ARCH-INAR209 Thermal Comfort PDF

ARCH-INAR209 Thermal Comfort Dr. Cemaliye Eken İlter Snr. Inst. Mojdeh Nikoofam PhD. Candidate Joy Uwa Nanlop 2024-2025 Fall Semester Cyprus International University Introduction to Thermal Comfort Thermal Comfort is defined as the condition...

ARCH-INAR209 Thermal Comfort Dr. Cemaliye Eken İlter Snr. Inst. Mojdeh Nikoofam PhD. Candidate Joy Uwa Nanlop 2024-2025 Fall Semester Cyprus International University Introduction to Thermal Comfort Thermal Comfort is defined as the condition of mind in which a person feels satisfaction with their thermal environment. It is a subjective state where the occupant is neither too hot nor too cold, but instead feels thermally ‘just right’ According to ASHRAE thermal comfort is achieved when the indoor environment is perceived as acceptable by at least 80% of its occupants. ASHRAE (American Society of Heating, Refrigerating, and Air-Conditioning Engineers) Introduction to Thermal Comfort Plants, animals, and humans each have a threshold of COMFORT ZONE. Introduction to Thermal Comfort The set of environmental HEAT conditions, which is within the range of regulating the body's metabolism, is called comfort ZONE. Introduction to Thermal Comfort In addition to the automatic body heat regulation mechanism, animals use other methods to adapt to the environment. One can mention the migration of birds or the hibernation of bears Thermal Comfort The human body is able to regulate its heat exchange with the surrounding environment. If the thermal changes of the environment are not more than the average, the body can regulate its heat exchange and feel comfortable. The condition in which a body achieves its thermal balance by using the least amount of energy. ASHRAE (American Society of Heating, Refrigerating, and Air-Conditioning Engineers) Thermal Comfort Unlike animals and plants, which use instinctive and natural mechanisms to adapt to the thermal conditions of the environment, thermal comfort threshold of the human is very limited. Importance of Thermal Comfort Health and Well-Being: Occupants are more in Building Design and comfortable, healthier, and experience lower stress Occupant Satisfaction levels when thermal conditions are optimized. Productivity: People are more productive and focused in environments where thermal comfort is maintained, particularly in offices, schools, and other work environments. Energy Efficiency: By designing buildings that promote thermal comfort naturally (through passive heating and cooling, insulation, etc.), energy consumption can be significantly reduced, which is both cost-effective and environmentally friendly. Occupant Satisfaction: Thermal comfort contributes to overall satisfaction with a building, impacting factors like occupancy rates in commercial buildings or the desire to return to public spaces, such as libraries or shopping centers. Importance of Thermal Comfort in Building Design & Occupant Satisfaction Design Considerations: Architects can use principles of thermal comfort to influence choices regarding building orientation, materials, insulation, and ventilation to create spaces that remain comfortable throughout the year. Have you ever wearing four jackets and a scarf just to tolerate your office’s frigid air conditioning? Truth be told, you can’t please everyone when it comes to adjusting an indoor climate. Human Thermal Comfort Parameters PERSONAL FACTORS ENVIRONMENTAL FACTORS METABOLIC RATE: Activity Level TEMPERATURE CLOTHING INSULATION HUMIDITY AGE AIR MOVEMENT SEX RADIANT TEMPERATURE DIET ADAPTATION PERSONAL FACTORS For the survival of a healthy person deep body temperature must be maintained at 37 o C. Deep body temperature may increase 1.5 o C during a heavy work. However, it stays at a narrow temperature interval. Human body has to produce heat to maintain the 37 o C body temperature. Body’s heat production is called METABOLISM PERSONAL FACTORS: METABOLIC RATE ACTION METABOLIC RATE, W/ m2 Sleeping 41 Sitting 58 Slowly walking 116 Dancing 140-256 Heavy work 204-262 There are two types of metabolism. Basal Metabolism – automatic heat production of the body. Muscular Metabolism – heat production of muscles while doing work. PERSONAL FACTORS: METABOLIC RATE & ACTIVITY LEVEL The rate at which a person’s body generates heat, often determined by their level of physical activity. Higher activity levels (like exercising or performing manual labor) increase the body’s heat production, making a person feel warmer. Conversely, a sedentary person will produce less heat and may feel cooler. PERSONAL FACTORS: METABOLIC RATE & ACTIVITY LEVEL Because there is action there, a sport center should be cool. However, an office where people are seated ought to be hotter than a sport center. PERSONAL FACTORS: AGE PERSONAL FACTORS: DIET PERSONAL FACTORS: ADAPTATION PERSONAL FACTORS: CLOTHING INSULATION Clothing acts as a barrier that traps body heat and can significantly influence thermal comfort. ▪ Clothing insulation is measured in “clo” units (a measure of thermal resistance). ▪ Lighter, breathable fabrics (low clo values) allow heat to escape, while heavier fabrics or layers (high clo values) retain body heat, affecting the wearer’s perception of temperature. ▪ For example, a business suit provides around 1.0 clo, while a T-shirt and shorts would offer about 0.36 clo. ENVIRONMENTAL FACTORS: Key Factors Influencing Thermal Comfort ▪Air temperature ▪Humidity ▪Air Movement (velocity) ▪Radiant Temperature AIR TEMPRATURE Air temperature is one of the primary factors influencing how warm or cool a person feels within a space. Generally, air temperatures between 20– 26°C are considered comfortable for most indoor environments, but this can vary depending on the season and individual preferences. Maintaining an ideal indoor temperature is crucial as it directly impacts the thermal comfort of occupants, helping to prevent discomfort caused by excessive heat or cold. HUMIDITY Humidity refers to the amount of moisture in the air and affects how we perceive temperature. High humidity levels make it feel hotter because it reduces the effectiveness of sweating, our body's natural cooling mechanism. Conversely, low humidity can cause dryness, making the air feel colder than it actually is. Ideal relative humidity for indoor spaces generally ranges from 30% to 60% to optimize comfort.  ▪ Air movement plays a vital role in thermal comfort AIR MOVEMENT by aiding the body’s ability to cool itself through the evaporation of sweat. ▪ Moderate air movement can make a room feel cooler, especially in warm conditions, without changing the actual air temperature. ▪ In cooler conditions, low air velocity is preferred to avoid a chilling effect on occupants. ▪ Effective ventilation and controlled air movement can enhance comfort while also improving air quality.  ▪ The temperature of surfaces (walls, floors, Radiant Temperature windows, furniture) around us impacts how we perceive warmth and coolness. ▪ Warm surfaces radiate heat, making a room feel warmer, while cooler surfaces can absorb heat from the body, creating a cooling effect. ▪ Surface temperature differences, like cold windows on a warm day, can cause discomfort even if the air temperature is optimal. ▪ Insulation, glazing, and the choice of materials in construction help regulate surface temperatures to contribute to a balanced indoor climate. HEAT TRANSFER Hot objects in a cooler room will cool to room temperature. Cold objects in a warmer room will heat up to room temperature. The transfer of heat is always from warm object cold object Why is it Windy at the Seaside? The cold air from above the sea moves in to take place of warm air that has risen. Techniques for Transferring Body Heat to the Environment Heat is transferred between human body and environment by four different ways. These are: ▪CONVECTION ▪CONDUCTION ▪RADIATION ▪EVAPORATION CONVECTION Convection is the transfer of heat through the movement of liquids or gases, such as water or air. Warm air rises and cooler air sinks, creating circulation patterns. Impact on Thermal Comfort: Convective airflow helps distribute heat evenly in a space. However, uncontrolled drafts or insufficient air circulation can cause discomfort, such as cold drafts in winter or uneven heating in summer. CONVECTION IS THE MOVEMENT OF GASES OR The warmer soup moves up from the heated area at the bottom of the LIQUIDS FROM A COOLER REGION TO WARMER pan to the top where it is cooler. The cooler soup then moves to take REGION. the warmer soup's place CONVECTION ▪ Many of our daily activities involve or observe convection. ▪ For example, if you drink coffee, you may notice steam rising up from your hot drink. ▪ In this case, we can visibly observe convection as the steam is transferring heat into the air.  Air rising and falling near a heater. CONVECTION ▪ Another example would be a heater during the winter. ▪ The heater produces warm air which will rise to the top of the room. ▪ The warm air will eventually cool and sink to the bottom of the room before getting pulled back into the heater. CONDUCTION Conduction is the transfer of heat through direct contact between materials. CONDUCTION An ice cube will melt if you hold it in your hand. The heat is being conducted from hand into the ice cube. CONDUCTION Metals are excellent conductors of heat energy. However Wood or plastics are not. That's why a pan is usually made of metal while the handle is made of a strong plastic or wood. These "bad" conductors are called insulators. CONDUCTION ▪ Example: In buildings, conduction occurs when heat moves through solid materials like walls, floors, or windows. For instance, touching a cold wall during winter can make a person feel chilly due to heat transfer from their body to the colder surface. ▪ Impact on Thermal Comfort: Poor insulation can lead to significant heat loss through conduction, making indoor spaces feel colder in winter or hotter in summer. CONDUCTION WINTER SUMMER CONDUCTION WINTER SUMMER RADIATION ▪ Radiation is the transfer of heat in the form of electromagnetic waves. Unlike conduction and convection, it doesn’t require a medium (solid, liquid, or gas) to transfer heat. ▪ Example: The sun warming a building through windows is an example of radiant heat. Similarly, occupants can feel radiant heat from warm surfaces like radiators, floors, or walls. ▪ Impact on Thermal Comfort: Radiant heat can directly affect occupants, making them feel warmer in a space even if the air temperature is cooler. Too much radiant heat from sunlight through large windows, for example, can make a space uncomfortably hot. EVAPORATION ▪ Evaporation occurs when moisture on the skin (such as sweat) changes to vapor, removing heat from the body and providing a cooling effect. ▪ Example: In warm environments, sweating helps regulate body temperature by releasing heat through evaporation. ▪ Impact on Thermal Comfort: In spaces with high humidity, evaporation is less effective,. making the air feel hotter and more uncomfortable In dry conditions, excessive evaporation can lead to a cooling effect, but also cause dryness and discomfort. How These Mechanisms Impact Thermal Comfort in Buildings CONDUCTION CONVECTION Proper insulation in walls, windows, and Effective air circulation and proper HVAC floors is essential to reduce unwanted heat (heating, ventilation, and air conditioning) gain or loss, ensuring that indoor spaces systems are necessary to maintain even remain comfortable without excessive heating temperatures and avoid discomfort caused by or cooling. stagnant air or drafts. RADIATION EVAPORATION The design of windows, shading devices, Controlling indoor humidity levels through and the orientation of the building can proper ventilation and air conditioning control the amount of radiant heat entering a ensures that evaporation effectively regulates space, improving thermal comfort by body temperature, maintaining a balance minimizing excessive solar gain or heat loss. between dryness and excess moisture. Adaptive Thermal Comfort Adaptive thermal comfort is a theory that suggests occupants can adjust their behavior, clothing, or environment to achieve comfort in response to indoor and outdoor climate conditions. This approach acknowledges that people’s thermal preferences vary based on ▪ their past experiences, ▪ the seasons, and ▪ the climate they are used to. Unlike the fixed indoor temperature ranges traditionally prescribed by thermal comfort models (like ASHRAE standards), adaptive thermal comfort assumes that people are more flexible and can feel comfortable in a wider range of temperatures. Key Principle: Occupants in naturally ventilated buildings can tolerate more variation in indoor temperatures because they have the ability to adapt their clothing, open windows, or move to different areas of the space. How Occupants Adapt Based on Indoor and Outdoor Climates Clothing Adjustments Behavioral Adjustments In warmer climates, people tend to wear Occupants often modify their behaviors to improve lighter clothing that allows heat to escape, comfort, such as opening windows to let cool air in, while in colder environments, people wear using fans, closing blinds to reduce solar gain, or layers or heavier clothing to retain heat. seeking out shaded areas. Environmental Controls Psychological Adaptation People can adapt to changing conditions People’s thermal comfort expectations are shaped by by using mechanical or natural methods, their familiarity with the local climate. For instance, like adjusting thermostat settings, residents of warmer climates are typically more tolerant controlling window shades, or using of higher temperatures, while people from colder portable heaters or fans... climates may feel comfortable at lower temperatures. Clothing Adjustments Behavioral Adjustments Environmental Controls Psychological Adaptation Adaptive Thermal Comfort The adaptive thermal comfort model is important in sustainable building design, especially for naturally ventilated buildings, as it reduces reliance on energy-intensive HVAC systems. By designing spaces that allow occupants to easily adapt to temperature variations, architects can promote comfort in more energy-efficient ways. Thermal Insulation in Buildings Importance of Insulation in Managing Heat Gain/Loss Insulation is essential for controlling the transfer of heat between the interior and exterior of a building, helping maintain a stable indoor temperature. It reduces heat loss during the winter and minimizes heat gain during the summer, ensuring thermal comfort for occupants. By improving insulation, buildings can maintain desired temperatures with less reliance on heating and cooling systems, reducing energy consumption and costs. Proper insulation also helps to prevent thermal bridging / transferring, where heat escapes through gaps or poorly insulated areas. Types of Insulation Materials and Their Properties Fiberglass: Widely used and effective at reducing heat transfer. It is affordable and easy to install, often used in walls, attics, and floors. Mineral Wool: Fire-resistant and offers excellent soundproofing along with thermal insulation. It’s often used in external walls. Spray Foam: Fills gaps and cracks well, providing an airtight seal that prevents heat loss. It has a high R-value (resistance to heat flow). Polystyrene (EPS/XPS): Rigid foam insulation that offers high moisture resistance, used for both above- and below-grade applications. Cellulose: Made from recycled paper products, it’s an eco- friendly option that offers good thermal and sound insulation properties. The Role of Building Materials How Different Materials Affect Thermal Comfort Thermal Properties: The choice of building materials significantly impacts a building’s thermal performance, influencing how much heat is absorbed, stored, or reflected. Thermal Mass: Materials with high thermal mass, such as concrete or stone, absorb heat during the day and release it slowly, helping to maintain a stable indoor temperature. Low Thermal Mass Materials: These include lightweight materials like wood or steel, which do not retain heat, allowing rapid temperature changes. Examples of High and Low Thermal Mass High Thermal Mass: ▪ Concrete: Absorbs heat during the day and releases it at night, helping to regulate indoor temperature. ▪ Brick: Has high thermal capacity, providing good insulation and contributing to overall comfort. Low Thermal Mass: ▪ Timber: Light and quick to heat up or cool down, making it less effective at stabilizing temperatures. ▪ Steel: Offers low thermal mass, meaning it transfers heat quickly and doesn’t store much thermal energy. Solar Gains and Shading Devices Impact of Solar Radiation on Thermal Comfort Solar radiation can lead to unwanted heat gains inside buildings, especially through windows and glazed areas. In hot climates, excessive solar gain can result in overheating and discomfort for occupants, increasing the need for air conditioning. South-facing windows typically receive the most sunlight, requiring careful design strategies to minimize solar heat during peak hours. Solar Gains and Shading Devices Use of Shading Devices to Control Heat Gain External Shading: Devices such as overhangs, louvers, or pergolas reduce direct sunlight entering the building. Blinds and Curtains: Internal shading options can help manage glare and heat while allowing flexibility for occupants. Solar Control Glass: Specially coated glass reduces solar heat gain while maintaining daylight. Vegetative Shading: Using trees or greenery to shade windows and walls is a natural, sustainable way to reduce heat gain. Dynamic Shading Systems: Adjustable systems like operable louvers or retractable awnings allow for better control over solar exposure. Thermal Comfort and Energy Efficiency Relationship Between Thermal Comfort and Energy Consumption Achieving thermal comfort often involves using heating, cooling, and ventilation systems, which consume significant amounts of energy. Poorly insulated or poorly designed buildings increase the reliance on these systems, leading to higher energy consumption and costs. Balancing comfort and energy efficiency requires reducing energy demand while ensuring indoor spaces remain comfortable for occupants. Thermal Comfort and Energy Efficiency Passive Design Strategies to Improve Comfort and Reduce Energy Use Orientation: Proper building orientation can take advantage of natural sunlight and wind to maintain comfort and reduce energy use. Natural Ventilation: Using cross-ventilation, stack ventilation, and other strategies to reduce reliance on mechanical cooling. Insulation and Thermal Mass: Improving insulation and using materials with high thermal mass can help stabilize indoor temperatures and reduce the need for heating and cooling. Solar Shading: Controlling solar gains with shading devices minimizes overheating, reducing the need for air conditioning. Green Roofs and Walls: These systems offer insulation, absorb solar radiation, and cool the building through evapotranspiration, improving energy efficiency. Why are houses in hot countries often painted white? White reflects heat radiation and keeps the house cooler. Why are houses in hot countries often painted white? Darker surfaces absorb more of the radiation and lighter surfaces reflect the radiation. So, you would be cooler if you wear light or white clothes in the summer. Why are shiny foil blankets wrapped around marathon runners at the end of a race? The shiny metal reflects the heat radiation from the runner back in, this stops the runner getting cold. 1. Which of the following is not a method of heat transfer? A. Radiation B. Insulation C. Conduction D. Convection 2. How does heat energy reach the Earth from the Sun? A. Radiation B. Conduction C. Convection D. Insulation 3. Which is the best surface for reflecting heat radiation? A. Shiny white B. Dull white C. Shiny black D. Dull black 4. Which is the best surface for absorbing heat radiation? A. Shiny white B. Dull white C. Shiny black D. Dull black  Radiation Travels In Straight Lines True / False Radiation Can Travel Through A Space True / False How does building orientation impact thermal comfort? Building orientation plays a crucial role in regulating indoor temperature by controlling how much sunlight the building receives. For example, ▪ In hot climates, orienting the building to minimize direct sunlight on south- and west-facing windows can reduce overheating. ▪ In cooler climates, orienting living spaces toward the south maximizes passive solar heat gain, improving comfort in winter. Proper orientation helps balance temperature, reducing the need for mechanical heating and cooling systems. What role does thermal insulation play in ensuring thermal comfort? Thermal insulation helps prevent heat transfer between the interior and exterior of a building, maintaining a more consistent indoor temperature. In winter, insulation reduces heat loss, keeping the building warmer, while in summer, it prevents heat from entering, helping keep the interior cool. By minimizing temperature fluctuations, insulation significantly contributes to occupant comfort while reducing energy consumption for heating and cooling. Why is thermal mass important in the design of energy-efficient buildings? Thermal mass refers to the ability of a material to absorb, store, and release heat. High thermal mass materials, like concrete or stone, can absorb excess heat during the day and release it at night, stabilizing indoor temperatures and reducing temperature swings. This passive heating and cooling effect enhances thermal comfort by keeping the building warmer during the winter and cooler during the summer. It also reduces the need for mechanical heating and cooling systems, promoting energy efficiency. How do shading devices contribute to thermal comfort in buildings? Shading devices, such as overhangs, blinds, and louvers, help control the amount of solar radiation entering the building. By reducing direct sunlight, especially on south- and west- facing windows, they prevent overheating and glare, improving occupant comfort. Shading devices also reduce the demand for air conditioning in hot climates. In colder climates, adjustable or retractable shading devices can allow for more solar gain during the winter, providing passive heating when needed. How do shading devices contribute to thermal comfort in buildings? How can architects use natural ventilation to enhance thermal comfort? Natural ventilation improves thermal comfort by promoting air circulation, which helps cool indoor spaces and removes excess heat. Architects can design buildings with strategically placed windows, vents, or louvers that allow for cross-ventilation or stack ventilation. This method is especially effective in climates with mild temperatures and good airflow. By using natural ventilation, architects can reduce the reliance on air conditioning, making buildings more energy- efficient and comfortable.