Keywords

1 Research Background

The kitchen is the most frequently used place in Chinese housing, and is the greatest concentration of domestic work. Its main functions are for cooking, washing and sometimes for dining [1]. Chinese people spend nearly 3 h a day in the kitchen, which is one of the most frequently used domestic spaces [2]. Due to the reduction of social activities, frugality and the tonic culture of China, the probability of the elderly using the kitchen for cooking has been greatly increased [3].The previous questionnaire study found that the kitchen layout of the elderly in small towns was mainly ‘L’ and ‘U’ shaped, so the subsequent study was carried out based on these two kitchen layout.

2 Research Method

2.1 Trace Observation

Trace observation is a common method of investigation in spatial planning and design, which focuses on observing the movement of space users. The results of trace observation can be applied to all stages of design, and are more commonly used in the planning and evaluation of design solutions [4].

2.2 Analysis of Therbligs

Therbligs are the basic actions required to complete a task and include effective, auxiliary and ineffective motifs. The analysis of kitchen behavior Therbligs focuses on the observation of actions in the kitchen of the elderly and the decomposition of continuous actions. The actions are categorised according to 18 kinematic factors and the process is optimised through ESRS (Eliminate, Combine, Rearrange, Simplify) [5].

3 Kitchen Activities Observation Planning and Operation

Three small town elderly households were selected for observation and their kitchen layouts included both ‘L’ and ‘U’ shapes. There are three camera positions, of which one high fixed position is used to capture the complete route of the user in the kitchen and the other two are used to shoot close-ups of the user’s action, with the camera crew adjusting the distance and position in real time. Throughout the filming process, the filmmaker neither interferes with the kitchen behavior of the elderly nor participates in the kitchen work of the elderly, but only completes the objective observation and recording work. Observation requires tools such as a tripod, camera, video camera, mobile phone and laser rangefinder. After the shooting, the photographer can ask the observed some related questions. The trace observations need to be carried out in terms of movement volume, time and trace, as shown in Table 1.

Table 1. Observed contents
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Movement Volume:

Number of passes refers to the number of times the user passes through the washing area, the preparation area and the cooking area. Number of moves refers to the number of times the user moves between the two functional areas. Amount of handling refers to the content and number of items transferred.

Time:

Dwell time refers to the time the user spends on moving and waiting in the cooking zone, washing zone and preparation zone respectively. Movement time refers to the total time spent on moving between the two functional zones.

Trace:

Tracks refers to the trajectory of the user’s movements in the kitchen.

4 Kitchen Behavior Survey Sampling of Older People

4.1 User’s Details

The basic information and residential conditions of the three selected elderly people are shown in Table 2.

Table 2. Basic information about users
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4.2 Abstract Representation of Kitchen Operations

The abstract representations of the kitchen actions of users 1, 2 and 3 are shown in Fig. 1, where the thickness of the lines represents the frequency of user movements in the two areas, the thicker the line, the higher the frequency. The amount of moves is represented by a simplified diagram and the number of moves is represented by a number.

Fig. 1.
figure 1

Abstract representation of movement lines

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4.3 Therbligs Records

The kitchen actions were categorized according to 18 kinematic factors (Fig. 2).

Fig. 2.
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Therbligs statistical

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5 Analysis of Observation Results

5.1 Analysis of Movement Volume and Therbligs

It is clear that users move most frequently between the washing area, the cooking area and the meal preparation area, which form the 'kitchen work triangle' in small town senior housing. The user moves most frequently between the cooking and meal preparation areas. User 1 does not have a full meal preparation area and some of the preparation area work is done in the washing area (e.g. setting up a chopping board on the sink), resulting in the highest frequency of activity between the cooking and washing areas. In essence, the area where this user moves to and from most frequently is still the cooking and meal preparation area. The second area is the washing area and the meal preparation area.

The delivery records show that pots and pans are the most common cooking utensils used in the washing and cooking areas. The elderly will simply rinse the pots and pans after cooking a dish, but due to the size of the sink, they need to hold the pots and pans with one hand and wash them with one hand, which puts a lot of pressure on their wrists. Users 2 and 3 placed their dishes in the cupboard of the floor cabinet after draining in the sink, causing the elderly to bend down several times to reach the dishes during cooking. The lids of pots are frequently moved between the cooking and preparation areas. They are often covered with oil and water vapour, causing them to drip onto the worktop when placed on the worktop, requiring several cleanings of the worktop. Through questioning, we learned that the elderly would place the lid of the pot over the sink when there was more water vapor on it.

5.2 Time

The stay time and moving time of the three older people in each functional zone are shown in Fig. 3. Due to the lack of space for user 1’s kitchen counter, the elderly complete part of the meal preparation tasks in the washing area, resulting in the elderly staying in the washing area longer than the cooking area. In the washing area, the elderly need to complete the cleaning of pre-dinner ingredients, after-dinner tableware and other tasks. When they are working, all three older people need to bend over. The height of each functional zone should be adjusted to varying degrees according to the residence time of the elderly. User 2’s kitchen layout is “U”-shaped with two opposite meal preparation areas, which increases the operating area of the meal preparation area and reduces the number of movements. The sum of the movement time of user 2 between different areas is less than the other two older people. Older people spend the most time moving between the washing and cooking areas. The elderly have the least number of round trips between the washing area and the cooking area, but they spend the longest moving time. This is because the distance between the cooking area and the cleaning area is farther. In the process of cooking, the older people usually need to add water, rinse the bowl and do other simple cleaning tasks. So only setting up a cleaning area is not the best design solution.

Fig. 3.
figure 3

Dwell time (left) and moving time (right)

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5.3 Analysis of Therbligs

Through the record of therbligs, it is found that each elderly person has more than 300 kitchen movements, of which the key behaviors mainly involve 9 kinds of therbligs. Analyzing the therbligs of the left hand and the right hand respectively, it is found that two auxiliary therbligs of the elderly’s operation in the kitchen including search and select have repeatedly appeared, which mainly occur in the stage of looking for items in the wall cabinet and the floor cabinet. As a result, reasonable storage layout can effectively reduce the occurrence of search and select.

The act of holding mainly occurs during cooking and washing. When cooking, the older people hold the pot with one hand and stir fry with the other. When washing, the older people hold the pot with one palm and wash with the other hand. It was found that the elder’s hands trembled when they hold a heavy object. Such phenomena should be reduced through reasonable design of pot placement. The three older people all lived with their spouses and usually prepared 1 or 2 dishes for a meal. Therefore, the three older people only used one gas stove during the cooking process, and the other gas stove was used to place idle pots. The total height of the operating table and the pot causes the elderly to frequently raise their elbows too high during the stir-frying process.

6 Design Suggestions of Kitchen Functional Layout

6.1 Design Suggestions of Kitchen Functional Layout

According to the analysis results of the observation of the trace, the “U” kitchen layout can reduce the number of moves for the elderly and shorten the moving time. The “U-like” kitchen layout not only does not affect the activity space, but also has an additional part of the preparation area compared to the “L”-shaped layout, and its width is less than that of the worktop. According to the operating habits of the elderly, a small washing area should be set on the right side of the cooking area. On the one hand, it satisfies the elderly’s needs to add water, to rinse the bowl and the pot during the cooking process. On the other hand, it can also be used for the placement of the pot lid to prevent water and oil stains on the pot lid from dripping onto the worktop. The washing area is used for the main washing tasks, while the small unit washing area is used for simple washing tasks. Most elderly people in small towns live alone or with their spouse, so a gas stove is enough for them to use in daily life. And a suitable condiment placement area should be designed on the right side of the cooking area (Fig. 4).

Fig. 4.
figure 4

Improvement of functional layout (“U-like” type, “A + a” double washing area)

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6.2 Suggestions on the Ergonomic Design of Kitchen Furniture

It is found that for so the utilization rate of the wall-hung cabinet is relatively low, as well as the utilization rate of the base cabinet. Appropriately lowering the height of the wall-hung cabinet and reducing its depth can increase the utilization rate and reduce the behaviors of tiptoe, head up and so on. When designing the height of the worktop in the cooking area, the height of the pot should be considered, and the height of the operating table should be appropriately reduced. The height of the worktop in the washing area should be appropriately increased to avoid the elderly bending over to work. When cleaning pots and utensils, the elderly need to hold the pot with their wrists due to the limitation of the pool size. To avoid such situations occurring frequently, the sink should be designed into the upper and lower levels. The upper level is a drain basket, and the lower level is a sink. Users can change the size of the sink by moving the upper drain basket to meet the cleaning needs of different sizes of items.

7 Conclusion

Based on the trace observation, the defects of the current kitchen design for the old people's residence in small towns were found mainly from the two aspects of moving quantity and time, and the layout of the “U-like” kitchen layout and the design of the “A + a” double washing area were put forward. Through the analysis of therbligs, some improvements to the human scale of kitchen furniture were proposed.

The disadvantage of the research is that all observations are recorded manually, resulting in inaccurate recorded data. Therefore, in the future research, the number of samples should be increased and the sample selection should be more differentiated.