (it does not take up space inside rooms and does not need to be re-sized for radiators).

I hope you find the information in the article interesting. If you think it would be useful to others, you can share it. If you have any questions or queries, please leave them in the space below.