Performance comparison table of major companies

Insulation, airtightness and earthquake resistance ratings of each company as of March 2019, 3 (in order of actual heat loss)

* Actual heat loss is calculated as Q value + C value/10.
*We believe that the company in yellow is the one that can create an ideal indoor environment in terms of both insulation and airtightness.
*UA values are taken from the internet where possible, and for companies where no value is listed, the value is deemed to be 0.6 if the property meets the ZEH criteria.
*Mitsui Home is ranked lower than Sekisui Heim because there is a high possibility that its C value is above 1.
*Window condensation is classified according to whether the sill can exceed a dew point of 20°C when the ideal human temperature is maintained at 50°C and 9.3%.

Explanation of how to read the table

The first thing to look at is "actual heat loss" and "earthquake resistance rating"

When considering heat loss (including both insulation and airtightness), a smaller "actual heat loss" figure is better. To keep the entire house warm in winter and cool in summer without incurring unaffordable heating and cooling costs for the average person, a Q-value of 1.6 or less and a C-value of 1 or less are essential. Based on these calculations, a minimum "actual heat loss" of 1.7 or less is desirable.

However, this alone does not determine the true warmth. The true warmth can be expressed by an index called "heating load." However, this can only be determined by inputting the weather data for the area, the conditions of neighboring houses, the layout of the house, etc., and running a simulation. At this point, the important thing is "solar radiation obtained in winter." Roughly speaking,

① Heating load = ② Actual heat loss - ③ Winter solar heat gain - ④ Internal heat generation

The internal heat generation in the home is determined by the number of people in the home and the operation of home appliances, so it has nothing to do with the performance of the home.

The smaller the heating load in ① , the warmer the room will be.

Most housing companies focus only on heat loss (②) such as Q value, UA value, and C value, but in reality, it is how much solar radiation gained in the winter (③) that makes a huge difference.

Specifically, the amount of sunlight gained in winter depends on how many south-facing windows are designed and how far apart they are from neighboring houses .

Our homes have an effective heat loss that varies between 0.87 and 1.56. We aim to achieve at least a 1.56 level, but everyone can fall within that range depending on their budget and preferences.

Although most properties lose out to Ichijo Komuten in terms of actual heat loss, this can be made up for by shading the sun in the summer and gaining solar heat in the winter, and by using an appropriate heating and cooling plan, which is not shown in the table, to achieve the same warmth, coolness, and running costs. Conversely, housing companies that are unable to shade the sun in the summer or gain solar heat in the winter will be completely defeated by Ichijo Komuten in terms of performance and cost-effectiveness.

Also, earthquake resistance grade 3 is a must, and if you don't like condensation on windows, which is ranked third in the complaints list, you need to choose a company that has a circle in the right-most column (wooden or plastic sashes).

Below is a description of each column:

There are two main types of ventilation systems : Type 1 has a heat exchange ventilation system, and Type 3 does not. Heat exchange is a system where, in winter, cold air is warmed by the heat of the warm air in the room before being introduced. Type 3 is a system where cold air is introduced as is, and warm air is exhausted as is.

There are two ways to express thermal insulation performance . The older method is called the Q-value, which is calculated by dividing the total heat loss of the entire house by the total floor area. The newer method is called the UA-value, which is calculated by dividing the heat loss other than that due to ventilation by the surface area of ​​the building envelope. In the case of the UA-value, you want it to be at least 0.5, and ideally below 0.46.

Airtight performance　The C value is an index that shows how many gaps there are in the walls, roof, windows, etc. of a house. If this is bad, the heating and cooling will not work well, but even before that, if it exceeds 1, ventilation will not be done properly. For example, it is the same as when a straw has a hole in it and you can't suck it properly. 1 is the minimum line.
The heat loss is calculated by dividing the total heat loss by the total heat loss.
The larger the C value, the greater the heat loss due to drafts. The heat loss due to this varies greatly depending on the wind speed outside and the temperature difference between inside and outside, but taking the average for all properties and situations, adding about C value/10 to the Q value will often be close to the actual heat loss. Calculations are made from that point.