Case study Passiv house Next generation model use

"Seseragi®" case study

World-class ductless heat exchange ventilation system

Note: all reviews were originally written in Japanese and have been translated as close to the original meaning as possible. The original versions can be found on our Japanese website.

Customer's review

Hirosaki city, Aomori prefecture Mr./Mrs. Y

"I moved in about 3 months ago and feel very comfortable."

Japanese style room with a 'Seseragi®' on the wall.

I moved in about 3 months ago and feel very comfortable.
The wall has antibacterial, deodorant, moisture absorption
and release functions. Following a recommendation, I had
a mortar made of natural scallop materials be applied,
and in combination with this ductless ventilation system,
there is no unpleasant smell and the whole family
lives with peace in mind.

Thank you for everything.

Newly built house with a 'Seseragi®' installed.

Customer's review

Hachinohe city, Aomori prefecture Mr./Mrs. K

"The heat exchange rate is good and there is not much of a temperature difference inside the rooms."

Room with a 'Seseragi®' installed.

The carpenter first told me about high heat exchange rates
and it became a deciding factor for me.
This is how I got introduced to the "Seseragi®".

When I first used the "Sesseragi®", I noticed that the
noise is quiet and there is almost
no temperature change in the rooms.

Spacious room with a 'Seseragi®' installed.

Customer's review

Oshu city, Iwate prefecture Mr./Mrs. K

"I felt sympathy with the founding story posted on the homepage and made the purchase, because I liked the ductless features."

As I was searching for a suitable ventilation system for a new house, I came across the "Seseragi®".
The main reason to make the purchase came after I read the "Seseragi founding story" and felt sympathy for Mr. Deutinger(CEO). Of course, I also liked the ductless features of the ventilation system.
Ventilation through ducts felt uncomfortable for me, as I previously lived in a house with natural ventilation (wind could freely pass), which became normality for me.
Therefore, the simplicity of not pulling the ducts around was attractive.
When I later had the opportunity, after buying the "Seseragi®", to actually have a look at all the pipes of a ventilation duct and realized their complexity, I thought going ductless was indeed a good idea. Also, although it is a matter of taste, I like the feeling the looks from in- and outside give me.
I didn't really like the shape of conventional ventilation hoods, but I like the different outside hood of the "Seseragi®".

Newly built house.

Customer's review

Saitama prefecture Mr./Mrs. T

"With the 'Seseragi®' we realize a small, but high-performance home."

The owner T. is the representative director of a construction office and a first-class architect.

White model house.

"At present, we have installed the 'Seseragi®'
in a small model house, right next to our office.

In pursuit of comfort, it was designed with a
strong commitment to heat insulation, air tightness
and ventilation in particular. However, in order to
realize the limited space at the slope ceiling and
beam, a duct could not be installed."

High room with 2 Seseragi®s installed.

"With the ductless heat exchange ventilation "Seseragi®",
there is no duct and no need to store one.
As a result, the ceiling height can be increased,
resulting in high performance and more open space.

The introspection has no partitions and is
constructed openly.

After being used as a model house for several
years now, I do think that it is a house in which
a couple is able live well."

Customer's review

Miyazaki prefecture Mr./Mrs. H

"I am satisfied with the feeling of good ventilation balance."

"Wanting to live in a home where I didn't have to care about heat or cold was a good opportunity to purchase the 'Seseragi®'.
I thought that maintenance and repair would be no problem from now on and having a recommendation from a designer, I could cheaply install the 'Seseragi®' without plan restrictions otherwise caused by duct piping. I am satisfied with the feeling of good ventilation balance."

Living room with a 'Seseragi®' installed.

The "Seseragi®" is well suited for
houses with a sloped ceiling or
high ventilation requirements.

The ceiling is high and very open.
Because of the high ceiling alone,
the volume of the room increases,
making insulation performance
an even more important factor.

Modern house front.

The "Seseragi®" has a simple outer
hood design, thus not conflicting with
the house's individuality.

Customer's review

Nagano prefecture Mr./Mrs. O

A room.

"When I had trouble, I received service until the very end
and for that, I am very grateful"

A nice review came from the house owner O. in Suwa-gun, Nagano prefecture, who installed our
ductless heat exchange ventilation system in their home.

Handwritten Japanese review by a customer.
"Our house is a high airtight, high insulation, wood based house, with German sashes and a heating stove. Among them, the ductless heat exchange ventilation system works well, which satisfies me.
Once (4 years after installation), there was a problem with the controller. At first, I was worried that it might be hard to fix, because it is an overseas product, but I received an immediate reply to my inquiry and had help until the very end. Everything is operating smoothly now. Replacement parts were supplied free of charge and I feel very grateful. Thank you for your good service."

An attic.

Mr./Mrs. O contacted us through the manufacturer, as the company
responsible for the installation was closed 4 years earlier.
We had to cope over the phone many times and utilize the help of Mr./Mrs. O.
It is a relief, that the problem could be solved thoroughly.
We hope our good cooperation continues on.

Customer's review

Kyoto city Mr. G

"Design and comfort coexist. High ceilings cause no complications, thanks to the ductless nature. My wife with hay fever can live without concern inside the house."

A Kyoto style house.

In accordance with obtaining a
low-carbon housing certification
and wishing to balance design and
comfort, we were considering to
introduce a heat exchange system.
However, since a general heat exchange
system relies on ducts passing through
the building, clearing the area under
the beam is necessary and the space
beneath the ceiling can not be utilized.
Therefore, I installed the 'Seseragi®'.

Living room with a 'Seseragi®' installed.

Since I moved in in February, and the cold
was especially severe, I didn't open the
windows much, but it was well ventilated
and the temperature inside was mostly

The house has about 99 m², but thanks to
the 'Seseragi®', I never have to use a heater
in more than 2 places at once.

On top of that, thanks to the pollen protection,
my wife with hay fever also says that
she feels well in the house.

Customer's review

Tottori prefecture comapny M owner H owner M

"We are very satisfied with the air conditioning effectiveness. Complete heat exchange ventilation and ductlessness were the deciding factors for the installation."

When coming home, I didn't feel the heat in summer, or the cold in winter.
The air conditioning effectiveness is also good.
(Tottori prefecture, Yonago city, owner H)

White house front. Room with 2 Seseragi®s installed.

"There is a distinct difference compared to my former residence. Even in summer the whole house can be quickly cooled down. I think it is not only due to the ventilation, but I am satisfied. After all, insulation and ventilation are important!"
(Tottori prefecture, Nishumuro-gun owner M)

Spacious room with a 'Seseragi®' installed.

Customer's review

Shizuoka city Mr./Mrs. N

"High insulation house + comfortable space = 'Seseragi®'.
 No need for an air purifier and introducing the 'Seseragi®' into the house to reduce utility costs was the correct decision."

"From hearing the explanation of company S. and aiming to build a high insulation performance house, we thought it necessary to install the 'Seseragi®' in order to maintain performance and a comfortable living space. The installation was convenient and so far we feel comfortable, while almost never using the air conditioner.
The pollen filter removes more than 99% of pollen and PM2.5, so there is no need for an air purifier, reducing utility costs. I'm very glad to have installed the 'Seseragi®'."

Living room with a 'Seseragi®' installed.

Customer's review

Okinawa prefecture, Kunigami-gun Mr./Mrs. O

"Perfect for Okinawa's hot and humid climate. I installed the 'Seseragi®' to keep the air clean for asthmatic family members."

"Not having a duct was the deciding factor for the installation. If there was a duct, and you'd neglect cleaning it, dust builds up and mold may develop. As I have a child with asthma, I was looking to eliminate such negative factors as much as possible. I am very grateful to always have clean air as a result of having no ducts."

"Our house in Okinawa is in a hot and humid
subtropical climate zone. Therefore, we did
some research about various ventilation
systems popular in Honshu" (main Japanese island)
"and whether they were suitable for use
in Okinawa and reinforced concrete housing.

Consequently, we decided that the 'Seseragi®'
is indeed suitable for Okinawa's hot, humid
and decided to install it."

A 'Seseragi®' is installed near the ceiling. A room with a 'Seseragi®' installed. modern, white house front.

Customer's review

Kanagawa prefecture, Kawasaki city Mr./Mrs. H

"The 'Seseragi®' is an absolute requirement for highly airtight, highly insulated houses.  The catalogue is easy to understand and the post move-in image is accurate."

"Aiming for a highly airtight and insulated residence, installation of a heat exchange ventilation system was an absolute requirement.
A construction company member had already introduced us to the 'Seseragi®', but it was the easy to understand catalogue, that gave us a good image of what the heat exchange ventilation system would be like, after moving in. When operating on a low air flow level, the noise is hardly noticeable."

Room with a 'Seseragi®' installed.

It is not only a highly airtight and insulated house,
but it also has rooms that take advantage of the height,
where you can feel the close attention to detail everywhere.

In such a case, installing a ductless heat exchange
ventilation system is suitable.

A staircase.

Customer's review

Niigata city Mr./Mrs. T

"The 'Seseragi®' has better heat exchange rates compared to other companies' products and pleases me more than I had expected."

"The reason to install was a
recommendation by the construction
company's employee, who suggested
the design in full consideration of the
effects on the air inside the whole building
including the corridor.

I didn't give much thought to the installation
because of the recommendation, but when the
time came, I was not let down!
I am satisfied when comparing the heat
exchange rate with other ductless products

Modern kitchen with a 'Seseragi®' installed nearby.

The design of the 'Seseragi®' naturally
goes well with Western style rooms, but
also, with Japanese style rooms.
Whatever the room, the design does
not interfere with the interior.

If you have a 'Seseragi®', you don't have to
prioritize performance over design at all.

Japanese style room with a 'Seseragi®' installed.

Customer's review

Niigata city Mr./Mrs. A

"I feel comfortable every day. Deciding factors for the installation were of course performance; careful planning and good compatibility."

"The thermal situation of the house was my first consideration.
We considered various elements, such as planning, structure, heat insulation method, window performance, facilities etc. and finally decided for the 'Seseragi®'.
On top of good performance, there is no duct to interfere with the interior, which made planning easy."

Living room and kitchen with a 'Seseragi®' installed.

"The local ventilation part comes with a shutter and
I felt like the 'Seseragi®' has better performance when
compared with other manufacturers' products.
I noticed that I felt very comfortable every day.
I adjust and try out a numerous settings, depending
on time and weather until I find just the right one."

The front of a house.

Customer's review

Saitama prefecture, Kumagaya city Mr./Mrs. M

"Even if I don't open the windows to ventilate, I don't notice an unpleasant smell at all. I feel like the air can be kept fresh and the temperature even."

House front with a 'Seseragi®' installed.

"I was looking for a system that could replace the air pollution
generated in a closed indoor space with fresh air without
disrupting the room's temperature and humidity

I learned about the 'Seseragi®' by looking at the homepage
and watching videos on YouTube, but I also went to an exhibition
to confirm the actual size and noise level of the machine."

Bedroom with a 'Seseragi®' installed.

"10 months have passed since the installation.
With the heat exchange system, there is no
need to worry about pollution sources, such as
CO2 exhaled by people or odor of the house.

I feel that in winter or summer, the
air is always fresh and the temperature
constant without having to open the windows

Customer's review

Saitama prefecture Mr./Mrs. K

-This is a case of an apartment renovation- "I don't feel cold when walking barefoot even in December. The onset of nail skin peeling was also suppressed."

Handwritten Japanese review by a customer.
We installed both double glazing and the 'Seseragi®'.
As of December, the temperature is constantly in the range of 21°C~22°C (69.8°F~71.6°F) and humidity between 50% and 60%. This uniformity is not only maintained in the living room, but in all rooms alike.
Until the renovation, each room was closed, but now it has changed to an open life with the door of each room open.
We also needed a hot carpet in winter. Now however, I don't even feel the cold when barefooted.
In winter, I used to be troubled with skin peeling off my fingertips due to dryness, but I am happy now that the onset is suppressed."

Construction company's review

Akita prefecture designer N

"The key reason of the installation was the ability to thoroughly clean the machine myself.  It came as a nice surprise that the temperature throughout the entire house equalizes."

"In the case of a duct type heat exchange ventilation system, cleaning can't be handled by oneself
and if filters don't get cleaned, it results in clogging and weak ventilation performance.
Also, there are many residents who sensuously dislike ducts but still use them for a long time.
However, when I saw the 'Seseragi®' with its self-explanatory cleaning procedure, I thought:
'Hey, that's nice!' and bought it.
Afterwards, the air could circulate through a private room to the living room, the corridor, and back again,
equalizing the temperature in the entire house
. That was an unexpected, but welcome effect."

Construction company's review

Mie prefecture, Ise city company K

"The Seseragi's ductlessness and simple room cover matches well with houses trying to show off their beams! The operating noise also doesn't bother you at all."

"This is a house that tries to show
off it's outer beam, so I couldn't
place the duct properly and thus,
thought about installing the 'Seseragi®'.
When trying it out, I felt that the noise
is almost unnoticeable and the
protrusion of the room cover is small,
integrating well into the room."

House front. Room with a 'Seseragi®' installed. Wall with a 'Seseragi®' installed.

The outdoor cover has a similar color to the
wall and is installed in an unobtrusive place.

Construction company's review

Miyagi prefecture, Sendai city company I

"Because the heat exchange runs properly, my worries about the cold have disappeared!  The noise level is low, so there is no problem to have it installed in the bedroom."

"Sendai had a minimum temperature of around 2°C
(35.6°F) to 10°C(50°F), that lasted for some time.
At the beginning of the installation, I was worried
about the cold.
At present, we have set the ventilation level to 2 and
when we measure the ceramic part with a pyrometer,
we can see that the heat exchange is stable, which
calms me.
Since the heat image turned red and the sound is
extremely quiet
, there is no problem installing the
'Seseragi®' in the bedroom.

With the total heat exchange and about 50% humidity
in each room
, just the right conditions are maintained.
It was the first installation of this kind for our company,
and the electric shop employee was also at loss,
but we still managed it somehow.
Removing the machine also seems doable."

House front. Staircase with a 'Seseragi®' installed. Room with a 'Seseragi®' installed. Room with a 'Seseragi®' installed.

Construction company's review

Tochigi city company O

"The big advantages are the ease of managing the thermal conditions and not needing space for ducts. The new design of the remote controller is also good!"

"Originally, I was considering to install duct
type 1 ventilation, but securing space for the
duct turned out difficult and the maintainability
of the duct also gave me a headache. That is when
I found the 'Seseragi®' on the homepage and decided
to install it. Not needing space for the duct and the simple
temperature regulation
are big advantages in my opinion.
I also really like the design of the new remote controller."

Dining room with a 'Seseragi®' installed. House front.

Construction company's review

Fukushima prefecture, Iwaki city company T

"Heating only from end of December to end of February!"
(1 air conditioner・3 hours on average)

*The owner is self-proclaimed "insulation nerd" and first class architect Mr. T.
He integrated the 'Seseragi®' into his home, which is also his office.

"Ductless was appealing to me.
Even in winter I can wear short sleeves.
I was only heating for 2 months from
end of December to end of February
(1 air conditioner, 3 hours on average) with
no other heating of any kind during that period!

Children plaing happily. House front.

Construction company's review

Ishikawa prefecutre Kaga city company O

"Low heat loss and easy construction were the deciding factors. Even on a hot summer day I could not feel warm air flowing in."

"As this was supposed to be a long-term, top-quality
house, I wanted to adopt a low-heat-loss ventilation
I learned about the 'Seseragi®' by the owner's
We decided to install this system due to its low heat
loss, workability and the owner's strong wish
I actually tried the 'Seseragi®' out and thought that the
workability was really good.

Additionally, during operation, the noise level of the fan
is so low that it doesn't concern me at all.
On a hot summer day (with outside temperatures
exceeding 35°C(95°F)) with the air conditioner keeping
the room at 25°C(77°F), I held my hand right at the
'Seseragi®' but couldn't feel warm air streaming in

Top right: A large open LDK for a sense of openness.
Planned for use of the ductless 'Seseragi®'.

Bottom left: The 'Seseragi®' viewed from outside.
It suits the house due to it's flat cover.

Kitchen with a 'Seseragi®' installed nearby. House front.

Construction company's review

Adopted to Q-value 1.0 housing                   Yamagata prefecture company K

"The search for a high cost-benefit ratio product led me to install the 'Seseragi®'. Power consumption, maintenance, heat exchange rate and operation noise are all excellent."

"In consideration for the main flux of the ventilation system, I was looking for a product with
emphasis on power consumption, maintenance, heat exchange and operation noise.
As it was a property with many sloped ceilings and beams I thought the ductless 'Seseragi®'
would make planning simple. Reasonable maintenance and no need for a duct, soon
convinced me to install it.
The noise of the fan is also extremely quiet. We want to put the heat exchange into
effect this winter."

Japanese style room with a 'Seseragi®' installed. A window.

The 'Seseragi®' also suits a wood grain outer wall.
We wanted to thank you for placing another order
later on for a different zero energy house!

House front.

Construction company's review

Akita city company K

"After careful consideration, we decided to adopt the 'Seseragi®'. We noticed that the temperature difference between all rooms and floors has become very small."

We were considering to implement a type 1 class ventilation system to reduce the house's heat loss. In that case however, the space used up by the duct could no longer be used and questions about cleaning and maintaining the duct still remained.

At that time, company S already knew about the 'Seseragi®' from the website or direct mails and after careful consideration, we decided to introduced the system.

Spacious, luminous Dining room with a kitchen.

Houses that typically install the 'Seseragi®'
have beams, graded ceilings or provide
easy air flow throughout the home.

High ceiling height alone increases the
volume enough so that insulation becomes
an even more important factor.

House front.

The house was move-in-ready
from hot July.

We received an impression by the
owner that the temperature difference
between the rooms and floors was
really small, probably because of the
alternating air flow direction.

Construction company's review

Miyagi prefecture, Sendai city company K

"Going out of my way for this house, I suggested the 'Seseragi®' without hesitation. No customer complaints, comfortable summer nights and good popularity."

By the owner's wish for the 'Seseragi®', I first
learned about the product. Having no duct,
I thought maintenance and construction
would become convenient.

Honestly, when I set the air flow on 'high',
I could notice the noise, but no customer
ever complained. In contrast, I heard that
the 'Night purge mode' makes summer
nights very comfortable
. It makes me
happy that there is no problem with the
ventilation, even on low settings and
maintenance is convenient.

Since the heat exchange is done properly
and caused no problems, I would like to
suggest the 'Seseragi®' to other houses
or projects with scarce duct space as well.

Room with a 'Seseragi®' installed. House front.

Construction company's review

Miyagi prefecture, Sendai city company K

"We recommend this product our customers, because of the reliable staff and products."

We installed the 'Seseragi®' on our customers request. When installing it, it seemed like a reliable product.
Recently, we recommend this product for customers with high ceilings and those, trying to avoid duct type
ventilation systems.
Even if you don't know everything about the product, you can safely order it, because the staff support of
Passiv Energie Japan is good

House front with 2 Seseragi®s installed. Room with a 'Seseragi®' installed. The outdoor cover is also shown.

Customers say the good things about the product are quiet operation noise and easy maintenance.
They are also pleased, that the filters can conveniently be purchased on the website or on Amazon.
I also heard a review, that the remote controller was cool. Though this is not related to performance,
I thought quality of design to be important, as the controller is also installed indoors. This time, we also
installed the 'KK2' outdoor cover, which has a backflow-prevention effect. The product itself is easily
installed and I feel like water tightness and drainage are better than in previous versions.

Construction company's review

Niigata prefecture company K

"The 'Seseragi®' scored well on the air tightness measurement, fueling high expectations!"

By the owner's request for a heat exchange type system, I searched for one
that is easily maintained and does not need regular professional cleaning.
When I then found the 'Seseragi®', I decided it would be suitable for this purpose.
The ductless heat exchange system 'Seseragi®' scored high on the air tightness
and with this result, I expect much from it come winter.

House front. A 'Seseragi®' being installed.

M's property - Air tightness measurement

With the model having beams, a graded ceiling and a big opening,
I couldn't properly lay a duct.
The 'Seseragi®' was appealing for having no duct and no need
for regular professional cleaning in a hardly reachable location

Itchinotsubo model house nr.49

Dining room with a 'Seseragi®' installed.

Construction company's review

Nagano prefecture company B

"It is appealing that the 'Seseragi®' is slim, compared to other products.
 Even in cold regions, the heat exchange runs soundly."

At first, we had planned to install a duct type
ventilation system. During construction however,
the duct turned out to be causing problems with
the design, so I went overhead in finding a ductless

Finding the homepage of Passiv Energie Japan was a
good opportunity for this change.
As the construction phase had already begun and
the product made a good impression, I quickly installed
it. Also appealing was that the product is slim,
compared to other products.

House front covered in snow. Corridor with a 'Seseragi®' installed.

Nagano prefecture is a region, in which winter can
be extremely harsh, but being able to comfortably spend
the winter
makes me very happy.

When operating on the highest air flow level the sounds gets
a little loud, but the heat exchange effect is noticeable even
on lower settings so it's not really a problem.

Construction company's review

Kyoto prefecture company M

"The 'Seseragi®' was recommended, because of high rooms and lots of space for ventilation.  We are happy that there is no temperature difference in any room."

When building this highly airtight and highly insulated house, we
started looking for a ventilation system that could run 24/7.
That's when we remembered one of our customers, who had
previously introduced us to the 'Seseragi®'. Ductless ventilation
was perfectly suited for this particular building.

Air supply and exhaust can be easily switched just by a single
fan and the ductless architecture is easily maintained.
The outdoor cover is simple in design, which gives the outside
look the perfect finish.

House front with 4 Seseragi®s installed. A modern kitchen.

Customers commented that "Even though the
rooms are large open-air rooms, temperatures
are mostly constant and equal throughout
the rooms, making living here very
I believe the 'Seseragi®' has a high impact
on life quality.

Construction company's review

Gifu prefecture company L

"Heat exchange, maintainability, workability, price. Overall excellent."

We installed the 'Seseragi®' after comprehensively judging energy saving performance, price, noise, size, heat exchange efficiency and operability.

  • Heat exchange ventilation makes it possible to save energy and improve the thermal conditions.
  • Renewable equipment is necessary to increase the machine's life span.
  • A simple construction to reduce installation costs and maintenance needs.
A spacious dining room and kitchen with a 'Seseragi®' installed.

Right up until the installation I was worried that the indoor cover might be a little too big,
but when it was installed it actually matched the interior smoothly and was hardly noticeable.

House front. Room with a 'Seseragi®' installed.

Construction company's review

Hokkaido company S

"Even in Hokkaido's harsh cold, the 'Seseragi®' cuts heating bills!
It provides a comfortable environment, while preventing condensation!"

In areas with severe cold and heavy snowfall, the indoor conditions and heating bills are cause for concern.
With general ventilation systems cold outside air can unhinderedly get into the room, causing discomfort and
a raise in heating efforts. The 'Seseragi®' however, recovers up to 93% of the room's warmth!
It is popular for being "really comfortable even in winter", because it is preventing unwelcome temperature drops and supplying air close to normal room temperatures. Moreover, we are pleased to save on heating bills, by reducing internal heat loss from ventilation.

Dining room with a 'Seseragi®' installed.

Not only temperature regulation, but also humidity control is one of the system's strengths.
In winter, condensated water tends to accumulate on the windows. With the 'Seseragi®' however, the built-in porous ceramic heat storage element collects water vapor as well as the air's heat, naturally keeping the humidity within a small margin around modest levels.

House front covered in snow. Bedroom with a 'Seseragi®' installed.

Passiv House

Image of the Yokohama Passiv House.

■ Yokohama Passiv House

The first Passiv House built in the Greater Tokyo area
Integrating various modern technologies, smoothly accepted
by Japanese society, it is well suited for the modern society
and the ultimate super-energy-saving future society.
In order to achieve the original German Passiv House
performance standards, numerous eco-technologies are deployed.

Location: Kanagawa Prefecture, Yokohama City, Kanazawa Ward
Construction: started 06.2010 (completed 10.2010)

Commitments of the Yokohama Passiv House

The following equipment was adopted to achieve the German passive house standard (annual heating/cooling load 15 kW/m² or less).

1. Ultra-high air tightness・high insulation methods

2. Type 1 ventilation system ('Seseragi®') adopted

3. Wall greening・Kitchen garden

Yokohama Passiv House photovoltaic data

It is data of the photovoltaic panel installed in the Yokohama Passiv House.

Energy saving・energy generation of the Next Generation model house

high performance

Type 1 eco-


energy saving - energy generating Next Generation model house adaptations

Power saving・power generation adopted in the Next Generation model research group's model house

Location: Saitama Prefecture, Kasukabe City
Construction: started in November 2010
[example photo above]