In passive buildings, the heat sources and the heating system only cover up to 20% of the heat consumption for heating. The decisive share of the heat consumption of the building is covered by heat profits of up to 80%.
The heat profits can be external-major solar profits and internal heat profits supplied from electrical appliances, lighting, human activities such as cooking food and the biological heat of humans.
Graph 1 Coverage of heat consumption for heating in passive buildings
In order to ensure the energy-efficient use of heat profits, it is necessary to ensure the priority of heat profits over heat supplied from the heating system!
The above data indicate that the operation of the heating system will be minimal during the heating season. The main heat supply will be provided by heat profits. Properly operating heating systems will only supply heat if heat profit
s are not available. The surface of the heating systems will generally be lower than the indoor air temperature during the heating season. Previously, the choice of radiant floor system was because of the idea of a still warm floor. This idea cannot be met by a floor heating system that is built with "cool" materials with the highest possible thermal conductivity - for example, ceramic tiles and concrete. Still warm floor we can choose from still warm materials and these are 100% natural wood products, which have low thermal conductivity. You can choose a still warm floor from still warm materials and these are 100% natural wood products that have low thermal conductivity. It is necessary to evaluate the choice of the floor according to the year-round impact on man and the main criterion is the thermal absorption of the floor construction. For heating we can choose a radiant system that is not installed in the floor.
Decrease in the floor temperature indicates the amount of heat that is absorbed when a weakly protected human body is in contact with the building structure. This situation occurs when we stand with one foot directly on the floor with ceramic tiles and the other foot on a carpet mat laid on the same floor - Figure 1.
We used thermal imaging to determine the impact of tread layer differences – Picture no. 2. After 10 minutes we left our position. The thermographic image - picture no.3 showed the effect of different tread layer materials. The textile (carpet) mat can be heated (red), the floor construction did not cause heat dissipation from your body. On the other hand, the footprint on the ceramic tiles showed a low temperature. This implies how much heat was taken by the floor structure - that is, there was also a significant transfer of heat from the human body to the floor structure. Any design can be evaluated in terms of body temperature drop. In most cases, it is practical to evaluate this parameter for floor constructions, because the human body is most often in direct contact with it. Contact with the floor is assumed by the foot in adults, in children it may be a larger body area when sitting or lying down. The decrease of the contact temperature contributes to ensuring the thermal comfort and the resulting comfort in the use of the given space - room.
For a person's thermal well-being, the temperature of the floor that a person touches with their feet or other body parts when playing children or exercising is very important. The tread layer material has an influence on the contact temperature drop value. Due to the fact that the floor layer is relatively thin-layered, the parameters of the distribution layer come to the fore. In the case of floor heating systems constructed with a wet structure, the distribution layer is concrete. Floors with low thermal absorption and usually with a low thermal conductivity coefficient are unsuitable for flat floor heating systems - thus creating system insulation. When the floor is touched with a bare foot, it depends on the thermal absorption of the surface layer material and the distribution layer B [W.s0,5.m−2.K−1].
Table 1. Overview of heat absorption of selected materials
|material||thermal absorption B [W.s0,5 .M-2 .K-1]|
The floor should be made of a material with as little heat absorption as possible. Suitable floors are mainly wood materials - solid flooring, large-area wooden parquet or cork. At the moment of contact of the foot with the floor and even for a longer period of time the contact temperature should not be too low. The time change of the foot temperature when touching the floor for 3 different materials is shown in Graph no. 1. WH water infrared heaters allow you to use any material on the floor without restriction. The pair with wooden floors creates unbeatable thermal comfort with a stable warm floor that does not absorb our biological heat and is very pleasant to the touch and feel.