BNCK07: Comparing energy use in microwave ovens with traditional electric fuelled methods
Version 1.1 This Briefing Note and referenced information is a public consultation document and will be used to inform Government decisions. The information and analysis form part of the Evidence Base created by Defras Market Transformation Programme.

Summary

This Briefing Note presents some test results that compare microwave oven and traditional electric oven and hob cooking methods. It discusses the potential to inform consumers of the most energy efficient way of cooking different foods. The level of savings potential is difficult to calculate without further detailed information about user habits but it is estimated to be in the region of 10%.

Introduction

Within the area of domestic cooking appliances product area there is potential for carbon reduction by switching the fuel source from electricity to gas ovens and hobs. However, because ovens and hobs have a long lifespan, there would need to be a long-term policy to promote this change. It would also require a confirmed test method to allow comparison between different models of gas oven and hob to identify the most efficient. Currently, the test method for gas oven energy consumption is in development and there is no test method that allows comparison between hob types. However, there are some activities that could be adopted which can lead to lower levels of carbon emissions in domestic cooking. A high percentage of households in the UK have a microwave oven. These are generally not used as the main cooking appliance and people often find them difficult to use successfully. This Briefing Note gives data from some tests that show there are some foods which can be cooked in a more energy efficient way in the microwave than the electric hob or oven. It estimates that 10% of cooking energy could be saved by changing cooking methods.
Version: 1.1 First created: 04/10/2006 Updated: 10/11/2006 Last reviewed: 18/01/2008

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www.mtprog.com 8951

Background

In early 2006, Defras Market Transformation Programme (MTP) commissioned Intertek to undertake some tests to compare the energy used in cooking a range of standard food products using a traditional electric hob and oven and microwave oven methods1. There is very little publicly available data on this subject and MTP undertook this work to contribute to the debate. The foods were selected on the basis that they were suitable for cooking in a microwave oven by microwave-only or combination2 microwave and convection methods. The foods were cooked according to manufacturers instructions for the portion sizes and for the chosen cooking methods which included on the hob, in the oven or in the microwave oven, as appropriate.
Foods cooked and methods used
Foods were selected that were suitable for cooking in a microwave oven and that carried microwave oven instructions. The exception was for the childrens meal of fish fingers and chips, where the microwave oven was tested on convection setting only without using the microwave function. A range of portion sizes was also cooked; where appropriate, one, two and four portions were cooked simultaneously or successively. Table 1 shows the foods cooked and the range of methods used for each. All performance tests were carried out at 240 V and under controlled ambient conditions of 20 2C and 65 15% relative humidity. Table 1

Food type

Foods and cooking methods
Combination microwave oven Basic microwave oven Electric hob Electric oven
Milk Porridge New potatoes Frozen vegetables Baked beans Fresh salmon fillet Fish fingers and chips
The full test report can be found at: http://www.mtprog.com/ReferenceLibrary/A63837%20MTP%20Cooking%20Energy%20Use%20Repo rt%20(Issue%201).PDF 2 A combination oven has both microwave and convection cooking methods, which can be used separately or together to reduce cooking time.

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Combination microwave oven

Basic microwave oven

Electric hob

Electric oven

Whole chicken Baked potatoes Lasagne Indian ready meal Frozen ready meal for one Frozen pizza
Ovens and cooker used for tests
A free standing electric oven with fan and convection cooking methods was selected for the tests. It had touchpad digital temperature control for the oven and control settings for the ceramic hob. The oven was EU Energy Label A-rated and this was checked before any comparative testing was undertaken. The oven cavity was medium sized. An A-rated oven was chosen because if savings could be demonstrated using the most energy efficient type on the market, they could also be assumed for less efficient ovens. The oven was not preheated prior to cooking, so all the energy consumed was recorded. When cooking on the ceramic hob, a set of non-stick saucepans with copper coated bases was used. A pan and cooking zone were selected of an appropriate size for the task and the power settings adjusted once the food had started to boil. Pan sizes and cooking zones were adjusted as the number of portions increased. Lids were used on saucepans when cooking new potatoes and frozen vegetables. Changing the type of saucepan, the cooking zone, the amount of liquid and whether or not the lid was used, could all change the results. Two types of microwave were also selected, a combination microwave oven and basic microwave oven. The ovens were checked for microwave leakage prior to testing and also for the IEC Power Output Test to ensure they were operating correctly. Table 2 lists the oven and microwave ovens used for tests. Table 2

Product Freestanding electric cooker Combination microwave oven Basic microwave oven
Oven and microwave ovens used for tests
Brand Electrolux Panasonic Panasonic Model Insight EXT6045X NN-A725 MBBPQ NN-T553WF

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Results
The Appendix gives the detailed results for all products in the order shown in Table 1. It gives the portion sizes, cooking times and energy consumption for each test. Each result is the average of three runs. The Appendix also gives summary comments for each test. The results (see Table 3) show that for some foods and in some circumstances, using a microwave oven was more energy efficient and takes less time than cooking by traditional methods in an EU Energy Label A-rated medium electric oven or on a ceramic hob. Table 3 Energy saving results
Food Milk Circumstance Up to 800 g cooked in 200 g portions in mugs in microwave vs a saucepan on the hob Cooked with little water, in microwave vs more water, on hob Cooked with little water, in microwave vs more water, on hob Cooked without water, in microwave vs poached in water, on hob Cooked using convection and microwaves in a combination microwave oven vs electric oven Cooked using convection and microwaves in a combination microwave oven and microwave only methods vs electric oven Cooked using microwave only vs electric oven Cooked using microwave only vs electric oven Cooked using microwave only vs electric oven Cooked using convection and microwaves in a combination microwave oven vs electric oven Energy-saving range* 25 - 50%

New potatoes

70 - 75%

Frozen vegetables

Fresh salmon fillet

63 - 78%

Whole chicken

Baked potatoes

21 61%

Lasagne

40 - 81%
Indian ready meal Frozen ready meal for one Frozen pizza

38 63%

55 73%
* energy-saving range varies with number of portions and microwave function.
For other foods the microwave oven used the same energy or more than the EU Energy Label A-rated medium electric oven or on a ceramic hob.

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These were: Porridge cooked in a bowl in the microwave vs a saucepan on the hob. Baked beans - cooked in a bowl in the microwave vs a saucepan on the hob. Fish fingers and chips cooked in a combination microwave using convection heat only vs electric oven.

Energy savings

There is potential for energy savings to be made by changing cooking methods and transferring from traditional methods to cooking with a microwave oven. However, because little is known about what the preferred methods are for cooking different foods, it is difficult to calculate what those savings might be. The following sections give the current assumptions made by MTP for the amount of energy used during cooking and calculate the benefits on the basis of a 10% energy saving made by transferring 20% of cooking from electric hobs and ovens to the microwave oven and a saving of 50% of that energy being possible. Further work is necessary to identify how much of the cooking could be transferred and what savings could be made. To give a better understanding of fan-oven use, user habits with fan ovens should also be investigated. This would help towards understanding whether consumers do typically preheat their fan ovens and whether they reduce the cooking times as a result.

MTP estimates

MTP models3 currently assume that 85% of households have a microwave oven, and that they are used 96 times per year and consume 0.945 kWh per use, giving an annual consumption of 91 kWh per year. For modelling purposes, MTP assumes that electric ovens in UK households consume 1.2 kWh per use and are used 223 times per year, giving an annual consumption of 267 kWh per year. Electric hobs are estimated to consume 0.725 kWh per use, and to be used 424 times per year, giving an annual consumption of 307 kWh per year.

Potential savings

The amount of energy that could be saved in the UK is difficult to calculate but could be estimated as a proportion of the annual consumption of electric ovens and hobs; a reduction of 10% is proposed in the following paragraphs. 5.2.1 Electric ovens If 20% of the cooking energy used by electric ovens was transferred to microwave ovens and 50% of that was saved, then the overall reduction in cooking energy would be 10%. Cooking energy used by electric ovens = 267 kWh per household Transfer 20% = 267 x 0.2 = 53.4 kWh Save 50% = 53.4 x 0.5 = 26.7 kWh
MTP assumptions for models can be found in Briefing Note BNCK01: Assumptions underlying the energy projections for cooking appliances. http://www.mtprog.com/ApprovedBriefingNotes/pdf.aspx?intBriefingNoteID=204

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Mintel found that only 16% of people claimed to be regular microwave users, saying that they regularly used the microwave to cook their evening meal, but Mintel assume that people are cooking other items such as vegetables in it, if not the whole meal. The regular microwave users tended to be older and less affluent people11.

Ownership

In the UK, the majority of sales of microwave ovens are of the basic type and without the convection option12, so most owners, for example, cannot be using them for browning meat or cooking baked potatoes. As a low-cost item, microwave ovens are probably seen by consumers as a small appliance similar to a toaster or kettle, but not part of the integral, key cooking appliances within design of the kitchen. They may be seen as an add-on item, and often not positioned within the layout of the kitchen in an optimum position for easy and frequent use.

Barriers to further use

While the majority of households have a microwave oven, the research shows that consumers do not generally regard them as primary cooking appliances, except for specific tasks. The MTP consumer research showed there are a number of barriers to be overcome before people would consider using their microwave more often. These included findings related to: The food itself: eg that the food was unappetising, it was difficult to learn how to use the microwave oven well, that the food cooked unevenly, that its easier to use the hob, that its not possible to cook everything in a microwave oven. Oven-design: eg that the cavity is too small, the controls are too difficult to use, the handbooks are too complicated, the microwave oven may be unsafe, that it is not possible see the food inside the oven. Other aspects: eg that using a microwave oven is unnatural, that microwavable food products are just fast food or convenience food and thus unhealthy. In addition, the cost savings demonstrated above may not be sufficiently significant to encourage greater microwave use. Raising awareness of the cost savings associated with this method may not be the best way to convince owners to use their microwave ovens more than they do.

Overcoming barriers

There are a number of ways that the barriers described above could be overcome. These include Making available improved, simple instructions on packaging, in cookbooks, magazines and online. Changing the perception that food cooked in the microwave is unhealthy and that convenience does not always mean an unhealthy option. Some convenience food manufacturers have already begun marketing frozen foods as being additive free and full of natural vitamins ie showing that these foods are as healthy as freshly prepared ones or even more so.

Mintel Microwave Ovens Market Intelligence Report April 2006. For more information see MTP Briefing Note BNCK05: Historical microwave oven use and options to increase oven use in future http://www.mtprog.com/ApprovedBriefingNotes/pdf.aspx?intBriefingNoteID=417

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Providing improved instructions for combination microwave ovens for use on a wider range of foods. Improving user handbooks and controls to make the products easy to use Developing the range of oven sizes so that users are not restricted to cooking one item at a time.
To increase the level of microwave oven use and to decrease the amount of energy used in domestic cooking by electric ovens and hobs, the food supply industry would need to be both engaged and involved.

Gas ovens and hobs

This Briefing Note and the test project have not discussed gas ovens and hobs. Without an energy label to rate an oven, it is difficult to know whether the appliance chosen for testing is representative of the stock average or is more or less efficient than the stock average. For the purposes of MTP models, gas ovens and hobs are assumed to use more delivered energy than their electric equivalents, however they use less primary energy and therefore produce lower carbon emissions13. A test project to measure the amount of gas used to cook foods would give useful comparative data that would suggest whether there are any carbon savings to be made from switching gas cooking to microwave ovens and fuel switching from electricity to gas cooking overall.

Related MTP information

Briefing Note BNCK01: Assumptions underlying the energy projections for cooking appliances http://www.mtprog.com/ApprovedBriefingNotes/pdf.aspx?intBriefingNoteID=204 Briefing Note BNCK05: Historical microwave oven use and options to increase usage in the future http://www.mtprog.com/ApprovedBriefingNotes/pdf.aspx?intBriefingNoteID=417
See Briefing Note BNCK01: Assumptions underlying the energy projections for cooking appliances http://www.mtprog.com/ApprovedBriefingNotes/PDF.aspx?intBriefingNoteID=204

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Appendix 1
Appendix 1 gives the detailed test results for all products tested in the order shown in Table 1 above. Each result is the average of three runs.
Milk Combi microwave oven 3 2C 200 g full-fat milk 01:40 0.g full-fat milk 03:40 0.0948 800g full-fat milk 08:05 0.1966 Basic microwave oven 3 2C 200 g full-fat milk 01:50 0.g full-fat milk 04:00 0.0951 800g full-fat milk 08:10 0.1931 Electric hob
Food temperature at start Quantity 1 portion Average time taken (min:sec) Average energy consumption (kWh) Quantity 2 portions Average time taken (min:sec) Average energy consumption (kWh) Quantity 4 portions Average time taken (min:sec) Average energy consumption (kWh)
3 2C 200 g full-fat milk 11:13 0.g full-fat milk 16:59 0.1235 800g full-fat milk 15:07 0.1921
The milk was heated in the microwave ovens in mugs. Up to four mugs were used simultaneously. The energy use increased in a linear fashion, doubling each time the quantity of milk was doubled. When milk was heated in a saucepan and the appropriate size of pan was used, the energy used increased by about half each time the quantity of milk doubled. Conclusion: For larger quantities of milk, over 800 g, heating on the hob is likely to be more energy efficient than using the microwave oven.

Porridge

Combi microwave oven Oats: 20 2C Milk: 3 2C Water: 20 2C 45 g Quaker porridge oats 160 g full-fat milk 160 g water 02:40 0.0707
Basic microwave oven Oats: 20 2C Milk: 3 2C Water: 20 2C 45 g Quaker porridge oats 160 g full-fat milk 160 g water 03:00 0.0710
Food temperature at start
Oats: 20 2C Milk: 3 2C Water: 20 2C 45 g Quaker porridge oats 160 g full-fat milk 160 g water 10:20 0.0766

Quantity 1 portion

Average time taken (min:sec) Average energy consumption (kWh)

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Combi microwave oven 90 g Quaker porridge oats 320g full-fat milk 320 g water 05:00 0.g Quaker porridge oats 640 g full-fat milk 640 g water 11:00 0.2636
Basic microwave oven 90 g Quaker porridge oats 320g full-fat milk 320g water 05:00 0.g Quaker porridge oats 640 g full-fat milk 640 g water 11:00 0.2578

Quantity 2 portions

90 g Quaker porridge oats 320 g full-fat milk 320g water 10:50 0.g Quaker porridge oats 640 g full-fat milk 640g water 13:30 0.2357
Average time taken (min:sec) Average energy consumption (kWh) Quantity 4 portions
The porridge was cooked in a single bowl in the microwave ovens and in an appropriately sized saucepan on the hob. There was little difference in the energy used between either microwave or hob. Cooking four portions of porridge on the hob was slightly slower but used slightly less energy than the microwave oven. Conclusion: Some time was saved using the microwave oven, but no method was more efficient than the others.
Combi microwave oven Potatoes: 20 2C Water: 15 2C g new potatoes 5 g water 03:00 0.2 g New potatoes 5 g water 04:00 0.1014
Basic microwave oven Potatoes: 20 2C Water: 15 2C g new potatoes 5 g water 02:45 0.2 g New potatoes 5 g water 04:00 0.0926
Potatoes: 20 2C Water: 15 2C
g new potatoes 500 g water 19:22 0.2g New potatoes 700 g water 19:32 0.3617
Average time taken (min:sec) Average energy consumption (kWh) Quantity 2 portions

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Combi microwave oven g New potatoes 10 g water 06:30 0.1587
Basic microwave oven g New potatoes 10 g water 06:30 0.1502

Quantity 4 portions

g New potatoes 1000 g water 24:30 0.5031
The new potatoes were cooked in the microwave ovens using very small amounts of water, but in a saucepan there was considerably more. In all cases using the microwave oven was more energy efficient and quicker than the hob. Conclusion: Using small amounts of water and a microwave oven to cook potatoes saves energy compared to the hob. Reducing the amount of water in the saucepan may also reduce the energy consumption. Other low water methods such as steaming may also reduce energy consumption.
Combi microwave oven Asda frozen cauliflower florets, peas and carrots. Frozen Veg: -18 2C Water: 15 2C 113 g frozen veg 15 g water 04:00 0.g frozen veg 15 g water 05:00 0.g frozen veg 25 g water 07:00 0.1703
Basic microwave oven Asda frozen cauliflower florets, peas and carrots. Frozen Veg: -18 2C Water: 15 2C 113 g frozen veg 15 g water 03:00 0.g frozen veg 15 g water 04:00 0.g frozen veg 25 g water 06:00 0.1429
Asda frozen cauliflower florets, peas and carrots. Frozen Veg: -18 2C Water: 15 2C 113 g frozen veg 600 g water 12:00 0.g frozen veg 800 g water 15:00 0.g frozen veg 1,500 g water 17:00 0.4065

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Combi microwave oven
The frozen vegetables were cooked with small quantities of water in the microwave ovens and larger quantities on the hob. In all cases the microwave oven was more energy efficient and quicker than the hob. Conclusion: Using small amounts of water and a microwave oven to cook frozen vegetables saves energy when compared with the hob. Reducing the amount of water in the saucepan may also reduce the energy consumption. Other low-water methods such as steaming may also reduce energy consumption.

Baked beans

Combi microwave oven C 200 g Heinz baked beans 02:00 83.8 0.g Heinz baked beans 04:20 91.2 0.g Heinz baked beans 08:00 86.9 0.1938

Basic microwave oven C 200 g Heinz baked beans 02:00 82.0 0.g Heinz baked beans 04:00 90.2 0.g Heinz baked beans 08:00 88.9 0.1883
Electric hob C 200 g Heinz baked beans 06:20 80.5 0.g Heinz baked beans 09:15 79.6 0.g Heinz baked beans 08:45 82.1 0.1132
Food temperature at start Quantity 1 portion
Average time taken (min:sec) Average temperature (C) Average energy consumption (kWh) Quantity 2 portions
Average time taken (min:sec) Average temperature (C) Average energy consumption (kWh) Quantity 3 portions
Average time taken (min:sec) Average temperature (C) Average energy consumption (kWh)
The beans were cooked in a bowl within the microwave ovens and in a saucepan on the hob. For one portion there was very little difference between the microwave oven and the hob. However, with larger quantities the microwave oven used more energy than the hob. The temperature of the microwavecooked beans was higher than that of the hob-cooked beans for all of the tests. Conclusion: Following manufacturers instructions and increasing cooking time by multiplying from a single portion to two or four portions may heat the product to a higher temperature than required and use more energy.

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Combi microwave oven 3 2C
Basic microwave oven 3 2C
Salmon: 3 2C Water: 15 2C 1 salmon fillet (~125g) 750 g water 18:00 0.salmon fillets (~250 g) 800 g water 17:40 0.salmon fillets (~500 g) 1,000g water 18:00 0.3372

1 salmon fillet (~125 g)

03:00 0.salmon fillets (~250 g)
04:30 0.salmon fillets (~500 g)

06:30 0.1217

06:30 0.1208
The salmon was cooked in the microwave oven without any water. The salmon cooked on the hob was poached in water. The amount of water affects the amount of energy used to cook the salmon. Using the microwave was both quicker and more energy efficient. Conclusion: Unless the liquid that the salmon is cooked in is to be used for another purpose, there would seem to be no benefit to cooking in liquid, the energy used to pan fry should be tested to compare the energy consumption of this method. The volume of liquid could also be reduced to lower the energy consumption.

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Fish fingers and chips Food temperature at start Quantity 1 childs portion
Combi microwave oven -18 2C 2 Birds Eye cod fish fingers + 125 g McCain oven chips 18:00 0.Birds Eye cod fish fingers + 250 g McCain oven chips 21:00 0.8399

Electric oven -18 2C 2 Birds Eye cod fish fingers + 125 g McCain oven chips
Average time taken (min:sec) Average energy consumption (kWh) Quantity 2 childs portions
15:00 0.Birds Eye cod fish fingers + 250 g McCain oven chips

18:00 0.7001

The microwave oven was set on the convection setting, and the electric oven on a fan setting. Neither was preheated prior to the food being placed in the cavity. The electric oven was both quicker and used less energy than the microwave oven. Conclusion: This test may indicate that microwave ovens that have convection heating may not be as well-insulated as standard EU Energy Label A-rated ovens. There is no standard test to measure energy consumption in microwave ovens using the convection setting. This may be an area where improvements can be made in microwave oven technology.

Chicken

Combi microwave oven 3 2C 00:26:46
Food temperature at start Average time taken (hr: min:sec) Average energy consumption (kWh)

3 2C 01:30:00

1.0169

1.3205

The oven was not preheated prior to the start of the test. The combination microwave oven used less energy and was quicker than the standard oven. The skin of the chicken cooked in the microwave was less crispy than that cooked in the oven, but the chicken was cooked to an acceptable level. Conclusion: For cooking single chickens, the combination microwave oven offers a quicker and more energy efficient option than the electric oven. However, to cook a complete meal it may be more energy efficient to use the electric oven, depending on the vegetables and accompaniments that are chosen.

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Combi microwave oven 20 2C Potato approx 250 g 00:11:33 0.potatoes 500 g 00:15:57 0.potatoes 1,000 g 00:19:21 0.7692
Basic microwave oven 20 2C Potato approx 250 g 00:05:24 0.potatoes 500 g 00:10:06 0.potatoes 1,000 g 00:17:24 0.3884
20 2C Potato approx 250 g 01:00:00 0.potatoes 500 g 01:00:00 0.potatoes 1,000 g 01:00:00 0.9759
Average time taken (hr:min:sec) Average energy consumption (kWh) Quantity 2 portions Average time taken (hr:min:sec) Average energy consumption (kWh) Quantity 4 portions Average time taken (hr:min:sec) Average energy consumption (kWh)
The fan oven was not preheated before introducing the potatoes. The combination and basic microwave oven both cooked the potatoes more quickly and used less energy than the traditional electric oven for all the portion sizes. The basic microwave oven did not crisp the skins, but the combination microwave oven did lightly crisp the skins. The electric oven crisped the skins. Conclusion: For when baked potatoes accompany a light meal, using a combination microwave oven is a good option, however, if the potatoes are to accompany an item which could also be cooked or reheated in the oven, it is likely that combining the items in the oven would be a more efficient option than cooking them separately.

Combi microwave oven 3 2C Asda lasagne (400 g) 04:30 0.1124 Medium Asda lasagne (800 g) 08:00 0.1934 Large Asda lasagne (1.5 kg)
Basic microwave oven 3 2C Asda lasagne (400 g) 05:00 0.1157 Medium Asda lasagne (800 g) 08:30 0.1953 Large Asda lasagne (1.5 kg)
3 2C Asda lasagne (400 g) 30:00 0.5779 Medium Asda lasagne (800 g) 30:00 0.6214 Large Asda lasagne (1.5 kg)

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Combi microwave oven 22:00 0.5012
Basic microwave oven 23:00 0.5016

45:00 0.8486

The lasagna was cooked according to the instructions on the packaging. The fan oven was not preheated prior to the test. In the microwave ovens the film was not pierced or removed and the cheese on the top did not go brown. The instructions do not give an option for combination ovens, although using the convection function might give a more appealing result. In the electric oven the film was removed. Cooking the microwave was both faster and more energy efficient than using the oven, although the microwave results might not appeal to consumers. Conclusion: Microwave ovens can produce an acceptable result for cooking this kind of food. They are likely to be faster and use less energy than an electric oven.

Indian ready meal

Combi microwave oven 3 2C Marks & Spencer Indian menu for two (1 kg) 09:00
Basic microwave oven 3 2C Marks & Spencer Indian menu for two (1 kg) 09:30
Food temperature at start Quantity 2 portions
3 2C Marks & Spencer Indian menu for two (1 kg) 30:00
Average time taken (min:sec)
Average energy consumption (kWh)

0.2164

0.2172

0.5746

Marks & Spencer Indian menu for two (1 kg) X2 18:00
Marks & Spencer Indian menu for two (1 kg) X2 19:00
Marks & Spencer Indian menu for two (1 kg) X2 30:00

0.4135

0.4173

0.6621

The fan oven was not preheated prior to the start of the test. The microwave ovens were quicker and used less energy than the electric oven when cooking one and two large packs of food. Conclusion: For foods like this where the final appearance does not require browning, the microwave oven offers the opportunity to save both time and energy over the electric oven. This is the case for quite large quantities, although the advantage of time and probably energy would be lost if more than two packs of food were heated.

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Frozen ready meal for one
Combi microwave oven -18 2C Birds Eye roast lamb dinner (frozen) 1 meal (340 g)
Basic microwave oven -18 2C Birds Eye roast lamb dinner (frozen) 1 meal (340 g) 07:30 0.1778
Food start temperature Quantity 1 portion
-18 2C Birds Eye roast lamb dinner (frozen) 1 meal (340 g) 40:00 0.6527

07:00 0.1717

Birds Eye roast lamb dinner (frozen) 2 meals (340 g each)
Birds Eye roast lamb dinner (frozen) 2 meals (340 g each) 15:00 0.3471
Birds Eye roast lamb dinner (frozen) 2 meals (340 g each) 40:00 0.7155

14:00 0.3289

The fan oven was not preheated prior to the start of the test. The microwave ovens were quicker and used less energy than the electric oven when cooking one and two meals. Conclusion: For households where foods of this kind are regularly consumed by one or two people at a time, the microwave oven would save both time and energy. Frozen pizza Food temperature at start Quantity 1 portion Combi microwave oven Electric oven
-18 2C -18 2C 1 Marks & Spencer Mozzarella, 1 Marks & Spencer Mozzarella, provolone cheese & tomato pizza provolone cheese & tomato - purchased chilled and frozen in pizza blast freezer. - purchased chilled and frozen in blast freezer. 11:00 0.3645 16:00 0.4664
The fan oven was not preheated prior to the start of the test. The combination microwave oven was quicker and used slightly less energy than the electric oven when cooking one pizza. However, if more than one pizza were cooked it is unlikely that the energy efficiency would be maintained, and the oven would use less energy. Conclusion: For cooking snacks the combination microwave oven was more efficient than the electric oven.

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Changes from version 1.0
Minor typographical changes after internal proof reading.
Consultation and further information
Stakeholders are encouraged to review this document and provide suggestions that may improve the quality of information provided, email info@mtprog.com quoting the document reference, or call the MTP enquiry line on +44 (0) 8951. For further information on related issues visit www.mtprog.com

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