Postimees · Energy-Efficient Home (Energiasäästlik kodu) · 2025
Energy efficiency through effective insulation
English translation of the original Estonian article. Original headline: Energiaefektiivsus tõhusa soojustuse näol
See the original design in the magazineIn our climate zone, the dream of a warm home with low heating costs is close to the heart of most homeowners, but the road to achieving it can be expensive and winding. The key word is building insulation, and for the best result a number of informed choices have to be made. The Ministry of Climate has also given its own push towards more effective insulation with ever stricter requirements, but the hard work and costs still have to be covered by the homeowner. What should you pay attention to in order to achieve ever better heat retention?
On 1 June 2025, updated energy efficiency requirements for buildings came into force. If nothing else, the state forces people to think through how to make their home more energy efficient. A great many different materials and methods are used to insulate a house. Which of them is chosen for a particular property is largely a combination of personal means, level of information and preferences.
The choice of insulation materials is wide
As science advances, both the range and the efficiency of insulation materials keep growing. What matters is the materials' thermal conductivity, or lambda value, and their compatibility with the building's structure. Just as important is quality installation, to avoid moisture-related problems and thermal bridges. To achieve the best energy efficiency, materials offering the optimal balance between heat retention, fire safety and moisture management must be planned from the very start of design.
Insulation materials in our climate must be able to withstand long periods of cold and damp, and help protect against storm winds. Which are the most popular and at the same time energy-efficient? Let's review the best-known materials on the construction market.
Mineral wool: stone wool and glass wool
Pros: fire resistance (non-combustible), easy to install, and offers good sound insulation as well as warmth.
Cons: needs proper protection from moisture; ultra-fine dust can irritate the airways.
EPS boards
Pros: very good moisture resistance, well suited for plinths and foundations. Lightweight, easy to install and inexpensive.
Cons: low fire resistance (combustible), brittle, a poorly "breathing" material, so it may not suit all types of construction.
Polyurethane foam, or PUR foam
Pros: very good heat retention – achieves the effect with a thinner layer and fills every gap.
Cons: higher price; requires special equipment and an experienced team to install.
Cellulose wool (cellulose-based loose-fill insulation)
Pros: environmentally friendly – made from recycled paper, lets the building "breathe". Installed by a wet method that fills all cracks.
Cons: when damp, it takes longer to dry than mineral wools. Requires a specialist installation team.
The real result depends on correct installation
It is extremely important to remember that besides choosing the insulation material, great emphasis must be placed on correct installation. In conversations with many builders and insulation sellers, poor installation is pointed out again and again as the biggest cause of heat loss.
"A considerable amount of heat can leak from a building through roofs and roof ceilings. What matters is not only the choice of insulation material, but precise and correct installation," explains Taisto Sõlg, head of TTK Grupp OÜ, a company that has been installing roofs for almost 20 years.
Ainar Albi, representative of Isover insulation materials, also places poor installation among the most common insulation mistakes. "An insufficient vapour barrier, poorly sealed joints or the formation of thermal bridges reduce the effectiveness of insulation. Another big mistake in insulating is poor ventilation: in an airtight building, bad ventilation can cause damp and mould," he explains.
Common mistakes in insulating a building
Mistakes are mostly due to a lack of knowledge. Insulation always involves other work as well, which is often overlooked at first. For example, facade insulation, where insulation both outwards and inwards must be planned separately when installing windows and doors – but often this isn't done.
"Another common mistake is taping the joints of windproof boards, which is actually prohibited. Taking the path of least resistance, people still do it. In that case neither the windproof board manufacturer nor the tape manufacturer is responsible for the solution lasting and working over time," explains Albi.
Isover's representative Ainar Albi also mentions that to avoid thermal bridges in various structures (for example corners and around windows), it is important to ensure a continuous layer of insulation. Skilful taping is important here, and it should definitely be left to professionals.
With cellulose wool made from recycled paper, for example, thermal bridges are avoided by installation with a special machine that fills all holes and cracks. "What's interesting about cellulose wool is that the exterior cladding is sprayed using a wet method. The mixture of glue and water helps fill every gap better and holds the insulation firmly in place," says Kaimar Kulbin, head of Werrowool OÜ, which produces cellulose wool.
A proper vapour and wind barrier is also important, ensuring that moisture and outside air cannot get into the building's structures. That way heat loss is minimal and the building lasts longer.
With effective and energy-efficient insulation, correctly planned ventilation cannot be overlooked either. If air moves poorly in a house, mould quickly appears, which in turn can be devastating for both the building's structures and the residents' health. A ventilation system with heat recovery helps increase energy efficiency and keeps indoor air quality at a good level.
Energy efficiency is a construction priority
Besides the homeowner's expectations and rising energy prices, ever more energy-efficient decisions in choosing insulation materials are also driven by the national requirement to build buildings meeting energy class A.
Although modern materials offer versatile options, high-quality and correct installation and properly planned ventilation are critical to achieving the best result. It is good to remember that insulation is a long-term investment that reduces costs, increases property value and ensures the building's durability for decades.