| In actual life,the mutation of metabolic rate often happen,from outdoor to indoor,from exercise to sedentary.The change of metabolic rate will have a great impact on people’s thermal sensation and thermal comfort after arriving at the indoor.Due to sweating and overheating during summer commutes,people often feel uncomfortable,especially when they reach the office on foot or by bike.During the commute,people store a lot of calories,which takes a long time to eliminate.Because of the thermal discomfort,people tend to reduce the set temperature,increase the cooling capacity of air conditioning.However,this measure will cause air temperature is too low in the office,and people are cold and feel uncomfortable after a period of time.Meanwhile the measure also causes the waste of energy.With a lag,temperature of overall office need a long time to drop.So,It can’t timely to improve the human thermal comfort.This study discuss two ways to improve human thermal comfort by lowering air temperature and increasing air movement.Thirty-five volunteers(17 men and 18 women),dressed in standard office suit(0.6 clo),were pre-exposed at a neutral environment for 30 minutes and then took moderate exercise(4.4 met)for 15 minutes in a summer climate(30 ℃,50 %RH)before entering the experimental room.The experimental room was precisely controlled at 24,26 or 28 ℃,with and without personalized fans.Volunteers were asked to office in the experimental room.Physiological parameters(skin temperature,skin moisture,heart rate and blood flow velocity)of the volunteers were collected within 60 min,and their subjective sensation(thermal sensation,thermal comfort,thermal acceptability,thermal preference,local thermal sensation,air movement acceptability and air movement preference)were asked intermittently.The study found that after moderate exercise,if the temperature setpoint drop from 28 ℃ to 26 ℃,the subjects’ thermal comfort has a great improvement,recovery time of thermal sensation is greatly reduced(from 60 min to 18 min),and the steady thermal comfort are also improved greatly.But from 26 ℃ to 24 ℃,the subjects’ thermal comfort are only slightly improved,recovery time of thermal sensation from 18 min to 13 min;After moderate exercise,the subjects were provided with a personalized fans at 28 ℃.It was found that the thermal comfort of the subjects was greatly improved.The recovery time of thermal sensation was only 8 min,and the steady thermal comfort reached 2.80 ±0.75,which was better than that without airflow at 24 ℃.Summarizing previous studies and real cases,four common transition space patterns were summarized,and energy consumption simulation was conducted by using Openstudio with xi ’an(cold region)as an example.According to the energy-saving design standards for public buildings,the envelopment structure,personnel,lighting and equipment as well as the actual situation are selected,and the air conditioning system is the ideal air conditioning system.Controling the temperature of the main space to 26 ℃ and the temperature of the transition space(24 ℃ ~ 28 ℃),the energy consumption of three different situations is simulated.The results show that the architect should minimize the arrangement of transition space on the premise of ensuring the traffic connection of each space,and the transition space should be arranged as centrally as possible.Moreover,the south transition space(the entrance hall)should be avoid as far as possible,and the linear transition space(the corridor)should be designed as east-west direction as possible.Increasing the temperature setpoint of the transition space can reduce the heat transfer and fresh air load of the enclosure structure,which effectively reducing the energy consumption of the air-conditioning system.When the setting temperature of the transition space rises from 24 ℃ to 26 ℃,the energy saving rate of the whole building space can reach 3.2%.When the setting temperature of transition space rises from 24 ℃ to 28 ℃,the energy consumption reduced by 5.5 %~6.2 %.According to this study,it is suggested to control the indoor thermal environment by space requirement: in hot summer,in the transition space,the indoor air temperature is control between 26 ℃ to 28 ℃(about 50%RH),and the ambient background wind speed is around 0.8 m/s,which can prevent the cold stimulation caused by large temperature difference and quickly restore people to thermal neutral.In the main space,each station is equipped with an adjustable fan with a maximum wind speed of 1.2m /s.Meanwhile,the air temperature is kept between 26 ℃ to 28 ℃,and the ambient air speed is at least 0.3 m/s.Giving people the right to adjust the thermal environment independently can improve people’s satisfaction. |
