Discrepancies of Functional Requirements of Façade Opening System between Real-Life Public and Built Environment Experts Focusing on Thermal Comfort and Ventilation

: A survey was conducted to analyze the discrepancies of the functional requirements of the façade system in residential units among 605 of the real-life public and 73 experts. Personal and housing information, resident life pa tt erns, public façade usage behavior, and functional requirements were collected from the respondents. Both the public and experts recognized insulation as the main function of façade opening systems. More than 85% of the public and experts opened windows for ventilation, but ventilation was ranked 3rd amongst the public and 4th amongst experts in the main functions list of façade systems. The public cited the in ﬂ ow of ﬁ ne dust as the main reason for dissatisfaction with opening windows. In contrast, the experts cited a decrease in thermal comfort due to the in ﬂ ow of external moisture as the reason for dissatisfaction with opening windows. The results showed that discrepancies exist between the public and experts’ perceptions of the main function of housing façade systems. Analyzing the common points and di ﬀ erences be-tween the public and experts’ perception can help in developing façade system design and control technology.


Introduction
Façade systems are important architectural elements that directly control the indoor environment quality [1,2].Windows of building façades are mainly made of glass, making them one of the most thermally vulnerable building elements [3][4][5].Various functional façade systems have been developed and applied to actual buildings to compensate for thermal vulnerabilities and to improve the performance of windows [6][7][8].Recently, insulated tempered glass with multiple glass layers or special films have been developed [9][10][11].Nevertheless, windows of building façades cause significant heat loss in winter and heat gain in summer.The thermal insulation standard for exterior walls and windows in the central region of Korea was strengthened from 0.36 W/m 2 •K and 2.1 W/m 2 •K in 2010 to 0.17 W/m 2 •K and 1.0 W/m 2 •K in 2018, respectively [12], which is similar to German passive house standards [13].In addition, to prevent indoor heat gain/loss due to natural ventilation during heating/cooling and to improve the indoor air environment, the ventilation rate is set at 0.5 h −1 to meet the indoor ventilation standard for apartment houses.Similarly, residential heat recovery ventilators are installed to supplement natural ventilation through windows [14].
In residential buildings, windows perform various functions, such as insulation, ventilation, daylighting, and outdoor viewing.Engineers design windows assuming ideal window control, considering the design criteria of the environmental performance of windows, and predict building performance accordingly.However, in many cases, the operation or control of windows by residents is not based on ideal control conditions for window performance but is determined by their perception of window functions based on their experience.Several studies have been conducted on the effect of windows on indoor thermal comfort and ventilation in residential buildings.Wong and Li [15] analyzed the effect of various factors of residential buildings including windows on indoor thermal comfort and cooling load.When the building direction is changed from east-west to south-north, the cooling load can be reduced by 8.57-11.54%and by 2.62-10.13%when the 0.3-0.9m horizontal window shading device is applied.Kubota et al. [16] measured the effect of window opening mode in two terraced houses on the indoor thermal environment.It was confirmed that night ventilation reduced indoor peak temperature by 2.5 °C and average nocturnal temperature by 2 °C compared to daytime ventilation.Tong et al. [17] analyzed the factors affecting the indoor thermal environment through on-site measurement of the indoor temperature near the windows of an apartment house.When the window-to-wall ratio was reduced from 0.9 to 0.6, the temperature near the windows decreased by 4.1 °C, confirming the importance of the windows in the indoor thermal environment.These previous studies focused on the technical functional characteristics of façades, including windows, from an expert point of view.However, the actual adjustment of façade systems is determined according to the perception of the window function based on the resident's experience.Therefore, it is also necessary to analyze the perception and behavioral characteristics of the public.The occupant behavior in buildings affects occupants' thermal comfort and energy consumption due to interactions with the build-ingsʹ indoor environment and its systems.It is necessary to assess occupant behavior [18][19][20], especially since occupant behavior has been found to significantly influence building energy performance and occupant comfort [21].In terms of the implementation of building energy policies, some policymakers and managers in the building sector have recognized that occupant behavior plays an important role in the effectiveness of relevant strategies [22,23].
Various studies have attempted to analyze the relationship between public perceptions and the indoor environment.Frontczak et al. [24] surveyed 645 people living in Denmark to analyze factors affecting residents' comfort in an indoor environment.The respondents confirmed that major indoor environmental variables such as visual, acoustic, and thermal conditions and air quality were the critical variables determining comfort.In addition, 54% of the respondents had at least one problem with the indoor environment, but the majority were not proactive in solving it.This study suggested the need to improve people's knowledge of the method.Mertz et al. [25] confirmed a difference in the risk perception from chemicals between experts and the public.Generally, there is a negative reaction toward chemical substances, and the sensitivity to harmful effects tends to be lower in the public than in experts regarding using chemical substances.Timmons et al. [26] evaluated the handling of different contextual factors influencing COVID-19 infection in 800 of the general population and 56 medical experts.Compared with medical experts, the public perceives lower risks related to environmental factors, confirming a difference in perception between experts and the public.Until now, most studies have focused on the technical functional characteristics of windows from an expert viewpoint.Considering the significant impact of windows on the indoor environment, it is important to investigate the difference in perceptions of window usage behaviors and required functions between the public and experts.
Several studies have demonstrated that, due to various behaviors of occupants, energy usage in residential buildings can vary by up to twice as much even under identical equipment and device conditions [27,28].Cole and Brown [29] showed that building designers often believe that occupants will act rationally and logically based on their beliefs and understanding to save energy.However, random decisions from occupants to adopt an energy-saving intention can lead to no impact on energy-saving behaviors [30].Also, Day and Gunderson [31] highlighted that the probability of utilizing the actual performance of high-performance buildings depended on the occupant's knowledge required to operate passive design systems and high-efficiency technology, as well as the occupants' expectations for comfort and satisfaction with the indoor environment.
Studies have been conducted to evaluate the impact of occupants' random decisions based on their personal satisfaction and knowledge of system operation on actual building behavior.However, there is a lack of research assessing the differences in the use of façade opening systems and building systems from the perspective of the general public with empirical knowledge and experts with theoretical knowledge.Therefore, in this study, a survey was performed to analyze the discrepancies of functional requirements of façade opening systems between the public and experts focusing on thermal comfort and ventilation.This study compared and analyzed the window usage behavior and required functions from the perspectives of the public based on real-life experience and experts working in the field of the built environment and HVAC systems based on the basic built environment theory and research results and clarified the gap between experience and expertise.The results of this study can help in developing window system design and control technology by increasing the understanding of the public' use of windows and analyzing the common points and differences between the public and experts' perceptions of the behavior and functions of housing façade systems.

Method
An online survey was conducted for six weeks, from September 2021 to October 2021, targeting married women living in residential buildings and experts working in educational and research institutes in the field of building environments and systems.Married women were selected as the general respondents of the public to assign one respondent for each household, which avoids the duplication of respondents.Married women in their 70s or older often live with their children or in nursing facilities; hence, the target age of the participants selected was between 20 and 69.The number of respondents was n = 605 for the public survey.The number of respondents by age was set as 10%, 30%, 30%, 20%, and 10% for respondents in their 20s, 30s, 40s, 50s, and 60s, respectively, considering the population ratio of married women by age in Korea [32].The regions of the respondents were determined according to the classification criteria for the thermal insulation standard of exterior walls and windows by region and were divided into central, southern, and Jeju (Figure 1).According to the population ratio of each climate zone in Korea, the number of respondents by region was set as 70%, 20%, and 10% in the central, southern, and Jeju regions, respectively [33].The higher proportion of respondents in the central region was because this region is comparatively large (72,457 km 2 ) and houses 69.9% of the population [34].In contrast, gender and region were not fixed for the expert survey.University professors and researchers majoring in built environments and building systems nationwide were considered.We listed professors at domestic universities and researchers working at national research institutes and relevant companies.A total of 120 of these experts were approached through their emails, with 73 experts participating in the online survey.The overall climate of Korea has four distinct seasons: spring, summer, fall, and winter.Among them, summer is hot and humid, while winter is cold and dry, representing the most significant seasonal differences [35,36].The average 10-year temperatures (2011-2020) in the central and southern regions of Korea, as well as Jeju, are 12.3, 13.6, and 16.5 °C, respectively.The monthly average temperature and relative humidity [37] are shown in Figure 2. The typical types of heating and ventilation systems applied in a Korean residential household are shown in Figure 3.A radiant floor heating system with a hot water pipe embedded in the floor is common in residential households (Figure 3a), and a packaged air conditioning unit is used for cooling.Only natural ventilation using windows was possible for household ventilation, but a heat recovery ventilator has been applied to residential units built since 2006 (Figure 3b).There are balconies overlooking the living room, bedroom, and kitchen of each household, which can be extended for use as desired.In non-extended balcony windows, a single window system is applied to the outside, while a double window system is applied to the extended balcony windows.
This study compared and analyzed the discrepancies of functional requirements of a façade opening system between the real-life public and experts focusing on thermal comfort and ventilation.Both groups were surveyed for personal and housing information, resident life patterns, resident window use behavior, and the functions expected of windows.Under personal information, gender, age, residential area, marital status, age of children, number of household members, and air quality sensitivity were investigated.Residential areas were selected by dividing the entire region into central, southern, and Jeju based on climate zones.Marital status and family composition were investigated to analyze the perspective of window function according to family composition.Participants who live with no children or with infants, toddlers, elementary school students, middle and high school students, and adults 19 years of age or older were considered.To determine the sensitivity of residents to the indoor environment, the degree of sensitivity to overall quality, including the indoor air temperature and humidity, was established.For housing information, the housing type, area, age, and balconies were investigated.The type of residence was broadly divided into single-family houses and multi-unit dwellings per the Building Act [38].Among multi-unit dwellings, houses with five or more floors were subdivided into apartments.Resident life patterns considered the length of time spent indoors, heating and cooling methods and satisfaction by season/day, ventilation methods and satisfaction, ventilation time by season/day, and ventilation methods on days with severe fine dust.In the survey of residents' use of windows and window function requirements, important factors were the age of windows in residences, extended or non-extended balconies, the need to install a shading device and satisfaction, and satisfaction according to windows and window functions.Survey questions for the public and experts are given in Appendix A. All respondents of the survey were given detailed information about this study before written consent was obtained.Frequency analysis was performed on the response results for each questionnaire item, and a 5-point scale analysis was performed for some questions.Statistical analysis was performed on the collected data using IBM SPSS 26.0 [39].A cross-analysis compared the perspectives of the public and experts on respondents' characteristics, residential unitsʹ and window systems' characteristics, heating/cooling behaviors, ventilation behaviors, and window usage conditions and required functions.In addition, a chi-squared test measured the correlation between two categorical variables.Moreover, Fisher's exact test was performed when the expected frequency of less than 5 was more than 20% of all cells.

Respondent Characteristics
Table 1 summarizes the demographic characteristics of respondents.Only women were surveyed as part of the public.For experts, the proportion of male respondents (69.9%) was 2.3 times higher than that of female respondents (30.1%).The age range of the respondents ranged from 20 to 69 years old, and overall, the respondents aged 30 to 49 accounted for the largest proportion with 60.1% of the public and 69.9% of the experts.The central region had the highest number of participants both for the public and experts, accounting for 70.1% and 78.1%, respectively, of the total respondents.This is followed by the southern region, accounting for 20.2% and 19.2%, respectively, and Jeju, accounting for 9.8% and 2.7%, respectively.Proportions of 60.5% of the public and 67.1% of the experts had 3-4 member households.Single-person households accounted for less than 2% of the general population including families such as widowed, divorced, and separated.The number of single-person households was ten times higher among experts.The education and job profiles indicate a difference in expertise level between the public and experts.Finally, 53.7% of the public stayed at home more than 12 h per day, whereas only 9.6% of the experts stayed at home more than 12 h per day.
Figure 4 shows the sensitivity toward the indoor air environment according to the number of family members.Overall, 76.7% of the public and 87.7% of the experts answered that they were sensitive or very sensitive to the indoor air environment.Among the public and expert group, the percentage of respondents who answered "Not sensitive" was highest at 10% and 7.7%, respectively, when there was only one family member.Moreover, the public's sensitivity toward the indoor air environment showed a strong correlation with region and residence time (p < 0.005), but no correlation was found in the case of experts (p > 0.05).

Characteristics of Residential Units and Window System
Table 2 summarizes the housing characteristics of survey respondents.Most respondents live in apartment buildings with five or more floors.The floor area of 99-132 m 2 is the highest for both groups, and the highest occupancy is in units aged 10 to 20 years for both groups.The completion period of the house and the window installation period were almost the same, showing a strong correlation between the two variables (p < 0.005).If there is a difference, it is the result of window replacement within the unit.The proportion of the public and the experts who extended the balcony was 41.7% and 49.3%, respectively, showing a slight difference.Both groups showed a strong association between the type of house in which they live and whether or not the balcony was extended (p < 0.005).

Seasonal Public Behavior for Thermal Comfort and Window Satisfaction
Figure 5 shows the survey response results for the first-priority action to reduce the heat in residential buildings in summer from the following: running the air conditioner (AC), opening the windows, running the fan, doing nothing, and others.The air conditioner was the preferred choice for both groups (46.1% (day) and 46.4% (night) for the public; and 64.4% (day) and 52.1% (night) for experts).Window opening was the secondmost frequently selected behavior (32.9% (day) and 27.1% (night) for the public; 26% (day) and 24.7% (night) for experts).Both groups have a lower rate of window opening and a higher rate of fan use at night.Air conditioner use is 18.3% higher during the day and 5.7% higher at night amongst experts compared to the public, confirming that experts actively use the air conditioning system to combat heat compared to the public.Figure 6 shows the survey response results on the satisfaction with opening windows in residential buildings in summer.The percentage of dissatisfied or very dissatisfied was 26.3% (day) and 17.7% (night) for the public, and 55.5% (day) and 33.3% (night) for the expert, which is more than twice as high.Moreover, both groups are more dissatisfied during the day than at night.In particular, the rate of dissatisfied or very dissatisfied with opening windows was 55.5% for experts during the day, 29.2% higher than that of the general population at 26.3%.Figure 7 shows the results of survey responses on the reasons for dissatisfaction with opening windows in residential buildings in summer.Proportions of 34.2% (day) and 44.2% (night) of the public and 48.1% (day) and 48.2% (night) of the experts answered that it is 'still hot' even with open windows in summer.For the public, 'fine dust inflow' was ranked second with an average of 23.1%, whereas, for experts, thermal comfort due to moisture inflow was ranked second with an average of 15.5%.In the case of the public, it can be seen that there is great concern about the inflow of fine dust due to the opening of windows during the daytime.In the case of the experts, the reason for dissatisfaction with opening the windows was the decrease in thermal comfort due to the inflow of external moisture when the windows were opened in summer.Figure 8 shows the survey response results for the first-priority action to increase heat in residential buildings in winter.Unlike summer, the opening of windows is limited in winter because of heating.Respondents chose one of the following actions to deal with the cold: running radiant floor heating, wearing extra clothes, using a heater, doing nothing, and others.The majority of residences in Korea are equipped with a radiant floor heating system.Depending on the resident, a fan heater, a radiant bar heater, a convector heater, and a heated blanket are also used.The public selected radiant floor heating at rates of 39.8% (day) and 44.5% (night); these are 63% (day) and 60.3% (night) for experts.Similar to the summer results, the use of the active system is higher amongst experts than the public to reduce cold.Wearing additional clothes (37.5%) was found to be almost equally preferable to radiant floor heating (39.8%) during the daytime by the public.As such, the public actively uses a passive control method that increases the amount of clothing in addition to an active heating system for thermal comfort during winter.There is a correlation between the first-priority action to address the cold during the day and night and the region (p < 0.05) in the case of the public, but no correlation is observed in the case of experts.

Seasonal Public Behavior for Ventilation and Window Satisfaction
Figure 9 shows the survey response results of the main ventilation methods in residential buildings.Respondents chose from natural ventilation through windows, operating heat recovery ventilators (HRVs), operating kitchen and bathroom exhaust fans, and others as actions for household ventilation.Most of the public (87.6%) and experts (83.6%) chose opening windows as the main ventilation method.For the public, there was a correlation between the main ventilation method and the age of the window (p < 0.05), whereas, for experts, there was no correlation (p > 0.05).The heat recovery ventilator is selected only by 6.9% and 8.2% of the public and experts, respectively, while 4.8% and 8.2% of the public and experts, respectively, chose exhaust fan operation.Figure 10 shows the satisfaction result when ventilation is performed by the opening of the window.The proportion of the public and experts who answered 'dissatisfied' or 'very dissatisfied' was 9% and 16.7%, respectively; the dissatisfaction rate was 1.9 times higher among experts.However, the level of dissatisfaction was lower than those of the public (22%) and experts (44.4%), who were dissatisfied with opening windows to relieve the summer heat.Figure 11 shows the survey response results on the reasons for the dissatisfaction when opening the windows for ventilation.The public answered with the inflow of fine dust (47.2%) as the main reason for dissatisfaction, followed by insufficient ventilation (35.8%).In contrast, experts answered with insufficient ventilation (75%), followed by thermal dissatisfaction (16.7%).Unlike the public, experts did not respond to the inflow of fine dust as a reason for dissatisfaction with the window opening.As such, the public perceive the inflow of fine dust as the main obstacle to opening windows for ventilation and heat movement.Figure 12 shows the survey response results on the main ventilation methods on days with severe external fine dust.Respondents selected from air purifier operation, no ventilation, open windows, operating the heat recovery ventilator, operating exhaust fan in kitchen and bathroom, and others as the ventilation method on days with high external fine dust concentration.Overall, operating air purifiers ranked first at 41.9.No ventilation took second place with 30.2%, and even when ventilation was performed on a day with severe external fine dust, ventilation by opening the windows (17.5%) was more effective than operating the heat recovery ventilator (7.5%).For both groups, the main ventilation method on days with severe external fine dust was not found to be correlated with area or residence time (p > 0.05).The public showed a strong association (p < 0.005) with the main ventilation method and the level of sensitivity toward indoor air quality on days with severe external fine dust, whereas the experts did not.Figure 13 shows the survey response results for the daily total ventilation time according to the season.Respondents were asked to select the total amount of time that they performed natural ventilation by opening windows, operating the heat recovery ventilator, and operating the kitchen and bathroom exhaust fans.Overall, the ventilation time in winter was lowest in both groups; in particular, the proportion of short-term ventilation time of less than one hour was 81.5% (public) and 85.2% (experts) in winter, 47.5% (public) and 36.6% (experts) in spring/autumn, and 38.4% (public) and 53.8% (experts) during the summer.While the public have a longer ventilation time during summer days than in spring/autumn, the opposite is true for experts.The public ventilated for more than 5 h during summer (34.6%) than in spring/autumn (22.7%), but for experts, this was lower in summer (16.9%) than in spring/autumn (28.2%).This means that the public ventilate for a long time for heat comfort in summer.In the general population, there was no correlation between ventilation time and home residence time in spring/autumn and winter, but there was a correlation in summer (p < 0.05).On the other hand, no association between ventilation time and time spent in the house was found for experts.

Perception of Housing Window System Demand
Figure 14 shows the response results of the public and experts regarding the main functions of windows.The public (54%) and experts (39%) chose insulation as the first major function; daylighting was second at 21% and 28%, respectively.The public chose ventilation (9.3%) as the third-most important function, while ventilation (12.3%) was the fourth-most important function for experts.Figure 15 shows the response results for the satisfaction of the public and experts for the top 4 items of the main functions of the window system.Daylighting had the highest satisfaction (satisfied and very satisfied) at 62.8% and 76.7% for the public and experts, respectively.However, 53.4% and 46.6% of the public and experts, respectively, found insulation to be less than satisfactory (neutral, dissatisfied, and very dissatisfied).The public showed the highest dissatisfaction with insulation at 19.3%, and the experts showed the highest dissatisfaction with ventilation at 26%.Both groups showed a strong correlation between the window installation period and satisfaction with insulation (p < 0.005).In addition, the public showed a strong correlation between the window installation period and satisfaction with daylighting (p < 0.005), whereas the expert showed no correlation (p > 0.05).

Discussion
A comparative analysis of survey results between the public and experts found a difference in the perception of the use of windows for seasonal thermal comfort and ventilation and the function of windows between the two groups.The real-life public showed more passive aspects in using air conditioning systems for relieving heat compared to the experts.This may be due to the burden of energy costs [40][41][42][43] or thermal discomfort [44,45] when using the cooling system.These results were repeatedly confirmed as they suggested passive use of the heating system in the questionnaire on using the heating system in winter.In particular, the public preferred the passive control method through adaptive behaviors, such as wearing more clothes during winter, more highly than the experts.The public control the indoor environment for thermal satisfaction by opening the windows or adjusting the amount of clothing without relying on the cooling and heating system.Considering that married women have a much longer residence time than experts and have more control over the actual housing environment, their responses can represent the actual housing environment adjustments and are as important as expert opinions.This difference in perception between experts and the public may cause errors in environmental control scenarios, such as opening/closing windows and using cooling and heating systems, which experts assume when evaluating the building's energy or indoor environment.
Another factor to consider is that experts cited thermal causes as the first and second reasons for dissatisfaction with the opening of windows for air conditioning, such as hot air or moisture inflow.In contrast, the public found that the influx of fine dust contributed to dissatisfaction.Therefore, when deciding on the behavior of the public to opening windows, the thermal environment and indoor air quality control that prevent the inflow of air pollutants have a high priority.Various factors, such as air pollution and thermal environment control, must be considered when deciding on opening/closing behavior.
Both groups preferred natural ventilation to mechanical ventilation.In Korea, to reduce the sick building syndrome which causes adverse effects including upper-respiratory irritative symptoms, headaches, fatigue, and rash, which are usually associated with a particular building by their temporal pattern of occurrence and clustering among inhabitants, the ventilation standards for apartment houses were established in 2006 [14], and the spread of mechanical ventilation systems increased.A survey study 10 years after the enactment of the law found that although the awareness of the importance of ventilation is very high at 96%, the public has insufficient or erroneous information about the usage of the mechanical ventilation system [46].The low preference of the public for using the mechanical ventilation system can be understood in line with the results of this study.However, it was unexpected that the experts with a good understanding of the role and effects of mechanical ventilation systems also showed a similar trend as the public.In particular, considering the responses of experts who actively responded to the use of cooling and heating systems, it can be expected that mechanical ventilation systems will be highly preferred.The cause of this requires additional analysis in the future because the satisfaction with the instantaneous ventilation obtained by opening the window is higher than that with the limited ventilation of the mechanical ventilation system set at 0.5 h −1 .In contrast, there was no significant difference in the responses of the public and experts on the ventilation method when fine dust in the air is high, which may be because education and public campaigns on health risks and countermeasures of fine dust that have been continued in Korea were effective.
The main functions requested by the public for windows are insulation, daylighting, ventilation, and noise blocking.Though daylighting and ventilation were highly satisfactory, they were dissatisfied with the insulation, which is consistent with those of experts.However, contradictory results were found in responses to satisfaction with ventilation, with a relatively high dissatisfaction level among experts.When analyzed in conjunction with the survey results, it can be inferred that the difficulties in controlling the thermal environment and inflow of fine dust, moisture, or insects by opening the window are an unresolved problem.Moreover, the difference between experts and the real-life public is confirmed in the perception of the air pollution problem when the window is opened and the resulting satisfaction.Furthermore, we confirm that the real-life public and experts demand various functions of windows, and a difference in perception exists in some factors such as ventilation method and satisfaction.The findings of this study demonstrate that, despite the availability of heating and cooling devices, the public exhibits a preference for regulating their thermal environment through passive control methods.Considering a previous study [31], even the development of high-efficiency technology in the future could lead to inefficient building operations if the public lacks the necessary knowledge to apply the technology effectively.Therefore, this study provides the implication of the importance of precedential efforts to enhance occupants' understanding through education on relevant technology, especially in the development of control logic for façade opening systems that consider occupant behaviors.
Our study had several limitations.First, our study does not include the surveying results of married men and single-person households.To obtain responses regarding the usage behavior and functional requirements of the façade opening system based on experiential knowledge, it is necessary to select respondents from the public who have resided in residential households for an extended period and primarily utilize the systems.Therefore, considering the number of respondents required for the study and research cost, this study was designed to assess the usage behavior and functional requirements of façade opening systems among married women as representatives of the public.Second, in our study, we did not provide survey results related to noise aspects and their impact on occupants' perception.This aspect is related to another factor that needs further exploration: the position of apartments and individual houses in relation to the surrounding context.For further studies, examining variations in responses based on factors such as apartment floor, orientation, and surroundings is necessary to analyze the functional requirements of façade opening systems.

Conclusions
A survey was conducted to compare and analyze the viewpoints on window use behaviors in residential buildings and required functions among the public and experts.The participants comprised 605 married women who operate windows in their residences based on their personal preferences and experiences and 73 experts with systematic knowledge about the building environment and systems.This study confirmed a difference in perception in various aspects relating to the required function of windows among residents and experts.Understanding the common points and differences in perception between the public and experts can be used in developing multifunctional window system designs and control technology and modeling public behavior when predicting the building energy and indoor environment.Although various mechanical systems for controlling the indoor environment of a building are available, the preference for a passive control method is high.Considering that the passive control method does not achieve continuous and rational control provided by using a mechanical system, this may suggest that the current air conditioning and ventilation system does not meet user expectations.This study suggests that further advancements should be made to satisfy the needs of heating and cooling and ventilation system users.

Figure 1 .
Figure 1.Region division based on climate zones in Korea.The number and proportion of married women respondents by region are also shown.

Figure 2 .
Figure 2. Monthly average temperature and relative humidity by region in Korea for 2011-2020.

Figure 3 .
Figure 3. Layout of a typical 108 m 2 residential household in Korea (with units mm).(a) Radiant floor heating pipe layout drawn in red line; (b) heat recovery ventilator and duct layout drawn in blue line.

Figure 4 .
Figure 4. Level of sensitivity toward indoor air quality according to the number of family members.(a) Public; (b) expert.

Figure 5 .
Figure 5. Percentage of respondents for the first-priority action to reduce heat in summer.(a) Public; (b) expert.

Figure 6 .
Figure 6.Level of satisfaction with opening window in summer.(a) Public; (b) expert.

Figure 7 .
Figure 7. Reasons for dissatisfaction with opening windows in summer.(a) Public; (b) expert.

Figure 9 .
Figure 9. Types of major ventilation methods.

Figure 10 .
Figure 10.Level of satisfaction with opening window.

Figure 11 .
Figure 11.Reasons for dissatisfaction with ventilation through open windows.

Figure 12 .
Figure 12.Main ventilation method on days with severe external fine dust.

Figure 13 .
Figure 13.Daily total ventilation time according to the season.

Figure 14 .
Figure 14.Main functions of the window system.

Figure 15 .
Figure 15.Level of satisfaction with the main function of the window system.
* More than one category may apply.

Table 2 .
Characteristics of residential units and window systems.