The ability of autoclaved aerated concrete (AAC) blocks or any other substance to conduct heat is called the coefficient of thermal conductivity or specific thermal conductivity (λ). This value is equal to the amount of thermal energy passing through a sample of aerated concrete (aerated concrete) with a thickness of 1 m and an area of ​​1 square meter per unit of time with a temperature difference of one degree.

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The product of the reciprocal of the thermal conductivity coefficient by the wall thickness (D) is called the thermal resistance (R):

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R = D / λ

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The amount of thermal energy (Q) arriving per unit of time (t) through a wall with an area (S) at a temperature difference (Tv-Tn) is determined by the formula:

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W = Q / t = S × (TV-Tn) / R

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Consider an example of calculating heat loss through a wall with an area of ​​120 square meters (3 m high and 40 m long, which corresponds to a house area of ​​100 square meters) made of aerated concrete (AAC block) from "Stonelight" with a thickness of 0.4 m and a density of 400 kg / cubic meter. The thermal conductivity coefficient of this aerated concrete (gas block) is 0.1 W / (m × deg.). The thermal resistance of such a wall is equal to:

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R = 0.4 / 0.1 = 4 m2 × deg / W

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Let's say the temperature difference on the outer and inner sides of the wall in winter is 30 degrees. (-10 C .... +20 C), then the power of heat losses through such a wall is equal to:

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W = 120 × 30/4 = 900 W

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Thus, without taking into account other heat losses (through windows, roofs, doors), for round-the-clock support of such a temperature difference within a month, Q = 900 × 24 × 30 = 648 kWh of heater energy (or 577 UAH when using an electric heater and cost electricity 0.89 UAH per 1 kWh)