Quality Assurance Association
CO2-neutral Wooden Buildings e.V.

International Statement

Climate Protection Through the Material Use of Wood
Facts for Legislators

International findings from calculations, studies and research projects on the aggregate environmental balance of construction (“environmental footprint”). Taking a holistic approach to energy conservation and energy efficiency



The methodology for calculating the thermal insulation properties of wood is based on principles and moisture assumptions that no longer reflect the current state of technology with exclusively kiln-dried lumber types.


All national and EU-wide energy conservation regulations refer exclusively to energy consumption during the use phase of buildings.


Considered holistically, however, there are considerable variations in the energy balance from construction to construction based on the age of a building once the production, usage and disposal of energy are factored in. These factors are becoming increasingly important due to the steadily decreasing energy consumption during the use phase.


The following abstracts of studies and research works document functional properties and holistic environmental balances with the appropriate reference materials, which should be considered not only in the context of balancing under the Kyoto Protocol, but also in the EPBD and national energy certificates.


I.  Studies in Austria:

A1. Arge Blockhausbau Projekt 20+

In a test building at the Lehrbauhof Salzburg location with single-layer 20 cm thick block exterior walls, the actual heating energy consumption during the two heating periods was about 35% lower than the results of mathematical analysis according to EU standards. Parallel to this, the energy behavior of residential buildings with the same construction technique was investigated with precisely documented heating energy requirements, and the results were also 35-40% lower than the calculations.


A2. Thermal insulation properties of solid wood in comparison to the OIB (Austrian Institute of Construction Engineering) guidelines

Bautechnische Versuchs- und Forschungsanstalt Salzburg

Just as with experiments at ETH in Zürich, the experimental results show that the thermal insulating properties of solid wood must be better assessed, and that the U-value is not the only way to demonstrate energy consumption.


A3. Environmental audit in accordance with ISO 14040/14044 and of energy use in accordance with EPBD

An equivalence to the passive house construction method can be verified in single-layer solid wood constructions with suitable heating systems, with reference to climate protection with holistic balancing in accordance with ISO 14040/14044.


II.  Studies in Germany:

D1. Thermal insulation properties of solid wood

Field test by J. Egle, laboratory study by MPA Leipzig, Baudir report a.D.B Radovic

Field and laboratory tests have independently shown that the insulation properties of wood are better than standardized values, e.g. in EN 12524. The relevant factors include, inter alia, the lower wood moisture using state-of-the-art techniques compared to the current standards in the use phase.


D2. CO2 sequestration

Study by Prof. Hauser and Dr. Lüking

The study shows that carbon can be stored very effectively through the material use of wood in construction, which significantly slows biogenic CO2 emissions. In addition, energy-intensive building materials are replaced. Taking this positive contribution to the CO2 balance into account, with solid construction using wood at least 20 cm thick, the reference U-values of these components should be raised by 0.14 W/(m²K) to determine the requirements in accordance with the Energy Saving Ordinance (Energieeinsparverordnung, ENEV).


D3. Environmental balance sheet for new single-family-house construction / conventional construction compared to solid wood construction

Study and component parts database by J. Egle

The use of solid wood construction methods contributes to an immediate and direct reduction of CO2 emissions in contrast with other designs, which lead to increased emissions right from the start of production. Using environmental product declarations in accordance with DIN EN 15804 modules A1-A3, CO2 equivalents are approximately - 25 tons of CO2 with a reference house in solid wood. In comparison, the same building has CO2 emissions of approximately 20 tons using the method of mineral construction.


III.  Studies in Finland:

SF1. Life cycle calculations of solid wood houses with environmental impact

Investigative organization VTT Technical Research of Finland

Solid wood houses save 10 times the amount of CO2 when wood is used as a building material, compared to energy production. Additional CO2-lowering energy is recovered from the byproducts.


SF2. Health and comfort study in solid wood houses

Researching organizations Nationales Institut für Gesundheit und Soziales /THGL) Finland and Finnish Log House Association HTT





IV.  Conclusions:

Approximately 40% of all global greenhouse gas emissions result from the construction, use and disposal of buildings. Amendments to guidelines undertaken in recent years in the EU have efficiently controlled the national building regulations of the EU countries, such that energy consumption for the use of buildings has been reduced and an even higher proportion of the required final energy for buildings can be created using renewable energy.


Recent studies confirm that the energy to be used in the production of building material or the energy waste resulting from by-products has a significant impact on the environmental footprint throughout the life cycle of a building. It is a central conclusion of this study that the ecological footprint of a building over its entire life cycle can be reduced effectively and directly by increasing the use of wood, taking into account sustainable forestry.


With reference to the attached study results, the undersigned declare the following:


  1. The influence of the entire life cycle of construction on the environmental footprint (from the cradle to the grave) may be taken into account promptly in the construction guidelines of the EU and the national building regulations of the different EU countries.

  2. The present basis of calculation for determining total energy consumption must be further developed such that it also considers the environmental footprint resulting from material production, the construction project, and the end use of a building (reuse / disposal). The carbon connected to construction ought to be considered in these calculations.

  3. No obstacles may arise for the thermal protection requirements for construction techniques which are proven to make a positive contribution to climate protection despite a computationally increased heating demand.
    It must be possible for the Energy Saving Ordinance (EnEV) requirements to be met by a free optimization between material selection, building components and building technology.

  4. Origin labeling of building materials should be extended to all raw materials.


With the principles outlined above, it is possible to reduce the greenhouse gas emissions generated during construction effectively within a few years. If the U-value requirements are tightened, both in new buildings and in existing buildings, a climate burden will not arise for decades. Furthermore, by managing construction with regards to building materials, which serve as carbon sinks, energy-intensive building products are replaced. This further reduces the “environmental footprint” of the building.


International Statement: Climate protection through using wood as a material - Facts for legislators


Download the statement.