The air conditioning system in hotels is not exactly the same as the one in residential buildings. Hotels have unique conditions that make the air conditioning design challenging for HVAC engineers. So, I spoke with a friend who had experience with hotel air conditioning.
Generally, luxury hotels require fast cooling and precise temperature and humidity control. Besides, low noise is a very important consideration for high-end hotels. In addition, the occupancy rate of hotels fluctuates and hence, the cooling demand of hotels changes consistently.
There are a few things to consider when designing the air conditioning system for hotels. Some parameters are critical while some of them are depending on the level of luxury needed.
Hotels Air Conditioning System Type
A hotel can be organized into three categories; a) budget hotel, b) standard hotel and c) luxury hotel. Budget hotels are hotels with 1-star to 2-star ratings. Standard hotels are 3-star to 4-star. Luxury hotels are 5-star and above.
|Budget Hotel||1-star to 2-star|
|Standard Hotel||3-star to 4-star|
|Luxury Hotel||5-star and above|
As the name suggests, budget hotels prioritize low cost and functionality over fancy features and high energy efficiency. Most budget hotels have limited space and aesthetics (interior/exterior) are not a big concern.
So, many budget hotels use the single-split type of air conditioning system. For bigger rooms, they often use the multi-split type of air conditioning system. I rarely see budget hotels use VRF air conditioners, let alone chillers.
Single-split and multi-split air conditioners are famous for their simplicity, low cost and easy maintenance. However, they don't have superior efficiency and features. Most of them are very good at cooling/heating which is exactly what budget hotels need.
For standard hotels, the VRF air conditioning system and the air-cooled chilled water system are the two most commonly used types of air conditioning systems. However, some 4-star hotels with over 500 rooms may use the water-cooled chilled water system.
However, many 3-star hotels are still prioritizing low cost over any kind of luxurious experience. Hence, they still prefer to use the single-split system and the multi-split system while some 3-star hotels with lots of rooms are going for the VRF system.
For 4-star hotels, the features and the efficiency of air conditioners matter. However, they often don't have much space for large chillers. So, the air-cooled system is a good option for 4-star hotels.
When it comes to luxury hotels, most of them prefer to use the water-cooled chilled water type of air conditioning system due to its high energy efficiency. Many luxury hotels have more than 1000 rooms and thus, energy efficiency matters.
Hotels Indoor Unit Type
There are more than 10 types of air conditioner indoor units available in the market. For hotels, certain types of indoor units are more preferred than others.
As far as I know, the most common type of air conditioning indoor unit used in hotels is the ceiling ducted unit followed by the wall-mounted unit.
Most budget hotels install a wall-mounted air conditioner in their rooms. For 3-star hotels, we may see a ceiling ducted air conditioner in the more expensive rooms. When it comes to luxury hotels and even 4-star hotels, almost all of their rooms are fitted with a ceiling ducted unit.
Many budget hotels don't have a ceiling in their rooms. So, a wall-mounted unit is the best option. Sometimes, you may find a window air conditioner in budget hotels. However, window air conditioners need a window to operate which, some budget hotels don't have.
Ceiling ducted units are extremely popular in hotels because they can be concealed above the ceiling. Besides, ceiling ducted units can be very slim (low in height/thickness) and thus, they can be fitted in tight spaces.
Generally, ceiling ducted units are very quiet. Hence, they offer a more luxurious experience. Furthermore, they can be integrated with a smart control system (display controller) to enhance the luxurious experience.
Below is the summary of the common air conditioning system in hotels:
|Hotel||System||Indoor Unit Type|
|Budget hotel||Single-split, Multi-split||Wall mounted|
|Standard hotel||VRF system, Air-cooled chiller, Packaged unit||Ceiling ducted|
|Luxury hotel||Water-cooled chiller, Air-cooled chiller||Ceiling ducted|
Hotel Air Conditioning System Design Considerations
Hotels have unique conditions which HVAC engineers must consider when designing the air conditioning system. Let's take a look at some of the design considerations:
Occupancy rate is a very important element to consider when designing the hotel air conditioning system. Occupancy rate is the percentage of the occupied rooms against the total hotel room.
Usually, a good hotel has an occupancy rate of around 70% and above. Since the capacity of the air conditioning system is sized based on peak cooling load, an occupancy rate of 70% means that the air conditioning system will operate at 70% capacity most of the time.
So, for large hotels, part-load efficiency is more important than full-load efficiency if you are using chillers.
Moreover, when the occupancy rate is around 50%, large water-cooled chillers may start to struggle. However, you can mitigate it with air-cooled chillers.
Air-cooled chillers have smaller compressors that do better than the large centrifugal compressors of water-cooled chillers when the cooling demand is low. Therefore, it is worth considering using air-cooled chillers for hotels.
Because it is very rare for hotels to have a 100% occupancy rate, some HVAC engineers apply a diversity factor when designing the VRF system for 3-star hotels so that the initial cost is optimized.
Temperature and Humidity Control
Hotels often require precise temperature and humidity control in order to provide a more comfortable environment and therefore, a more luxurious experience for their guests, especially 5-star hotels.
So, the ceiling ducted units in some high-end hotels have a heating coil through which hot water is flowing where the hot water is produced by hot water heat pumps. Together, they offer a better experience while keeping energy usage low.
Many chilled water fan coil units (ceiling ducted units) are not that good in terms of precise temperature control. Conversely, VRF air conditioners can offer a very precise temperature control with variable refrigerant flow and variable refrigerant temperature technologies.
Additionally, luxury hotels usually demand fast cooling times. So, most air conditioners in hotel rooms are slightly “oversized” compared to standard rooms.
Low Noise Operation
Low noise is one of the aspects of a luxurious experience. Hence, luxury hotels require air conditioners to be very quiet when running. Since most hotel air conditioners are ceiling ducted units, internal duct insulations are essential to reduce noise transmission.
A typical hotel room fitted with a ceiling ducted unit has a short supply air duct and a short return air duct. The end of both ducts is fitted with a diffuser/grille. If both ducts don't have internal insulations, unpleasant noise can be transmitted from the ceiling ducted unit to the room.
Besides, if the chilled water system is used, the chiller plant room should not be located near meeting rooms, grand ballrooms and event rooms because of the loud noise. Otherwise, wall and slab insulations may be required to suppress the noise.
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