Indoor air quality (IAQ) was investigated in 13 newly-built, occupied timber houses on a long-term basis. The study included a comparison of the construction types timber-frame (TF) and solid wood (SF), in addition two different ventilation types, controlled vs. window ventilation, were contrasted. The emission progression of volatile organic compounds (VOCs) including formaldehyde, was recorded and compared with the subjective well-being of the residents, which was identified by use of standardized questionnaires. This was completed with toxicological assessment and repeated measurements of specific medical parameters of health indicative character. It was found that VOC-emissions were initially elevated regardless of construction and ventilation type. However, after a period of up to 8 months emissions mostly decreased to an average level. Whereas, the SW constructions released distinctly more terpenes compared to the TF houses, there was no significant difference regarding the total concentration of emitted VOCs. The use of controlled ventilation systems resulted in lower VOC-concentrations and thus in higher IAQ compared to window ventilation. From a toxicological point of view the major part of the investigated houses were unobtrusive and IAQ was considered as "high" or "satisfactory." Residents were continuously very satisfied with their health and quality of life. This perception was confirmed by the results gained from the accompanying medical examinations, giving no indication for physical impairments.

This paper reports on first results from a recently finished project dealing with indoor air quality in timber constructed houses. The FLEC method was applied measuring single building products with respect to their emission of VOCs (i.e. volatile organic compounds) on a small scale. Furthermore, total emissions are investigated in full scale model rooms (30 m 3 ) equipped with variable panel product types and coverings. It has been shown that the total VOC (TVOC) value, consisting of a heterogeneous mixture of single substances (from 25 up to 68 within the test setup), decreases significantly with duration time. Within one year, ranking of the TVOC emission level for 26 individual building products including wood based panels, plasterboards, flexible insulations, adhesives, vapour barriers and sealing sheets changed. Approximately 30% of the single substances formed 80% of the TVOC fraction. This actually highlights the complexity of indoor air emissions from building products. Full scale box trials allowed a direct comparison of OSB and OSB that was covered by gypsum plasterboard. Whereas the TVOC level immediately after construction is higher for uncovered OSB, values of both construction setups decline rapidly. After 14 days and onto 19 weeks, TVOC values were comparable for uncovered and covered OSB within the test. Hence, plasterboards have only a small effect on TVOC levels, but are not capable of reducing VOC emissions from building products.

This paper is divided into two parts: In the first part, the model room VOC measurement concept is evaluated with specimens from different construction materials in order to estimate the safety margins when using day 28 as the time point for indoor air quality assessment. Safety margins between 2 and 20 were estimated for softwood-based products. In the second part, the theoretical restrictiveness of ECA-IAQ Report 18 derivative schemes (like AgBB or NH 105) towards the indoor-related industrial production in central Europe was evaluated.

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