Based on the information from climate.gov, the temperature of the Earth has been rising by 0.32°F per decade since 1981. However, the thermal comfort temperature for human occupancy has been the same, ranging between approximately 67 to 82°F (ASHRAE Standards). The ever-increasing temperature of the earth and the need for a comfortable environment has raised the demand for Air Conditioners (ACs) significantly. Along with maintaining a human comfort environment, ACs also serve the function of:
- Maintaining the humidity: The humidity of air is as important as the temperature of the air for human thermal comfort. The lower humidity level can lead to dehydration, which can cause dry skin, dry eyes, and nosebleeds. Likewise, bacteria and viruses can thrive and grow in higher humidity conditions. ASHRAE recommends a humidity below 65% for proper human comfort. The higher humidity is a concern during summer. The air conditioners eliminate this issue by condensing the water vapor in the air and supplying air with humidity below 65%.
- Improving Air Quality: ACs equipped with filters that help in eliminating dirt particles from outside, dust, and bacteria that come in through the doors and windows. This filtered air creates a healthier, cleaner environment, which is ideal for children and families, and commercial environments where large amounts of people are working together for many hours per day.
- Maintaining Human Efficiency: Studies show that a person feels fatigued more quickly in warm and humid temperatures. By providing cooler and properly humid air, AC creates a more comfortable and efficient temperature which increases human efficiency.
This article discusses the different types of air conditioners that are mostly used in residential conditions (single or multi-family). The types of ACs for residential conditions can be categorized into:
- Window Air Conditioning Units
- Wall Mounted Ductless Units
- Floor Mounted Units
- Ceiling Cassette Units
- Ducted Unit
- Window Air Conditioning Unit
A window air conditioner is a single packaged unit that is generally installed in a window or sometimes on the wall. It is a packaged unit where the heat is disposed to the outside and the cool air is blown into the room (See the link for basic operation). The window air conditioners have an option of a remote thermostat. Window air conditioners are one of the cheapest options for cooling and they are available in sizes ranging from a room to a one-bedroom dwelling unit. The significant advantages and disadvantages are listed below.
Advantages:
- Cost-effective
- Easier to install and maintain
- Compact and takes fewer space
Disadvantages:
- Aesthetically unpleasant
- Louder operation
2. Wall Mounted Ductless Unit
Wall-mounted ductless units are approximately 12” in height * 36” in width * 9” in depth and are mounted on the wall. The unit needs to be connected to an outside mounted unit through refrigerant pipings, along with controls and power cables. Refer to this link to understand how the system operates. Wall mounted ductless unit allows for an option to install several indoor units connected to a single outdoor unit. For example, you can have three wall-mounted units serving three different rooms and have a single outdoor unit. Each room can have its own thermostat and own local temperature controls. The significant advantages and disadvantages are listed below:
Advantages:
- Expensive than a window air conditioner but cost-effective compared to other options
- Relatively easier to install and maintain
- Each room has an option for individual control
- Also provides options for heating if required
Disadvantages:
- Looks better than a window air conditioner but less aesthetically pleasing than other options
- Integration of ventilation is slightly difficult
- The colder air might directly blow to the face if not installed in a right location
3. Floor Mounted Unit
Floor-mounted ductless units are approximately 24” in height * 30” in width * 9” in depth and are mounted close to the floor. Similar to the wall-mounted unit, the floor-mounted unit needs to be connected to an outside-mounted unit through refrigerant piping, along with controls and power cables. Refer to this link to understand how the system operates. This alternative also allows for an option to install several units into different rooms connected to a single outdoor unit. The significant advantages and disadvantages are listed below:
Advantages:
- Located near the floor so allows better accessibility
- Relatively easier to install and maintain
- Each room has an option for individual control
- Compact
- Also provides options for heating if required
Disadvantages:
- Integration of ventilation is slightly difficult
- Obstacles in the room can affect the proper air distribution
4. Ceiling Cassette Unit
These units are most suitable for a room with soffit space. They are available in sizes of 24” x24” or 36”x36” (Width x Length) with a height of around 10” and are placed on ceilings. Only the diffuser or grilles of the unit are visible on the ceiling as the main body of the unit remains hidden within the soffit space. As a result, ceiling cassette units are aesthetically pleasant. A ceiling cassette unit allows for an option to install several units in different rooms connected to a single outdoor unit. The significant advantages and disadvantages are listed below:
Advantages:
- Aesthetically pleasant
- Allows for a certain amount of ventilation.
- Relatively easier to install and maintain
- Each room has an option for individual control
- Compact
- Also provides options for heating if required
Disadvantages:
- Suitable mostly for spaces with soffit
- Only allows limited ventilation
- Relatively expensive
5. Ducted Unit
The ducted unit is also referred to as a central air conditioner as a single indoor unit can cool or heat multiple rooms at once. The ducted unit comes in vertical or horizontal orientation. The horizontal units can be installed on the soffit or false ceiling with a space height of around 14”. The vertical units need a dedicated closet or a basement. The ducted units supply the conditioned air to each room through ducting and the supply diffusers. The return air is supplied back to the ducted units through separate duct work and return grilles. The significant advantages and disadvantages are listed below:
Advantages:
- Aesthetically pleasant as diffusers and grilles are visible
- Allows for proper ventilation.
- Each room has an option for individual control
- Also provides options for heating if required
- Dedicated ducts provide conditioned air at a minimum time
- Proper air circulation in each room maintains proper humidity
Disadvantages:
- Need a dedicated space to install
- Need several penetrations of walls and maybe floor slabs for ductwork.
- This is the most expensive option
- Difficult to install because of ductwork
The right equipment for your cooling or heating needs can be selected by comparing your needs with the above-mentioned advantages and disadvantages. If you need further assistance, reach out to us. We are a team of registered professional engineers who can help with the selection of appropriate units for your needs.