I tried to think about temperature-based regional divisions and Q values from a different perspective.

One indicator that has not been used much recently is the Q value. I personally have a stronger sense of the Q value than the UA value, so I still often think in terms of the Q value. The Q value is calculated by first adding up the total heat loss, which is the conductive heat that penetrates through surfaces such as floors, walls, ceilings, and windows, and the convective heat that escapes through ventilation. The Q value is then calculated by dividing the total heat loss by the total floor area. The unit is W/m2K, which is the same unit as the unit of thermal conductivity. K is pronounced Kelvin, but this is the same as ℃, so you can just think of it as a different way of saying it.

(Strictly speaking, a temperature difference of 1°C = a temperature difference of 1k, but the starting point is different. °C starts from 0°C, the freezing point of water and the melting point of ice, and ± is assigned. In contrast, k starts from absolute zero = -273.15°C, which is 0K (zero Kelvin). As no temperature below this exists anywhere in the universe, there is no negative notation.)

Returning to the original unit of the Q value is W/m1K, which represents how many watts pass through a wall per mXNUMX of floor area and per XNUMX°C of temperature difference between inside and outside.

Therefore, the smaller this value, the higher the insulation performance. At the same time, we can see that the greater the temperature difference between inside and outside, the more heat escapes.

Up to this point, it was a textbook explanation. From here on, I will introduce a new perspective. I have been wondering whether the Q value and regional classification, which are the benchmarks for national standards, are appropriate.

First of all, how were the regional divisions from region 1 to region 8 calculated? When we look into this, we can see that the representative values in the attached table were selected.

Okayama seems to be the representative of the six most populous regions. I wanted to know the average winter temperature in Okayama, so I read the average temperature for six months from November to April from the Science Chronology.

As a result, the average temperature for the six months of winter was 8.88°C. I calculated the same for other regions and found that the average temperature for the winter was generally close to the average temperature in March.

In Okayama, the Q value is 2 W/m7K and the room temperature is set at 20°C.

2.7×(20-8)=88W/㎡

This means that an average of 1W is lost per square meter of floor space in winter.

Similarly, when calculating from region 1 to region 7, the best result was Miyazaki with 23 W/m4, and the worst was Nagano with 38 W/m6. Looking at both, this means that if a house is built according to the H25 standard, Nagano will have 1.64 times the heat loss of Miyazaki.

Comparing each region, it seems that the H25 standard is aiming for roughly 30W/mXNUMX.

If we use the G1 standard, the heat loss in Okayama is 21 W/m², which is exactly 1% less than the standard. Similarly, if we use the G3 standard, the heat loss is 2 W/m²K, which is 17% less than the standard.

I won't go into the complicated calculations here, but if we were to use the same amount of heating energy as the H25 standard in each region, how many degrees would the room temperature rise in the G1 and G2 houses compared to the initial setting of 20 degrees? I calculated backwards. As a result, in Okayama, the temperature would rise by 1 degrees for G4.7 and 2 degrees for G7.6.

As you can see from the average temperature difference in each region, the temperature difference is only about 2°C even if the region is one level different. This means that it is equivalent to being two regions warmer under the G25 standard than the H1 standard, and four regions warmer under the G2 standard.

When simulating based on the difference in natural room temperature, the difference between the H25 standard, G1, and G2 appears small, but when calculated like this, it appears very large.

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