Heat insulation
Wood is a natural insulator and thermal accumulator with low thermal conductivity.
Wood, as a natural material, has a significantly lower thermal conductivity compared to steel or concrete. This means that in winter, heat from the interior of the house passes through the wooden structure more slowly, while in summer, heat penetrates the indoor spaces more gradually.
By using CLT, thermal insulation is further improved with external insulation layers and within the walls, where different insulation materials are often combined. Due to the well-thought-out combination of solid wood and insulation layers, massive skeletal houses can achieve very low U-values (thermal transmittance indicator), which directly translates into lower heating and cooling demands.
THERMAL ACCUMULATION
Massive wooden houses are not only well-insulated and airtight but also have excellent thermal accumulation. This means that the material used for the building envelope stores and gradually releases heat. Thicker wooden CLT panels have a high accumulation capacity, which contributes to greater comfort. As a result, daily temperature fluctuations in the room are reduced, easing the load on the heating/cooling system.
REDUCING THERMAL BRIDGES
One of the main challenges in constructing energy-efficient buildings is thermal bridges. These are points in the building envelope (walls, window frames, roof structures, etc.) where heat more easily transfers from the interior to the exterior due to imperfect contact or inadequate insulation.
With massive CLT panels, the homogeneous wooden surface itself significantly reduces the occurrence of thermal bridges. The panel does not need to be interrupted by other poorly insulating elements, and the joints between individual CLT elements can be further sealed. The result is lower heat energy losses and a more stable indoor temperature.
AIRTIGHTNESS
High Airtightness and Controlled Air Humidity
For an energy-efficient house, good insulation alone is not enough—high airtightness is essential. Any (unwanted) air leakage in winter leads to heat loss, while in summer, it increases the infiltration of hot air. CLT panels form a solid and airtight shell, which can be further sealed at the joints between elements. High airtightness allows for controlled ventilation with heat recovery in ventilation systems, further reducing heat loss.
The wood used in CLT panels also has a natural ability to regulate air humidity. In spaces with excess moisture, the wooden elements absorb part of it, then release it back into the air during drier periods. This natural effect is why we say that wood "breathes". As a result, wood contributes to a more stable and comfortable indoor climate, reducing the need for additional humidity control systems.
LOW CARBON FOOTPRINT
The sustainability aspect means being friendly to nature and health.
When thinking about energy efficiency, we usually consider energy consumption for heating and cooling during use. However, it is equally important to account for the energy used for:
manufacturing building materials,
actual construction,
maintaining the building throughout its lifespan.
Wood is one of the most sustainable resources because it is renewable, and as trees grow, they absorb carbon dioxide from the atmosphere. This means that carbon is "trapped" in the wooden material and stored in its structure throughout the building’s lifespan, reducing its carbon footprint.
CLT panels are produced in high-tech facilities with precise resource planning, resulting in minimal waste. Compared to steel or concrete construction, wood-based building methods require less primary energy. All of these factors contribute to the overall energy balance of the house throughout its lifecycle.
REDUCED IMPACT FROM TRANSPORT AND CONSTRUCTION
CLT elements have a relatively low weight (compared to concrete slabs), making them easier to transport and requiring less energy for delivery to the construction site. Additionally, on-site construction is less energy-intensive, as massive concrete structures require extensive formwork, reinforcement, and prolonged drying times for concrete elements.
The installation of CLT panels is quick and efficient, reducing construction costs and minimizing the time during which the building is exposed to external influences. This means that the structure can be enclosed and heated sooner, positively impacting the overall energy efficiency of the building.
LONG LIFESPAN AND EASY MAINTENANCE
A common misconception is that wooden houses are more vulnerable to moisture, pests, and fire. However, modern mass timber CLT houses are designed with well-thought-out details that provide protection against weather conditions, humidity, insects, fungi, and other harmful factors. Thanks to the massiveness and high-quality production of CLT panels, wooden houses are exceptionally durable, with a lifespan at least comparable to masonry buildings.
Regular maintenance of the facade system and checking the sealing around joints, windows, and other openings is relatively simple. Over time, this means that there is no need for major, energy-intensive interventions or investments. Basic care and timely preventive measures are sufficient to avoid significant issues.
READY FOR THE FUTURE
Compatibility with Other Technologies and Regulations
COMPATIBILITY
Massive Skeletal (CLT) houses can be designed to integrate well with other sustainable solutions such as solar collectors, rainwater harvesting systems, or photovoltaic modules.
The skeletal construction easily withstands necessary loads and adapts to various requirements. Combined with a heating system (e.g., a heat pump) and controlled ventilation, CLT houses achieve low annual costs and energy consumption.
REGULATIONS AND STANDARDS
In many countries, (due to increasingly strict construction and environmental protection regulations), there is a growing emphasis on building in accordance with nearly zero-energy standards.
Mass timber CLT houses prove to be highly competitive in meeting these standards, as they combine excellent insulation, airtightness, and sustainable properties.