Karuizawa is a popular summer resort, but the winters are as cold as those in Hokkaido, with some years seeing days with temperatures as low as -15°C. In order to comfortably endure the harsh winters, it is necessary to have specifications and equipment suited to "extremely cold regions." Therefore, preparations for extreme cold regions must be added to the budget for construction costs in the general area. What should you be careful of? We will also introduce the measures we take!!
Building performance costs
We have listed some of the cost-increasing items that are necessary in Karuizawa that are different from general areas.
Please see the details of our Karuizawa specifications.
INDEX
Measures to prevent water pipes from freezing are necessary. *This is the most important item, and there are various countermeasures. Pipes should be installed underground deeper than the freezing depth (-70cm) / Above-ground pipes should be equipped with heaters / All equipment should be designed for cold regions / Automatic water drainage devices / Indoor heaters to maintain temperatures to prevent freezing / Hot water boilers installed inside the building / etc.
Various combinations of heating equipment: fan heaters (gas and kerosene), floor heating (hot water and electric), panel heaters, wood stoves, fireplaces, air conditioners, and heat exchange fans.
A septic tank and drainage infiltration trench must be installed on the premises. * Most areas do not have a sewer system .
The soil types that often require ground reinforcement work are those found in areas with soft ground such as black soil, sedimentary humus soil, and soil mixed with volcanic ash, so the construction method is selected based on the survey results.
If the land is sloping, it is likely to be more expensive due to the need for high foundations, etc.
From here, we will introduce our Karuizawa specification, which is suitable for the Karuizawa climate.
Building a house with high airtightness and insulation performance
We want to enjoy life in Karuizawa in a house that is cool in the summer without needing an air conditioner and warm in the winter! For that, airtightness and insulation are essential. High insulation performance leads to savings in heating and cooling costs, so it can be said to be a grade that is related to daily life. Kobo Shinshu's "Karuizawa specification" houses are designed with the insulation performance of "highest grade 4" as standard, which is the long-term excellent housing certification standard.
The standard value for meeting energy efficiency grade 4 varies even within Nagano Prefecture.
Nagano Prefecture is divided into eight regions, from "cold regions" to "warm regions." There are four regions in Nagano Prefecture, and the required insulation performance differs. Karuizawa is in region 2, which makes it clear that it is as cold as Hokkaido.
How to evaluate insulation performance
The insulation performance of Kobo Shinshu's houses is calculated using values calculated from the type and thickness of the insulation material, and the size of the windows.
The value that indicates the thermal performance of a house's envelope is called the envelope average heat transfer coefficient (UA value), and the smaller the UA value, the less heat escapes and the higher the building's insulation performance. The envelope refers to the exterior walls, floors, ceilings, roofs, windows, doors, etc. that form the thermal boundary, and the envelope area varies depending on the layout, roofing, window size, etc. Thermal boundaries generally refer to places that contain insulation, and often refer to the boundary between the inside and outside of a house.
Skin calculation simulation
By performing these calculations, we determine the thickness of the insulation based on the conditions of each home and plan a building that meets grade 4.
At Kobo Shinshu no Ie, all of our buildings are custom designed, and we consider the conditions for each building to provide highly insulated homes that meet the highest standards.
[The warmth of different insulation performance grades varies greatly]
This is a simulation comparing a typical house with a house with insulation grade 4 [Kobo Shinshu House *Energy Saving III Region]. ・Simulation of a day of -17℃ recorded in Ina City, Nagano Prefecture ・One air conditioner set to 20℃ in the living room, operating from 6:00 to 8:00 in the morning and 16:00 to 22:00 ・Comparison of buildings with insulation grade 2 and insulation grade 4
High-performance triple-glazed windows
Most of the heat that escapes and enters a room (a whopping 50% to 75%!) comes through the windows.
In other words , the most effective and essential way to insulate a home is to insulate the windows .
Percentage of heat flowing out in winter (outside temperature 2.6°C) Percentage of heat flowing in in summer (outside temperature 34.8°C)
High-performance "Low-E triple glass" that combines high performance and light weight
"Low-E triple glass" is glass with a special metal film (tin oxide or silver) coated on the surface of the glass, called a Low-E film. The Low-E film absorbs and reflects heat from the sun and from heating the room. As a result, it helps to increase indoor comfort by mitigating the heat in summer and increasing heating efficiency in winter. In addition, argon gas, which has low thermal conductivity, is sealed in the hollow layer, providing excellent insulation performance.
"Foundation insulation" and "Airpass solar construction method" protect buildings from moisture and frost
The depth below the ground surface where the ground does not freeze is called the "freezing depth." When the ground freezes in the cold of winter in Karuizawa, it expands and pushes up the ground surface, so the depth of building foundations and water supply pipes from the water main must be installed deeper than the freezing depth.
Measures to prevent freezing of building foundations
①Construct ruffle concrete under the foundation concrete down to below the freezing depth.
2. Ensure the thickness of the crushed stone under the rapple concrete
③Insulation is also installed on the flat and slanted parts of the floor to block out cold air and moisture.
④ Install insulation on the flat top of the floor, sandwiching it between the top and bottom. In addition, install insulation under the floor for a triple layer installation.
Foundation rise on the perimeter of the building, porch, curb, carport, and other earthen floor areas
Adopting slab foundation construction method (raft foundation) for moisture prevention and earthquake resistance improvement
Peace of mind starts with the foundation! This sturdy construction method involves placing reinforcement bars at close intervals on the foundation and covering the entire surface with concrete to prevent moisture from entering from the ground.
It is also resistant to lateral shaking (horizontal forces), and in the event of an earthquake the building moves as one unit, minimizing damage to the building and is also effective against uneven settlement.
Comfortable air environment "Airpass Solar Construction Method (Passive Solar House)"
In Karuizawa, where humidity is high, it is important to take measures against humidity in order to prolong the life of your home. In order to realize a healthy and rich life that can be enjoyed with the four seasons of Shinshu, we have adopted the "Airpass Solar Construction Method" that keeps your home warm in winter and cool in summer.
This system has an air layer (ventilation layer) between the insulation and the exterior wall, and by opening and closing the vents on the top of the roof and under the floor depending on the season, it changes the air flow and creates the optimal indoor environment for each season. It can control not only the temperature but also the humidity, so even if the house is not used for a long period of time, the room will not become humid and will always be kept dry and comfortable.
In addition, by making good use of natural energy rather than relying on electricity, utility bills are reduced, making the design kind not only to people but also to wallets.
Six benefits of the Airpass method
[Easy explanation with video! What is the Airpass Solar Method?]
*If you would like to know more about the Airpass Solar method and how it works, click here!
Detailed explanation of the Airpass ⇒https://youtu.be/79qW5KbJ97Q?si=fSEy65hizXyMJHIQ
Measures to prevent freezing of water pipes and equipment
In high altitude areas such as Karuizawa, the temperature drops below freezing in the middle of winter. When the temperature drops below freezing, the water remaining in the water pipes freezes, causing the water pipes, faucets, water heaters, etc. to burst.
In our Karuizawa specifications, we have installed freeze prevention heaters on the hot water supply pipes as a measure to prevent freezing, and by using cold climate faucets, we can also drain the water when you are away for an extended period of time. This is hassle-free and safe for those who are using the villa!!
◆Header method (blue: cold water supply, pink: hot water supply)
By running piping from the main pipe to each faucet, replacement is easy in the event of a breakdown.
◆ Cross-linked polyethylene pipe with heater guide
Prevents freezing under the floor. The heater turns on when the outside temperature is below 5°C and turns off when it exceeds 5°C.
◆ Cold climate faucets
Open the drain and drain any water remaining in the faucet.
Snow- and earthquake-resistant building "earthquake resistance grade 3"
In the snowy region of Shinshu, the weight of snow also has a major impact on building structures.
Even in Nagano Prefecture, where earthquakes are relatively rare, it is important to ensure that buildings have earthquake resistance in anticipation of a major earthquake.
Highest level of earthquake resistance
The house at Kobo Shinshu has achieved a seismic resistance rating of grade 3 while taking advantage of the spacious layout. For example, building more walls will increase the strength, but the connection and openness of the space will be lost. Building more fire beams will increase the strength, but a complex structure like a spider's web will not be beautiful. The skill of the planner is shown in whether the two elements of a spacious layout and seismic resistance can be achieved without compromising either.
[A house stronger than an evacuation facility] Earthquake resistance grade Building Standards Act x 1.5 times ★★★ Grade 3 or higher
How much difference is there between grade 1 and grade 3?
What is the difference in the shaking of buildings in earthquake-resistant grades 1 and 3? Let's take a look at this video comparing the shaking patterns.
Earthquake damage forecast
A simulation of the main shock of the Kumamoto earthquake on April 16, 2016 (Mashiki Town), with a magnitude of 7.3 and seismic intensity of 7.
At our company, we use the earthquake-resistant structural analysis software "Wallstat" to perform earthquake resistance simulations on each building, allowing us to create earthquake-resistant designs that are less likely to be destroyed.
Recommended heating equipment in Karuizawa
If you want to spend the winter in Karuizawa in a warm and fulfilling way, we have some heating equipment that we recommend.
The heated floor is warm!!
The radiant heat from the floor is reflected onto the walls and ceiling, warming not only your feet but the entire room. A comfortable warmth that cannot be achieved with a heater or air conditioner.
There are two types of underfloor heating: electric and hot water. We will introduce the features of each.
Hot water type
・Quick start-up
・A comfortable temperature of 40℃. No low-temperature burns.
・Economical as residual heat lasts
Electric type (PTC heater type)
・No need to replace boilers or piping
Easy to adjust temperature
・Reduce running costs with our fee plan
It's also OK for natural wood flooring!!
We recommend "wild cherry" and "chestnut", which are less likely to shrink or deform when exposed to heat.
It has a luxurious feel and beautiful aged appearance.
A wood stove is the best!!
The crackling sound of wood, the smell of wood slowly burning, and the warm color of the fire that reminds us of memories of living in the forest. A wood stove brings various warmth to family time. Since ancient times, people have gathered around the fire to spend quality time together. Why not gather around the wood stove with your family and friends and talk about the events of the day?
Introducing our recommended wood stoves!!
A perennially popular, long-selling product
Vermont Castings Encore
To the standard
BRUNNER Iron Dog No.7
Stylish
HWAM 3110c
Open to 2nd and 3rd sides
BRUNNER Panorama/Corner Fireplace
High performance and simply beautiful
Skantherm Elements 603 Tunnel
Cooking stove
de manincor domino 6/domino 8
Is it easy to light a fire? How do I get firewood? How about maintenance? There are many people who want a wood stove but are worried about it. But don't worry! We have built over 1,000 homes with wood stoves, so please feel free to ask us any questions you may have.
Septic tanks are the mainstream, not sewers
In Karuizawa, many properties have septic tanks instead of public sewerage, but some people don't know what a septic tank is. What exactly is a septic tank? Here's a simple explanation.
What is a septic tank?
A septic tank is a facility that uses microorganisms to purify wastewater and release it as clean water. In areas without sewer systems, it is the most common wastewater treatment facility installed on each household's premises.
What are the benefits and precautions of a septic tank?
There is no need to pay the initial beneficiary fee (300,000 to 600,000 yen) to the city or town. There are also no sewerage fees.
If the microorganisms in the septic tank become weak, they will cause bad odors. It is important to be careful not to kill the microorganisms with large amounts of oil or bleach.
Regular cleaning and inspection are required. A management contract will be signed with a facility company.
It is necessary to secure space for an "infiltration trench" to drain the purified water.
Infiltration trench
You will need a lot of space, so plan ahead carefully so that it doesn't affect your garden.
Three maintenance items and cost estimates
Regular statutory inspections include water quality testing, maintenance inspections, and cleaning, and contracts are signed with a management company and a cleaning company for each of these, and annual management fees are charged.
①Water quality testing: 1 time/year 5,000 yen *Water quality testing is mainly carried out by a contractor contracted by the Nagano Prefecture Septic Tank Association
②Maintenance inspection: 4 times/year 29,800 yen (excluding tax) *Contract with management company
③ Cleaning: 1-2 times/year, 14,000 yen/m3 (excluding tax) *The capacity of a typical residential septic tank is 2m3, and the cleaning company is contracted to clean the tank.
Various aspects of ground reinforcement work
If the ground on the site for building a house is weak, we will carry out ground reinforcement work to safely support the building. The need for ground improvement work is determined based on ground survey data such as Swedish sounding tests. In our case, the cost of the ground survey is 55,000 yen.
Karuizawa's geology is characterized by a wide distribution of soft ground, such as "humus soil" and "volcanic ash soil," and ground reinforcement work is carried out at most construction sites. As a rough estimate of costs, you should budget for ground reinforcement costs of approximately 1.5 million to 2 million yen for a house of 133 to 166 square meters.
Please check the construction methods below. Generally speaking, the further to the right you go, the higher the cost.
Surface improvement method
This is a ground improvement method that uses cement to harden the ground surface and surrounding areas. It is used when the weak ground is shallow, up to 2m below the surface.
Columnar improvement method
This is a construction method in which the ground is excavated, cement and soil are mixed and stirred, and the building is supported by cylindrical piles. It is used when the ground is 2 to 8 meters below the surface.
Small steel pipe pile method
This construction method involves driving steel pipe piles into hard ground deep underground to support buildings, making it possible to reinforce the ground up to 30m underground.
[Environmental pile construction method also adopted]
In cases where the geology makes it difficult for cement to solidify, the "environmental pile method" is often used. The environmental pile method is an "environmentally friendly ground improvement method" that uses wood to support houses. By implementing high-quality preservative and anti-termite treatment, it is highly durable and "resistant to corrosion" and "termite damage," and has the same level of support as other methods. The cost is about the same as the columnar improvement method.
summary
We have summarized the unique features of Karuizawa in terms of architecture. These are the questions frequently asked by our customers and the information we always provide.
Finally, please check again!!
◆High humidity and cold winter temperatures are important! Be sure to experience them for yourself. ◆Don't take it lightly just because it's a vacation home. You must take measures against humidity and cold! ◆When choosing a construction company, make sure to check not only the design and price, but also the performance, construction system, and aftercare.
We provide comprehensive support, from assisting with land selection to design, construction and after-sales maintenance.
We also offer guided tours of Karuizawa and tours of the homes of relocating owners. Please feel free to contact us with any concerns you may have about relocating, such as child-rearing, work, and lifestyle.
We look forward to seeing you at the "Kobo Shinshu no Ie" Karuizawa showroom !
While we are architectural professionals such as designers and construction managers, all of our employees act as "Shinshu concierges" to support a rich life in Shinshu.
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