Final ReportElectric Toilet Seats Evaluation Standard Subcommittee,
Energy Efficiency Standards Subcommittee ofthe Advisory Committee for Natural Resources and Energy

The evaluation standards for the manufacturers of electric toilet seats were presented in
the “Final Criteria Summary by the Sub-committee for Judgment Criteria for Electric
Heating/Warming Appliances, the Energy Conservation Standards Working Group, theResearch Committee for Total Energy (April 3, 2002)” , and its target year was fulfilled in FY
2006.
While each manufacturer has been making efforts to develop new products pursuing
better energy efficiency, such as a toilet seat that is instantaneously warmed only when it isused, the current measurement method is not necessarily appropriate for measuring productswith new system according to their usage reality.
To review the current measurement method and target scope and then determine newtarget standard values, Electric Toilet Seats Evaluation Standard Subcommittee wasassembled.
The subcommittee had deliberations on the evaluation standards for
manufacturers and importers (hereinafter referred to as “manufacturers”) and adopted thefollowing final report.
1. Evaluation of Current Standard
As for electric toilet seats whose target fiscal year was fulfilled in FY 2006, the weighted
average of energy consumption efficiency was 240 kWh/year. It is improved by 14.6 % from
281 kWh/year which is the value of those (shipped in FY 2000) before Top Runner standards
are introduced. In addition, the result is better than originally assumed efficiency of 253
kWh/year and assumed improvement of 10.0 %, which are the estimates when the Top
Runner standards are achieved.
In the light of the above, the energy saving of electric toilet seats has been progressing asa result of the manufacturers’ efforts, and it can be recognized that the current standards
based on the Top Runner method are working effectively.
2. Target Scope [See Attachment 1]
The target scope covers electric toilet seats except the followings: those to which the warm
water is supplied from other hot-water supply equipment (central hot-water supply system),those equipped with a warm-water-shower function only, those produced for the use inportable toilets, and those for the use at specific places such as in vehicles.
3. Details of the Evaluation Standards for Manufacturers(1) Target fiscal year [See Attachment 2]
FY 2012(2) Target standard values [See Attachments 3 and 4]
Concerning electric toilet seats to be shipped by a manufacturer for the domestic market
in the target fiscal year, for each category in the table below, the manufacturer has tomake sure that the value obtained by weighting and averaging energy consumption
efficiency (annual energy consumption) calculated according to (3) with the number ofshipped units shall not exceed the target standard value.
Category
I
II
III

Availability of Shower
Function
Warm toilet seat
(Without shower function)
Warm-water-shower toilet seat
(With shower function)

Availability of Warm-Water
Tank

Target Standard
Value (kWh/year)-

141

Warm-water storage type
(With warm-water tank)
Instantaneous type
(Without warm-water tank)

1

183
135

(3) Measurement method of energy consumption efficiency [See Attachment 5]
Energy consumption efficiency shall be a value (kWh/year) calculated by the following
formula.
P={(PWA+PSA+PCA) × T1 + (PWB+PSB+PCB) × T2 + (PWC+PSA+PCA) × T 3} × 365 / 24 × 10-3
where P, PWA, PSA,, PCA, T1, PWB, PSB, PCB, T2, PWC and T3 express the following values:
P:
Annual energy consumption (kWh/year)
T1: Operating time (h)T2: Power-saving time (h)T3: Recovery time to normal operation (h)PWA: Energy consumption of water warmer unit in normal operation (A water warmer
unit is a structural part of an electric toilet seat and warms up supplied water.
Hereinafter the same definition applies.) (It is applicable only to warm-watershower toilet seats.) (Wh/day)
PSA: Energy consumption of toilet seat unit in normal operation (Wh/day)
PCA: Energy consumption of control & operation unit in normal operation (A control &operation unit is a structural part of an electric toilet seat, which controls eachstructural part and operates every function. Hereinafter the same definition
applies.) (Wh/day)
PWB: Energy consumption of water warmer unit in power-saving mode (It is applicable
only to those having a power-saving function for a water warmer unit.) (Wh/day)
PSB: Energy consumption of toilet seat unit in power-saving mode (It is applicable
only to those having a power-saving function for a toilet seat unit.) (Wh/day)
PCB: Energy consumption of control & operation unit in power-saving mode (It isenergy consumption of a control & operation unit with power-saving functions
activated for a water warmer unit and a toilet seat unit.) (Wh/day)
PWC: Energy consumption of water warmer unit when recovering to normal operation(It is applicable only to those having a power-saving function for a water warmer
unit among warm-water-shower toilet seats with warm-water tank.) (Wh/day).
(4) Display items and others(a) Display items shall be as follows.
a) Product name and typeb) Categoryc) Energy consumption efficiency (annual energy consumption)d) Name of manufacturer(b) Compliance itemsa) Energy consumption efficiency shall be indicated as an integer value rounded at
the first decimal place and expressed in “kWh/year”.
b) When displaying energy consumption efficiency, annual energy consumption
without using power-saving functions (measured and calculated according to themeasurement method described in (3), with the T2 and T3 values set to 0) shall also
be displayed in parenthesis.
c) At consumer’s selection, the display items shall be clearly displayed in prominent
position in catalogs and instruction manuals which describe the productperformance.
d) It shall be noted that energy consumption efficiency is annual energy consumption
measured in accordance with the measurement method specified in the Energy
Conservation Law and also noted that annual energy consumption when not using
power-saving functions is displayed as well.

2e) Since the measurement method to measure energy consumption efficiency isrevised, the display items shall be updated as soon as possible. When displaying
the information in accordance with the new measurement method, it shall be
noted so.

(Reference) Example of Display
EnergyAnnual
省エネ基準
年間消費Conservation
EnergyStandard
Consumption
達成率
電力量
Achievement135
目標年度 100% (169)
Rate

Target fiscal
year
FY 20122012年度kkWh/year
Wh/年(Note 1) Energy conservation standard achievement rate and（注１）省エネ基準達成率、年間消費電力量
Annualenergy consumption are the values measured in
は新基準（2012年度基準）に基づく測
accordancewith the new standards (Standards for FY 2012).
定結果。
(Note 2) The value in parenthesis indicates annual energy（注２）（）は節電機能を使用しない場合の年
consumption
when not using energy-saving functions.
間消費電力量。

4. Proposals for Energy Saving(1) Actions of users(a) Efforts shall be made to select electric toilet seats with excellent energy consumption
efficiency by effectively using information such as “Energy-Saving Label”. Whenusing electric toilet seats, energy saving effort shall also be made through appropriate
and efficient usages (e.g. lowering temperature setting and deactivating warming
function when not needed such as during summer).
(b) Particularly, if electric toilet seats have power-saving functions, efforts shall be madeto utelize them.
(c) When electric toilet seats are installed at the time of the construction of housings orbuildings, efforts shall be made to select those with excellent energy consumption
efficiency.
(2) Actions of retailers(a) Sales of electric toilet seats with excellent energy consumption efficiency shall bepromoted, and efforts shall be made to provide appropriate information by use of“Energy-Saving Label”, etc., so that users are able to select such electric toilet seats.
Also, in utilizing Energy-Saving Label, it shall be displayed clearly so that users canunderstand it easily without misconception.
(3) Actions of manufacturers(a) Technical development for energy saving of electric toilet seats shall be promoted, andefforts shall also be made to develop products of excellent energy consumption
efficiency.
(b) Aiming at the spread of electric toilet seats with excellent energy consumption
efficiency, effort shall be made to provide appropriate information by means of“Energy-Saving Label”, etc. so that users are able to select such electric toilet seats.
Also, in utilizing Energy-Saving Label, it shall be displayed clearly so that users canunderstand it easily without misconception.

3

(c) To promote the use of power-saving modes by users, manufacturers shall make efforts
to develop products having a leaning control function and the like, so that users caneasily select the power-saving modes, and also they shall make effort to provide users
with appropriate information on power-saving.
(4) Actions of Government(a) Aiming at the spread of electric toilet seats with excellent energy consumption
efficiency, efforts shall be made to take necessary measures, such as spread andenlightenment activities, so as to promote actions of users and manufacturers.
(b) Implementation of the display items by manufacturers shall be checked periodicallyand continuously. Also, appropriate law management shall be made so as for correctand easy-to-understand information provision for users concerning energy
consumption efficiency.
(c) Energy conservation standards based on the Top Runner method is a very effectivemeans for energy-saving of products; therefore, efforts shall be made to promote better
understanding about the Top Runner method and to have it spread internationally bycatching appropriate opportunities. .

4

Attachment 1
Scope of Electric Toilet Seats
The evaluation standards are applied to all types of electric toilet seats except for thefollowing:(1) Electric toilet seats to which warm water is supplied from other hot-water supply
equipment (central hot-water supply system)
These products are used for specific applications such as in hotels and have no establishedmeasurement method to measure energy consumption efficiency, and thus they are
excluded.
* Shipment volume (FY 2005): Approximately 33,000 units(2) Electric toilet seats equipped with a warm-water-shower function only
Their production volume is extremely small, and thus they are excluded.
* Shipment volume (FY 2005): Approximately 40 units(3) Electric toilet seats produced for the use in portable toilets
These products are portable type and mounted on chairs for nursing care purposes.
Their production volume is extremely small, and thus they are excluded.
* Shipment volume (FY 2005): Approximately 1,300 units(4) Electric toilet seats for the use at specific places such as in vehicles
These products are placed in vehicles or the like and mostly used with non-commercial
power supply for specific purposes. There is no established measurement method tomeasure energy consumption efficiency, and their shipment volume is extremely low; thus,
they are excluded.
* Shipment volume (FY 2005): Approximately 20 units

5

Attachment 2
Target Fiscal Year for Electric Toilet Seats and Related Matters
1.

In general, a considerable improvement in energy consumption efficiency of electric
toilet seats is made when a model change takes place, and a typical development period ofthese new products is 4 to 5 years. For this reason, consideration should be given so that
manufacturers can take at least one to two opportunities of bringing out new models
before a target fiscal year.
With the above in mind, for electric toilet seats, it is appropriate to set the next target
fiscal year to be FY 2012, which is five years after the revision of standards.

2.

In addition, the improvement rate of energy consumption efficiency in the target fiscal
year is expected to be 9.7% based on the assumption that there will be no change inshipment volume and composition of each category from the current status (the result in
FY 2006).

<Overview of Estimation>(1) Energy consumption efficiency calculated from the actual achievement values ofelectric toilet seats shipped in FY 2006: 186 kWh/year(2) Energy consumption efficiency estimated from the target standard values for electric
toilet seats to be shipped in the target fiscal year: 168 kWh/year(3) Improvement rate of energy consumption efficiency:(186 − 168)× 100 = 9.7%
186
<Overview of Estimation: Warm Toilet Seats>(1) Energy consumption efficiency calculated from the actual achievement values of warm
toilet seats shipped in FY 2006: 158 kWh/year(2) Energy consumption efficiency estimated from the target standard values for warm
toilet seats to be shipped in the target fiscal year: 141 kWh/year(3) Improvement rate of energy consumption efficiency:(158 − 141)
× 100 = 10.8%
158<Overview of Estimation: Warm-water-shower Toilet Seats (Warm-water Storage Type)(1) Energy consumption efficiency calculated from the actual achievement values ofwarm-water-shower toilet seats (warm-water storage type) shipped in FY 2006:
204 kWh/year(2) Energy consumption efficiency estimated from the target standard values for warmwater-shower toilet seats (warm-water storage type) to be shipped in the target fiscal
year: 183 kWh/year6(3) Improvement rate of energy consumption efficiency:(204 − 183)
× 100 = 10.3%
204<Overview of Estimation: Warm-water-shower Toilet Seats (Instantaneous Type)(1) Energy consumption efficiency calculated from the actual achievement values ofwarm-water-shower toilet seats (instantaneous type) shipped in FY 2006:
144 kWh/year(2) Energy consumption efficiency estimated from the target standard values for warmwater-shower toilet seats (instantaneous type) to be shipped in the target fiscal year:
135 kWh/year(3) Improvement rate of energy consumption efficiency:(144 − 135)
× 100 = 6.3%
144

7

Attachment 3
Categories of Electric Toilet Seats for Setting Target Standards and Related Matters
1. Current Categories of Electric Toilet Seats
Electric toilet seats are categorized as below based on the two parameters that will
have impact on annual energy consumption (energy consumption efficiency). Concerning
warm-water-shower toilet seats (warm-water storage type), since annual energy
consumption correlates with warm-water storage capacity, the standard is expressed in a
linear function with warm-water storage capacity as a variable.
(a) Categorization by the availability of shower function(b) Categorization by the availability of warm-water tank
▪ Warm-water storage type (with warm-water tank):
Water is warmed up by a heater in a warm-water tank in advance and stored
there.
▪ Instantaneous type (without warm-water tank):
Water is heated instantaneously at the time of spout.
Table 1. Current Categories of Electric Toilet Seats
Current Categories (Electric Toilet Seats)
Warm toilet seats (without shower function)
Warm-water storage type(with warm-water tank)
Instantaneous type(without warm-water tank)Warm-water-shower toilet seats(with shower function)

2. Categorization Method for Electric Toilet Seats
Electric toilet seats shall be categorized according to the current categorization
method.
Concerning warm-water-shower toilet seats of warm-water storage type, the current
standard is expressed in a linear function with warm-water storage capacity as a variable.
However, instead of using a relational expression, a constant value shall be adopted as thestandard value for these products, taking into account that their energy saving has
progressed due to downsizing of warm-water tanks and aiming at further promotion ofdownsizing of the tanks.

8

Attachment 4

Target Standard Values for Electric Toilet Seats

1. Basic Concept
The target standard values are determined based on the idea of the Top Runner method.
Specific concepts are as follows:(a) Target standard values shall be set for every category that has been appropriately
defined.
(b) As for the categories where efficiency improvement due to future technologicaladvances is certainly expected by the target fiscal year, the target standard values
shall allow for the improvement as much as possible.
(c) Target standard values shall not conflict among categories.
2. Products to be Treated as Special Products
When target standard values are determined based on the Top Runner method, certain
products shall be treated as special products and considered as exceptions. These special
products are those which employ special technologies, whose current market share is fairly
low and which are considered to have many uncertain factors now and in future. If an
energy consumption efficiency of a product using such technology is taken as a target
standard value, products that employ widely used technologies could not exist, resulting inan extreme market distortion and causing disturbance in improvement and innovation ofother technologies. Therefore, such products shall be treated as special products andexcluded in the process of determining Top Runner values.
In this revision, the following products are defined as specially treated products foreach category:(a) Warm toilet seats▪ Those having a power-saving function
Due to their product characteristics, many of the warm toilet seats are low priced
products. Although there are four models which have an electronically controlled
power-saving function, their shipment volume accounts for only 8.8%. Thus, theyshall be treated as special products.
(b) Warm-water-shower toilet seats (warm-water storage type)▪ Those produced for public use
The maximum temperature of the public use is lower than that of the home use
because the public use products are used in a relatively comfortable and stableambient temperature. Thus, they are treated as special products.
(c) Warm-water-shower toilet seats (instantaneous type)▪ Those employing a system which instantaneously warms up toilet seat at the timeof use, while keeping it at lower temperature usually
These products are of a special type using a lamp heater and produced only by aspecific group company. Thus, they are treated as special products.
▪ Those whose toilet bowls are made of a plastic material having low heat
conductivity

9

Ordinary toilet bowls are made of ceramics to provide durability against chemicals
and abrasion for the sake of cleaning convenience. In contrast, toilet bowls of thistype of products are made of a specially processed plastic material, and thus theytreated as special products.
3. Room for Improvement in Energy Consumption Efficiency by Future Technological
Advancement
Concerning the improvement in energy saving performance of electric toilet seats,technological development has been conducted to achieve the current Top Runner standards,
and each technology has already reached close to its limit.
[Examples of Main Technologies for Efficiency Improvement of Electric Toilet Seats](a) Power-saving control technology▪ Power shutdown by timer or learning control▪ Heat-retention at a low temperature with use of learning control, human sensing,or closed-toilet-lid sensing▪ Adoption of toilet seats which raise the temperature instantaneously at the time ofuse, while keeping it at low in standby.
(b) Heat loss prevention technology▪ Improvement of the shape of toilet lid to prevent heat release from the periphery of
toilet seat
▪ Improvement from the non-uniform distribution of toilet seat temperature toprovide comfortable and uniform sensory temperature when seated▪ Reduction in the surface area of warm-water tanks, and adoption of insulating
materials to warm-water tanks▪ Application of heat loss prevention technologies, e.g. insulating materials, to toilet
seats▪ Adoption of toilet bowls that are made of a low heat release plastic material
While some of these technologies have already been applied to the current Top Runnerequipment, each manufacturer is making efforts for further efficiency improvement;
therefore, it can be said that there remains room for efficiency improvement in eachindividual element of technological development.
[Warm Toilet Seats]
An improvement from the Top Runner value by 3% is anticipated, resulting from theimprovement of the shape of toilet lids, the spread of products having a power-saving
function (10% or so), etc.
[Warm-water-shower Toilet Seats (Warm-water Storage Type)]
An improvement from the Top Runner value by 5% or so can be expected, resulting
from the application of heat loss prevention technologies, e.g. insulating materials, totoilet seats, the enhanced adoption of insulating materials to warm-water tanks, etc.
The current standard is expressed in a linear function with warm-water storage
capacity as a variable. However, instead of using a relational expression, a constantvalue shall be adopted as the standard value for this type of products, taking into
account that their energy-saving has progressed due to downsizing of warm-water tanks
and aiming at further promotion of downsizing of the tanks. Meanwhile, in thediversified consumer needs for shower function, a solid preference still remains for
products that spout a certain amount of warm water or have a warm-water tank of acertain capacity. Thus, even though the standard is not defined as a linear function
with warm-water storage capacity as a variable, the effect from these factors needs to betaken into consideration when estimating the future efficiency improvement.

10

The Top Runner product has a warm-water tank capacity of 0.85 L, while an averagecapacity of current warm-water tanks is 1.1 L. With an assumption that further
downsizing of warm-water tanks will result in an average tank capacity of 1.0 L or so,
the effect from the difference in warm-water storage capacity due to the diversified
consumer needs for shower function can be estimated as an increase of approximately 7
kWh/year (4% or so).
From the above discussion, for warm-water-shower toilet seats (warm-water storagetype), an improvement by 1% from the Top Runner value shall be anticipated.

Warm-water-shower Toilet Seats (Warm-water Storage Type)

Annual Energy Consumption (kWh/year)

290

270

250

230
Warm-water-shower toilet seats(Warm-water storage type)

210

190

170

Top Runner Value
185
Special products (products for hotel use)

150
0.00

0.50

1.00

1.50
2.00
Warm-water Storage Capacity (L)

2.50

3.00

[Warm-water-shower Toilet Seats (Instantaneous Type)]
An improvement from the Top Runner value by 6% is anticipated, resulting from theapplication of heat loss prevention technologies, e.g. insulating materials, to toilet seatsand the introduction of innovative technologies such as those seen in toilet seats which
instantaneously heat the seat unit and in toilet bowls made of plastic.
4. Specific Target Standard Values
Adding anticipated improvement by the future technological development to the Top
Runner value, target standard value is determined for each category as follows. With thesetarget values, efficiency improvement by 9.7% can be expected for electric toilet seats as awhole, compared to the weighted average values of annual energy consumption in FY 2006.

11

Category

Table 1. Target Standard Values for Electric Toilet Seats

Availabilityof Shower
Function

Availability of
Warm-water
Storage Tank

TargetStandard
Value(kWh/year)

Top
RunnerValue(kWh/year)

Improvement
Ratefrom theTop
Runner
Value
(%)

I

Warm toilet
seats

-

141

146

3

158

10.8

Warm-watershower toilet
seats

Yes
(Warm-water
storage type)No(Instantaneous
type)

183

185

1

204

10.3

135

144

6

144

6.3

II
III

Weighted
Average ofAnnualEnergyConsumption(note) in FY
2006(kWh/year)

Improvement
Rate onthe Basisof
Weighted
Average(%)

Note: Special products are included when calculating weighted average values.

Warm Toilet Seats
200

Annual Energy Consumption (kWh/year)

180
Top Runner Value
146

160
140

Target standard value 141

120
100
80
60
40
20
0
Models12

Special products(with a power-saving function)

Warm-water-shower Toilet Seats (Warm-water Storage Type)

Annual Energy Consumption (kWh/year)

300

250
Top Runner Value

185

Special products(for hotel use)

200
Target standard value 183
150

100

50

0
ModelsWarm-water-shower Toilet Seats (Instantaneous Type)

Annual Energy Consumption (kWh/year)

180
Top Runner Value

144

160
140
Target standard value 135
120
100
80
60
40
20
0

Models13

Specialproducts(Plastic
toilet bowl)

Special products(Thosewhich
instantaneously
heat the seatunit)

Attachment 5

Energy Consumption Efficiency of Electric Toilet Seatsand the Measurement Method
1. Basic Concept
Energy consumption efficiency of electric toilet seats currently defined under the
Energy Conservation Law is annual energy consumption (kWh/year), which is obtained bysumming up energy consumption measured for each function of water warmer unit, toilet
seat unit, and control & operation unit
Meanwhile, instead of existing toilet seats that are constantly warmed except in
power-saving mode, new products have been developed in pursuit of the energy-saving
performance, such as a product whose toilet seat is usually kept at a lower temperatureand instantaneously warmed up at the time of use.
According to the current
measurement method for toilet seat unit, power consumption is measured with the toilet
seat lid kept closed; thus, it does not include a procedure to measure the startup power
consumption at the time of use of the toilet seat.
Considering these situations, the measurement method which reflects the actual
status of the usage shall be established, by introducing the toilet lid open/close process,etc.
2. Specific Definition and Measurement Method of Energy Consumption Efficiency
Energy consumption efficiency is defined as annual energy consumption andcalculated by the following formula.
P = {(PWA+PSA+PCA) × T1 + (PWB+PSB+PCB) × T2 + (PWC+PSA+PCA) × T 3} × 365 / 24 × 10-3
where P, PWA, PSA,, PCA, T1, PWB, PSB, PCB, T2, PWC and T3 express the following values:
P:

Annual energy consumption (kWh/year)

T1:

Operating time (h)T2:Power-saving time (h)T3:Recovery time to normal operation (h)PWA: Energy consumption of water warmer unit in normal operation (A water
warmer unit is a structural part of an electric toilet seat and warms up
supplied water. Hereinafter the same definition applies.) (It is applicable
only to warm-water-shower toilet seats.) (Wh/day)
PSA: Energy consumption of toilet seat unit in normal operation (Wh/day)
PCA: Energy consumption of control & operation unit in normal operation (A control& operation unit is a structural part of an electric toilet seat, which controls
each structural part and operates every function. Hereinafter the samedefinition applies.) (Wh/day)
PWB: Energy consumption of water warmer unit in power-saving mode (It isapplicable only to those having a power-saving function for a water warmer
unit.) (Wh/day)14

PSB: Energy consumption of toilet seat unit in power-saving mode (It is applicable
only to those having a power-saving function for a toilet seat unit.) (Wh/day)
PCB: Energy consumption of control & operation unit in power-saving mode (It isenergy consumption of a control & operation unit with power-saving functions
activated for a water warmer unit and a toilet seat unit.) (Wh/day)
PWC: Energy consumption of water warmer unit when recovering to normal
operation (It is applicable only to those having a power-saving function for awater warmer unit among warm-water-shower toilet seats with warm-watertank.) (Wh/day).
(1) T1: Operating time (h)A value subtracting T2 and T3 from 24(2) T2: Power-saving time (h)T2 shall be the longest settable time for the power-saving function of each electric toilet
seat. If the power-saving duration can be set to 7.7 hours or longer, T2 shall be 7.7.
Supplement 1: Power-saving function may include power shutdown function, heat-retaining
function at low temperature, etc. If a product has multiple power saving functions, theone that provides the greatest power reduction (power shutdown function if available)
shall apply.
Supplement 2: While various types of power saving functions are available including thosewith timer control, learning control, and on/off switching, this measurement method
covers only a timer-controlled auto-recovery type power saving function, which isthought to be highly utilized by users.
Supplement 3: Concerning the models for hotel use which are lacking a temperatureadjustment function, for the purpose of energy conservation of a hotel, power supply ineach room including that for a electric toilet seat is often controlled by the centralized
power control system or key interlocking system installed in a hotel room; therefore,rooms are mostly in power shutdown during unoccupied hours. It can be assumed thatpower-saving state is maintained better in hotels than at homes. The hotel use
products are thus treated as those having a power shutdown function even if they are notequipped with any power-saving function.
(3) T3: Recovery time to normal operation (h)1 hour (It is applicable only to those having a power-saving function for a water warmer
unit among warm-water-shower toilet seats with warm-water tank.)
Supplement 4: For the instantaneous type warm-water-shower toilet seats and those having
no power-saving function, T3 shall be 0 because no recovery phenomenon occurs.
(4) PWA: Energy consumption of water warmer unit in normal operation (Wh/day)
For warm-water-shower toilet seats with warm-water tank, energy consumption ofwater warmer unit in normal operation shall be the value obtained by multiplying energy
consumption in 6 hours measured as specified in (11) by 4; whereas, for those without
warm-water tank, it shall be the value obtained by multiplying energy consumption per
warm-water spout measured as specified in (11) by 12.

(5) PSA: Energy consumption of toilet seat unit in normal operation (Wh/day)
Energy consumption of toilet seat unit in normal operation shall be the value
calculated by the following formula using the measurements obtained as specified in(12). (A calculated value shall be further multiplied by 1.06 if the vertical length ofthe opening of toilet seat is less than 280 mm, and by 1.03 if it is 280 mm or greaterand less than 300 mm.)
PSA = {(PS1M×KM / 2 + PS1W×KW / 4)×T4 + (PS2M×KM / 2 + PS2W×KW / 4)×T5} / (T4 + T5)

15

wherePSA:
Energy consumption of toilet seat unit in normal operation per day (Wh/day)
PS1M: Energy consumption in operation (not in use) at ambient temperature of 15ºC ±
1ºC (Wh/day)[Energy consumption per hour measured as specified in (12)] × 24
KM:
Actual usage factor at ambient temperature of 15ºC ± 1ºC: 0.7
PS1W: Energy consumption in operation (not in use) at ambient temperature of 5ºC ± 2ºC(Wh/day)[Energy consumption per hour measured as specified in (12)] × 24
KW:
Actual usage factor at ambient temperature of 5ºC ± 2ºC: 0.9
PS2M: Energy consumption in operation (in use) at ambient temperature of 15ºC ± 1ºC[(Energy consumption per single use in Mode A) × 13 + (Energy consumption per
single use in Mode B) × 3] × 24 / T5
PS2W: Energy consumption in operation (in use) at ambient temperature of 5ºC ± 2ºC(Wh/day)[(Energy consumption of single use in mode A) × 13 + (Energy consumption of
single use in Mode B) × 3] × 24 / T5
T4: Operating time (not in use) (T1 + T3 − T5) (h)T5: Operating time (in use) 16 (h)Supplement 5: Taking account of seasonal change in the ambient temperature, seasonal
weighting is applied assuming that the ambient temperature is 15ºC in spring andautumn (2/4 year) and 5ºC in winter (1/4 year) and that the toilet seat is not warmed insummer (1/4 year).
Supplement 6: Mode A refers to a case of use where a user is seated on a toilet seat, whereas
Mode B refers to a case of use where a user is standing. Mode weighting is applied
assuming that the average use frequencies in mode A and B are respectively 13 and 3 ina general household.
(6) PCA: Energy consumption of control & operation unit in normal operation (Wh/day)
Energy consumption of control & operation unit in normal operation shall be the value
obtained by multiplying energy consumption per hour by 24, where energy consumption
per hour shall be measured with a display unit in a normally selectable minimum display
mode.
(7) PWB: Energy consumption of water warmer unit in power-saving mode (Wh/day)
Energy consumption of water warmer unit in power-saving mode shall be the value
obtained by multiplying energy consumption per hour measured as specified in (11) by 24,
with a water warmer unit’s power-saving function set to provide the maximum energy
reduction.
(8) PSB: Energy consumption of toilet seat unit in power-saving mode (Wh/day)
Energy consumption of toilet seat unit in power-saving mode shall be obtained as follows.
First, energy consumption per hour is measured at each of the specified ambient
temperatures of 15ºC ± 1ºC and 5ºC ± 2ºC as specified in (12) (when not in use) with thetoilet seat power-saving function set to provide the maximum energy reduction. By
dividing the measurements at 15ºC ± 1ºC by 2 and the measurements at 5ºC ± 2ºC by 4,
two values are obtained. Then, these two values are summed and multiplied by 24 to be
the energy consumption of toilet seat unit in power-saving mode. (It shall be further
multiplied by 1.06 if the vertical length of the opening of toilet seat is less than 280 mm,
and by 1.03 if the length is 280 mm or greater and less than 300 mm.)

(9) PCB: Energy consumption of control & operation unit in power-saving mode (Wh/day)
Energy consumption of control & operation unit in power-saving mode shall be thevalue obtained by multiplying energy consumption per hour of a control & operation
unit by 24, where energy consumption per hour shall be measured with power-saving
functions activated for a water warmer unit and a toilet seat unit.
16

(10) PWC: Energy consumption of water warmer unit when recovering to normal operation(Wh/day)
Energy consumption of water warmer unit when recovering to normal operation shall be
the value obtained by multiplying energy consumption per hour measured as specified in(11) by 24. Prior to the measurement, a water warmer unit’s power-saving function shallbe set to provide the maximum energy reduction, and water temperature in thewarm-water tank shall be in a stable state. Then, the measurement is made right after
the cancellation of the power-saving setting.
Supplement 7: For the warm-water tank type, while recovering time of water warmer unit
varies depending on heater capacity, tank capacity, etc., most of the current models
restore the specified temperature within one hour in general. Thus, the measurement
time is specified as one hour.
(11) For energy consumption values defined in (4), (7) and (10) shall be measured under thefollowing conditions.
(a) Ambient temperature and temperature of water supplied to electric toilet seats shallbe set to 15ºC ± 1ºC.
(b) Water supply pressure shall be set to 0.2MPa.
(c) Temperature of spouting warm water shall be set to 38ºC (applicable only to themeasurement of energy consumption defined in (4) and (10)).
Supplement 8: For some models, the mechanism of temperature setting makes it difficult tomaintain warm water at this temperature. In such a case, as a basic rule, warm watertemperature and energy consumption shall be measured at two temperature points
which are over and below 38ºC to estimate energy consumption at 38ºC by linear
interpolation, and the estimated value is defined as the energy consumption efficiency ofthis model. If the model cannot be set at two temperature points over and below 38ºC,
such as temperature selection allowing only high (40ºC) and low (38.5ºC), the energy
consumption at 38ºC shall be estimated by extrapolating the measurements at two
selectable temperatures closest to 38ºC. For the models without any temperatureadjustment function, the measurement shall be performed at the temperature
predetermined in each model.
(d) Spouting amount of warm water shall be 400 cc ± 5% for the models with warm-watertank, and 200 cc ± 5% for the models without the tank (applicable only to themeasurement of energy consumption defined in (4)).
(e) For the models with warm-water tank, single warm-water spouting shall be madewhen starting the measurement, and two additional spouting follows with an intervalof 30 minutes (total 3 times of warm-water spouting). As a result, energy
consumption is measured for 6 hours (applicable only to the measurement of energy
consumption defined in (4)).
(f) Electric toilet seat shall be placed under a wind-free condition by, for example,
surrounding it with a box.
(12) The measurement of energy consumption defined in (5) and (8) shall be performed
under the following conditions.
[When not in use](a) Toilet seat lid shall be closed.
(b) Ambient temperature shall be set to 15ºC ± 1ºC and 5ºC ± 2ºC, and the measurement
shall be performed at each temperature.
(c) Temperature of toilet seat unit shall be set to the maximum level selectable in eachmodel.
(d) Electric toilet seat shall be placed under a wind-free condition by, for example,
surrounding it with a box.
[When in use](a) Toilet seat lid shall be treated as follows:(Mode A)At 60 seconds after the beginning of measurement, an operator enters a room
equipped with a toilet (activates a human sensor); open the toilet seat lid completely.

17

At 75 seconds after the beginning of measurement, the operator sits down on the toilet
seat (turns on a seat-occupied switch).
At 225 seconds after the beginning of measurement, the operator leaves the seat; close
the toilet seat lid completely (turns off the seat-occupied switch).
At 250 seconds after the beginning of measurement, the operator leaves the room
(deactivates the human sensor).
At 1 hour after the beginning of measurement, the measurement is terminated.
(Mode B)At 60 seconds after the beginning of measurement, an operator enters a room
equipped with a toilet (activates a human sensor); open the toilet seat lid completely.
At 65 seconds after the beginning of measurement, open the toilet seat completely.
At 160 seconds after the beginning of measurement, close the toilet seat and lid
completely.
At 180 seconds after the beginning of measurement, the operator leaves the room
(deactivates the human sensor).
At 1 hour after the beginning of measurement, the measurement is terminated.
(b) Ambient temperatures shall be set to 15ºC ± 1ºC and 5ºC ± 2ºC, and the measurement
shall be performed at each temperature.
(c) Temperature of toilet seat unit shall be set to the maximum level selectable in eachmodel.
(d) Electric toilet seat shall be placed under a wind-free condition by, for example,
surrounding it with a box.
(13) In (11) and (12), power supply voltage shall be 100 ± 2 V and power supply frequency
shall be 50 Hz or 60 Hz.

18

Reference for Attachment 5

Supplemental Remarks on the Revision of Measurement Methods

1. Water Warmer Unit
(1) Rationale for setting the supply water temperature at 15ºC
In the voluntary standards by the Association of Living Amenity and the Japan
Electrical Manufacturers’ Association, the supply water temperature is specified
depending on the season as follows:
Winter season: 5ºC
Spring and autumn seasons: 15ºC
Summer season: 25ºC
According to this method, the environment temperature needs to be changed in three
ways for each measurement; therefore, the following issues arise from the standpoint of
measurement simplicity:▪ It takes an extremely long time to adjust the temperature of an environmental test
room from that of external air to the above 3 stable environmental temperature
settings, resulting in inefficiency of measurements.
▪ Each model needs to be measured in three different environmental temperatures,
resulting in a long measurement time.
It is important to improve the accuracy of energy consumption efficiency. Whereas, it
is also important to simplify the measurement method taking account of the time and costthat it requires, without the comparison of energy consumption efficiency being impaired.
From these perspectives, it is desirable if a logical reason justifies the single-value setting
for the supply water temperature. Comparison was made for two sets of measurement
results on the power consumption of representative models: measurements only at 15ºC ±1ºC and measurements with the supply water temperature changed in three ways
according to the industry’s voluntary standards. It was found that all the measurements
were extremely close; therefore, the single value setting is thought to be sufficient for the
purpose of comparing energy consumption efficiency.
Thus, in this measurement method, the supply water temperature shall be defined as
to 15ºC ± 1ºC.
The comparison results are shown below for two representative models measured atthree different supply water temperatures and only at 15ºC ± 1ºC.

19

SeasonSpringSummerAutumnWinterTable 1. Vendor A, Warmth-Retention Temperature: 37.0ºC,
Shower Duration: 30 Seconds
Energy consumption for Energy consumption for warming
warming water for single water in each season (3 months)(estimated by assuming 4 washes
showerper day)
15.52 Wh5.67 kWh7.78 Wh
2.84 kWh15.52 Wh5.67 kWh25.31 Wh
9.24 kWh
Total (one year)
23.41 kWh
One month average
1.95 kWh
One month averagespring and autumn<Room temperature> Summer: 28ºC

SeasonSpringSummerAutumnWinterin

Spring and autumn: 15ºC

1.89 kWh

Winter: 5ºC

Table 2. Vendor B, Warmth-Retention Temperature: 37.5ºC,
Shower Duration: 30 Seconds
Energy consumption for Energy consumption for warming
warming water for single water in each season (3 months)(estimated by assuming 4 washes
showerper day)
21.55 Wh7.87 kWh10.94 Wh
3.99 kWh21.55 Wh7.87 kWh29.78 Wh
10.87 kWh
Total (one year)
30.59 kWh
One month average
2.55 kWh
One month averagespring and autumn<Room temperature>

Summer: 28ºCin

Spring and autumn: 15ºC

2.62 kWh

Winter: 5ºC

The measurements were carried out in two situations: changing the supply watertemperature in three ways to simulate seasonal temperature variation and fixing it to one
temperature to simulate spring and autumn. The values of energy consumption permonth in both situations are extremely close with the difference within 3%. Considering
the complexity of the measurement with the supply water temperature being adjusted 3
times, it is rational to set the supply water temperature to 15ºC ± 1ºC.
Example of Vendor A: 1.95 / 1.89 ∗ 100 = 103 (%)
Example of Vendor B: 2.55 / 2.62 ∗ 100 = 97 (%)

20

(2) Rationale for setting the temperature to 38ºC
The usage reality of shower temperature control shown in the chart below indicatesthat 63% of the users set the controller to the middle setting, and thus the middle settingis thought to be appropriate for the measurement at a warm-water heat-retention period.
Although the middle setting temperature varies among models, 38ºC (average of 3
representative models of 3 vendors) was adopted based on the survey on those having the
middle setting for the temperature control.

Actual Warm-Water
Temperatures at the “Middle”
Setting by Various Vendors
おしり洗浄に使う水温設定

Temperature Setting of Water for Shower Function
Source: National Consumer
Affairs Center of JapanNo
adjustment
7%

Others
2%

Low
21%

High
6%
Middle - High
14%

Off
1%

Sample Count684
Low - Middle
20%
Middle29%

Figure 1

21

Vendor A
Vendor B
Vendor C
Average of
3 vendors

37.5ºC
38.0ºC
38.0ºC
37.8ºC2. Toilet Seat Unit
(1) Seasonal ambient temperature setting
In the current measurement method, considering the efficiency of measurement aswell as the proportional relation between ambient temperature and energy consumption,
average annual temperature is defined as 15ºC ± 1ºC.
In this revision, considering the models that keep the toilet seat unit at 15ºC or below
but instantaneously warm it up at the time of use, the individual ambient temperature
was decided for each season. Specifically, the seasonal ambient temperatures provided in
the voluntary standards by the Association of Living Amenity and the Japan Electrical
Manufacturers’ Association shall be adopted. For summer season, however, the toilet
seats are not warmed, and thus no measurement is performed.
Spring and autumn (March − May, September − November):
Winter (December − February):
Summer time (June − August):

15 ± 1ºC
5 ± 2ºC
28 ± 1ºC.

(2) Revision of usage reality coefficient
In the current measurement method, energy consumption efficiency is measured withthe maximum toilet seat temperature, whereby an obtained value is multiplied by theusage reality coefficient of 0.75. In response to the adoption of seasonal ambient
temperatures as described above, this coefficient shall also be revised.
Based on the survey results as shown below, the usage reality coefficient for
spring/autumn (KM) is defined as 0.7 and that for winter (KW) as 0.9. However, thesecoefficients shall not be multiplied for the models without a temperature control
mechanism or those with temperature control mechanism but no temperature change.
(a) Survey on the actual status of toilet seat temperature setting by season
Table 3. Survey Results on Actual Status of
Temperature Settings in Spring and Autumn(Survey by 3 major vendors, members of the
Warm-Water-Shower Toilet Seat Council)
Season Spring and Autumn (March −May, September − November)
Average ofVendorA
B
C
3 vendors
High
4.9% 3.6% 1.5%
3.3%
Middle 32.0% 59.8% 18.3%
36.7%
Low
57.3% 32.6% 61.2%
50.4%
Off
5.8% 3.9% 19.0%
9.6%
Total
100.0%

22

Survey on Actual Status of
Temperature Setting in Springand Autumn
High
Middle
Low

Off
10%

High
3%

Off
Middle
37%

Low
50%

N=1141

Survey on Actual Status of
Temperature Setting in WinterTable 4. Survey Results on Actual Status of
Temperature Setting in Winter(Survey by 3 major vendors, members of the
Warm-Water-Shower Toilet Seat Council)
SeasonVendorHigh
MiddleLow
Off

Winter (December − February)
Average ofABC
3 vendors
23.3%
22.0%
17.7%
21.0%
60.2%
70.4%
50.3%
60.3%
15.5%
7.0%
29.7%
17.4%
1.0%
0.6%
2.3%
1.3%
Total
100.0%

Low
17%

Off
1%

High
21%
High
MiddleLow
Off

Middle61%

N=1141(b) Energy consumption measurements on representative models with various temperature
settings
Table 5 shows average values of seasonal energy consumption measured on 5
representative models at various temperature settings.
Table 5. Energy Consumption by Season and Temperature Setting Position(Survey by 3 major vendors, members of the Warm-Water-Shower Toilet Seat Council)
WinterTemperature
EnergyConsumption(Wh/h)
High
33.51
Middle
29.99
Low
23.69
Off
0

Spring and Autumn
Temperature
EnergyConsumption(Wh/h)
High
23.94
Middle
20.49
Low
14.68
Off
0

(c) Usage reality coefficient
From (a) and (b) above, the usage reality coefficient K are determined as follows(Spring & Autumn) KM(Winter)

KW= (23.94 × 0.033 + 20.49 × 0.367 + 14.68 × 0.504） / 23.94= 0.66= 0.7 (rounded up at the second decimal point)= (33.51 × 0.21 + 29.99 × 0.603 + 23.69 × 0.174) / 33.51= 0.87= 0.9 (rounded up at the second decimal point)23

(3) Number of days in each season
For the calculation purpose of energy consumption of toilet seat units, the number ofdays in each season shall be specified as follows. As shown in Table 6, warm toilet seatand the like are used approximately for 9 months, and thus the toilet seat units are
assumed to be powered off during summer.
Spring and autumn:
183 days = 6 months
Winter:90 days = 3 months
Table 6. Period of Use of Warm Toilet Seats
Duration of use (months)
Use of warmed toilet seat unit ofwarm-water-shower toilet seats
Warm toilet seat being connected
to an electric outlet

Average months
9.3
N=918

8.6

(Source: Standby Power Study Report FY 2005, The Energy Conservation Center, Japan)(4) Frequency of toilet use
For a four-member household (two men and two women), the frequency of toilet use
shall be set to the following values:
Defecation frequency: 4 (times a day) (one time each for all family members)
Urination frequency: 12 (times a day) (women: 8 times, men: 4 times)(Supplement: Rationale for the use frequency setting (Source: Report by Study Committee on
the Information Provision for the Energy Conservation and Security in Detached Housings,
March 2005))(a) Concept for the defecation frequency
Defecation frequency in a household is set to 1 (time / person a day) for all of the fourfamily members. (For three members who go out during the day, the frequency becomes
2 (times/day), if combining those made away from home (office). However, for simplicity,
it shall be set to 1 (time/day) at home.)(b) Concept for the urination frequency
Urination frequency is set to 6 times per day per person (which is the upper of thegeneral daily urination frequency according to the urological data.)• During the day, 3 out of the 4 family members urinate 4 times away from home, andthus the frequency at home shall be set to 2.
• One person out of the 4 family members is the housewife and always urinates athome, and thus the frequency at home shall be set to 6.
From the above, the frequency of toilet use for urination becomes:(2 times × 3 persons + 6 times × 1 person) / 4 persons = 3 (times / person day)24

(5) Styles when using toilet
When urinating, an increasing number of men sit on a toilet seat because of “itscomfortable position,” “prevention of urine splash (easy to clean),” etc. According to thesurvey conducted in 2004 by vendor A, approximately 23.7% of men sit on a toilet seat at
the time of urination. Another survey conducted by vendor B also indicates thatapproximately 30% of men sit on a toilet seat (including those who sometimes do) at thetime of urination.
To reflect this trend, it shall be included in this measurement method that 1 (time/day)out of the 4 (times/day) urination frequency of men is considered as a case in which men
sit on a toilet seat for urination.
Table 7. Survey Result on Styles of Men during Urination(Survey by Vendor A , June 2004)
Styles of men when urinating(Persons) Composition ratio (%)
Standing and facing against the
1512
65.4
sitting-on type toilet bowl
Sitting on the sitting-on type548
23.7
toilet seat
Standing and facing against the100
4.3
Japanese style toilet
Squatting over the Japanese style10
0.4
toiletOthers
142
6.1
Total
2312
(n = 2312)
Table 8. Survey Result on Styles of Men during Urination(Survey by Vendor B, 2004)
Styles of men when
(Persons)
Composition ratio (%)
urinating
Always sitting on
51
17
Sometimes sitting on
39
13
Always standing
210
70
Total
300
(n = 300)(6) Mode of using toilet
Table 9 shows the survey result on time duration required for each style of toilet use.
Table 9. Survey Result on the Time Duration Required(Survey by the Warm-Water-Shower Toilet Seat Council)
Use styleMode A Man (Defecation)
Woman( Defecation )Woman(Urination)
Man (Urination 1)
Mode B Man (Urination 2)

Frequency(time/day)2
2Single modeEnter the room − Using toilet Leave toilet −Ready in a position(Sec.)
Leave the room
(Sec.)(Sec.)
10
282
23
10
240
25
11

8

96

11
96
1
8
78
3
Note 2: Mode A (sitting), Mode B (standing)

25

23
22
16

However, it takes time and is inefficient to carry out the measurement for each use
style. For this reason, measurements for the same mode are weighted and averaged by
the frequency of use, and they are combined into one set of data.
Table 10. Combined Mode
Combined mode
(Weighted average)
Frequency Enter the Using Leave toilet Enter the Using Leave toilet Total− toilet − Leave the room
− toilet − Leave the (Sec.)(time/day) room
Ready in a (Sec.) room
Ready in a (Sec.) room
position
position(Sec.)(Sec.)(Sec.)(Sec.)
10282
23
2Single modeUse styleMode A Man(Defecation)
Woman( Defecation )Woman(Urination)
Man(Urination 1)
Mode B Man(Urination 2)

2
8
1

10

240

25

11

96

23

11

96

22

8

78

16

3

11

147

23

181

8

78

16

102

In addition, to prevent erroneous measurements, figures are rounded as tabulated inTable 11, without the total time in Table 11 falling below the total time in Table 10 above.
Table 11 Measurement Mode
Enter the room − Using toilet Leave toilet
Frequency Readyina(Sec.)− Leave the Total (Sec.)(time/day) position (Sec.)
room (Sec.)
Mode A
Mode B

13
3

15
10

150
90

25
20

190
120

Above described modes can be illustrated as follows.

Beginning of measurement −Completion of measurement: 1 (hour)

Mode A

26

Termination of measurement

25 sec.

(Human sensor is deactivated)

150 sec.

Leave seat, lid fully closed(Seat-occupied is switched off)

Sit down on the seat
(Seat-occupied is switched on)

15 sec.

Toilet lid fully opened(Human sensor is activated)

Beginning of measurement

60 sec.

Mode B

Termination of measurement

Beginning of measurement −Completion of measurement: 1 hour

(Human sensor isdeactivated)

20 sec.

Toilet seat, lid fully closed

90 sec.

Beginning of Urination(Assumption)

Toilet seat fully opened

Toilet lid fully opened(Human sensor is activated)

Beginning of measurement

60 sec. 5 sec. 5 sec.

Note 1: If no human sensor or seat-occupied switch is installed, the corresponding steps can beomitted. However, the total measurement time shall be unchanged.
Note 2: When the timing has arrived for the seat-occupied switch to be turned off (leaving theseat), if the toilet seat temperature is still rising to reach the pre-set degree, the switch
shall not be turned off until the temperature rising is completed. However, the total
measurement time shall be unchanged.

27

3. Timer Controlled Power-Saving
The power-saving time is based on the survey of actual status of usage which was
conducted at the determination of the current standards. Although the setting of powersaving time varies among models, it is defined as an average hours of use. The actual
power-saving time varies depending on the family structure and life pattern; however, it isconsidered as an average value reflecting actual status of usage.
In the current standards, the power-saving time is defined as 3.5 hours, which is obtainedby multiplying the average power-saving time, 7.7 hours, by the usage rate of power-saving
function, 0.45. However, for consumers who use the power-saving function, the power-saving
time is in fact 7.7 hours on average. In order to give incentive for the models having a
power-saving function, an evaluation with the full span of the 7.7-hour period shall be made.
To further spread the consumers’ use of power-saving functions, energy consumption
values without using power-saving functions shall also be indicated.
Table 12. Actual Status of Power-Saving Time
(Power-saving
Weighted(Persons) (Ratio %)time)average hours
3 hours2
1.3
0.04
5 hours3
2.0
0.10
6 hours
62
41.6
2.50
9 hours
58
38.9
3.50
10 hours
21
14.1
1.41
Unknown2
1.3
0.08
No reply
1
0.7
0.04
Total
149
100.0
7.7

10 hours
14%

3 hours
1% No reply
1%
5 hours
Unknown
2%
1%

3 hours
5 hours
6 hours
9 hours
6 hours42%

N=149

10 hours
Unknown
No repry

9 hours39%

28

4. Additional Functions(1) Warm-air-dry function
Figure 3 shows the shipment volume ratio by additional functions in FY 2005. The
shipment ratio of those having a warm-air-dry function is 45.9% in FY 2002, which
drastically decreases down to 30.5% in FY 2005.
Presumably, the low price orientation and the change in consumer needs for thisfunction are reflected in this trend. Figure 4 shows the usage ratio of the warm-air-dry
function among the users who purchased the models with this function. As shown in thisfigure, the percentage of users who always or sometimes use this function remains atapproximately 36%.
In addition, its energy consumption is low, and thus this additional function is
exempted.
Table 13. Shipment Volume Ratio by Additional Functions in FY 2005
(Survey by the Warm-Water-Shower Toilet Seat Council)
Equipped
Not equipped
Total
ShippedShippedshipments
Ratio
Ratio
units
units
Deodorant function
2,535,152
78.8%
680,23721.2%
3,207,823
Warm-air-dry function
979,91130.5%
2,235,478 69.5%
3,207,823
Room heating function
74,4212.3%
3,140,968 97.7%
3,207,823

Table 14. Usage Ratio of Warm-air-dry Function(Survey by two major vendors, members of
the Warm-Water-Shower Toilet Seat Council)
Usage status(Persons) Ratio (%)
Using
272
23.9
Sometimes using
140
12.3
Not using665
58.5
Unknown
60
5.3
Total
1137
100.0

Unknown5%

Not using
59%

Using
24%

Sometimes
using
12%

(2) Room heating function
As shown in Table 13, for the room heating function, the shipment ratio also
drastically decreases down to 2.3% in FY 2005 from 6% in FY 2002. Because of thisextremely small shipment ratio, this function is also exempted as at present.
(Reference: Summary of Final Criteria, the Sub-Committee for Judgment Criteria forElectric Heating/Warming Appliances (extract))
Since other additional functions are equipped in response to the consumers needs,
they are exempted from the determination of standard values. For your reference,current shipment ratio and average power consumption of the models having theadditional functions are as follows.

29

Function

Shipment ratio

Basis of estimation of average energy consumption
Heater capacity: 300 − 470 W
Hours of use per day/energy consumption
Dry function
45.9%
12 times ∗ 0.5 min. = 0.1 h/day
350 W ∗ 0.1 h = 35 Wh/day (3 model average)
35 Wh/day ∗ 365 days = 12.8 kWh/year (3 model average)
Motor capacity: approximately 3 W
Hours of use per day/energy consumption
Deodorant
86.5%
3 min./time ∗ 12 times = 36 min./day
function
3 W ∗ 0.6 h = 1.8 Wh/day (3 model average)
1.8 Wh/day ∗ 365 days = 0.7 kWh/year (3 model average)
Heater capacity: 210 − 500 W
Hours of use per day/energy consumption
Room heating
6.0%
6 h/day (used in winter season only)
function
357 W ∗ 6 h = 2142 Wh/day (3 model average)
2142 Wh ∗ 90 days = 193 kWh/year (3 model average)* Survey by 3 major vendors
Note: Hours of use and frequency of use are taken from the industry’s voluntarystandard.
As listed above, the shipment ratio of the models with dry/deodorant function is high.
However, these functions are made with only a Nichrome heater and a fan, which has no room
for technological improvement. In addition, daily energy consumption of the dry/deodorantfunctions is low, and thus they are exempted. Concerning the room heating function,although its daily energy consumption is somewhat high, the shipment ratio is low at 6.0%,
and thus it is also exempted.

30

Attachment 6

Electric Toilet Seats Evaluation Standard Subcommittee,
Energy Efficiency Standards Subcommittee ofthe Advisory Committee for Natural Resources and Energy
Background of Holding

1st Subcommittee Meeting (December 1, 2006)▪ Public opening of Electric Toilet Seats Evaluation Standard Subcommittee▪ Current status of electric toilet seats▪ Target scope of electric toilet seats▪ Definition of energy consumption efficiency and the measurement method
2nd Subcommittee Meeting (February 13, 2007)▪ Definition of energy consumption efficiency and the measurement method
3rd Subcommittee Meeting (April 25, 2007)▪ Categories of electric toilet seats for target setting▪ Concept of the target standard values for electric toilet seats
4th Subcommittee Meeting (May 8, 2007)▪ Target standard values for electric toilet seats▪ Interim report (draft)
Interim report was open for public comments during the period from May 9, 2007 throughJune 7, 2007; then, three comments were received from three stakeholders. Thus, it was
adopted as the final report after necessary modifications were made.

31

Attachment 7
Overview of Comments on Interim Report by Electric Toilet Seats Evaluation Standard Subcommittee andResponse by the Administrative Office○○Interim report by the Subcommittee was open for public comments for 30 days from May 9, 2007; then, three comments were received.
Overview of these comments and responses by the administrative office are as follows.

Item

Submitter

Overview of Comment

Categorization
methodfor electric
toilet seats

General(2 cases)

As for warm-water-shower toilet seats, the warm-water
storage type and the instantaneous type shall betreated within single category.
(Reason)• According to the basic principle of Top Runnermethod, categories shall be determined, taking
account of “1) basic physical quantity, etc. of thetarget products, which are closely related to energy
consumption efficiency of the products, and 2)
factors representing consumers’ needs”.
The
interim report states that “in the diversified
consumers’ needs for shower function, a solid
preference still remains for products that spout acertain amount of water or have warm-water tanks
of a certain capacity”. However, in the interim
report, consumers’ needs for shower function are notindicated; meanwhile, consumers’ dissatisfaction forthemaximumwater-spouting
abilityofinstantaneous type is not revealed either. There isa possibility that consumers select morewarm-water storage type than the other simply due
to its cheaper price. In light of the above, it is not
appropriate to categorize electric toilet seats further
than the availability of shower function.
• In addition, the basic principle of Top Runnermethod states that products shall be assigned
different categories, in case that “there is a highprobability that price increase of product due toincorporated advanced energy-saving technologies
cannot be recovered by reducing the running costs
in a certain period based on the actual status ofuse”. Compared to the status in 5 years ago, theprice difference between the warm-water storage
type and the instantaneous type has decreased, as
the instantaneous type spreads. Therefore, it ishighly possible to recover the price increase of theinstantaneous type in a certain period of use.

(Reference) Concept in “Interim Report”(Attachment 3)

Categories of Electric Toilet Seats for Setting Target Standard andRelated Matters

1. Current Categories of Electric Toilet Seats
Electric toilet seats are categorized as below based on the twoparameters that will have impact on annual energy consumption (energy
consumption efficiency). Concerning warm-water-shower toilet seats(warm-water storage type), since annual energy consumption correlateswith warm-water storage capacity, the standard is expressed in a linear
function with warm-water storage capacity as a variable.
(a) Categorization by the availability of shower function(b) Categorization by the availability of warm-water tank
▪ Warm-water storage type (with warm-water tank):
Water is warmed up by a heater in a warm-water tank in advanceand stored there.
▪ Instantaneous type (without warm-water tank):
Water is heated instantaneously at the time of spout.
Table 1. Current Categories of Electric Toilet Seats
Current Categories (Electric Toilet Seats)
Warm toilet seats (without shower function)
Warm-water storage typeWarm-water-shower(with warm-water tank)toilet seats (with shower
Instantaneous typefunction)(without warm-water tank)
2. Categorization Method for Electric Toilet Seats
Electric toilet seats shall be categorized according to the current
categorization method.
Concerning warm-water-shower toilet seats of warm-water storage
type, the current standard is expressed in a linear function withwarm-water storage capacity as a variable. However, instead of using a
relational expression, a constant value shall be adopted as the standard
value for these products, taking into account that their energy-saving has
progressed due to downsizing of warm-water tanks and aiming at further
promotion of downsizing of warm-water tanks.

(Attachment 4)

Target Standard Values for Electric Toilet Seats

3. Room for Improvement in Energy Consumption Efficiency by Future
Technological Progress[Warm-Water Shower Toilet Seats (Warm-water Storage Type)]
An improvement from the Top Runner value by 5% or so can be
expected, resulting from the application of heat loss prevention
technologies, e.g. insulating materials, to toilet seats, the enhanced
adoption of insulating materials to warm-water tanks, etc.
The current standard is expressed in a linear function with

32

Proposal by the administrative officePrice difference between the instantaneous
type and the warm-water type is about 20,000 yen,
and it is highly probable that the price increase
due to the adoption of energy-saving technology
cannot be recovered by reducing the running costs
in a certain period based on the actual status ofuse (48 kWh/year: difference in target standard
values for the instantaneous type and thewarm-water storage type).
Price difference: approximately 20,000 yen
Reduction in running cost:
48 kWh/year ≈ 1056 yen
In addition, at this moment, the warm-water
storage type accounts for about 80% of total
shipment volume of warm-water-shower toilet
seat. Such high percentage reveals that there is amarket needs for lower-priced products.
Therefore, in the development of standards thistime, warm-water-shower toilet seats shall be
categorized into either instantaneous type or
warm-water storage type.
However, compared to the warm-water storage
type, instantaneous type of warm-water-shower
toilet seats has better energy-saving capability;
thus, to increase the penetration rate of theinstantaneous type may lead to the reduction ofenergy consumption of Japan. In future, when
the price difference in these types of toilet seats
decreases and when the market needs forlower-priced products is weakened, it is considered
to be desirable to treat them in single category.
By the way, the point that “a solid preference
still remains for products that spout a certain
amount of water or have warm-water tanks of acertain capacity” was taken into consideration,
when reviewing a room for efficiency improvement
due to technical advancement but not whensetting categories.

warm-water storage capacity as a variable. However, instead of using a
relational expression, a constant value shall be adopted as the standard
value for this type of products, taking into account that theirenergy-saving has progressed due to downsizing of warm-water tanks andaiming at further promotion of downsizing of warm-water tanks.
Meanwhile, in the diversified consumers’ needs for shower function, asolid preference still remains for products that spout a certain amount ofwater or have warm-water tanks of a certain capacity. Thus, eventhough the standard is not defined as a linear function with warm-water
storage capacity as a variable, the effect from these factors needs to betaken into consideration when estimating the future efficiency
improvement.
The Top Runner product has a warm-water tank capacity of 0.85 L,
while an average capacity of current warm-water tanks is 1.1 L. With anassumption that further downsizing of warm-water tanks will result in an
average tank capacity of 1.0 L or so, the effect from differences inwarm-water storage capacity due to the diversified consumers needs forshower function shall be estimated as an increase of approximately 7
kWh/year (4% or so).
From the above discussion, for the warm-water shower toilet seats(warm-water storage type), an improvement by 1% from the Top Runnervalue shall be anticipated.

Room for energy
efficiency
improvement
due to futuretechnologicaldevelopment

General(1 case)“Instantaneous toilet seat” shall be corrected as “toilet
seat which instantaneously heat the seat unit”.
(Reason)• In general, when sales staffs at shops explain toconsumers, they often use the word “instantaneous
type” toilet seat to refer to those which
instantaneously heat up water for shower; thus, it
may cause misunderstanding.

(Attachment 4)

Target Standard Values for Electric Toilet Seats

3. Room for Improvement in Energy Consumption Efficiency by Future
Technological Progress[Warm-water-shower Toilet Seats (Instantaneous Type)]
An improvement from the Top Runner value by 6% is anticipatedresulting from the application of heat loss prevention technologies, e.g.
insulating materials, to the toilet seat and the introduction of innovativetechnologies such as those seen in instantaneous heating toilet seats andin plastic toilet bowls.

33

In some cases, the instantaneous type models
cannot be used because the power consumption forthe simultaneous use of plural units may over thecontract demand of electricity.

Correction shall be made as pointed out.

Attachment 8

Electric Toilet Seats Evaluation Standard Subcommittee,
Energy Efficiency Standards Subcommittee ofthe Advisory Committee for Natural Resources and Energy
List of Members
Chairman:

Tetsuji Oda

Professor, Graduate School of Engineering, The Universityof TokyoMembers

Hitoshi Aida

Professor, Graduate School of Frontier Sciences, The
University of Tokyo

Shoichiro Ozeki

General Manager, Energy Environment Technology
Division, Energy Conservation Center, Japan

Tamaki Kamata

Assistant to Director, Products Testing Department,
National Consumer Affairs Center of Japan

Toshikazu Kenmostu Executive Director, Japan Consumer’s Association
Fumio Takemura

Senior Researcher, Thermal and Fluid System Group,
Energy Technology Research Institute, National Instituteof Advanced Industrial Science and Technology

Akio Tanaka

Director of Research Office, Jyukankyo Research InstituteInc.

Kiyoshi Fujino

Advisor, Energy Conservation Promotion Committee,
Warm-Water-Shower Toilet Seat Council

34

Reference

Current Status of Electric Toilet Seats

35

1. Market Trend of Electric Toilet Seats
1 − 1 Domestic Shipment Volume of Electric Toilet Seats
Electric toilet seats are categorized into two groups: warm-water-shower toilet seats having ashower function and warm toilet seats for seat warming function only. Figure 1 shows the
shipment volume of electric toilet seats in the previous seven years. Because of the increase inwarm-water-shower toilet seats, the total number of electric toilet seats has been increasing every
year. On the other hand, warm toilet seats are expected to continue decreasing in number, as
they are replaced by warm-water-shower toilet seats.
千 台 units
1000
4,000
3,500
3,000
2,500
2,000
1,500
1,000
500
0

電気便座出荷統計
Electric Toilet
Seats Shipment Statistics
Warm-water温水洗浄便座
shower toilet seats
暖房便座
Warm
toilet seat

1999

2000

2001

年度
Fiscal
Year

1999

2000

2001

2002

2003

2004

2005

2 ,2 2 0

2 ,3 9 1

2 ,5 3 2

2 ,6 4 8

2 ,8 0 5

2 ,9 8 8

3 ,2 0 8

530

500

462

519

512

492

466

2 ,7 5 0

2 ,8 9 1

2 ,9 9 4

3 ,1 6 7

3 ,3 1 7

3 ,4 8 0

3 ,6 7 4

Warm-water温水洗浄便座
shower toilet seat
Shipment
出荷台
数
volume
暖房便座（ 千 台 ） Warm toilet seat
(1000
Total
合計

2002

2003

2004

2005

Figure 1. Changes in Total Domestic Shipment Volume(Survey by the Warm-Water-Shower Toilet Seat Council and Association of Living Amenity)

1 − 2 Domestic Shipment Volume of Warm-water-shower Toilet Seats
The domestic shipment volume of warm-water-shower toilet seats has been increasing every
year, along with the increased consciousness about cleanliness/amenities among Japanese people
and the improved functionality of the products by the efforts of manufacturers. According to thesurvey by the Cabinet Office (results from a research conducted in March 2006), the penetration
rate has reached 62.7% in FY 2005 as shown in Figure 3, coming closer to that of fan heaters(67.5%) and personal computers (68.3%). From now on, demand for this product due toreplacement, etc. is expected.
1000 units
3,500

Warm-Water Storage Type/Instantaneous Type Shipment Statistics％

Instantaneous water heater type35

Warm-water storage type

3,000
2,500

30
25

Ratio of instantaneous type

2,000

20

1,500

15

1,000
500

10
5

0

0
1999

2000

Fiscal year
Shipment
volume(1000 units)

Warm-water
storage typeInstantaneous
water heater type

Total

2001

2002

2003

2004

2005

1999

2000

2001

2002

2003

2004

2005

2,086

2,091

2,136

2,204

2,245

2,313

2,503

134

300

396

444

560

675

705

2,220

2,391

2,532

2,648

2,805

2,988

3,208

Figure 2. Changes in the Shipment Volume of Warm-Water-Shower toilet seats(Survey by the Warm-Water-Shower Toilet Seat Council)

36

Penetration Rate

(％）
100.0
90.0
80.0
70.0
60.0
50.0
40.0
30.0
20.0
10.0
0.0

Penetration rate

30.3

33.9

36.5

1996

1997

1998

41.0

43.2

1999

2000

51.7

47.1

2001

2002

53.0

2003

62.7

59.7

2004

2005

(Fiscal year)

Figure 3. Penetration Rate of Warm-Water-Shower Toilet Seats(Consumer Trend Survey conducted by the Cabinet Office in March 2006)
1 − 3 Energy Consumption of Electric Toilet Seats
Composition ratio of the household energy consumption is as illustrated below. Electric toilet
seats account for approximately 4% of the total household energy consumption.

OthersAir conditioner

Dish washer/dryer 1.6%
Clothes dryer 2.8%
Warm-water-shower toilet seat
3.9%

Refrigerator

Electric carpet 4.3%

TV

Lighting
fixtureSource: Outline of Electric Power Supply and Demand in FY 2004,
Agency for Natural Resources and Energy (Estimation for FY 2003)

1 − 4 Major Domestic Manufacturers (in Alphabetical Order)
Major domestic manufacturers are as follows.
AISIN SEIKI Co., Ltd., Asahi Eito Co., Ltd., Hitachi Housetec Co., Ltd.,INAX Corporation, Janis Ltd., Matsushita Electric Industrial Co., Ltd.,
Matsushita Electric Works, Ltd., SAN-EI Faucet Mfg Co., Ltd.,
Tega SANYO Industry Co., Ltd, TOTO Washlettechno Co., Ltd.

37

2. Achievement Status of Energy Conservation Standards of Electric Toilet Seats
2 − 1 Categories of Evaluation Standards under the Energy Conservation Law
Current categories of electric toilet seats specified by the Energy Conservation Law are asshown in Table 1.
This fiscal year (2006) is the target fiscal year for them, and it is mandatory to achieve thestandards based on the actual shipment volume of this fiscal year. For each manufacturer andeach category, a weighted average value obtained with the shipment volume shall not exceed thevalue listed in the right column of Table 1.
Table 1. Categories under the Energy Conservation Law
Category

Standard energy consumption
efficiency or
the calculation formula
162 (kWh)

Warm toilet seatWarm-water-shower toilet seat without warm-water tank 189 (kWh)(Instantaneous type)Warm-water-shower toilet seat with warm-water tank P = 38.3 × L + 243 (kWh)(Warm-water storage type)
L: Warm-water storage capacity (unit: liter)2 − 2 Achievement Status of Standards Specified under the Energy Conservation Law
Table 2 shows the achievement status of the overall industry in the first quarter of FY 2006.
(Weighted average of achievement rate shown in row B is used for the evaluation of achievement.)
Table 2 Achievement Status of Energy Conservation Standards of Electric Toilet
Seats(Survey by the Warm-Water-Shower Toilet Seat Council, April – June, 2006)
Item
A
B
C
D
E

Sales volume (units)(April – June, 2006)
Weighted average ofachievement rate (%)
Number of models soldNumber of models
achieving the standards
Percentage of models
achieving the standards(%)(D/C × 100)

Warm toilet seatsWarm-water-shower toilet seatsWarm-water
storage typeInstantaneous
type

89,590583,722

128,495

100.5(4 vendors)
11

104.7
(9 vendors)
142

104.2
(4 vendors)
25

11

104

22

100.0

73.2

88.0

Concerning the warm-water-shower toilet seats, as shown above, the industry as a whole has
already achieved the standards. In addition, a further shift from old models of before themeasures to new energy efficient type models is expected. Thus, it is almost certain that thestandards will be achieved.
In contrast, the weighted average of achievement rate indicates that the warm toilet seats
have just cleared the target standards because of the shrinking market size and the limited
adoption of energy-saving technologies due to the cost problem.

38

3. Efforts for Energy Saving Technologies
Core technologies for the energy saving of electric toilet seats are “power-saving control
technology” and “heat loss prevention technology,” and the efforts have been made to reduce power
consumption taking into consideration the safety, cost and usability as an electric heating
appliance.
3 − 1 Power Saving Control Technology
The nature of electric toilet seat is that the timing of use during the day or night isunpredictable, and thus technology has long been focused on keeping the toilet seat warm.
However, coupled with electric toilet seats being designated as the designated machineries andproducts of the Energy Conservation Law and coupled with the consumers’ growing interests inenergy conservation, as a result of manufacturers’ voluntary efforts, products are now equippedwith various types of usable energy-saving technologies (e.g. timer controlled power-saving,functions concerning users’ life pattern, functions maintaining warmth at low-temperature when
not in use) which can minimize sacrifice of comfort; and, such products have already been
introduced to the market. In this way, the efforts have been made for electric toilet seats to
reduce energy consumption.
Condition

Method ofpower-saving
control(a) Timer(Microcomputer)Power
shutdown(b) Learning
control(Microcomputer)(c) Learning
control(Microcomputer)
HeatRetention (d) Humanat low
sensortemperature (Sensor)(e) Toilet-lidclosed
sensor(Sensor)Power Saving Method, Description

Characteristics• While users are not using a toilet, e.g. atnight, power supply to a heater of toilet
seat is automatically shutdown for acertain period of time every day.
• Power-saving time is selectable from 1 −3 settings.
• In case of being used during the powersaving period, power supply to theheater is activated at the time when theuser is seated, etc.

• The maximum power-saving effectis provided every day for a certain
period of time.
• To increase the frequency of use of
power-saving function is an issue
to be tackled.
• Toilet seat is cold at the time of use
during a power-saving period (e.g.
night).

• The maximum power-saving effectis provided every day for a certain
period of time.
By learning a toilet usage pattern, power• To increase the frequency of use of
supply to a heater of toilet seat is
power-saving function is an issue
shutdown during hours of the least
to be tackled.
frequency of use.
• Power saving is automaticallycarried out.
• Toilet seat is cold at the time of use
outside the pattern.
•Powersaving is automatically
By learning a toilet usage pattern, power
carriedout.
supply to a heater of toilet seat is• Easy to match the users life
controlled to keep the seat unit at a low
pattern.
temperature during hours of the least• The seat is cold at the time of use
frequency of use.
outside the pattern.
•Powersaving is effective while
While nobody is present (= not in use), the
being
not
used.
temperature is kept low; and upon the•Thetemperature
at the time ofdetection of human entry, the temperature
being
seatedisanissue to be
is raised to the preset level.
tackled.
While the toilet lid is closed (= not in use), • Power saving is effective while
being not used.
the temperature is kept low; and upon the•Thetemperature at the time of
opening of the lid, the temperature is
being
seated is an issue to beraised to the preset level.
tackled.

Figure 13. Power saving control for electric toilet seats
Recently, in addition to the timer controlled power-saving function [method (a)], increasing
number of models are equipped with other power-saving functions [(b) through (e)] considering
users’ life and usage patterns. To ask users to fully utilize the functions according to their life
patterns, the industry is actively performing promotion activities.

39

(Reference: See attached materials)
3 − 2 Heat Loss Prevention Technology
Efforts have been made to improve the prevention of heat loss from the toilet seat unit and water
warmer unit in heat-retention state.

3 − 2 − 1 Toilet Seat Unit
Example of improvement on the shape of toilet lid
It is well known that “closing the toilet lid” is one action item for improving the energy
saving effect.
If the toilet seat is warmer than the room temperature, heat is continuously released fromthe toilet seat. The closed toilet lid prevents the heat loss and improves the energy saving
effect. Compared to when the lid is open, the closed lid provides a reduction of annual energy
consumption by approximately 10% (in the case of warm-water storage type).
To improve this effect, for example, the toilet lid is shaped to cover the toilet seat periphery.
In this case, heat release from the periphery is prevented whereby the heat from the toilet seatis held in the space created between the toilet seat and the lid. However, this design needs
additional raw materials, and thus the resource saving issue still remains.
In addition, since a toilet lid determines the exterior appearance and affects the productdesign as well, it is also necessary to fully consider the consumers’ needs for design.

Upper surface of the toilet seat
Lower surface of the toilet lid
Figure 14. Product with the toilet lid closed
3 − 2 − 2 Example of Improvement on Temperature Distribution in the Toilet Seat
On the overall surface of the toilet seat, temperature distribution shows a complex pattern
as shown in Figure 15. It is important, when seated, for the sensory temperature to be
comfortable and uniform.
By leveling out the non-uniform areas (high-temperature area) with a close investigation
into temperature distribution, energy consumption can be reduced. Therefore, meticulous
considerations are given in designing with respect to the surface temperature distribution (finetuning of the heater pattern, etc.).
[Example of Improvement]
If the condition on the left is modified to the condition on the right, energy consumption of
the toilet seat unit can be reduced by approximately 2% (in the case of this toilet seat).
Before Improvement

After Improvement

40Figure 15. Improvement of temperature distribution on the toilet seat3 − 2 − 3 Water Warmer Unit
In a warm-water storage type product, a heater is immersed in the water and directly
heats it up; thus, there remains little room for improvement in energy conversion efficiency.
This is the same for the instantaneous type products in which the water is heated up at thetime of use. However, for the warm-water storage type products, the following efforts havebeen made to improve the prevention of heat loss at a water warmer unit in a heat-retention
state.
(1) Example of the reduction in the surface area of warm-water storage tankIn addition to the improvement as described in 1, for further reduction of the surface
area, ribs (protruding parts) on the outer surface are removed as much as possible without
interfering with its essential function. By doing so, prevention of heat loss is attempted.

Figure 16. Example of the reduction in the heat releasing surface area

(2) Example of attachment of insulation materials to warm-water tank
In a warm-water storage type product, warmed water is maintained at around 38ºC.
Heat release occurs at a warm-water tank due to the difference with the ambient
temperature. To reduce the heat loss, the outer surface of the storage tank is covered withinsulation materials without interfering with the safety and merchantability of the product(e.g., compactness).
However, an insulation effect as great as in electric hot water pots cannot be expected
because of the warm-water storage temperature being near body temperature and its storage
capacity of around 1 L. In addition, the attachment of materials seen in this example raises
the issue of saving resources.

Figure 17. Example of insulation materials attached to the warm-water tank41

3 − 3 Various Power Saving Systems
Power-saving technologies adopted in currently commercialized products are as follows.
3 − 3 − 1 Timer Controlled Power Saving
The user sets up the power-saving time (e.g., 6 hours or 8 hours) which is a not-in-use
period, e.g. at night, whereby the power supply to the water warmer unit and toilet seat unit isshut down for the preset hours everyday.
[Advantage] Maximum power saving effect is provided by single switch operation to shut down
the power supply to the heater.
[Disadvantage] On rare occasions, the seat is cold at the time of use during the power saving
period (e.g. at midnight).
Toilet seat/Water heater
ON
OFF

Shut down for apreset time period

Power OFFIn Operation

Figure 18. Timer controlled power saving system
3 − 3 − 2 Learning Control System
The toilet seat automatically learns the user’s toilet usage pattern and predicts the hoursof the least frequency of use. During the hours, the water warmer unit and toilet seat unit
are kept at a low temperature (heat-retention at low temperature), or the power supply is shut
down. Usage in a more stable life pattern brings about a greater effect.
[Advantage] Power saving is automatically carried out according to the user’s life pattern.
[Disadvantage] On rare occasions, the seat is cold at the time of use outside the usage pattern.
Toilet seat/Water warmer
Preset temperature
Heat-retention at low temperatureOFF

Heat-retention
at Low Temp.

In Operation

Power OFF

Heat-retention
at Low Temp.
Heat-retention
at Low Temp.

Figure 19. Leaning control system

42

In Operation

3 − 3 − 3 Human Detection/Closed-toilet-lid Detection System
This is a power saving method that is to lower the temperature of water warmer unit
and/or toilet seat unit or to shut down the power supply when detecting the not-in-use
condition (where nobody is present).
Detected
Not detected
Preset temperature
Heat-retention at low temperature
OFF

Figure 20. Closed-toilet-lid Detection system[Advantage] Low temperature is maintained or power supply is shut down while not in use(the toilet lid is closed), resulting in greater power saving effect.
[Disadvantage] In case of a low capacity heater, it is difficult to sufficiently warm up the seat
unit by being seated.
Power-saving methods described the above are currently available, and manufacturers
have equipped their products with multiple power-saving methods. They can be activated inparallel (combination of timer controlled power-saving system and other systems); therefore,
further energy-saving effect can be achieved.

3 − 4 Improvements Achieved by Efforts for Energy Saving Technologies
Energy-saving improvement effect as a result of utilization of technologies described in “3.
Efforts for Energy Saving Technologies” are as follows.
1) Instantaneous type
When Top Runner standard was developed (April 2002)
Annual average energy consumption 208 (kWh/year)⇒

2) Warm-water storage type
When Top Runner standard was developed (April 2002)
Annual average energy consumption 348 (kWh/year)

in 2006 ∗
189 (kWh/year)
Approx. −9%⇒3) Warm toilet seats
When Top Runner standard was developed (April 2002)
Annual average energy consumption 183 (kWh/year)

in 2006 ∗277 (kWh/year)
Approx. −20%⇒

in 2006 ∗
156 (kWh/year)
Approx. −15%

∗ Source: The Energy Conservation Center, Japan

43

4. New Warm Toilet Seat System
In addition to the conventional system that keeps the toilet seat warm at the use temperature,
products with a new warm toilet seat system are emerged. In that system, a new technology is
employed that is to heat up the toilet seat only when it is used but otherwise maintain it below theuse temperature.
Structural differences are compared in the illustration below.
Conventional Technology- Heating with a cord heater
A toilet seat heater is made of a cord heater,which is adhered to aluminum foil. Using theadhesives on the reverse side of the aluminum foil,
the seat heater is then adhered to the inner surfaceof the upper part of the toilet seat (plastic).
The energized toilet seat heater generates heat,
which is then diffused through the highly heat
conductive aluminum foil to warm the upper surfaceof the toilet seat.

Heat

New Technology- Heating with a lamp heater
A lamp heater and a reflector are installed inside
the toilet seat. The upper part of the toilet seat is
made of aluminum with a heat-absorbing layer
attached to the inner surface.
Radiation heat from the energized lamp heater isefficiently transferred to the upper part of the toilet
seat with a use of reflector and then diffused throughthe highly heat conductive aluminum body to warm
the upper surface of the toilet seat.

Toilet seat
(Plastic)

Heat absorbing
layer

Heat

Toilet seat
(Aluminum)

Aluminum foil
Cord heater

Reflector

Figure 1

Lamp heater
Figure 2

Conventional technology employs a structure as illustrated in Figure 1. With this structure,
it takes a certain time for the toilet seat surface to reach the preset temperature after the heater
starts warming up the seat; hence it needs to be always kept warm near the preset temperature
while usage is expected, although the users sit on the toilet seat only for a short time in a day. To
satisfy both energy saving and the consumers’ needs, various power saving control technologies are
employed such as the power shutdown and the heat-retention at a low temperature during
not-in-use hours (e.g. night time).
With the new technology, the toilet seat surface is warmed up in a short time upon detecting
the user, whereby the seat temperature can be maintained at low in a heat-retention state,
resulting in a significant reduction in the power consumption used for keeping the toilet seat warm.
As for the specific structure shown in Figure 2, radiation from a lamp heater is converted to heatthrough a heat-absorbing layer attached to the inner surface of the toilet seat body (aluminummaterial), and the heat is then transferred to the surface of the toilet seat. Whereby, thetemperature rise-time of the toilet seat is reduced down to approximately 6 seconds, which is
1/30th of the conventional rise-time of approximately 3 minutes (data by Matsushita ElectricIndustrial Co., Ltd.).
This result has been realized by integrating two technologies: (a) a lamp heater having an
extremely fast start-up as a high-temperature radiation source and whose filament has muchsmaller heat capacity than those of other heat sources; and (b) a toilet seat made of highly
heat-conductive aluminum material which is able to homogenize the radiation heat from the lamp
heater and quickly create a comfortable surface temperature distribution.
A human detection sensor is used as a means for detecting the user. The sensor is installedfacing to the restroom door, so that an entering person can be immediately detected when the door
is opened, ensuring enough time for the toilet seat to be warmed to the level which does not allow
for any cold sensation.

44

Figure 3 shows a relationship between the surface temperature of toilet seat made withaluminum and the degree of comfortableness when the user is seated. As the toilet seattemperature rises, the comfort level also increases; and it reaches the comfortable zone when thesurface temperature becomes 29ºC or higher. Figure 4 shows a survey result on the time elapsed
from the activation of human detector by opening the restroom door to when the user is seated on.
While the time varies depending on the clothes worn, age, gender, etc., the result shows that the
average time is 8 seconds, and the fastest time is 6 seconds. Based on these results, the new
warm toilet seat system is designed to keep the toilet seat unit warm at a low temperature while itis not being used and to warm it up to the cold sensation threshold temperature, i.e. 29ºC, within 6
seconds only when being used. Due to this new technology, a warm toilet seat achieves excellent
energy saving while providing a level of comfort unchanged from the conventional warm toilet
seats.

Aluminum Toilet Seat
Temperature vs. Comfort

Room Temp. 5 ºC

20Time from Door Opening/Human Detected to Sitting Down

100%

18

−•− Just after
seated90%16Frequency

ComfortablenessUncomfy
Neither
Comfy
Little uncomfy
Little comfy

It is desirable that effort will be made for the further penetration of this new warm toilet seatsystem through working on the cost reduction.

n=84
Average： 8 sec
Shortest：6 sec（Pajamas）

14
12
10

80%
70%
60%
50%

8

Frequency

6

Accum. %

4

40%
30%
20%

2

10%

0

0%
1

2

3

4

5

6

7

8

9

10 11 12 13 14 15 16 17 18 19 20 21

Time (Second)Toilet Seat Temperature

Figure 3

Figure 4(Data by Matsushita Electric Industrial Co., Ltd.)(Data by Matsushita Electric Industrial Co., Ltd.)A comparison between conventional and new technologies for miscellaneous items
No.
1

2
3
4
5

6
7

8

Goal

Conventional Technologies
New Technologies- Warm and comfortable toilet seat at- Warm toilet seat only when seated- Safety, cleanliness, corrosion resistanceany time when seated- Safety, cleanliness, corrosion resistanceand energy saving
and energy saving

Warm-upHeating with a cord heatersystemRated power Approximately 50 W

Heating with a lamp heater

Approximately 1200 W
Radiation
thermostat,
Temperature
Safety device Temperature fuse
thermostat
Toilet seat Upper and lower surface of the toilet Toilet seat upper surface: Aluminum
Toilet seat lower surface: Polypropylenematerials
seat: Plastics
Toilet seat heater: Cord heater,
Toilet seat heater: Lamp heater, Reflector,
Aluminum foil, Thermistor,
Thermistor, Thermostat, etc.
Temperature fuse, etc.
Power supply Temperature proportional control, or Temperature proportional control, or on/off
systemon/off switch control
switch control
Energy- Further homogenized temperature- Drastic reduction in power consumption forsaving
distribution on the toilet seatheat retention by means of lowering theeffect- Reduction in the power consumption
temperature of the toilet seat in standby- Further homogenized temperaturefor heat-retention during not-in-use
distribution on the toilet seat
period by means of power
shutdown/power supply control
Technical - Further energy saving- Capability to raise the toilet seatchallenge
temperature faster(Further energy saving by further lowering
the temperature in a heat-retention state)

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Reference (Examples of operation manual)Set the temperature adjustment to alower level

Keep the toilet lid closed
Save electricity bykeeping the toilet lid
closed to reduce heatloss from the toilet
seat surface.

Save electricity byadjusting the preset
temperature to alower level within arange that does notcause a cold
sensation. (Page 18)

When not in use for a long time, set the“Operation On/Off” switch to the “Off”
position

Select the appropriate switch, “Large”
or “Small” (feces/urine) on the “Toilet
wash remote control”

Save electricity by setting the “On/Off”
switch to the “Off” position when goingout.

Save water byappropriately
selecting the “Large”
or “Small” switch.

Save power, save water, and protect the global environment
Timer controlled powersaving(Page 38)
Once you set a timer, thetoiletseat
heaterisswitched off every day at
the preset time, and you
can save power. The powersaving time can be preset to3, 6 or 9 hours.

Automatic powersaving(Page 38)

Super Automatic
power saving(Page 38)

The least frequently used
hours are memorized toautomatically lower the
toilet seat temperature,and you can save power.

While performing theautomatic power saving,
the toilet seat heater is
automatically switched
off when not in use.

While in automatic
power saving mode,
toilet seat temperature
is approximately 26ºC.

Switched
OFF
when not in use“Timer controlled power saving” and “(Super) Automatic power saving” can be
simultaneously used.

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