PENOPLEX boards® from extruded polystyrene foam are widely used for thermal insulation of underground enclosing structures of buildings and structures. Over time, this direction of using high-quality thermal insulation will only expand. For two reasons.
World and Russian trend in underground construction
First, the global trend of active development of underground space continues. In megacities, whole cities are growing underground. A typical example is the city in Toronto named Path from the English word for path, passage, trajectory. According to the Guinness Book of Records, it is considered the largest underground city in the world; more than 30 km of tunnels have been laid to create it.
Secondly, and this already concerns the situation inside Russia, since June 15, 2019, it has become mandatory to insulate structures buried at least 1 meter underground. Amendment No. 1 to SP 50.13330.2012 "Thermal protection of buildings" entered into force, according to which the same standardized value should be used to calculate the reduced heat transfer resistance of such structures as for structures located above ground level.
For conscientious designers, this practice existed before, just from June 15, 2019, it was legalized. There was also another approach, which is now de facto unacceptable. The rationale for the refusal of thermal insulation of underground structures was the assertion of the alleged "additional insulation" from the ground. However, recent studies at the Research Institute of Building Physics of the RAASN did not confirm this factor in the cold season. This is most likely due to the freezing of the soil and an increase in its thermal conductivity.
Thus, the need to use high-quality thermal insulation materials in underground construction is becoming more and more urgent.
Optimum thermal insulation for buried building envelopes
For insulation of underground enclosing structures, many consider extrusion polystyrene foam (EPS) as the only alternative. Let's take a closer look at some of the technical characteristics of PENOPLEX boards® - the first domestic brand of thermal insulation made of this material, which has been produced since 1998.
1. Low thermal conductivity
Does not exceed 0.034 W / m ∙ K under operating conditions "B" (see clause 4.3 SP 50.13330.2012). This is one of the best indicators among modern heaters, in the same regulatory document (Appendix T) even lower values of thermal conductivity of extruded polystyrene foam are given. No other insulation has lower thermal conductivity values in this source.
It is important to note that the thermal conductivity of EPPS remains stable throughout the entire service life due to the following technical characteristics.
2. Zero water absorption
Tests of PENOPLEX boards® at the Research Institute of Building Physics showed that when fully immersed in water, they absorb no more than 0.5% moisture by volume. This is a negligible value, which indicates that the thermal conductivity of the material will not increase during the entire period of operation. The value of this parameter for extruded polystyrene foam can hardly be overestimated in relation to the underground space. The inevitable contact of the enclosing structures with groundwater actually excludes the use of non-moisture-resistant heat-insulating materials underground.
Moreover, the resistance of PENOPLEX® in case of flooding of heat-insulated building structures. At the Tambov State University, the effect of periodic moistening on the material was studied, described in the monograph "Operational properties and durability of extruded polystyrene foam PENOPLEX®". The board samples were repeatedly immersed in water for 8 hours followed by drying for 16 hours. Then they were weighed on an electronic balance with an accuracy of 0.01 g. It was found that the thermophysical properties do not change, the thermal conductivity retains its value, and the water absorption changes insignificantly. Even some growth of the third parameter, important for the thermal insulation of underground structures, is recorded - strength.
3. Compressive strength at 10% deformation for all PENOPLEX boards® not less than 15 tons per sq. meter (0.15 MPa). In underground construction, the manufacturer recommends using the PENOPLEX brand® GEO with this parameter from 30 t / m2… Even more durable PENOPLEX is also used.® 45 (from 60 t / m2) and PENOPLEX® 45 C (from 50 t / m2).
Due to the high strength of PENOPLEX® finds wide application for thermal insulation of slab foundations. Examples include not only prefabricated buildings, such as the Auchan Retail logistics center in the Domodedovo district of the Moscow region or the Nara production and logistics complex of the Ministry of Defense of the Russian Federation in Naro-Fominsk, but also residential complexes with high-rise buildings, in particular, the Moskovsky quarter in Yekaterinburg with houses from 16 to 32 floors, residential complex "Primorskiy Kvartal" in St. Petersburg with houses from 12 to 25 floors.
Along with high heat-shielding properties, zero water absorption and high strength PENOPLEX® has a wide temperature range of application, environmental safety, biostability, durability. Biological resistance has been proven by mycological tests, as a result of which it was found that PENOPLEX boards® are not a matrix for the growth of fungi, mold and other harmful microorganisms. The durability of at least 50 years was established based on the results of tests in the laboratory of the Research Institute of Building Physics, where PENOPLEX samples® went through freeze-thaw cycles, each of which is conditionally equivalent to one year of operation.
Practical experience of using PENOPLEX® in underground construction
The best proof of the quality of thermal insulation is its widespread use in the construction of the subway, especially as large as the Moscow one, which is one of the seven longest in the world. Using PENOPLEX® most of the new metro stations are being built in Moscow. Recent projects include thermal insulation of ventilation ducts, lobbies and running tunnels at Stolbovo station, insulation of the foundation at Kosino station, thermal insulation of the running tunnel between Filatov Lug and Salaryevo stations.
PENOPLEX® it is also used for the construction of subways in other cities of Russia, for example, in Kazan, and abroad, in particular, in Minsk.
The PENOPLEX SPb company has supplies to many objects for thermal insulation of underground parking lots, as well as underground floors with technical and other premises.
Thermal insulation PENOPLEX® reliably protects underground structures of buildings and structures, increasing their energy efficiency.
