If a new, highly insulated house is too expensive for you, consider renovating it to have high insulation!!
The price of newly built custom homes is steadily rising. As a result, many people are finding it impossible to afford high-performance homes even if they want to. Our proposed solution is "high-insulation renovation . "
With a highly insulated renovation, you can often achieve high insulation and earthquake resistance while still being able to build a new custom-built home with equivalent performance for around 500 to 1000 million yen less.
This website provides detailed explanations on the benefits, specific procedures, and how to search for properties. It also provides free access to much of the information that is provided to construction companies for which it provides technical guidance. It is intended for the general public, as well as construction companies that are having trouble receiving orders for new buildings.
Five things every home should do
1. High insulation of windows
If you're not replacing the exterior walls, install interior windows . If you are replacing the exterior walls , replace the windows with resin windows . Replacing the exterior walls means removing the existing siding or mortar walls and installing exterior insulation. When replacing the exterior walls, if the windows on the east, west, and north sides are large, filling them in to make them smaller is very effective in both summer and winter.
As a price guideline, it would cost approximately 15 yen for the living room only, and approximately 10 yen for the bedroom (installation of interior windows). We would like you to have as many windows as possible installed, but the priority order is large windows → rooms where you spend the most time → rooms where heat shock is likely to occur (for example, toilets, washrooms, and bathrooms).
2. Floor insulation reinforcement
Floor insulation reinforcement can be done by crawling under the floor in some houses, but not in others. In older houses, there is often no insulation under the floor at all. In houses built 20 years ago, while there may be some insulation, it's usually only a minimal amount, resulting in poor airtightness.
By spraying polyurethane foam insulation from under the floor, insulation and airtightness can be completed in one go without removing the flooring. The effect is tremendous. In winter, the coldness in your feet caused by the cold air at your feet will stop completely . The purpose of making the underfloor area airtight is to prevent cold air from entering from underneath.
When the air conditioner is turned on in a cold room in a high-airtight house, the process of cold air flowing in from under the floor occurs when warm air accumulates from above and over time the floor becomes warm. However, in a low-airtight house, the warm air flows upwards easily and escapes to the outside from above. The more the warm air escapes, the more cold air is drawn in from below as a reaction. This phenomenon occurs in most wooden houses, and the more the heating is turned up because it is cold, the more warm air escapes from above and the more cold air is drawn in from below. Therefore, by making the house airtight, the amount of warm air escaping and the amount of cold air flowing in are reduced.
The price is roughly 20 yen and up, but depending on the recent price rise and the size of the property, it can be as much as 25 yen or 30 yen.
3. Water heater replacement
In older houses, it's almost always better to replace them . The most common issue in existing homes is the gas water heater. While many homes now use city gas, the worst offenders are propane gas and electric water heaters (not EcoCute). These two consume a lot of energy and money . Electric water heaters consume a lot of energy and money. Propane gas water heaters don't consume as much energy, but they consume a lot of money. Therefore, these two should be replaced immediately.
The estimated cost is about 40 yen. I'm thinking of using an eco-cute as a base.
4. Unit bath
In truly old houses, you often find traditional bathtubs, where the floor and walls are tiled. Converting these to unit bathrooms is extremely important. Matsuo Design Office has carried out many high-insulation renovations, and when we demolish wooden houses with traditional bathtubs, 100% of the time the foundation and the base of the pillars are rotten . It's not 99%. Therefore, we often replace the foundation and pillars in those areas.
The latest unit bathrooms have highly insulated bathtubs, so the water stays hot for a long time. A very thick layer of something like styrofoam is lined inside the bathtub, which makes it extremely difficult for the water to cool down. In older houses, the water often cools down almost immediately after being heated, but with the latest highly insulated bathtubs, the temperature will only drop by 2°C in 6 hours if the lid is closed.
I mentioned that replacing the water heater is important, but even if you replace your electric water heater with an EcoCute system, if heat is leaking out of the bathtub in the first place, the EcoCute system won't be effective. In that sense, a highly insulated bathtub is extremely important, whether it's a new build or a renovation.
In Japanese homes, the bathroom is the most energy-intensive area . With rising electricity prices, energy efficiency in the bathroom is extremely important. High insulation can be easily achieved by using products with insulation built into the walls and ceiling. However, insulating the exterior walls is expensive and often not feasible for all homes. In such cases, installing a prefabricated bathroom unit is an effective solution. Other advantages include lower cost than traditional bathrooms, shorter construction time, and virtually no water leaks . Homes with prefabricated bathroom units are unlikely to experience rot at the base of the foundation or pillars in the future. Both durability and safety can be maintained at a high level. Another advantage is that the bathroom stays warm while bathing, reducing the risk of heat shock.
[Cost recovery time and energy saving effect of replacing water heaters]
If you change from propane gas to eco-cute,Cost recovery in about 4 yearsYes, you can. Of course, it will be more economical after that. If you also install solar panels, the Ohisama Ecocute will have a shorter payback period and is even more recommended.
The estimated cost is 80 to 120 million yen, depending on the grade of the unit bath.
5. Ceiling or roof insulation reinforcement
Most houses have unbearably hot second floors in the summer. This is because the roof or ceiling insulation is insufficient , and the windows are not properly shaded from sunlight . We recommend reinforcing the roof insulation with spray foam polyurethane. Like reinforcing the floor insulation, this can be done in one go. It has a great effect in winter, but the effect in summer is especially tremendous. In summer, you won't feel that sudden change in air as you go up the stairs, so even a child will notice.
The estimated cost is 20 yen and up. As with floor insulation reinforcement, it may be 25 yen or 30 yen depending on the area and recent price increases.
Why there are no exterior walls and no solar panels
Renovating exterior walls, whether from the inside or the outside, is quite time-consuming and expensive. However, if you're going to repaint the exterior walls anyway, external insulation renovation is a worthwhile investment. For houses larger than 30 tsubo (approximately 100 square meters), it often costs over 7 million yen. If you're in your 30s or 40s and planning a renovation for a house you'll live in for a lifetime, it's definitely worth doing.
From the perspective of earthquake resistance, the lighter the roof, the better. If solar panels weighing several hundred kilograms are placed on an existing roof, the structure will definitely be weakened. There is no problem if the exterior walls are reinforced against earthquakes before the solar panels are placed on. If solar panels are installed without roof remodeling, the chances of leaks increase. If you take measures to prevent leaks when remodeling the roof, such as installing solar panels with pre-attached metal fittings or using a catch method on a galvalume steel roof, then it is of course better to place solar panels on it.
