---
title: "Short note: Air conditioning"
subject: "Building Technology"
chapter: 1
key: "semester_6/building_technology:short-air-conditioning"
source: https://www.bctengineer.com/q/semester_6/building_technology/short-air-conditioning
site: BCT Engineering
---

# Short note: Air conditioning

Building Technology · Chapter 1: Functional Requirements of Buildings

- Asked in: 2072 Magh, 2 marks; 2070 Chaitra (old course), 4 marks; 2068 Baisakh (old course), 4 marks (asked 3 times)
- Video: [Air Conditioning System Basics  hvacr how does it work](https://www.youtube.com/watch?v=SfuSzBja8QA) — 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/short-air-conditioning
- Whole chapter: https://www.bctengineer.com/md/semester_6/building_technology/chapter-1

## Question

Write a short note on air conditioning.

## Short answer

Air conditioning controls temperature, humidity, cleanliness and distribution of air. Main parts are compressor, condenser, expansion valve, evaporator, air handling unit, ducts and controls. Types include comfort and industrial, and window, split, packaged or central systems; it gives comfort but has high cost and needs sealed, insulated, maintained buildings.

## Answer

**Air conditioning** is the process of treating air to control its temperature, humidity, cleanliness and distribution together, to meet the needs of the occupants or of a process.

#### Four functions
1. Temperature control (heating or cooling).
2. Humidity control (humidifying or dehumidifying).
3. Air cleaning (filtering dust, pollen, bacteria).
4. Air distribution and circulation through ducts.

#### Main parts
- **Compressor, condenser, expansion valve, evaporator** (refrigeration cycle) for cooling.
- **Air handling unit** with blower, filter and coils.
- **Ducts, diffusers and grilles**.
- **Thermostat and controls**.

```text
 Room air --> Filter --> Cooling coil --> Fan --> Duct --> Room
                          ^ refrigerant from outdoor unit
```

#### Types
- **Comfort air conditioning**: offices, homes, hospitals, cinemas.
- **Industrial air conditioning**: textile mills, laboratories, computer rooms.
- By system: window unit, split unit, packaged, central plant (chilled water).

#### Advantages and limits
Gives comfort in all seasons and a clean room. But the initial and running costs are high, it needs a sealed building with good insulation, and it needs regular maintenance. In Nepal, it is mainly used in hotels, hospitals, offices and malls.

## Check yourself

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

1. Air conditioning controls which items together?
   A. Only temperature
   B. Only fresh air supply
   C. Temperature, humidity, cleanliness and distribution of air
   D. Only air cleaning
   Answer: C. It treats air for temperature, humidity, cleanliness and distribution together. (Key point: Definition)

2. Which set is the refrigeration cycle for cooling?
   A. Compressor, condenser, expansion valve, evaporator
   B. Blower, filter, duct, grille
   C. Thermostat, fan, diffuser, filter
   D. Pump, tank, collector, valve
   Answer: A. Cooling uses compressor, condenser, expansion valve and evaporator. (Key point: Refrigeration cycle)

3. Which is a limit of air conditioning?
   A. Cannot control humidity
   B. High initial and running cost and need for a sealed insulated building
   C. Cannot filter dust
   D. Needs no maintenance
   Answer: B. AC is costly and needs a sealed, insulated building and regular maintenance. (Key point: Limits)

4. Industrial air conditioning is used in
   A. Homes and cinemas
   B. Hospitals only
   C. Offices only
   D. Textile mills, laboratories and computer rooms
   Answer: D. Homes, offices, hospitals and cinemas are comfort AC; industrial AC serves processes. (Key point: Types)

## Related in Building Technology

- [Ventilation versus air-conditioning](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Aventilation-vs-ac) — Building Technology, chapter 1
- [Building types and essentials of air conditioning](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Aac-essentials-building-types) — Building Technology, chapter 1

## Related in other subjects

- [Air-conditioning: definition and scope](https://www.bctengineer.com/question.md?key=semester_3%2Fapplied_thermodynamics%3Aair-conditioning-definition-scope) — Applied Thermodynamics, chapter 4
- [True/false: air conditioner is closed loop](https://www.bctengineer.com/question.md?key=semester_3%2Fcontrol_systems%3Atf-air-conditioning-closed) — Control Systems, chapter 1