Thermal conductivity and heat capacity of building materials

Comparison of the thermal conductivity and heat capacity of a single-layer masonry of aerated concrete and a frame wall

One sq.m. wall of a single-layer masonry gas silicate 400 mm thick has a heat capacity of 228800 J / ha, and one sq.m. frame wall thickness of 176 mm 61548 J / ha (fiberboard 14 mm, 150 mm frame with eco wool, gypsum board 12 mm). The heat capacity of the aerated concrete walls is four times higher than that of framed walls, BUT... Let's take a conditional house 10h10h2, 5 m; the surface area will be 300 sq m and the volume of 250 cubic meters. In winter, when the street is -20 ° C, and you need the house was +20 ° C. Let's assume that you have a boiler with a capacity of 20kWh or 72000kJ. Let's omit the fact that the boiler first heats the water carrier, it passes through the pipes, warms them, and they, in their turn, give the heat to the surrounding air. Using convection, the air will be heated in the whole house in 10 minutes, but it will heat the surfaces of walls, floor, and ceiling, and that is why the air temperature will not be 20°Ñ in 10 minutes. The air will give its heat to the plaster. In the whole house, Cement-sand plaster with a thickness of 10 mm weighs 4800 kg and can accumulate heat 51 kWh. Therefore, it takes 2.7 hours to heat the dressing to 20 degrees and all the air in the house. But during this time, the application will give 227 watts to the gas concrete, which needs much more heat to heat to 20 degrees.  The thermal resistance of the plaster of the whole boiler consumes 9152000 J x 0.000277778 W/h x 300 m² = 762.6 kWh to heat the building envelope of the gas concrete house + 3.36 kWh of air and lose 344.7kW. 775 kWh.

To heat 1 square meter of the frame wall, the boiler will expend 61548 J x 0.000277778Wh= 17.1Wh +3.36kWh and lose 3.6kWh 24kWh. In other words, a 20kWh boiler will require about 

This means that your heating boiler will work longer to heat the room to a comfortable temperature because it will heat the air and the walls, but while the walls will be heated, they will also cool, giving the heat to the street. Following the Fourier heat conduction law, the flow of heat transfer will be directed towards the hard road. Your mother must have told you more than once as a child: "Don't sit on a concrete floor, sit on a bench." Because concrete takes heat from the body, and a person can catch a cold. That's why all seats are made of wood or other poorly heat-transferring materials.

The heat loss through the wall can be calculated according to the formula:

 [W/(m-K) - (m2-K)/m = W/(m-K) - (m-K) = W].

Each square meter of gas silicate masonry at a temperature difference of 40° will leak 30Wh. At the same heat loss through the frame wall, the thickness of 150 mm will be 12W / hour. The south wall of the house of aerated concrete on a hot day is more heated by the sun than the frame wall and gives all the heat into the room, so in the summer, in a house made of aerated concrete hotter.

Heat capacity is essential in the heat carrier and the floor. If you need heat capacity in a frame house, make a "warm floor." 

Therefore, gentlemen, build a house on frame technology. There will be you, and high thermal resistance and sufficient heat capacity or, in simple terms, the place will be warm and comfortable.