1 Introduction

1.1 Comfort Standards and Gender

Building technology developments towards low-energy-, passive house-, or positive energy buildings made standards and regulation of the indoor climate a central aspect of energy-efficient construction . In this context, comfort criteria and standards have been established and implemented with a focus primarily on energy efficiency. In attempting to follow energy efficiency standards, a narrow view of comfort is unavoidable (Ortiz, Kurvers, & Bluyssen, 2017). Comfort has been studied in terms of values and standards for the thermal environment, air quality, acoustic, and lighting. Accordingly, indoor environmental quality (IEQ) factors are based on single standard values for thermal comfort, the quality of air, light, and acoustics. The approach of measuring these factors separately, according to standardized parameters, neglects possible interactions or differences in the perception of different people (Ortiz et al., 2017).

Although energy monitoring analyses were frequently supplemented by social science surveys, the questions focused on average values, and limited to the overall satisfaction and acceptance by the users (i.e., Ornetzeder, Wicher, & Suschek-Berger, 2016; Pastore & Andersen, 2019). An analysis of existing works on the subject of user behavior in energy-efficient or green buildings shows that, although certain diversity aspects (primarily socio-demographic characteristics, such as education, income, and household size) are included, it is not sufficient to derive solution strategies able to adequately address different target groups (Haselsteiner, Susanne, Klug, Bargehr, & Steinbach, 2014). In particular, the gender aspect is usually only considered as a social demographic factor in the study design, and often neglected in the evaluation (Haselsteiner, 2017).

Whereas categories of sex are defined according to biological differences, gender focuses on roles that are constructed and reproduced by society, and these roles can also change over time. It is, consequently, crucial to reveal unilateral or restrictive gender ascriptions and practices in any field of action. This also applies to IEQ parameters. The objective of this article is to outline the gap in gender aspects when considering IEQ, and to look at them in a more differentiated manner. People cannot be categorized according to homogeneous groups, and are confronted with different role expectations, attributes, and different opportunities and framework conditions (i.e., Hanappi-Egger & Bendl, 2015). Hence, this means that thermal comfort and indoor environmental quality should not only focus on single gender but rather addressing “users”, trying to understand different needs while taking diversity into account. The intersectionality of various diversity dimensions – such as age, origin, disability, economic conditions, etc. – have to be taken into account. Only further differentiations enable a precise analysis of subjective needs and interests. This can only be met if an intersectional approach is also included in the IEQ assessment.

1.2 Indoor Environmental Quality and Its Importance for Well-being, Health, and Productivity

The indoor environment quality (IEQ) is an essential factor for well-being, health, and productivity (Al Horr et al., 2016; Al Horr et al., 2016). Findings in the literature show eight physical factors that affect user satisfaction and productivity in an office environment (Al Horr, Arif, Kaushik, et al., 2016).

  1. 1.

    Indoor Air Quality and Ventilation

  2. 2.

    Thermal Comfort

  3. 3.

    Lighting and Daylighting

  4. 4.

    Noise and Acoustics

  5. 5.

    (Office) Layout

  6. 6.

    Biophilia and Views

  7. 7.

    Look and Feel

  8. 8.

    Location and Amenities

Although thermal comfort is the most important parameter of IEQ, other aspects interact with the ambient temperature in a complex interplay (Frontczak & Wargocki, 2011). In western countries, people spend more than 90% of their time indoors. The indoor environment quality is therefore decisive for physical and mental health. The most important, although not given enough attention yet, is the adaptation of IEQ to individual preferences. How important it is to pay particular attention to gender criteria can be derived from the medical field. In medicine, it has slowly been recognized that medical research and treatment shows a clear gender bias. Drugs are tested on men, guidelines are written by men and symptoms of women, that of a heart attack, for example, are often not recognized because these symptoms have been classified as “atypical” and not “according to the standards”. Women still die more often than men after a heart attack (Mehta et al., 2016). Moreover, a recent study shows that mortality also depends on who treats them. If women are treated by a female doctor, the chance of survival is significantly higher (Greenwood, Carnahan, & Huang, 2018).

In building technology , gender-specific approaches which imply a differentiated body reaction between the sexes, or differences in the perception of indoor climate according to sexes, if not negated, are at least dismissed as very small and negligible. Since research on physiological differences and the medical treatment of women and men has already received widespread recognition, it is surprising. Karjalainen (2012) states in her literature review that study results can be traced back to 1970, in which differences in thermal comfort between men and women were demonstrated (i.e., Fanger, 1970). Even if some of the results of the study found only slight or no differences (Amai, Tanabe, Akimoto, & Genma, 2007; Liu, Lian, Deng, & Liu, 2011, see review from Karjalainen, 2012), it is obvious that, similar to medicine, women also perceive indoor qualities, such as air quality, thermal comfort, or lighting – which are very much connected with physiological properties – differently compared to men.

1.3 Objectives

The objective of this chapter is to outline individual aspects that address the interplay between gender and the perception of indoor environmental quality. Relevant scientific publications were searched in which gender differences are shown based on their findings. The aim is to raise awareness of these aspects to advance equality orientation as an integral part of planning and energy-efficient building concepts. This study does not pretend to be a complete literature review. Rather, the basis of this article is an exploratory literature study, in which key individual aspects are collected, main gaps are identified, and some questions are formulated, in order to state where the author considers essential to continue researching.

2 Method

The research is based on an exploratory literature review. To collect relevant research publications, the following keywords were used: “indoor environmental quality + gender” and “thermal comfort + gender”. Google Scholar and ScienceDirect have been the major electronic databases. As a first step, papers were analyzed that had already carried out a comprehensive literature study on the subject of gender, individual differences, and IEQ (i.e., Karjalainen, 2012; Wang et al., 2018). Additionally, the method “reference by reference” was used to find relevant publications. From this, research gaps were identified in connection with the time of the respective publication. The search was then repeated, and only papers published in 2019–2020 were selected and examined in detail. Additional selection criteria that were applied include:

  • adult users (>18 years),

  • gender-specific evaluation (title, abstract, or author-specified keywords),

  • building typology: residential buildings, offices, and educational buildings,

  • publication years: 2019, 2020.

The search on the two electronic databases Google Scholar and ScienceDirect showed only slight overlaps. From both databases, the first 50 most relevant papers according to the ranking were examined more in detail as to whether gender aspects were used not only as a socio-economic aspect in the selection of the subjects but as an actual evaluation criterion. To close further gaps in research, 2019 and 2020 publications were also subjected to a “reference by reference” search. Finally, 20 papers explicitly addressing gender aspects in their studies, published in 2019–2020 were identified. In total, 44 papers were analyzed, and the findings included and documented. Table 9.1 provides an overview of the literature review studies which formed the basis for further literature search. More publications are shown in Tables 9.2–9.6, at the beginning of each section as an overview of findings assigned to the respective topics.

Table 9.1 Summary of literature reviews that investigated IEQ gender differences
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3 Literature Review: Findings and Discussion

3.1 Individual Sensitivity and Comfort Criteria

3.1.1 Thermal Comfort

Field studies and studies in controlled environments have been carried out to assess parameters for thermal comfort and determine individual differences (see Table 9.2). A significant number of these studies have analyzed gender issues in more detail. Table 9.2 provides an overview of these studies and shows key results.

Table 9.2 Overview of IEQ studies that investigated thermal comfort and gender differences (listed in alphabetical order)
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It becomes clear that women and men rate the environmental conditions differently (Bae et al., 2020; Choi et al., 2010; Frontczak & Wargocki, 2011; Indraganti, 2020; Karjalainen, 2007; Rupp, Vásquez, & Lamberts, 2015). Under the same thermal conditions, women are 50% more often dissatisfied with the indoor climate than men (Karjalainen, 2012). Women are more likely to perceive the indoor temperature as too cold or, in some cases, too warm (Bajc & Milanović, 2019; Indraganti & Rao, 2010; Jowkar et al., 2020; Karjalainen, 2007; Jimin Kim et al., 2019; Parsons, 2002). Karjalainen (2007) found in a quantitative study in Finland that 18% of women, but only 8% of men, feel uncomfortably cold on a weekly basis, or more often (weekly, daily, or continuously) at home. The percentage is even higher in offices: 40% of women stated that they feel uncomfortably cold weekly or more often, while only 16% of men stated the same. Overall, Karjalainen (2007) concludes that women feel more comfortable at higher temperatures. These results coincide with results from other studies (Bajc & Milanović, 2019; Indraganti & Rao, 2010; Jowkar et al., 2020; Jimin Kim et al., 2019; Jungsoo Kim et al., 2013; Parsons, 2002). Women have a preference for a slightly warmer environment, while men prefer slightly cooler conditions. However, only a few differences between men and women were found at neutral temperatures. This means that women are much more sensitive to temperatures that are too warm or too cold, while they hardly feel normal temperatures significantly differently than men (Karjalainen, 2012; Lan, Lian, Liu, & Liu, 2008). Nevertheless, it should be highlighted that women have a more urgent need for individual adjustment to a comfortable temperature level than men (Karjalainen, 2012; Jungsoo Kim et al., 2013; Wang et al., 2018).

In part, these differences can be justified physiologically. On average, women have 20% less body mass, 14% more body fat, and 18% less body surface than men (Burse, 1979). The skin temperature of women is lower than that of men (Lan et al., 2008; H. Liu et al., 2018; Schellen et al., 2013; Yeom et al., 2019), women have lower blood circulation in their hands when it is cold (Karjalainen, 2012), and sweat less in presence of hot temperatures than men (Mehnert, Bröde, & Griefahn, 2002). Another study (Schellen et al., 2013) showed that among women the overall thermal comfort sensation is significantly affected by the temperature of the skin and extremities. Despite these physiological distinctions, other authors consider differences in thermal comfort to a limited extent to be physiologically justified, but cite cultural and psychological factors as more likely (Karjalainen, 2007; Luo et al., 2016; Nicol & Humphreys, 2002). This is why cultural adaptation and country-specific acceptance and adaptation behavior should be taken into account (Lu et al., 2019; Luo et al., 2016; Thapa, 2019; Zhang, Cao, Wang, Zhu, & Lin, 2017). Behavioral adjustment, such as clothing due to outside temperatures, or individual devices to regulate thermal comfort, for example, the use of fans in warm regions or electric blankets in cool countries, could justify differences based on gender-specific behavior. Nevertheless, both in field studies and especially in laboratory situations, clothing is an influencing factor, and the insulation values of clothing in men and women were explicitly taken into account (Al-Khatri et al., 2020; Parsons, 2002; Thapa, 2019).

In building design, it is now recommended, even with central control, to always allow an individual adjustment of the room temperatures of ±2 °C. As a study from Japan shows, the differences reinforced by cultural variances can also be higher. A field study in an office building in Japan with a very multinational workforce found that Japanese women preferred a 3.1 °C higher neutral temperature level than a male comparison group with non-Japanese (Nakano et al., 2002). This indicates that gender aspects intersect with cultural aspects, which highlights the intersectionality and shows the necessity of understanding (and acting upon) gender in connection with various diversity dimensions, such as age, origin, disability, economic conditions, etc.

Perception of comfort not only differs because of individual preferences, but also because of behavioral aspects, or in combination with other comfort aspects. Rupp et al. (2019) reported that women were significantly more sensitive to indoor temperature-changes than men in naturally ventilated buildings and office buildings. Muzi, Abbritti, Accattoli, and dell’Omo, M. (1998) found gender differences in buildings with air conditioning systems; however, no differences in naturally ventilated buildings. In the field study conducted in Italy in air-conditioned offices, more women than men found the temperatures to be too hot (Muzi et al., 1998). Other study results show that the perception of comfort varies when people are allowed to have control over the air conditioning and ventilation (Schiavon, Yang, Donner, Chang, & Nazaroff, 2017). Negative effects of higher temperatures can be mitigated when personally controlled air movement is used. Thermal comfort, perceived air quality, feelings of sick building syndrome, or cognitive performance are equal or better at 26 °C and 29 °C than at the typical indoor air temperature setpoint of 23 °C, if a personally controlled fan is available for use (Schiavon et al., 2017).

Although studies show that women have different thermal comfort requirements than men and that these are also physiologically justified, the gender aspect is not adequately taken into account in IEQ assessments. The results show a differentiated picture of distinguishing features, which can vary depending on the cultural conditions of the clothing, building type, or building technology . To meet these different needs, the existing buildings and IEQ standards would have to be subjected to a gender-specific analysis.

3.1.2 Light Sensitivity

The different sensitivity to artificial light and brightness was examined by several authors (Chellappa et al., 2017; Cirrincione et al., 2018; Knez & Kers, 2000). The results indicate significant gender-specific differences in light sensitivity. Table 9.3 shows an overview of relevant findings.

Table 9.3 Overview of IEQ studies that investigated light sensitivity and gender differences (listed in alphabetical order)
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In contrast to women, men had higher brightness perception and faster reaction times in a sustained attention task during blue-enriched light than non-blue-enriched . After blue-enriched light exposure, men had significantly higher all-night frontal NREM (Author’s note: Non-Rem) sleep slow-wave activity (SWA: 2–4 Hz) than women, particularly during the beginning of the sleep episode. Furthermore, brightness perception during blue-enriched light significantly predicted men’s improved sustained attention performance and increased frontal NREM SWA (Chellappa et al., 2017: 1).

Men react to blue-enriched light more clearly than women, even in very poor lighting conditions (i.e., 40 lux). Moreover, authors found significant differences in light preferences and subjective perception of brightness between men and women: women preferred light at 2500 K (87.5%) rather than 6500 K (12.5%), while the opposite was observed for men (6500 K: 62.5%, 2500 K, 37.5%) (Chellappa et al., 2017). The subjective perception of brightness of light revealed similar gender-specific differences: men perceived light at 6500 K as significantly brighter than at 2500 K, whereas women perceived no significant differences between light at 6500 K and 2500 K (Chellappa et al., 2017). These results also confirmed evidence produced by other authors (i.e., Knez, 2001; Knez & Kers, 2000).

Artificial lighting in offices and other workplaces plays a central role for many people throughout the day. Knez (2001) examined memory and problem-solving skills with different light intensities and colors. In a multi-criteria analysis, gender-specific differences with different lighting were found to be significant. Men performed better than women with tasks to memory and problem-solving skills in the ‘warm’ (3000 K) and ‘cool’ (4000 K) lighting, and poorest in the artificial ‘white daylight’ (5500 K). Conversely, women performed better in artificial white daylight lighting and perceived the room light, across all light settings, as more expressive than men (Knez, 2001). Studies show that subjective and individual aspects emerge also in the perception of different light colors (Cirrincione et al., 2018; Gennusa et al., 2017).

Moreover, Andersen et al. (2009) found a significant gender difference in window opening behavior influenced by brightness. Females opened the window more often when they perceived the environment as bright, while men were not affected by the illumination. Likewise, women were less likely to have the lights on when they felt warm or cold as compared with neutral, while conversely, men were more likely to turn on the lights when they felt warm or cold, compared to neutral (Andersen et al., 2009).

The effect of artificial light on humans is known in medicine as increased health risk (e.g., permanent exposure to artificial light, night shift work, etc.), but is also used in reverse in some medical treatment methods (i.e., light therapy; blue light therapy in newborns to prevent newborn jaundice, or therapy for skin diseases such as neurodermatitis, psoriasis, or acne). This suggests that there is a close connection between comfort criteria and health and that significant differences between the sexes should not be neglected.

3.1.3 Other Comfort Criteria, Corresponding Aspects, and Health

In addition to thermal comfort, lighting and daylight, air quality, humidity, and acoustics are essential comfort criteria. However, very little research has been done into the interaction between different comfort criteria, although this is just as important. Table 9.4 shows an overview of relevant studies.

Table 9.4 Overview of studies that investigated other comfort criteria, corresponding aspects, health and gender differences (listed in alphabetical order)
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In a study in France, tolerance to noise was examined in parallel with thermal behavior (Pellerin & Candas, 2003). The respondents were able to choose between adopting the temperature or the noise level. The study authors came to interesting results: women are more tolerant of noise than men, but more critical of thermal aspects than men. A study from Belgrade (Bajc & Milanović, 2019) came to different conclusions: men were more tolerant to noise, while women were more sensitive to poor air quality. Nevertheless, that gender is not only affecting thermal perception, but also other comfort criteria like acoustic, humidity comfort, visual comfort, air quality or lighting, as confirmed in other studies (Bae et al., 2020; Jungsoo Kim et al., 2013; Kraus & Novakova, 2019; Pigliautile et al., 2020; Yang & Moon, 2019).

Studies that have not explicitly examined the aspect of gender show that thermal comfort dominates overall satisfaction with the indoor climate and, for example, is rated as more important than visual and acoustic comfort or good air quality (Frontczak & Wargocki, 2011; Rupp et al., 2015). Further, the dissatisfaction with the thermal environment leads to lower comfort expectations regarding other indoor environmental quality factors, and conversely increases expectations if the thermal environment is rated as satisfactory (Geng, Ji, Lin, & Zhu, 2017). Andargie and Azar (2019) found that gender was a significant driver of satisfaction with air quality, reported happiness, as well as measured productivity.

Other important and gender-relevant findings are related to health. Sick-building syndrome is more common among women than among men (Bakke et al., 2007; Brasche et al., 2001; Lee et al., 2018; Reynolds et al., 2001). A study in an office building in Japan also pointed out the connection with dissatisfaction with thermal comfort (Nakano et al., 2002).

In summary, the literature confirms that thermal comfort should be given a special priority over other comfort criteria, and this in turn has a high priority, especially for women, but also other aspects should be taken into account.

3.2 Behavioral Aspects, Information, Knowledge, and Participation

To achieve balanced interior qualities, behavioral aspects, information, knowledge, and participation are further points that should be considered differentiated according to aspects of gender. Table 9.5 provides an overview of relevant studies and results.

Table 9.5 Overview of IEQ studies that investigated behavioral aspects and gender differences (listed in alphabetical order)
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The results of an Austrian study on energy-efficient buildings (passive houses) indicate increased interest and greater concern among women about air quality (Haselsteiner et al., 2014). They ventilate more often, and are sensitive to poor air quality. Ventilation, or ensuring good air quality, is more often seen as a task by women. Accordingly, dissatisfaction is higher if it is not possible to produce sufficient air quality. The fact that women are more dissatisfied with the quality of air than men is particularly evident in studies of productivity in offices and schools (Indraganti et al., 2015; see Sect. 9.3.3).

Although women are more dissatisfied with the room temperature than men, they are less likely to use the thermostat to regulate the temperature (Chen et al., 2020). Fifty-one percent of respondents in a study in Finland state that men use the thermostat more frequently to regulate temperature, while only 31% of women do so (Karjalainen, 2007). The additional laboratory experiment showed that women would set higher temperatures than men with the thermostat. To exclude differences in clothing, the study points out that in Finland, clothing for men and women in offices is not a significant distinguishing feature (Karjalainen, 2007). Women have the feeling that they cannot control the room temperature, whereas the majority of men state that they know how the air conditioning and ventilation system works.

Gender-specific criteria for indoor environmental quality also relate to different information behavior, such as the prioritization of costs, or other decision criteria about energy-efficient construction methods, technologies, and their use. Different information behavior and knowledge aspects regarding the use of energy-efficient technology between women and men should be emphasized. Information behavior is largely shaped socially and culturally (Chen et al., 2020). It is much more relevant for women to obtain concrete application-oriented information, and they are less interested in technical background information, i.e., on the topic of the Passive House (Haselsteiner, 2017).

As a result, participative approaches to achieve planned indoor environmental quality goals that include diversity aspects of user groups should be implemented more frequently. This requires an interdisciplinary approach and an integrated planning process that includes various technical disciplines.

3.3 Productivity, Indoor Environmental Quality, and Gender

Differences between men and women seem more remarkable in the office environment than in the home environment (Karjalainen, 2007; Jungsoo Kim et al., 2013; Rupp et al., 2019). Surprisingly, the relationship between temperature and cognitive performance has hardly been researched according to gender criteria. Table 9.6 summarizes some studies that examined IEQ and gender-specific effects in connection with productivity.

Table 9.6 Overview of studies that investigated productivity, indoor environmental quality, and gender (listed in alphabetical order)
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A large laboratory experiment, in which more than 500 individuals were asked to accomplish a set of cognitive tasks (math, verbal, and cognitive reflection), showed that the effects of temperature vary significantly across men and women: “At higher temperatures, women perform better on a math and verbal task while the reverse effect is observed for men. The increase in female performance in response to higher temperatures is significantly larger and more precisely estimated than the corresponding decrease in male performance. In contrast to math and verbal tasks, temperature has no impact on a measure of cognitive reflection for either gender.” (Chang & Kajackaite, 2019: 1). A study by Bajc and Milanović (2019) came to similar results: men in office environments were more sensitive to higher temperatures but more tolerant to noise, while women tolerated higher temperatures but were more sensitive to poor air quality. The higher sensitivity of women compared to men about IEQ, particularly thermal comfort and air quality, is also confirmed in other studies (Simone & Fajilla, 2019). Findings suggest that simple variations in room temperature have a marked impact on cognitive performance and that taking into account gender-specific considerations could increase productivity significantly.

Studies on whether thermal comfort is perceived differently in the workplace than in apartments show both differences due to the location and gender-specific differences. A quantitative survey was carried out among 3094 people (1556 women and 1538 men) in Finland, with questions about satisfaction with their home-related indoor climate, and another 1000 respondents about the indoor climate at work (Karjalainen, 2007). In a controlled experiment, it was also possible to adopt a fictitious room thermostat in a range from −2 (−3) to +2 (+3) °C. In addition to their preferences, the age and gender of the test subjects were also recorded. Both in the apartment and at the workplace, significant differences by gender were found in the quantitative survey using interviews: men were more satisfied with the room temperature in offices than women in both winter and summer. Yet, women rate summer temperatures at home better than men (Karjalainen, 2007).

This literature review has shown that there are only a few studies that examine the effect of temperature and cognitive performance by gender. Further research that takes overlapping effects into account or investigates the linking of cognitive performance and potential heterogeneous effects across gender along with other confounding variables (i.e., age, professional position, working hours, design of the workplace, air conditioning, or natural ventilation) would be particularly important.

4 Conclusion

In this chapter, an explorative literature review was carried out to describe particularly gender-relevant aspects in all indoor environmental qualities. The results showed that: (1) thermal comfort, in particular, is an essential parameter, and differences of up to 3 °C between women and men were measured; (2) Studies that investigated light sensitivity revealed gender differences in brightness perception and light preference; (3) Gender was found to be also an influencing factor of satisfaction with air quality, humidity, acoustic conditions, visual comfort, privacy, and health aspects; (4) Different levels of satisfaction with IEQ are probably decisive for a differentiated ventilation behavior determined by gender and different application of thermal control features; (5) Gender differences in thermal comfort become particularly relevant when it comes to requirements and cognitive performance at the workplace. Women perform better cognitively in a warmer environment, while men do better in colder temperatures, yet women are more affected by poor air quality. Considering that essential IEQ parameters vary significantly across men and women, these aspects should receive more attention.

The results’ consistency makes clear that women perceive indoor qualities, such as air quality, thermal comfort or lighting, differently than men. Hence, people should be the focus of attention and their individual needs should be taken seriously. The fact that women suffer more from sick building syndrome than men, is attributed to the fact that they suffer more from what they perceive as poor thermal comfort, which ultimately highlights the urgency for increased research in this field.

So far, a deeper segmentation according to social aspects has not been explored, nor has the explicit focus on gender aspects, gender mainstreaming, and gender equality as an integral part of planning and an energy-efficient building concept. Besides, further differentiations according to various diversity dimensions in connection with gender, such as age, origin, disability, economic conditions, etc., have so far hardly been investigated.

Even if the proportion of women in technical and male-dominated professions is increasing, women can only be found occasionally, for example, in training as a system technician for heating, air conditioning, and ventilation. Likewise, there are very few women in technical planning offices, or in the development of technical products and components for building technology . This results in a very male-dominated understanding of the functionality and application of these technologies. Aspects of gender and diversity-specific considerations should, however, be firmly anchored in different sustainability standards and IEQ assessments. More women employed in building technology and technological development and planning would ultimately contribute to sensitize practitioners and the construction industry to all the above mentioned comfort, as well as health and well-being issues.