With regard to the research questions to be examined focusing on usability, user satisfaction and price-performance ratio of the installed smart home solutions and the conventional mobility supporting aids, it can be concluded that the installation of the corresponding solutions was positively evaluated by the tenants (overall rating 1.41).
In general, the installed smart home solutions were rated better by the users than conventional aids. At this point, however, it should be pointed out that the poorer evaluation of the installed conventional aids was partly due to unfavourable structural conditions for the optimal installation of the devices. For example, bathrooms were too narrow to adequately install grab handles, and balcony elevations for easy entry and exit, which had actually been evaluated and carried out positively, created a difference in altitude between the apartment and the balcony, which had to be adjusted afterwards.
Analysis of the price-performance ratio has shown that the installed smart home solutions are basically more cost-intensive than conventional aids. However, in contrast to the less expensive built-in conventional aids, it must be taken into account that, although smart home solutions are more expensive, they also contribute significantly to an increased security for the tenants. Inactivity detectors and fall detections can, for example, be linked to different terminal devices, and the notification of the home emergency call may directly be connected to a home emergency call provider. If an emergency call is not available, the information on the event can be transmitted to the mobile devices of the caregiving relatives. Moreover, with regard to the total price it must be considered that certain solutions which have been installed separately are expensive but price competitive in combination with other components. This is especially the case for the smart home solutions, which additionally require a base station (Table 5, lines 3–6). In view of the results with an average grade of 1.83 for the tablet and 1.54 for the lighting control (Table 5), it must be taken into account that tablet training courses were being coordinated at the time of the survey and that problems with lighting control were currently being dealt with by the manufacturer. In the case of lighting control, there were occasional difficulties with the automatic switch.
Not all of the products classified at high quality by the tenants belonged to an expensive price category. Price category 1: up to 200 euros and price category 2: 201 to 250 euros include products that were rated "very good" by the tenants and can therefore be recommended both, from a nursing science and health economics point of view. These include in particular the "home emergency call", the "visual doorbell" and the "orientation light".
Overall, it is noticeable that all technologies improve communication possibilities and increase the feeling of security. Visitors are less often "overheard" by the visual doorbell, an emergency call system contributes to the sense of security from the user's point of view, and orientation lighting offers tenants the opportunity to move around safely even in the dark and thus prevent falls. Another study points to the benefits of technical innovations in the home setting . These assessments are also reflected in the comparative survey between the 37 tenants with built-in solutions and the control group. The 37 tenants tended to show a better evaluation of communication and autonomy aspects in their newly created living environment. In some aspects – despite the small sample size – statistically significant differences were even found, for example with regard to the statement that the smart home solutions enable a greater sense of security in the apartment.
In addition to the communication possibilities and the feeling of security, another important aspect is the user-friendly handling (usability) of smart home solutions. A prior examination of the usability and user-friendliness (benefit estimation) is an essential prerequisite for the purchase and subsequent integration of smart home solutions in the households of the users . The assumption that older people generally have a low level of acceptance of technology cannot be supported. Although there is general uncertainty about the new technical devices, this is due to little or no previous technical experience [20, 21]. Since almost all users (96.3%) rated the smart home solutions as positive, a negative attitude of older people towards new technologies can be largely ruled out. However, trainings could contribute to reduce existing uncertainties among users.
Moreover, a focus must be placed on the financial implementation or the assumption of costs for the acquisition and installation of smart home solutions. With regard to the German legislator's target of "outpatient rather than inpatient", it is essential to create conditions to enable elderly people (in need of care) to remain in their own homes as long as possible. Higher additional payments by the health insurance funds for remedies and aids are a first step in this direction. Current questions regarding whether there should be a cost sharing by the users and, if so, how much, or whether selected smart home solutions can be included in the catalogue of assistive devices for services financed by the health insurance funds should be evaluated in the near future . At the same time, the possibility of integration in households should also be examined in advance, since not all households may have connections or suitable structural conditions, and configurations may interfere with other technologies . These are currently important and necessary developments, but this is not enough: With regard to demographic changes and the fact that more and more old and very old people want and "should" continue to live in their own homes, innovative solutions to improve their situation must be considered. In the future, solutions will be needed to ensure the safety of the (care-dependent) residents, which will enable them to live in their own homes until old age. Smart home solutions allow early detection and elimination of dangers, for example to avoid falls or emergencies or to be able to react appropriately and immediately in emergencies [23, 24].
A further point to be considered is the safety of the newly installed smart home solutions. Failure risks or defects of the systems should be checked precisely in advance, so that suitable measures can be taken if necessary. This means that the installed systems must be suitable for everyday use. Another important point is to ensure accessibility in order to guarantee prevention of possible care phenomena and care problems. In the future, it can be assumed that the possibilities of smart home solutions, especially with regard to networking, will be expanded, so that privacy and data protection will become increasingly important .
From the information available, it can be concluded that, in view of the ongoing demographic changes and the associated social changes towards a more dynamic lifestyle for older people, a special focus should be placed on the further development of smart home solutions .
With regard to the initial research questions in this study, it can be stated that tenants report an effective benefit in the installed smart home solutions. In addition, the study showed that smart home solutions generally have a benefit for tenants in terms of the price-performance ratio, even taking into account the more cost-intensive smart home solutions. Finally, the technical solutions were predominantly rated "very good" in terms of the price-performance ratio.
Overall, smart home solutions were rated slightly better than conventional solutions, although the significance threshold was only just missed. This can also be understood as an indication for a high degree of willingness to use technical solutions among elderly and old people.
Three limiting methodological problems have to be considered in the study carried out: On the one hand, the small sample size was small, which is due to the fact that smart home solutions were only installed in 27 apartments of the respective housing association. On the other hand, the actual testing phase of the installed smart home solutions and conventional mobility supporting aids by the users was quite short due to the fact that the installation of the corresponding solutions was completed four weeks before the start of the survey. A third methodological problem is, as it is often the case in surveys, the social desirability of the response behaviour. Social desirability is promoted, among other things, by the adaptation to structural characteristics, in this case the installation of smart home solutions and conventional aids by the own housing association. However, socially desirable behaviour may also be promoted by the design of the survey instrument. In order to prevent this tendency as far as possible, emphasis was placed on specific questions oriented towards the individual installed solution or aid in order to reduce the willingness and also the possibilities for criticism. An additional methodological precaution against socially desirable response behaviour was the accompanying letter, in which the tenants were informed that they would participate in the survey voluntarily and anonymously.