Measurements of temperature and moisture properties of the building structures
The objective of temperature and relative humidity measurements on the surface and inside the peripheral structures of the timber building is to verify the temperature-humidity behaviour of structures under realistic conditions. In particular, attention is paid to a potential risk of condensation of water vapour inside the structure during the winter season and also to the impact of solar radiation on overheating of structures in the summer. Temperature sensors for measuring the surface temperatures of the structures and the temperatures and relative humidity inside the structures are placed in 8 positions in the peripheral wall and in two positions in the roof structure (see Figure Location of temperature and humidity sensor in the walls ).
Location of temperature and humidity sensor in the walls h
- Particular positions of sensors are to enable monitoring of the temperature-humidity behaviour of the structure with respect to different factors:
- the impact of the structure composition,
- the impact of the compass orientation of construction towards the cardinal directions,
- the impact of the thermal bridge,
- the impact effect of the thermal coupling (corner),
- the impact effect of the ventilated space on the outerexternal side of the structure,
- the impact effects of internal and external environments parameters
Location of the temperature and humidity sensors inside the perpheral wall structure and the roof structure
Other temperature-humidity sensors are placed in the attic and in the interior of the rooms for the possibility of monitoring so that the parameters of the internal environment could be monitored. The temperature and humidity sensors had to be placed inside the building structures while the structures of individual peripheral parts were manufactured. Figure 3.15 illustrates fitting the temperature-humidity sensor into the peripheral wall construction in the assembly hall in Rýmařov.
Installation of temperature-humidity sensors into a part of a peripheral wall
Installation of temperature-humidity sensors into a part of a peripheral wall
Peripheral wall of the timber building
- The peripheral wall of the timber building is designed as a diffusion structure in two design options:
- external wall with contact insulation,
- external wall with a ventilated air gap.
V Tab. shows basic thermal properties of used building materials which have a decisive influence on the course of the temperature and humidity inside the structure.
Tab. Thermal properties of the building materials
| Building materials | Bulk desity | Coefficient if thermal conductivity | Specific heat capacity | Coefficient of thermal conductivity | Water vapour resustance factor |
| ρ [kg/m3] | λ [W/(m.K)] | c [J/(kg.K)] | a [m2/s] | µ [-] | |
| Fernacell gypsum fibre-board | 1250 | 0,320 | 1000 | 2,56.10-7 | 13 |
| Fermacell Vapor gypsum fibre-board | 1250 | 0,32 | 1000 | 2,56.10-7 | 200 |
| Steico Flex wood-fibre thermal insulation | 50 | 0,039 | 2100 | 3,7.10-7 | 2 |
| Steico Therm wood-fibre thermal insultation | 160 | 0,043 | 2100 | 1,28.10-7 | 5 |
| Steico Protect wood-fibre thermal insultation | 250 | 0,053 | 2100 | 1,00.10-7 | 5 |
| Steico Special wood-fibre thermal insultation | 240 | 0,047 | 2100 | 0,93.10-7 | 5 |
| timber beam | 400 | 0,180 | 2510 | 1,8.10-7 | 157 |
| Baumit plaster | 1800 | 0,800 | 850 | 5,23.10-7 | 12 |
The higher the coefficient of thermal conductivity of the material is, the faster the temperature inside the material alters due to changes of temperatures on its surface.
Course of the realative humidity measured in the peripheral wall – south facing
The curves of measured temperatures show how the structure, thanks to its thermal insulation properties, copes with differences between indoor and outdoor temperatures in winter. While the external surface of the structure is strained with large differences of between surface temperatures during January (from -15.3°C to 9.1°C), the internal layers of the structure including the surface show only very small variations of temperatures (15.2°C to 21.2°C). However, the course of the internal structure surface temperature is affected by the indoor air temperature and by the operating mode of the heating. The course of the relative humidity inside the structure proves that there is no condensation inside this diffusionopen structure during December.
Fig. shows the measured temperature curves in the peripharel wall of the south facing timber building in the summer period – in August 2013.
The measured temperature curves show how, thanks to its thermal insulation properties, the construction copes with the heat strain in the summer. While the external structure is strained with a large difference of surface temperatures during the month of August (from 44.7°C to 7.1°C), the internal structure layers including their surfaces show only very small variations of temperatures (32.9°C to 26.8°C). The measured higher internal air temperatures were affected by the operating mode when the internal space was not cooled by external air ventilation at night or by a forced air Exchange in order to ensure the same marginal conditions for the measurement. Fig. 3.19 and 3.20 show the time delay between reaching the maximum temperature on the external and internal surfaces of the structure in the two selected days in August (8.8. – 9.8.), which reached 26 hours.
Fig.: Course of temperature measurements in the construction of the peripheral wall-south facing
Course of temperature measurements in the construction of the peripheral wall-south facing
Roof construction of the timber building
The roof construction of the timber building is designed as a diffusion-open structure (for the structure composition see Chap. 2.2). Tab. 3.2 contains the basic thermal technical properties of the basic used building materials, which have a decisive influence on the course of the temperature and the humidity within the roof structure.
| Bulding Materials | Bulk density | Cieffucuabt of thermal conductivity | Specifik heat capacity | Coefficiant of thermal conductivity | Water vapour resistance factor |
| r [kg/m3] | l [W/(m.K)] | c [J/(kg.K] | a [m2/s] | m [-] | |
| GKF gypsum-fibre board | 800 | 0,220 | 1060 | 2,59.10-7 | 2,5 |
| Fermacell Vapor gypsum-fibre board | 1250 | 0,32 | 1000 | 2,56.10-7 | 200 |
| Steico Flex wood-fibre thermal insultation | 50 | 0,039 | 2100 | 3,7.10-7 | 2 |
| Steico Therm wood-fibre thermal insultation | 160 | 0,043 | 2100 | 1,28.10-7 | 5 |
| dřevovláknitá tepelná izolace Steico Universal | 270 | 0,048 | 2100 | 0,85.10-7 | 5 |
| timber beam | 400 | 0,180 | 2510 | 1,8.10-7 | 157 |
Fig. shows an installation of temperature and moisture sensors (positions 4 and 5) into the roof structure during the construction
Fig. show the measured courses of the temperature and the relative humidity in the roof construction of the timber building in winter – in December. The figures of the temperature and relative humidity inside the structure labelled with positions 1-5 show the location of the measuring sensors leading from the internal side of the structure out.
Course of the measured temperatures in the roof construction
Course ot the relative humidity measured in the roof construction.
The measured courses of temperatures show, similar to the case of the peripheral structure, how the roof deck, thanks to its thermal insulation properties, copes with the courses of temperatures in the winter. While the external surface of the structure is strained with large differences between the surface temperature in the month of December (from 16.1°C to 8.4°C), the internal structure layers including the surface have an average surface structure temperature of 20.5°C. However, the course of the internal surface temperature is affected by the inside air temperature and the operating mode of the heating.
The course of the relative humidity inside the roof structure shows that there is no condensation inside the diffusion-open structure during the month of December. The maximum value of the relative humidity, which was obtained in the structure in December, is 98.2% (measured at position No. 4 – on the external side of the structure in the place of a ventilated gap).
The maximum external structure surface temperature of 51.1°C in the ventilated air gap and the minimum temperature of 3.9°C were measured in the summer period – in August (Fig. 3.24). However, the internal surface temperature ranged from 33.7°C to 27.5°C on the internal side of the structure. The measured higher internal air temperatures were affected by the operating mode where the internal space was not cooled by outside air ventilation at night in order to ensure the same marginal conditions for the measurement.