Final Report by Microwave Oven Evaluation Standard
Subcommittee, Energy Efficiency Standards Subcommitteeof the Advisory Committee for
Natural Resources and Energy

The Microwave Oven Evaluation Subcommittee had deliberations on judgment
standards for the manufacturers and importers (hereafter referred to as “manufacturers”)
concerning performance improvements of microwave ovens, and prepared a final summary
report as below.
Target Scope [See Attachment 1]

1.

The report shall cover microwave ovens.

However, microwave ovens forbusiness use, those dedicated to rated input voltage of 200V, those of embedded type,those having a gas oven, and those whose interior height is less than 135 mm shallbe excluded.
2.

Items to be Judgment Standards for Manufacturers(1)

Target fiscal year [See to Attachment 2]
It shall be the fiscal year 2008.

(2)

Target standard values [See Attachments 3 to 4]
With regard to microwave ovens that manufactures ship within Japan for thetarget fiscal year, the weighted average of energy consumption efficiency (annual
energy consumption) calculated in (3) by the volume of shipments for eachmanufacturer per category in the table below shall not exceed the target standard
values.

Category

Function

Heating Method

Inner Volume

TargetStandard
Value[kWh/year]

A

Without oven function(single-function
microwave oven)

－

－

60.1

Less than 30 L

73.4

30 L or greater

78.2

With oven function(oven-microwave oven)With an exposed heater(except for those of hot
air circulation heating
method)Without an exposed
heater (except for thoseof hot air circulation
heating method)
Hot air circulation
heating method

Less than 30 L

70.4

30 L or greater

79.6

－

73.5

B
C
D
E
F

Note: “Inner Volume” refers to a numeric value computed from usable dimensions of aheating chamber defined by Electrical Machinery and Appliance Quality Labeling
Regulations based on Household Goods Quality Labeling Law (Law No.104 of 1962).

1

(3)

Measurement method of energy consumption efficiency [See Attachment 5]
The energy consumption efficiency of microwave ovens shall be the annual
energy consumption, and it is a numeric value [kWh/year] calculated by thefollowing expression.
E = [(580.8*AV285 + 66*AV245 + 571.1*AV125 + 205*AV185 ) + 31*B + 6400*C ]/ 1000
In this equation, E, AV285, AV245, AV125, AV185, B, and C shall represent thefollowing numeric values.
E:

Energy consumption efficiency [kWh/year]

AV285: Energy consumption per use of microwave function to heat dummy-load of285[g] [Wh/time]
AV245: Energy consumption per use of microwave function to heat dummy-load of 245[g] [Wh/time]
AV125: Energy consumption per use of microwave function to heat dummy-load of 125[g] [Wh/time]
AV185: Energy consumption per use of microwave function to heat dummy-load of 185[g] [Wh/time]

(4)

B:

Energy consumption per use of oven function [Wh/time]C:

Standby energy consumption per hour [Wh/time]

Display items and others
Items to be displayed shall follow the provisions in the Household Good Quality
Labeling Law.
1)

The items concerning energy-saving shall be as follows.

Display items shall be as follows:a) Categoryb) Annual energy consumption of microwave functionc) Annual energy consumption of oven function (limited to those with ovenfunction.)d) Annual standby energy consumptione) Energy consumption efficiency (annual energy consumption)f) Manufacturer’s name(Note) Regarding the display of a) to e) in the above, revision of the Electric
Machinery and Appliance Quality Labeling Regulation is required.

2)

Compliance itemsa) The energy consumption efficiency shall be in kWh/year displayed to one
place of decimals. In this case, the energy consumption efficiency shall be2

106% or below of the displayed value.
b) The annual energy consumption of microwave function shall be a numericvalue calculated by the following expression, and in kWh/year displayed to
one place of decimals:
Annual energy consumption of microwave function = (580.8*AV285 + 66*
AV245 + 571.1*AV125 + 205*AV185 ) / 1,000c) The annual energy consumption of oven function shall be a numeric value
calculated by the following expression, and in kWh/year displayed to one
place of decimals:
Annual energy consumption of oven function = 31*B / 1,000d) The annual standby energy consumption shall be a numeric value calculatedby the following expression, and in kWh/year displayed to one place ofdecimals:Annual standby energy consumption = 6400*C / 1,000e) The display items shown in 1) above shall be put in a prominent place incatalogues or instruction manuals explaining products’ performance, when
consumers select appliances.
3.

Proposals for Energy-saving(1)

Actions of users
1)

Utilizing information such as “energy-saving label”, efforts shall be made to selectmicrowave ovens with excellent energy consumption efficiency; and on occasions
when using microwave ovens, efforts shall be made to reduce the energy
consumption by appropriate and efficient use.

(2)

Action of retailers
1) Microwave ovens with excellent energy consumption efficiency shall be promoted,
and by use of “energy-saving label”, appropriate information shall be provided forusers to select a microwave oven with excellent energy consumption efficiency.
Also, in using the energy-saving label, its display shall be easy to see for users, so
as not to misconceive.

(3)

Actions of manufacturers

3

1)

Technical development for energy-saving of microwave ovens shall be promoted by,for example, carrying out an efficiency analysis of microwave heating, and the
products with excellent energy consumption efficiency shall be developed.

2)

From viewpoint of promoting the spread of microwave ovens with excellent
energy consumption efficiency, “energy-saving label” shall be swiftly introduced,
and appropriate information shall be provided for users to select them.

Also, inusing the energy-saving label, its display shall be easy to see for users, so as not
to misconceive.
(4)

Actions of Government
1)

From viewpoint of promoting spread of microwave ovens with excellent energy
consumption efficiency, efforts shall be made to take necessary measures such as
spread and enlightenment activities, so as to promote actions of users andmanufacturers.

2)

Implementation of the display items by manufacturers shall be checked
periodically and continuously, and appropriate law management shall be made soasforcorrect

andeasy-to-understandinformation

concerningenergyconsumption efficiency to be provided for users.
3)

The energy-saving standard based on the Top Runner Program is a very effective
method for energy-savings of products; therefore, efforts shall be made to spreadit internationally by catching appropriate opportunities.

4

Attachment 1

Target Scope

The criteria shall be applied to all microwave ovens.

However, the followings shall be

excluded from the scope:- Microwave ovens for business use
The measurement method for household microwave ovens cannot be applied tomicrowave ovens for commercial use such as in convenience stores, restaurants, etc.,
because the number of use times is different between those for household use and forcommercial use.

Since not only the measurement method for the latter has not yet

been established, but also the number is extremely small (fiscal year 2003:
approximately 25,000 units), they shall be excluded from the scope.
- Microwave ovens dedicated to rated input voltage of 200V
They shall be excluded from the scope, because engineering works for 200V arenecessary to use, because the usage is generally different from those for household
use, and because the number is extremely small (fiscal year 2003: approximately
10,000 units).
- Microwave ovens of embedded type
They are used in a built-in kitchen, and thus their adiabatic efficiency, etc.
varies depending on design, materials, etc. of the built-in kitchen which they areembedded in.

Because a measurement method concerning such factors has not yet

been established and because the number is extremely small (fiscal year 2003:
approximately 23,000 units), they shall be excluded from the scope.
- Microwave ovens having a gas oven
They shall be excluded from the scope because gas ovens have already been
designated as specified equipment of Top Runner Program.
- Microwave ovens whose interior height of less than 135 mm
Because measurement by using a tall beaker, which has been defined in the5measurement method of energy consumption efficiency, is not possible for them, it isdifficult to set a target standard value.

Also, they are the particular kind of

products whose main function is oven (referred to as so-called toaster ovens), andtheir number is extremely small (fiscal year 2003: approximately 10,000 units); thus,
they shall be excluded from the scope.
Shipment volumes of the equipment listed above are little, in general, and consumer
needs for them have not yet been defined.

Depending on future developments, however,

we shall conduct a necessary review when it is considered appropriate to include them inthe scope.
Note) The scope shall not cover microwave ovens for industrial use, such as highfrequency thawing equipment, high frequency dielectric heater, etc. that utilize
generation of high frequency by magnetron.

6

Attachment 2

Target Fiscal Year, etc. for Microwave Ovens

1.

In general, a considerable improvement in energy consumption efficiency of
microwave ovens is made when a model change takes place, and a typical development
period of these new products is approximately 1 year.

For this reason, consideration

should be given so that the manufacturers can take at least two opportunities ofbringing out new models before the next target fiscal year.
On the other hand, in light of measures against global warning, in order toensure that products that achieved the target standard value become widely usedamong consumers during the first commitment period of Kyoto Protocol (2008 to 2012),
it would be desirable to achieve the target in as short time as possible, assuming thatthe tenure of use of microwave ovens would be approximately 10 years.
With the above in mind, the target year of microwave ovens shall be set to fiscal
year 2008, three years after establishment of the criteria.
2.

In addition, the improvement rate of energy consumption efficiency in the target
fiscal year is expected to be approximately 8.5%, on the assumption that there will be
no change from the current volume of shipments (results of fiscal year 2004) andcomposition by each category.

<Overview of Estimation>(1)Energy consumption efficiency estimated from values of actual achievements of
microwave ovens shipped in fiscal year 2004: 77.2 kWh/year(2)Energy consumption efficiency estimated from target standard values of microwave
ovens to be shipped in the target fiscal year: 70.6 kWh/year(3) Improvement rate of energy consumption efficiency(77 . 2 − 70 . 6 ) ∗ 100 =77 . 2

7

Attachment 3
Classification of Microwave Ovens

1.

Basic Idea
In the case of microwave ovens, functions, heating systems and inner volume have alarge impact on energy consumption efficiency (annual energy consumption).

Hence,

microwave ovens shall be classified based on them.
2.

Specific Classification Method(1)Classification by function
Two types of microwave ovens exist; namely, microwave ovens that have oven function(oven-microwave oven) and that do not have oven function (single-function microwaveoven).

It is reasonable to classify them by the function because the difference influences

energy consumption efficiency and development of energy saving technologies in the
future.
1) Microwave ovens without oven function (single-function microwave oven)2) Microwave ovens with oven function (oven-microwave oven)(2)

Classification by heating method
As for microwave ovens having oven function, they can be divided by heating methodof oven function into the followings: those of direct heating method (those with an exposed
heater inside of a microwave oven), those of radiation heating method (other than thosewith an exposed heater inside of a microwave oven), and those of hot air circulation
heating method.

Because the differences in the heating methods influence energy

consumption efficiency, it would be reasonable to classify them by the heating method.

In

addition, for microwave ovens of hot air circulation heating method with a heater, as theheater is supplementary, they shall be classified into the category of hot air circulation
heating method, which is the main heating method (See Figure 1).
1) Microwave ovens with an exposed heater (excluding those of hot air circulation
heating method)2) Microwave ovens without an exposed heater (excluding those of hot air circulation
heating method)3) Microwave ovens of hot air circulation heating method8Annual Energy
Consumption [kWh/year]
年間消費電力量［kWh/年］

95.0
90.0
85.0
ヒーター露出あり
ヒーター露出なし
Hot
air circulation heating
熱風循環加熱80.0

With an exposed heater

Without an exposed heater

75.0
70.0
65.0
60.0
0

10

20

30

40

Inner volume (L)
庫内容積［Ｌ］
Figure 1 Relationship of Heating Method and Annual Energy Consumption(3)

Classification by inner volume
The products having oven function can be divided at around the inner volume of

30L into the followings: products that enable multifunctional cooking such as cooking
using two square plates (two-level cooking) and those used for simple cooking. As thedifference can influence energy consumption efficiency, it is reasonable to classify theminto those having the inner volume of less than 30 L and those having the inner volume of
30L or greater (See Figure 2).
“Inner volume” refers to a numeric value computed from usable dimensions of aheating chamber defined by Electrical Machinery and Appliance Quality Labeling
Regulations based on Household Goods Quality Labeling Law (Law No.104 of 1962).
1) Microwave ovens having the inner volume of less than 30L
2) Microwave ovens having the inner volume of 30L or greater

9Annual年間消費電力量［kWh/年］
Energy Consumption [kWh/year]

95.0
90.0
85.0
80.0

30L未満
30L以上

Less than 30L

75.0
70.0
65.0
60.0
0

5

10

15

20

25

30

35

Inner
Volume (L)
庫内容積［Ｌ］
Figure 2
3.

Relationship of Inner Volume and Annual Energy Consumption

Proposal for Basic Classification
Based on the above, we shall set the proposal for basic classification, as shown in thefollowing table:
Temporary
CategoryaFunction

Heating Method

Inner Volume

Without oven function(single-function
microwave oven)－－Less than 30 L

With oven function (oven– microwave oven)With an exposed heater(excluding those of hot air
circulation heating method)
Without an exposed heater(excluding those of hot air
circulation heating method)
Hot air circulation heating
method

b
c
d
e
f
g

10

30L or greater
Less than 30 L
30L or greater
Less than 30 L
30L or greater

Attachment 4

Target Standard Values of Microwave Ovens

1.

Idea on Establishment of Target Standard Values(1)Basic idea
We shall set target standard values based on the idea of Top Runner Method.

The

specific policy shall be as follows:
1) Target standard values shall be set for every category that has been appropriately
defined.
2) As for the categories where future technological advances are expected to improve
efficiency, the target standard value shall allow for the improvement as much as
possible.
3) Target standard values shall not conflict among categories.
(2)Room for improvement in energy consumption efficiency through technologicaladvances in the future
Engineering developments of microwave ovens have been carried out mainly withthe objective of improving taste quality.

In addition, although engineeringdevelopments have also been taken place for improving energy consumption efficiency
such as reduction of standby power consumption, it can be said that there is still someroom for improvement in efficiency of microwave ovens.
Although efficiency of magnetron that comprises a large percentage of power
consumption of microwave function is saturated, the efficiency is expected to increase bychanging a radiating method of microwave and by improving thermal insulation
performance, etc. Taking into consideration that these factors might contribute to higher
efficiency, we set the target standard value by 1% up from the current Top Runner Value.
2.

Specific Target Standard Values
Target standard values of microwave ovens shall be represented in real numbers.
To be specific, for each category, the best value of energy consumption efficiency shallbe a Top Runner Value, and the value obtained by adding improvement of efficiency to the
Top Runner Value shall be a target standard value (See Figure 1 to 6).

11

The category of less than 30 L of hot air circulation heating method in which no
products exist (temporary category f) shall be integrated into a category of 30L or greaterof hot air circulation heating method (temporary category g).
Table 1 Top Runner Values of Microwave Ovens
Temporary
Category

Function

Heating Method

Inner Volume

Top Runner
Value[kWh/year]aWithout oven function(single-function
microwave oven)

－

－

60.7

Less than 30 L

74.1

30 L or greater

79.0

Less than 30 L

71.1

30 L or greater

80.4

Less than 30 L－

30 L or greater

74.2

b
c
d
e

With oven function(oven-microwave oven)fWith an exposed heater(except for those of hot
air circulation heating
method)Without a exposed
heater (except for thoseof hot air circulation
heating method)
Hot air circulation
heating methodg

Table 2 Target Standard Values of Microwave Ovens
Top
Improved
RunnerEfficiency
Value
[%]
[kWh/year]

TargetStandard
Values[kWh/year]

Category

Function

Heating Method

Inner
VolumeA

Without ovenfunction(single-function
microwave oven)

－

－

60.7

1.0

60.1

Less than
30 L

74.1

1.0

73.4

30 L orgreater

79.0

1.0

78.2

Less than
30 L

71.1

1.0

70.4

30 L orgreater

80.4

1.0

79.6

－

74.2

1.0

73.5

B
C
D
E

F

With an exposed
heater (except
for those of hot
air circulation
With ovenheating method)function
Without an(oven-microwave
exposed heateroven)(except for thoseof hot air
circulation
heating method)
Hot air
circulation
heating method12

(Reference)

年間消費電力量［kWh/年］
AnnualEnergy Consumption [kWh/year]

90.0
85.0
80.0
75.0
70.0
65.0

Target Standard Value (60.1)
目標基準値（60.1）

60.7

60.0
55.0
50.0
0

5

10

15
Inner
Volume [L]
庫内容積［Ｌ］

20

25

30

Figure 1 Top Runner Value and Target Standard Value of Category A

AnnualEnergy Consumption [kWh/year]
年間消費電力量［kWh/年］

95.0
90.0
85.0
80.0

Target Standard Value (73.4)
目標基準値（73.4）

74.1

75.0
70.0
65.0
60.0
55.0
50.0
0

5

10

15

20

25

Inner
Volume [L]
庫内容積［Ｌ］

Figure 2 Top Runner Value and Target Standard Value of Category B

1330

AnnualEnergy Consumption [kWh/year]
年間消費電力量［kWh/年］

95.0
90.0
85.0

目標基準値（78.2）
Target Standard Value (78.2)
79.0

80.0
75.0
70.0
65.0
60.0
55.0
50.0
0

5

10

15
20
庫内容積［Ｌ］
Inner
Volume [L]

25

30

35

Figure 3 Top Runner Value and Target Standard Value of Category C

Annual 年間消費電力量［kWh/年］
Energy Consumption [kWh/year]

95.0
90.0
85.0
80.0
TargetStandard Value (70.4)
目標基準値（70.4）

75.0

71.1

70.0
65.0
60.0
55.0
50.0
0

5

10

15
庫内容積［Ｌ］
Inner
Volume [L]20

25

Figure 4 Top Runner Value and Target Standard Value of Category D

1430

AnnualEnergy Consumption [kWh/year]
年間消費電力量［kWh/年］

95.0
90.0
85.0

目標基準値（79.6）
Target Standard Value (79.6)

80.4

80.0
75.0
70.0
65.0
60.0
55.0
50.0
0

5

10

15
20
庫内容積［Ｌ］
Inner
Volume [L]

25

30

35

Figure 5 Top Runner Value and Target Standard Value of Category E

AnnualEnergy Consumption [kWh/year]
年間消費電力量［kWh/年］

95.0
90.0
85.0
80.0

Target Standard Value (73.5)
目標基準値（73.5）

74.2

75.0
70.0
65.0
60.0
55.0
50.0
0

5

10

15
20
Inner
Volume [L]
庫内容積［Ｌ］

25

30

Figure 6 Top Runner Value and Target Standard Value of Category F

15

35

Attachment 5

Energy Consumption Efficiency of Microwave Ovens and Method of Measurement

I.

Basic Idea
We studied energy consumption efficiency of microwave ovens and a measurement

method thereof based on result of the study conducted by “Microwave Oven Energy
Consumption Study Panel” (Chaired by: Makoto Ando, Professor of Tokyo Institute ofTechnology) of the Energy Conservation Center, Japan.
Microwave ovens are products that consume power mainly in three states: namely,
microwave function, oven function, and standby state.

Thus, the energy consumption

efficiency thereof shall be defined as annual energy consumption to be obtained bycomputing the power consumption in these three states based on the status of use by
general households. Specifically, the energy consumption of microwave function, ovenfunction, and standby state is individually measured.

Then, the energy consumption

efficiency of microwave oven is obtained by summing all the values calculated by means ofmultiplying those measured power consumption values by respective utilization
coefficients (such as number of annual heating times by microwave function) that are
determined from a questionnaire survey (“Questionnaire Survey of Microwave Utilization”
conducted by the Energy Conservation Center, Japan).
In addition, the measuring method described above is to evaluate energy saving
performance of equipment in actual operating state, so that the cooking performance suchas taste quality or finished state, etc. is not necessarily considered.

II.

Specific Measurement Method
The energy consumption efficiency of microwave oven shall be annual energy

consumption, and it is a numeric value [kWh/year] computed with the following expression:
E = { [(NA1 + K1 * NA2) * AV285 + K2 * NA3 * AV245 + (NA4 + K3 * NA5 + K4 * NA6) * AV125 + NA7* AV185] + [NB * B] + [HC * C] } / 1000
Wherein E, AV285, AV245, AV125, AV185, NA1, NA2, NA3, NA4, NA5, NA6, NA7, B, NB, C, and HC

16

shall represent numeric values listed below:
E:

Energy consumption efficiency [kWh/year]

AV285: Energy consumption per use of microwave function to heat dummy-load of285[g] [Wh/time]
AV245: Energy consumption per use of microwave function to heat dummy-load of
245 [g] [Wh/time]
AV125: Energy consumption per use of microwave function to heat dummy-load of
125 [g] [Wh/time]
AV185: Energy consumption per use of microwave function to heat dummy-load of
185 [g] [Wh/time]
NA1:

Annual heating time [time/year] of refrigerated food of 285 [g] by microwave
function = 363

NA2:Annual heating time [time/year] of frozen food of 285 [g] by microwave
function = 99

NA3:

Annual thawing time [time/year] of perishable food of 245 [g] by microwave
function = 55

NA4:Annual heating time [time/year] of refrigerated food of 125 [g] by microwave
function = 314

NA5:Annual heating time [time/year] of frozen food of 125 [g] by microwave
function = 115

NA6:Annual thawing time [time/year] of perishable food of 125 [g] by microwave
function = 13NA7:Annual heating time [time/year] of drink of 185 [g] by microwave function =
205

K1:

Heating coefficient of frozen food of 285 [g] = 2.2

K2:

Heating coefficient of thawing perishable food of 245 [g] = 1.2

K3:

Heating coefficient of frozen food of 125 [g] = 2.1

K4:

Heating coefficient of thawing perishable food of 125 [g] = 1.2

B:

Energy consumption per use of oven function [Wh/time]

NB:

Annual heating time［time/year］by oven function = 31

C:

Standby energy consumption per hour [Wh/h]HC:

Annual standby hour [h/year] = 6400

1. Energy consumption per use of microwave function [Wh/time]
Energy consumption per use of microwave function shall be power consumption
required for heating from 4 to 70 degrees using a real container with the following method,and it is the mean value of two measurements.

17

However, if a divergence between themean of 2 computed values and each of the 2 computed values is ± 1.5% and greater, twomore measurements shall be conducted, and the mean of the four measurements shall betaken.
(1) The energy consumption required for heating from 4 to 70 degrees using a realcontainer shall be a numeric value to be computed by the following expression foreach dummy-load mass (See (2) below).
Numeric values of mJ and CP shall be from Table 1:⎧2257 ∗ (M 10 - M 70 )A = A 1070 ∗ ⎨(1 )⎩ (4.187 ∗ M + 0.55 ∗ m) ∗ (T70 - T10 ) + 2257 ∗ (M 10 - M 70 )∗4.187 ∗ M + C p ∗ m J
66⎫2257 ∗ (M 10 - M 70 )∗+⎬T70 - T10 4.187 ∗ M + 0.55 ∗ m (4.187 ∗ M + 0.55 ∗ m) ∗ (T70 - T10 ) + 2257 ∗ (M 10 - M 70 ) ⎭In the expression shown above, A, A1070, T10, T70, M10, M70, M, m and mJ shallrepresent the following values, respectively:
A:

Energy consumption required for heating from 4 to 70 degrees using a realcontainer [Wh/time]

A1070: Energy consumption required to heat to T70℃
T10:

Temperature of dummy-load before heating [℃]

T70:

Temperature of dummy-load after heating [℃]

M10:Mass [g] of dummy-load and test container at T10 [℃]

M70:

Mass [g] of dummy-load and test container at T70 [℃]

M:Mass of dummy-load [g]m:Mass of test container [g]mJ:

Mass of real container [g]CP:Specific heat of real container [J/g･K]

Table 1: Coefficients of a Calculation Formula of Energy Consumption
Mass of Dummy-Load, M

ｍJ

ＣＰ

400

1.07

125

200

1.07

185

250

0.55

[g]
285
245

18

(2) Dummy-load shall be water and have the mass listed in the left column of Table 2
below:
Table 2 Mass of Dummy-Load and Specification of Test Container
Mass of Dummy-load, M [g]Specification of Test Container

285

A crystallizing plate having outside diameter of 150

245

mm and height of 75 mm specified in JIS R 3503

125
185

A crystallizing plate having outside diameter of 90 mm
and height of 45 mm specified in JIS R 3503
A tall beaker having outside drum diameter of 66 mm
and height of 135 mm specified in JIS R 3503

(3) A test container listed in the right column of Table 2 shall be used, according to themass of dummy-load shown in the left column.

Also, its mass m[g] shall bemeasured.
(4) If equipment is provided with an additive function for improving taste quality thatcan be turned ON/OFF by a user, measurement may take place with the additive
function turned OFF.
(5) Temperature inside of a microwave oven before starting a test shall be 23±2 ℃.
(6) In case of conducting 2 tests continuously, the second test shall be performed after aforced cooling period of at least 15 minutes, following the termination of the firsttest.
(7) Mass of dummy-load and test container, M10 [g], shall be measured.
(8) Temperature of dummy-load and container before starting a test shall be 10±1℃,
and the container shall be placed at the geometric center of a plate inside of a
microwave oven.
(9) Using microwave function, heat to raise temperature of dummy-load up to 70±2 ºC.
(10)Measurement shall be made at the maximum output setting, which is manually
settable, of a microwave oven.
(11)After heating, the dummy-load shall be promptly stirred, and the temperature ofdummy-load, T70 ℃, shall be measured.

Also, the mass of dummy-load andcontainer, M70 [g], and the required energy consumption, A1070 [Wh], shall bemeasured.
2. Energy consumption per use of oven function [Wh/time]

19Energy consumption per use of oven function shall be energy consumption measured
with the following method, and it is the mean of two measurements.

However, if adivergence between the mean of 2 computed values and each of the 2 computed values is ±1.5% and greater, two more measurements shall be conducted, and the mean of the fourmeasurements shall be taken.
(1) Temperature inside a microwave oven before starting a test shall be 23±2 ℃.
(2) Nothing shall be inside the microwave oven; neither load nor tray shall be placed
inside.

However, for a microwave oven with a rotary stand on which the tray isplaced; measurement shall take place with the rotary stand installed.
(3) Mounting location of a thermocouple shall be the center of the inside of a microwave
oven, which is at one-half of width, depth and height respectively, according to thesecond appendix (related to article 2) of Electric Machinery and Appliance Quality
Labeling Regulation, fourteen (two) (See Figure 1).
(4) Power consumption for increasing inside temperature of a microwave oven from theinitial temperature by 177 [K] shall be B1 [Wh], and power consumption for
subsequently and continuously maintaining the state for 20 minutes shall be B2.
Then, a combined value of B1 and B2 shall be taken.
(5) Note, however, that, depending on a model, it may be difficult to keep a certain
temperature due to its temperature setting mechanism.

In such a case, in principle,

retention temperatures and power consumptions at 2 points under and over thetemperature that has risen by 177 [K] from the initial temperature shall bemeasured.

Then, the power consumption at the temperature that has risen by 177[K] from the initial temperature shall be computed with a linear interpolation (SeeFigure 3 (1)).

In the case of a model for which those 2 points cannot be taken, 2

points which are closest to the temperature that has risen by 177K and also which
can be selected with the model shall be taken (See Figure 3(2)).

In either case,energy consumption at the temperature that has risen by 177 [K] from the initial
temperature shall be calculated with the following expression:

B = B L + (B H − B L ) ×

T - TLTH - TL

Wherein,
B: Energy consumption at temperature that has risen by 177 [K] from theinitial temperature [Wh]BL: Energy consumption at lower retention temperature [Wh]BH: Energy consumption at higher retention temperature [Wh]TL: Lower retention temperature［℃］20

TH: Higher retention temperature［℃］
T: Temperature that has risen by 177 [K] from the initial temperature

Thermocouple
熱電対aTurntable
ﾀｰﾝﾃｰﾌﾞﾙ

a
b

b

１77K上
昇
Risingby 177K

Figure 1 Mounting Diagram of Thermocouple

Ｂ１

Ｂ２(Measuring for 20 minutes)（２０分間測定）

Figure 2 Measuring Method of Energy Consumption of Oven

Starting point of
measurement for 20 minutes

Starting point of
measurement for 20 minutes＋177[Ｋ]＋177[Ｋ]+180

Starting point of measurement
when in proportional distribution(1) In the case of a model for which thetemperature that has risen by 177 [K] cannot
be retained for 20 minutes.

2 points of the closest temperature
setting;Starting point of measurement
when in proportional distribution(2) In the case of a model for which thetemperature of 177 [K] or greater cannot beretained for 20 minutes.

21

Figure 3: Measurement Method in Cases with Linear Interpolation
3. Standby energy consumption per hour [Wh/h]Standby power consumption per hour shall be a numeric value of energy
consumption measured for one hour, under the condition where the microwave oven is
supplied with alternating current power, not used for cooking, and in a stable condition
without subsequent changes.
4. Measurement of energy consumption efficiency of a microwave oven shall take place
under the following conditions:(1) Ambient temperatures shall be 23±2 ℃.
(2) The equipment shall be installed in a normal condition on a flat wooden standhaving thickness of 10mm or greater.
(3) The power supply voltage shall be 100±1V, and the power supply frequency shall be
50±0.1 Hz or 60±0.1 Hz.
(4) A scale shall be able to measure up to 0.1 g, and magnitude of relative error tomeasurements shall be maintained within ±0.5%.
(5) A watt-hour meter shall ensure the magnitude of relative error to measurements
within ±2%.
(6) A thermometer shall be a bar thermometer specified in JIS B 7411 (Glass bar
thermometer for general use), appendix table 2, M, or its equivalent.
(7) A thermocouple shall be “Type K, Class 1” specified in JIS C 1602 (Thermocouple).

22

Attachment 6

Microwave Oven Evaluation Standard Subcommittee,
Energy Efficiency Standards Subcommittee of the Advisory Committee
for Natural Resources and Energy
Background of Holding

First Subcommittee Meeting (January 31, 2005)- Disclosure of the Microwave Ovens Evaluation Standard Subcommittee- Current situation of microwave ovens- Scope of microwave ovens to be covered- Energy consumption efficiency and its measurement method
Second Subcommittee Meeting (July 12, 2005)- Scope of microwave ovens to be covered- Classification of microwave ovens for target setting- Target standard values and target fiscal years of microwave ovens
Third Subcommittee Meeting (September 2, 2005)-

Interim summary report

Fourth Subcommittee Meeting (October 26, 2005)-

Comments on the interim summary report; and final summary report23

Attachment 7

Microwave Oven Evaluation Standard Subcommittee,
Energy Efficiency Standards Subcommittee of the Advisory Committee
for Natural Resources and Energy
List of Members
Chairman:

TETSUJI ODA

Professor in Department of Electrical Engineering,
Graduate School of Engineering,
The University of Tokyo

Members:

MAKOTO ANDO

Professor in Electrical and Electronic Engineering
Department, Graduate School of Science andEngineering, Tokyo Institute of Technology

MARIKO ICHIKAWA

Consultant for Consumers’ Affairs, Japan
Consumer’s Association

SHOICHIRO OHZEKI

Senior General Manager of Energy Environment
Technology Division, The Energy Conservation
Center, Japan

TAKAHIRO KANAI

Chairman of Microwave Oven Technology Expert
Committee, The Japan Electrical Manufacturers’
AssociationKIKUKO TATSUMIManaging Director of Nippon Association ofConsumer Specialists

OSAMU HASHIMOTO

Professor in Department of Electrical Engineeringand Electronics, College of Science and Engineering,
Aoyama Gakuin University

CHIHARU

Director and General Manager of Laboratory,

MURAKOSHIJyukankyo Research Institute Inc.

HIROSHIManaging Director of Japan Machinery Importers’

HARUHARA

Association (Resigned as of March 31, 2005, due todissolution of the association)

24

Reference Material 1

Current Situation of Microwave Ovens

1.

Market Trend

1.1 History of Microwave Ovensz

Appearance of first domestically-produced microwave oven (in 1962)
Microwave ovens for business use were released.

Fast cooking which was neverimaginable before was realized by entirely new cooking equipment that heats without
fire.
Initially, these microwave ovens were used in restaurants, etc. as equipment forbusiness use.

At that time, they were also used in dining cars of JR (Japan

Railways) or private railways.

In 1964 when Shinkansen bullet trains started

service, it got into the news that their dining cars were equipped with microwave
ovens.
z

It let the speedy heating of microwaves become publicly known.

Release of microwave ovens for household use (in 1965)
Microwave ovens for household use appeared for the first time.

z

Release of oven-microwave oven (in 1977)
Oven-microwave ovens that are microwave ovens equipped with oven function werereleased in 1977.

Combined operations of microwave function and oven function

expanded the variations of cooking.

In addition, for users who need both microwave

oven and oven, it resulted in reduced space, as they could have only one device, nottwo.
z

Release of hot air circulation type oven-microwave oven (in 1978)
Hot air circulation type oven-microwave oven were released.

As for oven function,

not only top-bottom heating method but also hot air circulation method that bakeswith hot air have appeared, and the new function has been added to a microwave oven,the compound cooker.
*Table 1-1 shows a relationship of microwave oven types and heating methods.

25

Table 1-1 Relationship of Nominal Designations of Microwave Ovens

Control
MethodHeating
Methodand Heating Methods
Single-function microwave ovens
Oven-microwave ovens
MechanicalMicrocomputer type
type
Electronic control by a microcomputer
Control by aElectronic control by- Microwave
mechanicala microcomputer
A sensor senses finishing state, and atimer switch
A sensor senses
microcomputer controls the amount of
A timer switch finishing state, and aelectricity based on the information fromturns ON/OFF microcomputer
the sensor.
electricity.
controls the amountAn electronic timer of the microcomputerof electricity based onturns ON/OFF electricity.
the information from- Oventhe sensor.
A sensor senses the inside temperature andAn electronic timer offinishing state. Based on the information
the microcomputerfrom the sensor, a microcomputer controls
turns ON/OFF
the inside temperature and the amount ofelectricity.
electricity.
An electronic timer of the microcomputer
turns ON/OFF electricity.
Microwave heating
Microwave
Hot air circulation heating
Heating takes place by conversion ofheatingHeating takes place byelectric energy of microwave into
circulating heat of a heater
Heating takes
vibrational energy of water molecules.
place byby fan.
conversion ofTop-bottom heating
electric energy(radiation type)of microwave
Heating takes place byinto vibrational radiant heat.
energy of water Top-bottom heating (direct
molecules.
projection type)Heating takes place bydirect projection of heat of aheater.

1.2 Volume of Domestic Shipments
Since the first domestic microwave oven was released for household use in 1965,
microwave ovens have become widely used as multifunctional cooking equipment without
fire for warming, baking, boiling, steaming, etc.
Table 1-2 and Figure 1-1 show transitions in domestic shipment volume since 1990, in
domestic production output including products for export, in overseas production output(quantity of overseas production by Japanese-affiliated firms), and in the number ofimported units.

As shown in Figure 1-1, a volume of domestic shipments have remained

unchanged on the level of 3.5 million units.

As Japanese manufacturers shift production

base from Japan to overseas, domestic production output is on a downward trend, and thenumber of imports is growing.

26

Table 1-2

Transitions in Domestic Shipment Volume, in Domestic and Overseas

Production Outputs, and in Number of Imports of Microwave Ovens
Unit: 1,000 units

Fiscal year
(FY)1990
FY 1991
FY 1992
FY 1993
FY 1994
FY 1995
FY 1996
FY 1997
FY 1998
FY 1999
FY 2000
FY 2001
FY 2002
FY 2003

1. Domestic
Shipment Volume(JEMA, voluntary
statistics)

2. Domestic Production
Output (METI, current
survey of industrial
production)

3. Overseas
Production Output(JEMA, voluntary
statistics)

4. Number of Imports(Ministry of Finance,
customs statistics)

3,145
3,108
2,791
2,757
2,808
3,079
3,582
3,524
3,494
3,518
3,770
3,614
3,533
3,547

4,666
4,185
3,714
3,393
3,117
3,273
3,513
3,442
2,964
2,858
2,951
2,416
1,956
1,589

3,869
5,384
6,786
5,959
6,770
8,233
10,103
10,168
11,164
10,694
10,70810,361
9,284
9,764

115
53
99
200
634
981
994
845
1,033
1,289
1,721
1,736
1,865
2,394

27

Figure 1-1:

Domestic
Production

Overseas
Production

FY 2003

FY 2002

FY 2001

FY 2000

FY 1999

FY 1998

FY 1997

FY 1996

FY 1995

FY 1994

FY 1993

FY 1992

FY 1991

FY 1990

Units (in 1000 units)

Domestic
Shipments

ImportTransitions in Domestic Shipment Volume, in Domestic and Overseas
Production Outputs, and in Number of Imports of Microwave Ovens
Source: Domestic Production Statistics: METI current survey of industrial production.
Import Statistics: Ministry of Finance, Customs Statistics.
Domestic Shipment Statistics and Overseas Shipment Statistics: Japan
Electrical Manufacturers’ Association (JEMA).

28

1.3

Domestic Shipment Volume of Microwave Ovens by Type

Table 1-3 shows domestic shipment volume of single-function microwave ovens andoven-microwave ovens.

In addition, Figure 1-2 shows proportions of each type of

microwave ovens based on the volume of shipments.

Although in 1990 thesingle-function microwave ovens and the oven-microwave ovens accounted for almost
the same percentages in the total domestic shipment volume, recently the latter
constitutes about 75%.
Table 1-4 shows the domestic shipment volume of microwave ovens of 1000W or greaterfor business use and its proportion to the total domestic shipment volume of microwave
ovens.
Table 1-3

Domestic Shipment Volume of Single-Function Microwave Ovenand Oven-Microwave Oven
Unit: 1,000 units

Fiscal Year

Single-Function

Oven-Microwave(FY)

Microwave OvenOven

FY 1990

1,586

1,559

3,145

FY 1991

1,403

1,705

3,108

FY 1992

1,166

1,625

2,791

FY 1993

1,014

1,743

2,757

FY 1994

821

1,987

2,808

FY 1995

652

2,426

3,079

FY 1996

758

2,825

3,582

FY 1997

831

2,693

3,524

FY 1998

780

2,713

3,494

FY 1999

801

2,717

3,518

FY 2000

865

2,905

3,770

FY 2001

836

2,778

3,614

FY 2002

898

2,635

3,533

FY 2003

912

2,634

3,547

29

Total

FY 2003
FY 2002
FY 2001
FY 2000
FY 1999
FY 1998
FY 1997
FY 1996
FY 1995
FY 1994
FY 1993
FY 1992
FY 1991
FY 1990

Single-Function Microwave oven

Oven-Microwave oven

Figure 1-2 Percentage of Each Type of Microwave Ovens
Based on Domestic Shipment Volume
Source: Japan Electrical Manufacturers’ Association (JEMA)

Table 1-4 Domestic Shipment Volume of Microwaves for Business Use and its Percentage

Fiscal year
(FY)
FY 1993
FY 1994
FY 1995
FY 1996
FY 1997
FY 1998
FY 1999
FY 2000
FY 2001
FY 2002
FY 2003to Total Domestic Shipment Volume
Domestic Shipment
Domestic Shipment
Percentage ofVolume ofVolume ofMicrowave Oven
Microwave Ovens for
Microwaves ovenfor Business Use
Business Use(in 1,000 units)(%)(in 1,000 units)
2,757
18
0.65%
2,808
20
0.71%
3,079
22
0.71%
3,582
29
0.81%
3,524
23
0.65%
3,494
19
0.54%
3,518
18
0.51%
3,770
21
0.56%
3,614
24
0.66%
3,533
25
0.71%
3,547
25
0.70%
Source: Japan Electrical Manufacturers’ Association (JEMA)

30

1.4

Domestic Shipment Volume of Oven-Microwave Ovens by Price

Table 1-5 shows domestic shipment volume of oven-microwave ovens by price.

In

addition, Figure 1-3 shows percentage of oven-microwave ovens by price based on thedomestic shipment volume.
Table 1-5

Domestic Shipment Volume of Oven-Microwave Ovens by Price
Unit: 1,000 units
80,000 to
100,000
below
yen orTotal
100,000 yen
more

Fiscal year
(FY)

Below
40,000 yen

40,000 to
below
50,000 yen

50,000 to
below
60,000 yen

60,000 to
below
80,000 yen

FY 1997

730

778

499

407

189

89

2,693

FY 1998

1,069

575

467

361

137

105

2,713

FY 1999

1,115

556

459

381

112

95

2,717

FY 2000

1,275

598

458

318

195

62

2,905

FY 2001

1,377

383

448

352

162

57

2,778

FY 2002

1,374

263

414

376

158

50

2,635

FY 2003

1,373

409

342

316

164

30

2,634

FY 2003
2003年度FY 2002
2002年度FY 2001
2001年度FY 20002000年度FY 1999
1999年度FY 1998
1998年度FY 1997
1997年度

0%

10%

20%

30%

40%

50%

60%

70%

80%

Below
40,000 yen
40,000円未満

40,000to below 50,000 yen
40,000-50,000円未満

50,000to below 60,000 yen
50,000-60,000円未満

60,000to below 80,000 yen
60,000-80,000円未満

80,000to below 100,000 yen
80,000-100,000円未満

100,000
yen or more
100,000円以上

90%

100%

Figure 1-3 Percentages by Price Based on Domestic Shipment Volume
Source: Japan Electrical Manufacturers’ Association (JEMA)

31

1.5

Major Manufacturers and Distributors of Microwave Ovens in JapanThe following are domestic major manufacturers and distributors of microwave ovens (inrandom order):[Domestic Businesses]
SANYO Electric Co., Ltd., Sharp Corporation, ZOJIRUSHI CORPORATION, Tiger
Corporation., TOSHIBA Corporation, Hitachi Home & Life Solutions, Inc., Matsushita
Electric Industrial Co., Ltd., Mitsubishi Electric Corporation, YOSHII ELECTRIC Co.,
Ltd.(Abitelax), KOIZUMI SEIKI CORP., MITSUBOSHI BOEKI LTD., IwataniInternational Corporation, Kyushu Takemura Electric (SKJ), etc.
There are some brands of microwave ovens imported from overseas.

Overseasbusinesses are as follows:[Overseas Businesses]
LG, Samsung, Daewoo, Haier Japan, Electrolux, EUPA, GE, etc.
2.

Users’ Requests for Microwave Ovens

2.1 Attention-grabbing Features of Microwave Ovens at the Time of Purchase
Table 2-1 shows the result of a survey on “Attention-grabbing Features of Microwave
Ovens at the Time of Purchase” conducted by a manufacturer:
Table 2-1:

Attention-grabbing Features of Microwave Ovens at the Time of Purchase(The Number of Samples: 409)
Reasons for Selection

The Numberof Answers

Equipped with a needed function

192

Reliable manufacturer

163

Easy to operate

143

Good product quality

118

Just fit size

114

Low-priced main body

106

Japanese manufacturer

77

Favorite manufacturer

73

32

Reasons for Selection of Currently Using Product“Why did you choose the product you are now using?”

Health- and beauty-conscious

Topical in the public

Looks enjoyable

Seems suitable for own sense ofvalue or life style

Energy-saving

Cheap running cost such as
electricity
High-tech cutting edge being
incorporated
Maybe easy-to-use for children
or husband

Favorite design

Favorite manufacturer

Looking rugged and durable

Japanese manufacturer

Low-priced main bodySeems to be more effortless than
beforeEquipped with a needed function

Good product quality

Easy to operate.

Just fit size

Reliable manufacturer

Microwave
Ovens(n=409)Source: Survey by manufacturers

As can be seen from this survey result, user’s request for microwave ovens mostly
include the reasons for selection, such as “function”, “quality”, and “brand”, which
represent reliability, a sense of reassurance, and multifunctionality of cooking.

Onthe other hand, the percentage of users who answered “Cheap running cost such as
electricity” and “Energy-saving” is not so high. The result seems to reflect the factthat operating time of microwave ovens is usually not so long that consumers’
awareness about energy saving is low.
3.

Energy Saving in Microwave Ovens – Efforts Up to Now

3.1

Energy Saving in Microwave Ovens
So far efforts to promote energy saving in microwave ovens have focused on increaseof efficiency of magnetrons, which is a major component of the appliance. Figure 3-1
shows a transition in increase of efficiency of magnetrons.

Although the efficiencyof magnetrons increased from 63.8% to 70% in the period of 1960 to about 1970, it
only rose about 3% in the following 30 years.

The efficiency in recent few years has

been flat. In addition, Figure 3-2 shows one example of outline of energy balance.
When we look at breakdown of power loss of microwave ovens, it can be divided into“power consumption of accompanying electrical components”, “loss in high-voltage
transformer”, and “feeding loss”. Energy-saving efforts for the accompanying
components have been made till now.

Moreover, a voluntary declaration aboutstandby energy consumption has been made, and energy-saving efforts areproceeding.

33

80

70

68.5

70.8

70

69.1 69.1

70.8

70.8

73

73

63.8

Efficiency (%)

60

50

40

30

20

10

0
1960

1965

1970

1975

1980

1985

1990

1995

2000

Year

Figure 3-1 Transition in Magnetron Efficiency

Outline of Energy Balance

Wave

Low-voltage
transformer

Wave-guide

Secondarycircuit

Inside run Cooling fan motor

Load

About
4kV

Turntable
motor

Magnetron
High-voltage
transformer

Microcomputer

Display Tube
Power consumption of accompanying electriccomponents

Total power
consumption

Loss in high-voltage
transformer

Feeding loss
High frequency output- Inside lamp: 20W- Turntable motor: 3W- Cooling fan motor: 20W
Etc.

Constant

Magnetron loss (when matched):
Approx. 31%
Loss in wave conducting route:
Approx. 3%- Copper loss
- Iron loss

It widely varies
depending on loading
amount.

It slightly varies depending on
loading amount.
It is because not only output but also
input current change depending on
loading amount.

It widely varies dependingon loading amount.

Figure 3-2 Outline of Energy Balance

34

2005

3.2 Energy Saving During Standby
Standby power consumption of appliances holds a place that cannot be ignored fromthe standpoint of energy saving.

Hence, Japan Electronics and Information

Technology Industries Association, the Japan Refrigeration and Air Conditioning
Industry Association, and the Japan Electrical Manufacturers’ Association made a
voluntary declaration in their joint names that, by the end of fiscal year 2003
(September, 2004 in the case of air conditioners), they would reduce the standby
power consumption of products without a timer as close to zero as possible and thatof those with a timer to 1W or lower.

In order to adhere to the declaration, eachmanufacturer improved control circuits and attained the goal 100% as far as
microwave ovens are concerned.
Table 3-3

Transitions in Standby Power Consumption

Standby Power Consumption inStandby Power Consumption in

Fiscal Year 2003*1

April 2004*2

0.9 W

0.0W

Sources *1: Survey on Standby Power Consumption in fiscal year 2003: The Energy
Conservation Center, Japan*2: The Japan Electrical Manufacturers’ Association

35