---
title: "Air-conditioning: definition and scope"
subject: "Applied Thermodynamics"
chapter: 4
key: "semester_3/applied_thermodynamics:air-conditioning-definition-scope"
source: https://www.bctengineer.com/q/semester_3/applied_thermodynamics/air-conditioning-definition-scope
site: BCT Engineering
---

# Air-conditioning: definition and scope

Applied Thermodynamics · Chapter 4: Air-Conditioning

- Asked in: year not given, 4 marks
- Video: [Application and Scope of Refrigeration and Air conditioning](https://www.youtube.com/watch?v=OvEEHlu-DTQ) — Avesahemad Husainy
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_3/applied_thermodynamics/air-conditioning-definition-scope
- Whole chapter: https://www.bctengineer.com/md/semester_3/applied_thermodynamics/chapter-4

## Question

Define air-conditioning. State the functions of an air-conditioning system, and classify air-conditioning systems with their applications.

## Short answer

Air-conditioning is the simultaneous control of temperature, humidity, cleanliness, and air motion in an enclosed space. Its functions include temperature control, moisture control, filtration, air movement, and ventilation. Systems are classified as comfort (homes, offices) or industrial (textile mills, clean rooms), by season (summer, winter, year-round), and by configuration (central or unitary).

## Answer

**Air-conditioning** is the process of simultaneously controlling the temperature, humidity, cleanliness and motion (distribution) of air in an enclosed space to meet the requirements of the occupants or of a process.

#### Functions
1. Control of temperature (heating or cooling).
2. Control of moisture (humidification or dehumidification).
3. Filtration: removing dust, smoke, pollen and odours.
4. Air movement and distribution without draught.
5. Ventilation with the correct amount of fresh air.

#### Classification and scope
| Class | Purpose | Examples |
|---|---|---|
| Comfort air-conditioning | Comfort of people | Homes, offices, cinemas, hospitals, hotels, vehicles |
| Industrial air-conditioning | Needs of a process or product | Textile mills, printing, pharmaceuticals, electronics clean rooms, laboratories, computer rooms |
| Summer AC | Cooling and dehumidifying | Hot, humid season |
| Winter AC | Heating and humidifying | Cold season |
| Year-round AC | Both, with control | Offices in varied climates |
| Central / unitary | Central plant with ducts / window or split unit | Large buildings / rooms |

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. Air-conditioning is best defined as simultaneously controlling which air properties in a space?
   A. Temperature only
   B. Temperature, humidity, cleanliness and distribution (motion) of air
   C. Pressure and oxygen content only
   D. Humidity and noise level
   Answer: B. It is the simultaneous control of temperature, humidity, cleanliness and air motion to meet occupant or process needs. (Key point: Definition of air-conditioning)

2. Which of these is NOT a listed function of an air-conditioning system?
   A. Filtration of dust, smoke and odours
   B. Ventilation with correct fresh air
   C. Generating electricity for the building
   D. Moisture control by humidification or dehumidification
   Answer: C. Functions are temperature control, moisture control, filtration, air distribution and ventilation. Power generation is not one. (Key point: Functions)

3. A textile mill, printing press or electronics clean room is an example of which class?
   A. Comfort air-conditioning
   B. Industrial air-conditioning
   C. Winter air-conditioning only
   D. Unitary air-conditioning only
   Answer: B. Industrial AC serves the needs of a process or product, while comfort AC serves people. (Key point: Comfort vs industrial)

4. Which pairing of season and process is correct?
   A. Summer: heating and humidifying
   B. Winter: cooling and dehumidifying
   C. Summer: cooling and dehumidifying; winter: heating and humidifying
   D. Year-round AC: no control of humidity
   Answer: C. Summer AC cools and dehumidifies; winter AC heats and humidifies; year-round AC does both with control. (Key point: Summer and winter AC)

## Related in Applied Thermodynamics

- [Boiler: definition and applications](https://www.bctengineer.com/question.md?key=semester_3%2Fapplied_thermodynamics%3Aboiler-definition-applications) — Applied Thermodynamics, chapter 1
- [Classification of air compressors](https://www.bctengineer.com/question.md?key=semester_3%2Fapplied_thermodynamics%3Aair-compressor-classification) — Applied Thermodynamics, chapter 2

## Related in other subjects

- [Short note: Air conditioning](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Ashort-air-conditioning) — Building Technology, chapter 1, asked 3×
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- [Multiplexing: definition and applications](https://www.bctengineer.com/question.md?key=semester_5%2Fdata_communication%3Amux-define-why) — Data Communication, chapter 6, asked 5×