Thermal Comfort – Section 2

Differences in Thermal Comfort Between Men and Women
1. Introduction
Indoor air conditioning is based on experimental models of thermal comfort developed in the 1960s.
2. Metabolism and Standards
• Standard values for one of the fundamental variables, the metabolic rate (the amount of energy expenditure and heat production of each individual), are determined based on the metabolism of an average man.
• This value is 35% higher than the predicted basal metabolic rate of an average woman.
3. Women’s Metabolic Rate
• According to recent findings, the metabolic rate of women during light administrative tasks is approximately 48 watts per square meter.
• This situation makes buildings inefficient in providing thermal comfort for women.
4. Energy Consumption Optimization
With the ongoing efforts to optimize energy consumption in buildings, it is essential to accurately assess the heating needs of all occupants.
5. Differences in Comfort Temperature
• Research shows that the comfort temperature for men and women can differ by up to 3 degrees Celsius.
o The comfort temperature for men in similar conditions is about 22 degrees Celsius.
o The comfort temperature for women in the same conditions is about 25 degrees Celsius.
6. Skin Temperature
• Interestingly, the average skin temperature of men and women does not differ significantly:
o Men’s skin temperature: Between 32.8 to 33.8 degrees Celsius.
o Women’s skin temperature: Between 32.4 to 33.6 degrees Celsius.
7. Effects on Comfort and Energy Consumption
• This temperature difference can cause women to feel colder in homes or office buildings, which can lead to challenges between the genders.
• Additionally, energy consumption of air conditioning systems is often higher than necessary, especially if a significant number of women are in the building.
Thermal Comfort Systems
2. Important Air Conditioning Equipment
• Air handling units
• Fan coils
• Ducted split systems
These systems are among the most important air conditioning systems.
3. Buildings Without Mechanical Systems
Some buildings, especially in developed countries with moderate climates, do not use mechanical systems for air conditioning. These buildings can significantly save on energy consumption by not using advanced equipment.
4. Risks and Challenges
• Design and Insulation: If the building is not properly designed and constructed, and suitable insulation does not exist, its residents will never experience the desired temperature.
• Results of Proper Design: If the building design is executed correctly, residents can easily achieve thermal comfort by simply opening and closing windows, maintaining appropriate clothing, or even using a simple fan.
5. Research Methods in Thermal Comfort
1. Research on thermal comfort is generally conducted through two main methods:
o Laboratory studies
o Field studies
First Method: In this method, individuals are placed in a laboratory environment under controlled weather conditions and are questioned.
Second Method: In this method, questions are asked of individuals in the same environment where they are present.
2. Desire for Thermal Comfort
Humans always have the desire to feel comfortable and at ease in any conditions, which can also be a weakness. We strive to achieve living conditions that are:
o Not too cold
o Not too hot
o Not too humid
o Not too dry
Achieving such conditions is not easy, considering human expectations and the fact that weather generally lacks these qualities.
3. Difficulties in Achieving Comfort
Achieving thermal comfort requires continuous effort against factors that disturb comfort, including:
• Fluctuations in temperature
• Changes in humidity
4. The Concept of a Heat Engine
You may be familiar with how a heat engine works, which dates back to ancient times.
• Function of a Heat Engine: In these engines, heat is transferred from a high-temperature source to a low-temperature sink, and during this transfer, some of the thermal energy is converted into work.
• Molecular Functioning: The basic principles of these machines are based on the intensification of molecular motion due to heating.
5. The Human Body as a Heat Engine
The human body can be considered an example of a heat engine with some differences:
• Input Energy: The input energy for the human body is food.
• Unusable Heat: Compared to a heat engine, the human body produces unusable heat and must exchange this heat with its surrounding environment to survive.