# The Ability to Control VOC Emissions from Multilayer Building Materials
## 3 Results and Discussion
At lower temperatures, the retardation of the peak is greater, and it is connected to the fact that the lower are diffusion coefficients \(D\). The next two Figures 10 and 11 show the same test condition for an experiment as for W3, but for the D1 sample at a lower temperature of 29 \({}^{\circ}\)C and lower humidity RH = 50% (D type, dry rooms); later, the same system is analysed for 23 \({}^{\circ}\)C. The D1 sample has a layer sequence: Concrete \(\rightarrow\) Primer \(\rightarrow\) Adhesive \(\rightarrow\) Oak parquet and is composed of products described in Tables 1 and 2. The regression profiles \(C(t)\) fits and the R\({}^{2}\) coefficient ranges from 0.61 to 0.94 (Figure 10). The values of the \(k_{1}\) coefficients for the \(C(t)\) model are in the range 0.01-0.023 and \(k_{2}\) in the range 0.001 to 0.002. For the D1 system (dry conditions, 29 \({}^{\circ}\)C), similarly to the W3 wet conditions, the same trend of TVOC in time was found; the TVOC concentration in the chamber decreases as the number of exchanges in the chamber increases. The curve fits by providing that the model is just satisfactory, and the R\({}^{2}\) coefficient ranges from 0.77 to 0.78 (Figure 11). In the case of a flow of \(n=1\), the experimental points do not follow the typical \(C(t)\) curve. In the authors' opinion, this is most likely due to the test method uncertainty (\(\sim\)24%). However, for this non-obvious experimental trend, the authors set a curve based on a proposed model with R\({}^{2}\) equal to 0.78.The values of the \(k_{1}\) coefficients for the \(C(t)\) model are in the range 0.002-0.009 and \(k_{2}\) in the range 0.0012 to 0.0013. As for the W3 samples at 23 \({}^{\circ}\)C, the trend towards a peak in the profile D1 at a lower temperature is lower. An increase in TVOC concentration \(\Delta C_{max}\) (\(\mu\)g m\({}^{-3}\)) caused by an increase or decrease of emission test parameters T1 and \(n\) (from 1.0 to 0.5 h\({}^{-1}\)) for samples W3 and D1 are presented in Table 5. As a measure of IAQ deterioration, the percentage increase in \(\Delta C_{max}\)-ventricular TVOC concentration related to \(C_{max}\) at a lower temperature was assumed. Comparison of the Emission Profiles of W- and D-Type Samples with Similar Floor System Layers (Air Exchange ACH = 0.5)  
The comparison of the emission profiles from W1 and D2 samples with similar layers (air exchange ACH = 0.5) (Figure 12) shows that the maximum TVOC concentration in an environment with increased humidity (W1 profile) is reached later (delayed) by several dozen hours, and the higher TVOC concentration also lasts longer on a higher level. Type W1 sample has a sequence: Concrete \(\rightarrow\)Primer \(\rightarrow\)Waterproofing \(\rightarrow\)Adhesive \(\rightarrow\)Tile and is composed of materials described in Table 4.The D2-type sample has a sequence of layers: Concrete \(\rightarrow\)Primer \(\rightarrow\)Adhesive\(\rightarrow\)Oak parquet and is composed of materials described in Table 3.  
The peak of TVOC concentration value for W1 sample (approx. 8500 \(\mu\)g/m\({}^{3}\)) is higher because the emissions from the waterproofing layer (here, according to the product profile tests, the composition of VOC compounds for waterproofing product is repeated in the composition of the entire sample: butyl acetate, m-p-xylene and o-xylene). Moreover, taking into account the results of emission tests from a single waterproofing layer present in W1 (see Table 2), it was found that the two compounds emitting from this layer, cyclohexanol and styrene, did not pass through the surface layer, i.e., ceramic tiles, in the test of sample W1. Unfortunately, the comparison of these two samples contained, apart from the different structure of both multilayer samples (type D and type W with an additional layer of waterproofing), also changed the two environmental parameters, T and RH.