--- title: "Thermal comfort and its classification" subject: "Building Technology" chapter: 1 key: "semester_6/building_technology:thermal-comfort-classification" source: https://www.bctengineer.com/q/semester_6/building_technology/thermal-comfort-classification site: BCT Engineering --- # Thermal comfort and its classification Building Technology · Chapter 1: Functional Requirements of Buildings - Asked in: 2074 Bhadra, 8 marks - Video: [Thermal Comfort in Buildings Explained - HVACR Design](https://www.youtube.com/watch?v=yEWT_XmqCtQ) — The Engineering Mindset - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_6/building_technology/thermal-comfort-classification - Whole chapter: https://www.bctengineer.com/md/semester_6/building_technology/chapter-1 ## Question What do you mean by thermal comfort for the building purpose? Explain its classification with appropriate examples. ## Short answer Thermal comfort is occupant satisfaction with the thermal environment. Classified as subjective (ASHRAE scale votes), physiological (body heat balance), physical (environmental indices like effective temperature), by season (summer 24-28°C, winter 18-24°C), and by model (static PMV/PPD for AC, adaptive for naturally ventilated buildings). ## Answer **Thermal comfort** in buildings is the condition in which occupants are satisfied with the thermal environment (temperature, humidity, air movement and radiation) and want neither warmer nor cooler surroundings. #### Classification Thermal comfort is classified by the basis of assessment. 1. **Subjective (psychological) comfort**: The person's own feeling of the environment, from votes on the 7-point ASHRAE scale from -3 (cold) to +3 (hot). Example: students voting on the classroom temperature. 2. **Physiological comfort**: Based on the body's heat balance and on skin and core temperatures. When heat produced equals heat lost with little sweating or shivering, there is comfort. Example: a person resting at 24 °C needing no extra effort of the body. 3. **Physical (environmental) comfort**: Based on measurable parameters and indices such as dry-bulb temperature, effective temperature, and the comfort zone on the psychrometric chart. Example: ET of 22 to 25 °C is comfortable for sedentary work. #### By season or condition - **Summer comfort**: Needs cooling and ventilation; 24 to 28 °C with air movement. - **Winter comfort**: Needs heating and insulation; 18 to 24 °C. #### By model - **Static (heat balance) model**: Fanger's PMV/PPD, assumes steady indoor conditions (air-conditioned rooms). - **Adaptive model**: People adapt through clothing, windows and fans, so comfort range follows the outdoor temperature (naturally ventilated buildings, common in Nepal). Understanding these helps the designer choose passive or active methods to meet the comfort needs of the users of the space. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. Thermal comfort in buildings means: A. The temperature is exactly 20 C B. Occupants are satisfied and want neither warmer nor cooler surroundings C. Only the humidity is controlled D. The building uses air conditioning Answer: B. It is a state of satisfaction with the thermal environment, not a single temperature. (Key point: Definition) 2. Subjective comfort is assessed by: A. Skin temperature measurements B. Votes on the 7-point ASHRAE scale from -3 to +3 C. Dry-bulb temperature alone D. Psychrometric chart Answer: B. Subjective comfort is the person's own feeling, voted on the ASHRAE scale. (Key point: Subjective comfort) 3. Physiological comfort is reached when: A. Heat produced equals heat lost with little sweating or shivering B. The room is above 30 C C. Wind speed is high D. Humidity is zero Answer: A. It is based on the body's heat balance. (Key point: Physiological comfort) 4. Which model suits naturally ventilated buildings as in Nepal? A. Static PMV/PPD model, as comfort is fixed B. Adaptive model, as comfort range follows outdoor temperature C. Neither, as comfort is constant D. Only the physical model Answer: B. People adapt through clothing, windows and fans, so the comfort range moves with outdoor temperature. (Key point: Adaptive model) ## Related in Building Technology - [Human thermal comfort and thermal balance](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Ahuman-thermal-comfort-balance) — Building Technology, chapter 1, asked 4× - [Thermal comfort and its factors](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Athermal-comfort-factors) — Building Technology, chapter 1, asked 2× - [Achieving thermal comfort, active and passive methods](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Aachieve-thermal-comfort-active-passive) — Building Technology, chapter 1 - [Thermal performance and building geometry](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Athermal-perf-geometry) — Building Technology, chapter 1 - [Thermal insulation of walls, doors, windows, roofs](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Athermal-insulation-exposed-walls) — Building Technology, chapter 1, asked 3× - [Factors affecting thermal performance](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Athermal-perf-factors) — Building Technology, chapter 1 ## Related in other subjects - [Purpose of soil classification](https://www.bctengineer.com/question.md?key=semester_4%2Fsoil_mechanics%3Apurpose-of-soil-classification) — Soil Mechanics, chapter 3, asked 3× - [Factors affecting human comfort](https://www.bctengineer.com/question.md?key=semester_3%2Fapplied_thermodynamics%3Ahuman-comfort-factors) — Applied Thermodynamics, chapter 4 - [Appropriate technology and sustainable development elements](https://www.bctengineer.com/question.md?key=semester_7%2Fenergy_environment_and_society%3Aappropriate-technology-sustainable-elements) — Energy Environment and Society, chapter 1 - [Appropriate technology and impact on society](https://www.bctengineer.com/question.md?key=semester_7%2Fenergy_environment_and_society%3Aappropriate-technology-society-impact) — Energy Environment and Society, chapter 1