Architecture, from prehistoric human caves to tree nests, to the towering skyscrapers of today, all reflect and attest to the development and progress of human civilization. In today's unprecedented human civilization, the significance of architecture is no longer just about providing shelter from wind and rain, but also a reflection of humanity.

With the strengthening of people's awareness of health and comfort, more and more people are pursuing comfortable indoor environments. More than 80% of a person's life is spent indoors, and a good indoor thermal environment has a positive and beneficial impact on human health, comfort, and work efficiency. Human thermal sensation and comfort cannot be regarded as the same concept. Comfort has a broader meaning, which is not only related to air temperature and humidity, but also closely related to airflow velocity and indoor air quality. Thermal sensation undoubtedly plays a crucial role in comfort.

major factor

The so-called human thermal comfort refers to the subjective and objective evaluation of the human body's satisfaction with the thermal environment. The factors that affect human thermal comfort include air temperature, relative humidity, air flow rate, average radiation temperature, human metabolic rate, clothing thermal resistance, and personal psychological factors. The first four factors are indoor physical factors, and the last three factors are personal factors. When a certain element fails to meet the expected requirements, the adverse effects can be compensated for within a certain range by adjusting other elements.

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Research shows that the most suitable indoor temperature is between 20 ℃ and 24 ℃. In an artificial air conditioning environment, when the temperature is controlled between 16 ℃ and 22 ℃ in winter and between 26 ℃ and 28 ℃ in summer, the energy consumption is relatively economical and comfortable. When the indoor temperature is below 16 ℃, the temperature of human fingers will be below 25 ℃, and it will not be able to be used normally. According to research, the efficiency of mental labor is highest when the air temperature is around 25 ℃; When the temperature is below 18 ℃ or above 28 ℃, the work efficiency will sharply decrease. The working efficiency at an air temperature of 35 ℃ is 50% of that at 25 ℃; The working efficiency at an air temperature of 10 ℃ is only 30% of that at 25 ℃.

The Influence of Relative Humidity on Human Thermal Comfort

Within the comfort zone (dry bulb temperature 16 ℃~25 ℃), a relative humidity range of 30%~70% has little effect on human thermal sensation. It is generally believed that the most comfortable relative humidity should be 50%~60%. Excessive indoor humidity can accelerate the growth of bacteria, mold, and microorganisms, leading to a significant decrease in indoor hygiene and causing respiratory, digestive, and various allergic diseases. Low indoor humidity can reduce a person's resistance to diseases.

The impact of wind speed on human thermal comfort

The flow of indoor air provides a simple and effective way to ventilate the indoor environment, and a reasonable range of air flow velocity ensures good indoor air quality. In general, the comfortable airflow velocity for the human body should be less than 0.3m/s. Most people feel happy when the indoor wind speed in Guangzhou, Shanghai and other places is between 0.3 m/s and 1 m/s in summer.

The impact of thermal radiation on human thermal comfort

The average radiation temperature Tmrt is a complex concept that is related to the position, clothing, and posture of a person indoors. It is an indoor thermal radiation index that depends on the surface temperature around the space. In addition, thermal radiation has directionality, so under unidirectional radiation, only the side facing the radiation can feel cold or hot, and the human body cannot feel comfortable with heat. Therefore, improving the thermal performance of the enclosure structure can enhance the level of thermal comfort.

Factors affecting human thermal comfort

Subjective factors:

Metabolic rate; People with high metabolic rates are not afraid of cold, but they are afraid of heat; People with low metabolic rates are not afraid of heat, but they are afraid of cold

Clothing situation: People's clothing situation varies depending on different types of buildings and functional rooms

Objective factors:

Air temperature: The most important factor that directly determines whether the human body feels cold or hot. The most suitable indoor temperature for the human body is 24-28 degrees Celsius

Relative humidity of the air: High relative humidity makes people feel stuffy and sticky; Low relative humidity makes breathing uncomfortable, and the large amount of floating dust in the air further pollutes indoor air. The relative humidity of indoor air in winter should be between 40% and 80%

Air flow velocity: indirectly affects the thermal comfort of the human body. Air flow can take away the exhaust gases emitted by the human body and reduce the concentration of carbon dioxide around the body. Appropriate speed can increase the evaporation of the human body surface, giving people a fresh feeling. The optimal air flow velocity in winter is 0.2~0.5 meters per second.

The issue of thermal comfort during the heating season in China

Excessive or insufficient heating: Due to different levels of solar radiation, rooms on the south side are excessively heated, causing people to open windows to cool down and lose heat. Outdoor dust also pollutes indoor air; The temperature in the north room is low and uncomfortable.

Poor air mobility and severe pollution: Old buildings do not pay much attention to building ventilation, resulting in low oxygen content and high concentration of dioxide indoors, which poses a great threat to human health.

Indoor dryness and low relative humidity in winter: In northern regions, there is less precipitation, higher indoor temperatures, greater air evaporation, more pollutants, and more water loss from the human body, which can cause discomfort and dryness.

Passive improvement measures

Avoiding the short board effect to enhance insulation capacity: For the insulation performance of buildings, the insulation capacity of the building envelope is determined by the parts with the worst insulation performance. The glass in the window is the weakest part of the building's thermal energy and should be specially designed. In addition, it is necessary to avoid building cold bridges caused by various unreasonable designs.