## 6 Discussion
Table A3 reveals that the use of conditioned seats allows to extend the acceptable ambient air temperature range in office buildings within a range between 18 \({}^{\circ}\)C and 30 \({}^{\circ}\)C. [PERSON] et al. [78] showed that heated seats can have an energy consumption of about 20 W and cause an improvement of thermal sensation by one scale point. However, the system's overall energy consumption is strongly depending on the used system components and the used control algorithms. Corresponding studies listed in Table A3 show that the energy consumption of conditioned seats is very low, but their influence on thermal comfort is high. There are only a few literature sources that deal with local foot heating systems. According to [PERSON] et al. [25], local heating of the lower body ensures global thermal comfort at very low ambient temperatures that can reach down to 14 \({}^{\circ}\)C (Table A4-37). Furthermore, current research (Table A4-36) shows that local cooling of the feet is inefficient and worsens the overall thermal sensation of individuals at ambient temperatures of up to 32.3 \({}^{\circ}\)C. A heated foot pad has negligible impact on a person's thermal comfort at an air temperature of 17.7 \({}^{\circ}\)C (Table A4-34). [PERSON] et al. [112] developed a closed construction of a foot heater, which is able to improve thermal comfort at an ambient temperature of 18.9 \({}^{\circ}\)C. Their system was shown to save about 500 W of heating energy per occupant (Table A4-35). The use of combined multiple personal climate actuators has a higher and more uniform thermal impact on the human body than the use of single thermal actuators that are locally applied to individual body parts. Here, the results of [PERSON] et al. [12; 13] indicate that reduced indoor temperatures require a combination of multiple thermal actuators in order to keep a person in thermal neutrality. As already mentioned before, the main reason for dissatisfaction and discomfort, while using a single actuator,  
Figure 4: Percentage of dissatisfied individuals with respect to indoor temperature; each depicted point corresponds to a single study extracted from the literature. is the resulting temperature asymmetry across the body surface. [PERSON] et al. [95] showed that the use of a heated seat has a higher energy efficiency (20 W/1 TS) than the combination of a heated seat in combination with a desk and floor pad (80 W/1 TS), which is the logic consequence of the increased number of energy consuming actuators. However, the combined heating power of these actuators is advantageous compared to a single actuator (Table 1-2, Table 3-4, Table 5-38). Such a combined system provides thermal comfort for ambient temperatures down to 17.9 \({}^{\circ}\)C. According to [PERSON] et al. [116], a conditioned seat can provide thermal comfort at ambient temperatures between 18 \({}^{\circ}\)C and 29 \({}^{\circ}\)C (Table 3-4, Table 5-40) with an overall energy consumption of less than 16 W. This is a fractional amount of the energy required for mixed ventilation systems (about 750 W) that aim to achieve the same thermal impact. Personal face ventilation with preconditioned air (Table 10) is mainly used to ensure a high air quality. Such systems direct cool fresh air towards the respiratory area of a person. According to [PERSON] et al. [86], face ventilation can be used to reduce the risk of cross-infections and decreases the absence days of the staff. Furthermore, the face ventilation provides a comfortable room climate at ambient temperatures up to 30 \({}^{\circ}\)C (Table 10-45, 10-46). The studies listed in Table 11 show that the use of combined thermal actuators (Table 11-38, 11-12) can extend the acceptable ambient temperature range to values between 17.9 \({}^{\circ}\)C and 32.3 \({}^{\circ}\)C. Considering all above mentioned systems, it can be concluded that a minimum ambient temperature of 16 \({}^{\circ}\)C can be regarded as comfortable, when using personal HVAC systems (Table 11-24).