About 45% Answered They 'Didn't Know At All' About Housing Performance Before Building a Home. No. 1 'Wish I Knew More' is 'Meaning and Standards of Insulation Grade and UA Value'

■ Housing Performance of Custom Homes: How Satisfied and Knowledgeable Are the Residents?

Cool in the summer, warm in the winter.

What determines such comfort in a home is its insulation and airtightness performance.

In recent years, we have had more opportunities to hear terms like insulation grade, UA value, and C value.

However, how satisfied are people who actually built custom homes with their home's housing performance, and to what extent do they grasp those numerical values?

Therefore, this time, jointly with 'Fukuoka Komuten', a custom home builder of high airtightness and high insulation, we conducted a questionnaire on 'Satisfaction regarding housing performance (high airtightness/high insulation)' targeting 119 men and women nationwide who answered 'I have experience purchasing a custom home' in a preliminary survey.

* When quoting the contents of this press release, please take the following actions:
- State that the source is a 'Survey by NEXER Co., Ltd. and the highly airtight and insulated custom home builder 'Fukuoka Komuten''
- Place a link to Fukuoka Komuten (https://www.fukuoka-k.jp/)

'Survey on Housing Performance (High Airtightness/High Insulation)' Survey Overview
Survey method: Internet questionnaire
Survey period: May 25, 2026 - June 3, 2026
Target respondents: Men and women nationwide who answered 'I have experience purchasing a custom home' in a preliminary survey
Valid responses: 119 samples

Question contents:
Question 1: To what extent are you satisfied with the 'insulation performance (coolness in summer/warmth in winter)' and 'airtightness performance (lack of drafts/difficulty of air leaking)' of the house you currently live in?
Question 2: Please tell us the reason.
Question 3: Do you know the 'insulation grade' or 'UA value (average heat transmission coefficient of the outer envelope)' of the house you currently live in? If you know, please choose the closest one.
Question 4: Do you know the 'airtightness performance (C value: equivalent clearance area)' of the house you currently live in? If you know, please choose the closest one.
Question 5: Having actually lived there, have you experienced anything in terms of comfort in summer/winter or utility costs?
Question 6: Specifically, in what ways do you feel it?
Question 7: Before building a house, to what extent did you understand housing performance (insulation grade, airtightness performance, ZEH, HEAT20, etc.)?
Question 8: Is there anything you think 'I wish I had known more about before building the house' regarding housing performance?
Question 9: If you were to build a house again, how do you think your priorities regarding housing performance (insulation, airtightness, etc.) would change?
Question 10: Please tell us the reason why you think so.

* As a rule, totals may not equal 100% because figures are rounded to the nearest first decimal place.

■ 66.4% Answered They Are 'Satisfied' with Their Home's Insulation and Airtightness Performance

First, we asked to what extent they are satisfied with the 'insulation performance (coolness in summer/warmth in winter)' and 'airtightness performance (lack of drafts/difficulty of air leaking)' of their current home.

As a result, 24.4% were 'very satisfied' and 42.0% were 'somewhat satisfied', making a total of 66.4% who answered they were 'satisfied'. On the other hand, 26.1% were 'not very satisfied' and 7.6% were 'not satisfied at all'.

We asked about the reasons for each answer, and here are some of them.

Those who answered 'Satisfied':
- It turned out as I imagined. (Male in his 30s)
- Because it is generally comfortable. (Female in her 30s)
- Because when I enter the house, it feels cool in summer and warm in winter. (Female in her 40s)
- Because I think the effectiveness of the air conditioner on cold and hot days is efficient. (Female in her 40s)
- Because summer cooling costs and winter heating costs are relatively cheap, I think it is probably well insulated. (Male in his 60s)

Those who answered 'Not satisfied':
- Dissatisfied because the humidity is always high, perhaps due to airtightness or poor ventilation. (Female in her 30s)
- In winter, the 1st floor is cold and there is a temperature difference with the 2nd floor. (Female in her 40s)
- The heat and cold pierce through. (Male in his 40s)
- Because it's cold in winter and hot in summer, making it hard to spend time. (Female in her 50s)
- Because condensation has gotten worse year by year. (Male in his 60s)

From those who are satisfied, comments such as 'cool in summer, warm in winter', 'air conditioner works well', and 'heating/cooling costs are kept down' were seen. It suggests that high insulation and airtightness performance translate into actual feelings of daily comfort and utility costs.

On the other hand, those who were not satisfied voiced complaints like 'cold in winter, hot in summer', 'temperature differences between floors', and 'severe condensation'. It shows that dissatisfaction with insulation/airtightness performance often manifests as concrete inconveniences in daily life, such as indoor temperature gaps, condensation, and poor heating/cooling efficiency.

■ 48.7% Answered They 'Don't Know the Words Themselves' for Insulation Grade and UA Value

Next, we asked whether they grasped the 'insulation grade' or 'UA value (average heat transmission coefficient of the outer envelope)' of their current home.

The most common response was 'I don't know the words insulation grade/UA value themselves' at 48.7%.

This was followed by 'I know the words, but I don't know the values of my own house' at 38.7%.

Only a minority knew the specific insulation performance of their home: 'Insulation Grade 7 (equivalent to HEAT20 G3)' was 3.4%, 'Insulation Grade 6 (equivalent to HEAT20 G2)' was 2.5%, 'Insulation Grade 5 (equivalent to ZEH standard)' was 4.2%, and 'Insulation Grade 4 or lower' was 2.5%.

While many people are satisfied with their insulation performance, many also do not even know the words denoting performance like 'insulation grade' and 'UA value'. It suggests that while the comfort of a home is easily judged by bodily sensation, those who grasp it as numerical values are still limited.

■ 63.9% Answered They 'Don't Know the Word Itself' for C Value

Furthermore, we asked whether they grasped the 'airtightness performance (C value: equivalent clearance area)' of their current home.

The most common response was 'I don't know the word C value itself' at 63.9%, an even higher percentage than for insulation grade/UA value. Next was 'I know the word, but I don't know the value of my own house' at 27.7%.

Only a minority knew the specific C value of their home: 'C value 0.5 or less' was 2.5%, 'C value 0.6-1.0' was 3.4%, and 'C value 1.1-2.0' was 0.8%. Also, 1.7% answered 'It was measured but I don't remember the specific value'.

The C value is an important indicator showing the airtightness performance of a home, but it turns out many people do not know the word itself. It suggests that figures regarding airtightness performance have not permeated among general residents, even more so than insulation grade and UA value.

■ 55.5% Answered They 'Felt an Effect' in Summer/Winter Comfort and Utility Costs

Next, we asked if they had ever felt the effect in terms of summer/winter comfort and utility costs after actually living there.

As a result, 55.5% answered 'Yes' and 44.5% answered 'No'.

It shows that more than half of the respondents realize the effects on comfort and utility costs due to insulation and airtightness performance in their daily lives.

We asked in what specific ways they felt it, and here are some responses.

Specifically, in what ways do you feel it?
- Summer became easier to spend time in. (Female in her 20s)