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From the user observation study a wider understanding was developed of why participants used more energy and time than needed. Out of the 20 participants, five of them did not read the packet instructions at all. Ignoring the instructions meant that they did not pay attention to the amount of water and the time it takes to cook. Even those who read the instructions did not follow all the recommendations. All participants cooked the noodles for longer than recommended on the packet, therefore resulting in extra energy being used. Just five participants measured the volume of water to bring to boil, while the others used more water than needed. Overlooking the amount of water substantially increased the overall energy expenditure because more energy is necessary to heat more water. The volume of water also had an indirect influence in the energy consumption as three participants kept the noodles boiling for longer, did not use the lid and used high temperature marks in order to make the extra water evaporate. To speed up the process, 16 of the participants used the kettle first then poured boiling water into the pan. Four participants used the medium sized pan provided instead of the small one. Twelve participants used a big hob and a small pan resulting in wasted energy to the air. Just four of the students covered their pans. Only four of the participants turned the hob off more than 20 seconds before the end of the cooking process.

4.8.2.1 Appliances and interaction

It was observed that each of the four hobs produces different heat. Two of them have a diameter of about 6 inches and the other two 7 inches. But even with hobs of the same size, the energy consumption (and consequently the heat produced) is different. It happens because the two at the front contain a ‘rapid heating element’, but the interface or even the user manual does not give any more information about it (Beko 2006, Beko 2011). Only after analysing the energy consumption per hob and for each mark was it possible to comprehend that the rapid heating feature only occurs when the control is on mark 6. This creates enormous differences in heat production that could potentially confuse users, with mark 6 using almost double the energy of mark 5 for the two specific hobs at the front. Four participants had their hob overheating and, since it stays hot for a long time, had to keep just half of the pan on the hob to limit the heat transfer (Figure 16). This observation is in accordance with findings from previous research: Even experienced catering chefs perform this common ‘control’ practice,

Chapter 4: First Study – Understanding cooking behaviours – 4.8: Results and discussion

since the total power dissipation from solid hobs often remains high and the cook “arranges the pans so that they cover only partially the available heat source” (Newborough, Probert et al. 1990). One participant realized that the hob was hotter than needed and decided to start heating another hob to finish the cooking process with less heat.

Figure 16 - Participants trying to minimize the heat transfer due to overheated hobs

The electricity monitoring showed that mark 1, 2 and 3 use about the same energy across all hobs, as Figure 10 illustrates. Regarding variation of heating control, two participants used only one single heat level during the whole process, nine participants used two different marks to cook, seven moved the control between three marks, and the remaining two participants used four different marks to cook. This suggest that maybe six options are more than needed, especially considering that three marks produce about the same heat.

According to a comprehensive study by Mansouri et al (1996) the two rings at the front are used more often and for longer than those at the back. Their results are similar to what was noted during this cooking observation study. Seventeen of the participants used the hobs at the

Chapter 4: First Study – Understanding cooking behaviours – 4.8: Results and discussion

this information with the electricity consumption per hob observed during this study (Figure 10) provides interesting inferences. Since the hobs that are used more frequently have higher energy consumption, it indirectly causes unnecessary extra energy use. The user is not aware of this expenditure since there is no clear information about the different energy used by each hob.

Figure 17 - Hobs used per number of participants

The cooker used in this study has four burners arranged in a square but the controls are arranged in a line. Norman (2002) comments on this issue: “Most stoves have controls arranged in a line, even though the burners are arranged rectangularly. Controls are not mapped naturally to burners. As a result, you have to learn which control goes with which burner.” Studies show that “control configurations should match those of the displays in a one-to-one geometrically corresponding linkage, that is, they should be isomorphic” (Chapanis, Yoblick 2001). Previous research (Ray, Ray 1979) proved that when having controls on the same disposition as the burners, “no subject incurred any errors”, whereas if the controls were disposed in a line and the hobs in quadrature, a minimum of 8.6% of errors occurred, up to 19.2% depending on the arrangement. In accordance to these studies, participants from this experiment also showed difficulty in relating the control with the burner that they were using, heating a different hob than intended or having to bend down in order to see closer or from a better angle, to refer to the little diagram and choose the right control (Figure 18).

0 1 2 3 4 5 6 7 8 9 10

Big front Small front Big back Small back

Pa rt ic ip an ts

Hobs used

Chapter 4: First Study – Understanding cooking behaviours – 4.8: Results and discussion

Figure 18 - Participants bending down to deal with the controls

In addition, the cooker model used has just one pilot light for all hobs, making it difficult to know which one is being used. This is particularly important with this sort of appliance as there is no visual feedback on the hob comparing to gas cookers where the flame is visible or ceramic and coil hobs that glow red-hot. For that reason, eight of the participants had to put the hand over the burner to check if it was heating (Figure 19), and one of them ended up using the biggest hob because he selected its control unintentionally in the first place.

The design of cooking appliances appeared to determine how comfortable people feel when interacting with them, cause errors during the cooking process and increase the final energy use. These results came from a study with young undergraduate students, and these issues can be even more acute if other demographic groups are considered. Previous research demonstrates that limitations regarding vision, hearing, mobility, reaching and stretching, and dexterity imposed difficulties for older adults in their attempts to perform daily activities in the kitchen (Maguire, Nicolle et al. 2011, Sims, Maguire et al. 2012), therefore indicating that other demographic groups might be even more vulnerable to cooker design limitations.

Chapter 4: First Study – Understanding cooking behaviours – 4.8: Results and discussion

Figure 19 - Participants checked the heat from the hob using their hands