Buildings account for 40% of total energy consumption in the EU. This sector is growing, which is associated with an increase in its consumption. Therefore, reducing primary energy consumption and the use of renewable resources in the buildings sector are an important measure to reduce the Union's energy dependence and greenhouse gas emissions.
The goal in the field of construction and major reconstruction of buildings is to build almost zero-energy buildings - passive buildings. Mandatory construction of passive buildings has been determined since 2020.
1.1.Passive buildings from the perspective of architecture
Photographs of passive buildings with distinctive shading elements - Vienna
To compare the properties of thermal systems and to determine the assumption of utilization of thermal profits, a method of monitoring the heat accumulation in the heating system is suitable. The heating systems are not insulated towards the interior of the building and we cannot regulate the discharge of accumulation. Discharge of the accumulation takes place depending on the current heat loss of the building.
In this case, the actual heat output and the surface temperature of the system are dependent on the system's accumulation status.
The energy-efficient use of heat profit is decisively influenced by the thermal delay = accumulation load of the heating system. The accumulation load of the heating system is the charging time and the discharge time of the system accumulation. The heating system is made up of a heat-carrying medium - heating water and a construction material that forms a thermal system. These materials accumulate heat and transfer it to the interior with a time shift = accumulation load.
In order to ensure use the priority of the heat profits, it is necessary for the heating system to have zero accumulation load, or to minimize this load. An example is the ideal heating system on the following chart.
Graph .2. The accumulation of an ideal heating system
Description of graph No.2
2.2.Example - calculation of accumulation and accumulation load of heating systems for a building with a calculation area of 100m²
-WH water infrared heaters 3 pcs WH20, 4pcs WH 15
-Plasterboard ceiling heating system 15mm (9,9x1,1 ,r= 100mm)
-Concealed ceiling heating system 24mm (9,9x1,1 ,r= 100mm)
-Floor system in screed with thickness 45 mm ( 17x2, r= 150mm , R= 0,1 m².K/W)
-Thermally activated building structure TABS 150mm ( 17x2, r= 150mm )
For surface radiant systems, the ratio of active area to total area 0,7.
Formula for calculating heat storage Q=c.m.∆ϴ (W)
c- specific heat capacity of the material W/kg/K
m- weight of material kg
∆ϴ -temperature difference before and after heating (ϴ1 - ϴ0) , K
Table 1 Physical properties of thermal system materials used
|System construction material||Specific weight ρ [kg/m3]||Heat capacity of material C [w/kg/K]||Heat capacity of water C [W/kg/K]|
Table 2 Source table for calculating the accumulation of heat systems
|Heating system||System volume [m3]||System weight [kg]||Water volume [kg]||Heat storage [W]||Charging accumulation [hr]||Discharging accumulation [hr]|
|WH-water infrared heaters||107||58||1893||0,2||1,1|
|Plasterboard heating system||1,5||1260||47||5264||0,7||3,3|
|Concealed ceiling heating system||2,4||2016||47||6290||0,8||4,0|
|Floor heating system in concrete||4,6||7728||62||33889||4,2||21,2|
|Thermally activated building structure TABS||15||25200||62||86446||10,8||54,0|