This research aims to clarify the significance of incorporating visual stimulation, in the form of foliage plants, into office desktop spaces. The experiments were conducted in a thermal environment with a temperature range that was slightly uncomfortable. The indoor thermal environment evaluation index ETF was used to measure the effects that brain stimulation of foliage plants have on comprehensive thermal senses. We focus on visual stimulation with foliage plants, and quantitatively measure shifts in thermal senses that affect the body. Thermal environment conditions were established with air temperature in three stages (25 ℃, 28 ℃ and 31 ℃) and the atmosphere was kept homogeneous with wall surface temperature equal to air temperature. The visual stimulations consisted of seven types of office desk image: benjamin, pothos, oxycardium, baby tears, moss ball, cacti, and no plant. At around 27 ℃ to 29 ℃ ETF, improvements in thermal sensation, as measured by thermal sensation statements, were shown to have resulted from visual stimulation benefits. Also, at around 26 ℃ to 29 ℃ ETF, improvements in comfort were shown, due to visual stimulation benefits as well, in subjects’ comfortable-sensation statements. This benefit was significant when a foliage plant’s green coverage ratio came between 0.75% and 4.67%, the range which does not create an overwhelming feeling from the foliage plant.
The comprehensive thermal senses that people experience are not expressed simply by the thermal balance between the physical environment and the body. Effects of visual and auditory stimulation create differences in thermal sense, due to high-level brain processes. In air-conditioned spaces indoors, as opposed to extreme temperature settings outdoors, one can create temperature environments that are slightly hot or slightly cold, which people will experience as slightly uncomfortable.
It is difficult to control auditory stimulation with any precision, but visual stimulation can be selectively controlled. Therefore, if one can quantitatively clarify the benefits of using visual stimulation to relieve the minor discomfort of a thermal environment that is set at a particular temperature, it could be very cost-effective for the running costs of air-conditioning equipment.
According to the Biophilia Hypothesis advanced by Wilson [
Ulrich [
Non-heat factors such as vision and hearing are also shown to affect sensation and comfort for the thermal senses [
Kurazumi et al. [
Energy conservation propaganda in Japan encourages people to set the air conditioning at 28˚C during the summer. This can have large benefits for private building spaces that pay the expense of air conditioning. On the other hand, this can prove less beneficial in public building spaces, where it can cause dissatisfaction.
An air temperature of 28˚C is a thermal environment that maintains a naked, seated, resting human body in a neutral status. In private building spaces where people can adjust their clothing and posture, they can use behavioral thermoregulation to adjust their sensational and physiological temperature based on heat exchange between the body and the environment.
However, in public building spaces where the thermoregulation behaviors described above are difficult, this temperature setting can make it impossible to maintain a neutral thermal status, and can affect concentration and harm health. Room temperature set at 28˚C is not a thermal environment conducive to concentration and performance of light tasks [
Also, from an energy conservation viewpoint, there are hopes that the Task and Ambient Air Conditioning System is a next-generation innovation that can obtain both comfort and energy conservation. The fields of work people are performing (Task) and the spaces around them (Ambient) are divided, and cooling and heating is concentrated only where needed, for efficient and comfortable control. By relieving some of the subtle problems that air conditioning creates in the ambient space, this can work to reduce costs by energy conservation. However, office spaces with frequent entry and exit, among other variables, can create large temperature variation. For a global warming countermeasure, Japan’s Ministry of the Environment created a campaign that calls on the people to make a “COOL CHOICE” [
To achieve the target of fiscal 2030 global warming gas emissions being 26% less than in fiscal 2013, “COOL CHOICE” is a national campaign that encourages various “clever choices” that contribute to global warming reduction, and indeed Japan leads the world in energy-conserving, low-carbon products, services, and behaviors. As one of various actions towards achieving a low-carbon society, it has been advocating “COOLBIZ” since summer 2015, so people can be comfortable in offices even with the air conditioning set at 28˚C. “COOLBIZ” calls for people to engage in behavioral thermoregulation by wearing clothing that feels comfortable at room temperature of 28˚C.
As noted above, setting the air temperature at 28˚C is feasible in private spaces such as residences, where environmentally conscious behavior is possible, but it is undeniable that this can force people to endure discomfort in public work spaces like offices. Focusing on this point, Kurazumi et al. [
For visual stimulation, it was found that elements with less than a 70% green coverage ratio are suitable; this gives a sense of depth with three-dimensional plants, and a dynamic benefit is expected for thermal environment conditions. Even in air-conditioned spaces that are slightly hot and have a high possibility of forcing people to endure, brain stimulation by greenery such as plants was found to benefit comprehensive thermal senses, and actively incorporating visual stimulation by the green of plants in indoor space was found to be significant. This suggests that visual stimulation of natural-view elements by greenery such as plants can be used to create environmentally friendly energy-conserving spaces.
Therefore, in air-conditioned spaces such as offices, instead of extreme temperature settings, these become thermal environments that are slightly hot and uncomfortable. Applying audio stimulation is not realistic in office work spaces, but foliage plants can be placed on desktops, and such visual stimulation can be expected to bring beneficial relief to thermal senses. If foliage plants placed on desktops are shown to improve thermal senses, then one can conjecture that air-conditioned spaces that would otherwise seem to be too warm can be shifted to become more comfortable.
Thus this research aims to use the 28˚C air-conditioned temperature as a reference point, experiment on subjects in a thermal environment with a temperature range that is slightly uncomfortable, and use the ETF indoor thermal environment evaluation index to clarify the effects that brain stimulation by the visual presence of foliage plants has on comprehensive thermal senses. We thus seek to clarify the significance of actively incorporating greenery of foliage plants as visual stimulation in office desktop spaces.
We focus on visual stimulation with foliage plants, and quantitatively measure shifts in thermal senses that affect the body. We thereby study effective actions for summer air conditioning set at 28˚C. If visual stimulation can be clearly shown to benefit thermal senses by high-level brain processes, then environmentally friendly energy-saving spaces can be created.
The conduction-corrected modified effective temperature (ETF) is indoor thermal environment evaluation index. The ETF was developed by Kurazumi et al. [
The effects of these five environmental factors that contribute to the body’s heat exchange can be expressed by newly defined thermal environment evaluation indices: Thermal Velocity Field, including effects of convective heat transfer area (TVFhta) for air velocity; long-wavelength Effective Radiative Field, including the effects of radiant heat transfer area (ERFhta) for long-wavelength thermal radiation; Effective Conduction Field, including effects of conductive heat transfer area (ECFhta) for surface temperature of material touching the body; and Effective Humidity Field at temperature ETF (EHFETF) for humidity. Each factor individually converted into temperature can be added to air temperature, and comprehensive effects on sensational and physiological temperature and effects of individual thermal environment factors can be quantified on the same evaluation axis. Heat exchange is standardized by all the body surface area of the human body.
where
ETF: conduction-corrected modified effective temperature [K];
Ta: air temperature [K];
TVFhta: convective heat transfer area of the combined thermal velocity field [W/m2];
ERFhta: radiant heat transfer area combined with the effective radiation field for thermal radiation [W/m2];
ECFhta: conductive heat transfer area combined with effective conduction field [W/m2];
EHFETF : effective humid field at ETF temperature [W/m2];
fcl: effective surface area factor of clothing [-];
fconv: convective heat transfer area factor [-];
fcond: conductive heat transfer area factor [-];
frad: radiant heat transfer area factor [-];
Fcl: thermal efficiency factor of clothing in the exposed airflow area [-];
Fcld: thermal efficiency factor of clothing in the heat conduction area [-];
Fclo: thermal efficiency factor of clothing under standard conditions [-];
Fpcl: permeation efficiency factor of clothing [-];
hc: convective heat transfer coefficient [W/m2K];
hr: radiant heat transfer coefficient [W/m2K];
hd: resultant heat conductance [W/m2K];
hf: sensible heat transfer coefficient [W/m2K];
ho: convective heat transfer coefficient under standard conditions [W/m2K];
L: Lewis relation coefficient [K/kPa];
pa: water vapor pressure at outdoor air temperature [kPa];
pETF*: saturated water vapor pressure at conduction-corrected modified effective temperature [kPa];
Ts: convection-corrected mean skin temperature [K];
Tf: surface temperature of the contacted material [K];
Tr: mean radiant temperature for long-wave radiation [K];
w: skin wettedness [-].
The experiments were carried out from July to August in 2015 and 2016. The ex- periment used the experiment room shown in
onto a screen installed in the environment experiment room. The thermal environment conditions set were in three stages―25˚C, 28˚C, and 31˚C air temperature―with the homogeneous condition of the wall surface temperature the same as the air temperature. In all conditions, air velocity (slow air flow of 0.2 m/s or less) and relative humidity (60% RH) were the same.
Due to the necessity of minimizing effects on visual stimulation and the necessity of clarifying body shape effects, the subjects were dressed lightly in white clothing. Subjects were in sitting postures during the experiment, and subjects’ work status was at rest.
Each subject maintained a resting status in a sitting posture for at least 45 minutes in a controlled, tranquil anteroom, with wall temperature equal to air temperature, and with air temperature and relative humidity the same as the initial environment condition settings. After that, the subject quickly moved into the experiment room, and was exposed for at least 15 minutes to the thermal environment condition settings. Considering that the thermal environment’s effects on the human body due to the environment history ended, and they adapt to the thermal environment condition settings, we set at least 60 minutes of exposure time for adaptation to thermal environment conditions. After that, the subject maintained the set posture at the exposure location in a status maintaining the thermal environment condition settings, and the experiment that applied visual stimulation began.
There were six types containing foliage plants that were at most 0.3 m high and an additional condition type with 0% green coverage ratio as control stimulation and a visual stimulation of only the desk, for seven total types of desktop images. The green coverage ratio is the green area of foliage plants as a percentage of the visual stimulation image projected on a screen. Each visual stimulation was presented for 180 seconds, and each subject stated his or her psychological senses 30 seconds after each visual stimulation was presented. The visual stimulations were presented randomly.
Kurazumi et al. [
Thus we selected foliage plants presented as visual stimulation with a maximum 0.3 m height planted in pots, and varying green ratios. For the images presented as visual stimulation, we assumed a sitting office worker focusing on a foliage plant placed on a desktop surface that is 1.3 m ahead. The office desk is 0.7 m high. The visual axis of the office worker gazes at the foliage plant at a depression angle of 22.6˚.
For visual stimulation, we used six types of foliage plants (benjamin, pothos, oxycardium, baby tears, moss ball, and cacti), and the condition of no foliage plants in the visual stimulation, for a total of seven conditions of office desktop images. We used potted foliage plants approximately 10 cm in diameter.
Visual stimuli scene | Green factor |
---|---|
baby tears | 0.39 |
moss ball | 2.24 |
benjamin | 4.67 |
pothos | 1.41 |
oxycardium | 0.75 |
cacti | 0.27 |
none foliage plant | 0.00 |
Green factor is green covering factor. Green covering factor is defined as the ratio of green surface areas to a picture area.
For cacti, we used spherical golden barrel cacti: two of approximately 4 cm diameter, and two approximately 2 cm in diameter, grouped in a pot. The leaves of this species are gold color spines. These are the most popular cacti seen in gardens and such and have 0.27% green coverage ratio.
For the moss ball, we used an acorn tree approximately 20 cm high, with a small crown architecture spread packaged in a ball, its surface covered with Hypnaceae. Adding the thick growth of acorn tree leaf surfaces, it has a high green coverage ratio. This plant is suited for humid environments, and is used for bonsai. It has a 2.24% green coverage ratio.
For the benjamin, we used an approximately 30 cm high starlight plant with a large crown architecture spread. Dense leaves hang vertically and cover a large area. This is a popular foliage plant. It has a 4.67% green coverage ratio.
For baby tears, we used a mat form with the plant pot’s soil surface covered by dense leaves. The leaves are very small, at approximately 2 to 3 mm. This plant is suited for humid environments, and is also used for ground cover. It has a 0.39% green coverage ratio.
We used an approximately 20 cm high Pothos N’Joy for the pothos. Young leaf period plants are used as foliage plants, so it has a small crown architecture spread, but dense leaves. Its leaves are 4 to 7 cm, green with white spots. It has a 1.41% green coverage ratio.
For oxycardium, we used approximately 15 cm high-straight-stalk standing plants: Philodendron Scandins and oxycardium. Its leaves are 3 to 5 cm, egg- shaped, glossy light green. It has a 0.75% green coverage ratio.
At 1.2 m eye height at the subject’s position, the solid-angle ratio of visual stimulation when the center of the image is presented in the line of vision direction was 0.09 at Position A, 0.10 at Position B, and 0.09 at Position C. These were differences of 0.01 in the solid-angle ratio of visual stimulation at the subject’s position, so these were not large differences.
The subjects were volunteers. Based on the mean height and weight and the standard deviation of height and weight [
In accordance with the Declaration of Helsinki [
For thermal environment conditions, we measured air temperature, humidity, air velocity, and wall surface temperature. For air temperature and humidity, we
Subject | Sex | Age | Height [cm] | Weight [kg] | B-area [m2] | Rohrer Index | Native place |
---|---|---|---|---|---|---|---|
OZ | Female | 21 | 163.4 | 54.3 | 1.58 | 124.5 | Aichi |
UM | Female | 22 | 154.1 | 48.4 | 1.45 | 132.3 | Aichi |
KA | Female | 22 | 161.8 | 45.9 | 1.47 | 108.4 | Aichi |
TA | Female | 21 | 158.3 | 44.9 | 1.44 | 113.2 | Aichi |
MO | Female | 21 | 147.1 | 41.0 | 1.32 | 128.8 | Shizuoka |
AR | Female | 22 | 158.0 | 52.4 | 1.53 | 132.8 | Shizuoka |
IW | Male | 22 | 163.3 | 51.4 | 1.55 | 117.8 | Fukuoka |
UE | Male | 21 | 175.4 | 67.1 | 1.80 | 124.3 | Yamaguchi |
UT | Male | 20 | 174.3 | 67.4 | 1.80 | 127.3 | Shimane |
OT | Male | 20 | 180.1 | 69.6 | 1.86 | 119.1 | Fukuoka |
KO | Male | 21 | 181.6 | 57.9 | 1.75 | 96.7 | Fukuoka |
TN | Male | 21 | 174.4 | 63.5 | 1.76 | 119.7 | Kagoshima |
B-area is the calculated body surface area by Kurazumi’s formula [
measured at 0.6 m height above the floor using a small humidity data logger (ESPEC MIC: RS-13, temperature measurement range 0˚C - 50˚C, precision 0.3˚C, humidity measurement range 10% - 95%, precision 5%). We measured the air velocity at 0.6m height above the floor with a hot-ball-type omnidirectional anemometer (Kanomax Japan: 6533, measurement range 0.05 to 5.00 m/s, precision 2%). The surface temperature of each surface of the room was measured with a 0.3 mmφ type T thermocouple.
For the solid angle of visual stimulation, we measured by the photo-taking method, using an equisolid angle fisheye projection-type lens (Olympus: Fisheye Zuiko 8 mm f/2.8) and 35 mm digital single-lens reflex camera (Canon: EOS 5D) to take fisheye photos in the line of direction of the image presentation center, with subject position at 1.2 m above the floor, assuming a sitting-position eye height.
For physiological conditions of the body, we measured skin temperature by a thermistor thermometer (Nikkiso-Therm N542R data logger, measurement range −50˚C to 230˚C, precision 0.01˚C, and a Nikkiso-Therm Surface type probe for body surfaces: ITP8391). We measured skin temperature in eight places: head, trunk, arm, hand, thigh, lower leg, foot, and foot sole.
The female subjects wore light clothing: only a short-sleeved shirt, short pants, panties, and bra-camisole. The male subjects also wore light clothing: a short- sleeved shirt, knee-length underpants, and pants.
Subject | Description | Material [%] | Weight [g] |
---|---|---|---|
Male | Pants | - | 52 - 70 |
Short-sleeved shirt | Cotton | 114 - 118 | |
Knee-length underpants | Cotton | 84 | |
Female | Panties | - | 20 |
Bra-camisole | - | 110 | |
Short-sleeved shirt | Cotton | 114 - 118 | |
Short pants | Cotton 98%, PU 2% | 84 |
PU is polyurethane.
This research measured psychological reactions 30 seconds after visual stimulation was presented, by a discrete grade scale of thermal sensation (seven stages), cool/warm sensation (seven stages) and thermal comfort (seven stages) as psychological conditions of the body.
Thermal sensation was given the end points of “cold” or “hot”, cool/warm sensation was “cool” or “warm”, and thermal comfort was “uncomfortable” or “comfortable”. For each, the “cold”, “cool”, and “uncomfortable” endpoints were recorded as −3, while the “hot”, “warm”, and “comfortable” endpoints counted as 3; numbers were allocated in equal intervals in between.
ETF [
However, using an experimental method that can only measure body weight immediately before and immediately after the start of exposure to thermal environment conditions, one cannot calculate the latent heat loss of the human body in each visual stimulation condition. Therefore, for skin wettedness, we used values calculated by the behavioral thermoregulation model of Kurazumi et al. [
As explanatory variables of thermal senses, environmental stimulations that directly affect thermal senses, such as air temperature, humidity, air velocity, long-wavelength thermal radiation, and surface temperature of material touching the body, greatly affect physiological and psychological reactions of the human body. On the other hand, environmental stimulation that indirectly affects thermal senses, such as visual stimulation, may not greatly contribute to the body’s physiological and psychological reactions. In particular, environmental stimulation that indirectly affects thermal senses, such as visual stimulation, is expressed as a shift in comprehensive thermal senses by high-level brain processes.
In indoor air-conditioned spaces, instead of extreme temperature settings, thermal environments are slightly uncomfortable (slightly hot or slightly cold). In this research, considering the great noise and likelihood of variability in physiological reactions of the human body in indoor environments, we investigated with significance probability at 20% as a standard for comparison of explanatory variables to derive results of regression analysis, which would be more useful in practice. For statistical analysis, we used JMP12.2.0 (SAS Institute Japan).
Air temperature measurement results were at most 2.1˚C higher than the value set; the temperature fluctuated within ±1.1˚C. Wall surface temperature measurement results were at most 1.5˚C higher than the value set; fluctuation there was within ±0.4˚C. Relative humidity measurement results were at most 1.3% higher than the value set; that variable fluctuated within ±4.3%. Air temperature fluctuated a little more, but standard deviation was within 1.1˚C. Air velocity was measured in advance at 0.2 m/s or less. These conditions were almost stable through all the experiments.
As described above, variables in the physical-environment that directly stimulate the thermal senses, such as air temperature, humidity, air velocity, long-wavelength thermal radiation, and surface temperature of material touching the body, greatly affect physiological and psychological reactions of the human body. Therefore, in the consideration section below, based on heat exchange between the human body and the environment, we investigated the effects of the ETF indoor thermal environment evaluation index [
shows that, at higher ETF, mean skin temperature also tends to be higher. Focusing on almost the same ETF stage, compared to when ETF is around 28˚C, dispersion is a little greater when ETF is around 25˚C.
Focusing on the regression line, mean skin temperatures were slightly higher where cacti, moss ball, pothos, and oxycardium were used. On the other hand, mean skin temperature was slightly lower with baby tears. However, those differences are within the level of measurement error and therefore not considered significant.
The result of investigation of parallelism of regression was p > 0.05 (F = 1.83, p = 0.09); the regression line did not show significant differences in parallelism. The result of investigation of homogeneity of regression line was p > 0.05 (F = 0.37, p = 0.90); the regression line did not show significant differences in homogeneity. We performed multiple comparison by Tukey-Kramer HSD; this was p > 0.05 between the condition of foliage plants not in visual stimulation, against conditions with foliage plants added, showing no significant difference due to visual stimulation. Therefore, in the range of ETF results of this research, as Kurazumi et al. [
Focusing on the regression line, when thermal environment conditions are 25˚C or 31˚C, large differences due to foliage plants are not found in thermal sensation statements. However, we found that when thermal environment conditions are 28˚C, the condition of no visual stimulation by foliage plants, and
thermal sensation statements with cacti, tend to be on the hotter side compared to conditions which presented other foliage plants. We found that thermal sensation statements tend to be lower with pothos and moss ball. Thermal sensation statements with baby tears, oxycardium, and benjamin fall in the middle of the foliage plant groups described above.
Moss ball and baby tears are plants suited for wet conditions; they are utilized as ground cover, so they make people think of wetness. Baby tears does not have a high green coverage ratio, but it makes people think of wetness, which could have the effect of lowering thermal sensation statements.
Fukagawa et al. [
At 25˚C thermal environment conditions with statements around “−1,” and at 31˚C thermal environment conditions with statements around “1,” the regression lines cross, and the difference in benefits from visual stimulation by foliage plants may be tiny. Second-order regression coefficients of the regression equation are positive for pothos, moss ball, baby tears, and oxycardium, but they are negative for cacti, benjamin, and the condition where foliage plants are not present in visual stimulation. Therefore, under thermal environment conditions of approximately 27˚C to 29˚C ETF with neutral thermal sensation statements (i.e., neither hot nor cold), visual stimulation of foliage plants may have benefits.
We used a non-linear second-order regression model to check for homogeneity between the condition with no foliage plants in visual stimulation and conditions with foliage plants added. For moss ball against the condition of no foliage plants in visual stimulation, p < 0.20 for intercept and slope, showing significant differences. For baby tears against the condition of no foliage plants in visual stimulation, p < 0.20 for intercept and slope, showing significant differences. For pothos the condition of no foliage plants in visual stimulation, p < 0.20 for intercept and slope, showing significant differences. The condition of no foliage plants in visual stimulation resulted in statements on the hottest side, so placing these foliage plants in the desktop space can be said to have a benefit that relieves hotness.
Matsubara et al. [
Also, Kurazumi et al. [
Focusing on the regression line, when thermal environment conditions are 25˚C or 31˚C, large differences due to foliage plants are not found in cool/warm sensation statements. However, we found that when thermal environment conditions are 28˚C, the condition of no visual stimulation by foliage plants, and cool/warm sensation statements with cacti, tend to be on the warmer side compared to conditions which presented other foliage plants. We found that cool/ warm sensation statements tend to be lower with pothos, oxycardium, moss ball,
and baby tears. Thermal comfort statements with benjamin are cool/warm sensation statements, which fall in the middle of the readings from the foliage plant groups described above.
As described for the relationship between ETF and thermal sensation statements, moss ball and baby tears have a dense shape of very small leaves; people look at a point on the green crown architecture, a shape which makes people think of wetness. Benjamin has a crown architecture that spreads in the desktop space near the body, which gives a sense of being closed in, which may weaken the relief of warm feelings [
At 25˚ thermal environment conditions with statements that are approximately “−1”, and at 31˚ thermal environment conditions with statements that are approximately “1”, there may be tiny differences in benefits of visual stimulation by foliage plants. However, second-order regression coefficients of the regression equation are negative for pothos, oxycardium, moss ball, and baby tears, but they are positive for cacti, benjamin, and the condition of no plants. Therefore, under thermal environment conditions of approximately 27˚C to 29˚C ETF, which has neutral cool/warm sensation statements―neither cool nor warm―visual stimulation of foliage plants may have benefits.
We used a non-linear second-order regression model to check for homogeneity between the condition with no foliage plants in visual stimulation and conditions with foliage plants added. In all conditions with plants, compared to the condition without plants, p > 0.20 for intercept and slope, showing no significant differences.
In research by Matsubara et al. [
statements are concentrated at “−1” or “0” for a 25˚C thermal environment condition setting, “0” or “1” for 28˚C, and “−1” for 31˚C. The tendency of thermal comfort statements indicates that the 26˚C to 29˚C ETF range may be the most comfortable thermal environment.
Focusing on the regression line in the range of 26˚C to 29˚C ETF, thermal comfort statements tend to be low with cacti or the condition with no foliage plants in visual stimulation. Thermal comfort statements tend to be high with pothos, oxycardium, or benjamin. Thermal comfort statements with baby tears or moss ball are in the middle of the foliage plant groups described above.
Compared to other visual stimulation conditions, the second-order coefficients of the regression coefficient for moss ball tend to differ from all of the others. Moss balls do not spread in a tree architecture, so even if we try to give them a high green coverage ratio, their psychological green coverage ratio may be recognized as relatively low.
We used a non-linear second-order regression model to verify homogeneity between conditions with no visual stimulation by foliage plants against conditions with foliage plants added. Comparing moss ball to the condition with no foliage plants in visual stimulation, we found that intercept, slope, and second order coefficient all have p < 0.20, showing significant differences.
Fondness for foliage plants may have effects, but it is possible that, if foliage plants with a coverage ratio approximately 0.75% or higher are placed on the side of the desk, then the thermal environment of an inorganic office working space may be organically improved to be more pleasant.
Consistent with what Kurazumi et al. [
This benefit was significant when the green coverage ratio of foliage plants ranged from 0.75% to 4.67%, which does not create a sense of crowding from the foliage plant. This research incorporates foliage plants as natural environment elements into personal space, with a relatively small distance between the body and the plants, so one can say there is a need to study crown architecture spreads that do not give a sense of crowding.
Kurazumi et al. [
In Japan, as one of various actions to achieve a low-carbon society, in order to conserve energy, cut costs, and reduce greenhouse gas emissions, there is a push for behavior that reduces the energy expended on air conditioning by setting room temperature at 28˚C.
In contrast to the home, in the office it is difficult to use behavioral thermoregulation to improve heat exchange between the body and the environment. Thus we performed subjective experiments designed for office desktop spaces in environments with a temperature range that is slightly uncomfortable, with a high likelihood of forcing people to endure, and investigated the effects on comprehensive thermal senses of brain stimulation from the viewing of foliage plants.
Due to the relationship between ETF and thermal senses, when ETF was approximately 27˚C to 29˚C, improvement in thermal sensation from the benefits of visual stimulation was shown. Also, when ETF was approximately 26˚C to 29˚C, improvement in thermal comfort was also evident, again due to the benefits of visual stimulation. This benefit was significant when the green coverage ratio of foliage plants was between 0.75% and 4.67%, which does not cause one to feel crowded or overwhelmed. This research incorporates foliage plants as natural environment elements into personal space, with a relatively short distance between the body and the plants, so one can say there is a need to study crown architecture spread that does not give a sense of crowding in the selection of foliage plants.
This suggests that, by incorporating the natural elements of foliage plants into office desktop environments, one can create environmentally friendly energy-conserving office spaces.
We would like to express our sincerest gratitude to the study subjects who participated in the present study.
Kurazumi1, Y., Kondo, E., Fukagawa, K., Hashimoto, R., Nyilas, A., Sakoi, T. and Tsuchikawa, T. (2017) The Influence of Foliage Plants on Psychological and Physiological Responses. Health, 9, 601-621. https://doi.org/10.4236/health.2017.94043