Selecting an Air Conditioning System That
Best Meets Your Needs
Know the Requirements for Your AC System
Cooling/heating capacity is where commercial/industrial air conditioning systems differ significantly from residential air conditioners. Commercial/industrial air conditioning systems are divided into two general classifications according to their capacity:those that are for medium-size offices and those that are for buildings and large facilities.
Determine Needed Capacity Appropriate to the Intended Use
Unlike residential air conditioners, what the room is for and what the size of the room is should be factored in when selecting a packaged air conditioner.
For example, air conditioning capacity requirements for an office and a with a kitchen differ significantly even when they have the same floor area. Below is a list of some elements to be considered, taking into account the intended use of room/building, that may help you select the capacity of a packaged air conditioner.
Heat gain from office equipment is an important contributing factor to the overall heat gain of a space and consequently, to the overall heating/cooling load.
Extra capacity is often required to compensate for heat loss through doors and windows. The larger the opening or the area exposed to outdoor air, the more heat that is lost.
Ventilation and heat gain from restaurant equipment must be factored in.
For a setting where customers are seated for a relatively long period of time, the airflow volume and the direction of the wind from an air conditioner should be carefully calculated.
Select a Properly Sized Air Conditioner
An oversized/undersized air conditioner is less effective. Determine the model with the correct air conditioning capacity to the square footage of the space.
■ Floor Area & Basic Air Conditioning Capacity (Typical Japanese Air Conditioning Load)
Types of Air Conditioning Systems—Commercial Air Conditioning
Commercial/industrial air conditioners come in a variety of models. Selecting one that meets your business scene involves additional considerations, e.g., the intended use of the space, where it is to be installed. It is recommended to seek advice from an expert.
Office/Store Air Conditioning System
Single-Split Packaged Air Conditioner
In a single split air conditioner, one outdoor unit runs the system to provide conditioned air from an indoor unit. Various types are available for indoor units, from which users can select one that best meets the requirements of space where it is to be used, for example, a server room.
Multi-Split Packaged Air Conditioner
With one outdoor unit running more than one indoor unit, multi-split air conditioners are the popular choice for small-to-medium sized buildings. Indoor units of multi-split packaged ACs come in a variety of models. Select one that best meets the requirements of your business scene.
Because only one outdoor unit is needed, a multi-split system is suitable for buildings with limited outside space.
Building/Factory Air Conditioning System
In a variable refrigerant flow (VRF) air conditioning system, a single outdoor unit runs multiple indoor units.
VRF systems are classified as packaged air conditioning but are typically the choice for mid-to-large office/commercial buildings.
Mini VRF's outdoor units are more compact in size than those of standard top blow regular VRFs. However, their design of emitting discharged air sideways does not allow them to be used in combination with other units. Therefore; they are more suited for small-to mid-sized buildings.
Gas Heat Pump (GHP) Air Conditioning System
A gas heat pump (GHP) air conditioning system has a gas engine-powered compressor inside the outdoor unit and a heat pump to heat or cool air in living spaces.
It works in a similar way as an electric heat pump (EHP) system. The difference is it uses a gas engine instead of an electric motor.
Lowers Peak Demand
Air conditioning may account for the largest electricity use during periods in the summer when the most energy is required in cities. GHP systems which consume less electricity than EHP systems contribute to cutting peak demand.
Peak Electricity Loads, GHP vs EHP
Cuts Air Conditioning Costs
Gas-powered GHP systems use electricity only for auxiliary equipment such as fans, meaning a significant reduction in power consumption.
Power Consumption Comparison, GHP vs EHP:
Lets You Stay Warm During the Winter
Other than the heat pump, a GHP system uses waste heat from the gas engine for the heating cycle during winter. With no defrosting required, the heating cycle of GHP air conditioning quickly warms up the entire building even on very cold mornings.
A chiller is a machine that removes heat from a liquid via a vapor-compression or absorption refrigeration cycle. This liquid called refrigerant is circulated through a heat exchanger to cool equipment. Chillers are used for industrial machines and laboratory instruments, to continually maintain optimum temperatures. Commercial buildings and factories also use chillers for air conditioning. The term chiller comes from the fact that they are most commonly used for cooling; however, some chillers are designed for heating, as well.
The two main types of vapor compression chillers are air-cooled and water-cooled.
An air-cooled chiller expels heat produced from the heat exchanger into the atmosphere.
A water-cooled chiller has a cooling tower to chill water refrigerant.
An absorption chiller, a variant of water-cooled chillers, requires very little electrical power. It is in use as a heat source refrigeration system for the central air conditioning systems of mid-to large-sized buildings.
How an Absorption Chiller Works
An absorption chiller is different to other chillers because it does not employ a compressor for refrigerant compression.Instead, it uses principles of evaporation to remove heat from the chilled water.
The benefits of chillers include flexibility in installation spaces and water piping layouts. The chiller cools water being circulated to cooling coils that in turn transfers heat and latent heat from the air to the chilled water. The selection of how many components are used and how they are laid out is relatively flexible; thus, this system meets various requirements for high air conditioning capacity and larger spaces, which in turn widens commercial and industrial applications. For a chiller system, you don't have to take account of constraints in direct expansion air conditioning, e.g., height differences and length of refrigerant piping.
It effectively uses waste heat, steam, and/or hot water produced in the manufacturing processes. Cogeneration systems that leverage waste heat (from hot water) are the common applications that benefit from chiller cycles.
Air Handling Unit
An air handling unit (AHU) is the key component of an air conditioning system. It takes in outdoor or ventilated air, removes particles and dust, controls temperature and humidity levels, and supplies conditioned air via ducts.
Inside an AHU casing are water cooling/heating coils, reheating coils, a humidifier, an air filter, and blower. An AHU is typically installed in a machine room specifically designed for it. With all the components modularized and packaged in a single unit, most AHUs provide ease of maintenance. Typically, the heat source of an AHU is a chiller or VRF that exchanges heat between chilled/heated water or refrigerant and ambient air for creating conditioned air. Combining a chiller and AHU can build an air conditioning system suited for mid-to large-sized buildings, while VRF and AHU used together to provide a system that works best for small-to mid-sized buildings.
Central Air Conditioning
In a central air conditioning system, a heat source device installed in the building heats the water circulating in the system. The water flows to and from an AHU to provide conditioned air. By contrast, individual air conditioning systems have heat sources for each floor and area.
How a Central Air Conditioning System Works
A central air conditioning system employs heat source equipment, e.g., refrigerator, boilers, fitted with an evaporator fan coil of an air handling unit or fan coil. The term comes from the fact that all heat source components are accommodated in a single housing, from which conditioned air is delivered via a warm/cold air supply duct.
Often, central air conditioning systems are the choice for large buildings and facilities.
There are many advantages to a central unit system that can make it a worthwhile investment. You have a choice from among hundreds of different models of central air systems. Freely locatable chiller/AHU, piping layout, and fewer constraints in ductwork and piping lengths, allow for building design flexibility. During a cooling cycle, for example, the water cooled in the chiller travels to the condenser coil that expels heat into the atmosphere, then the fan delivers cooled air into the duct. These components can be flexibly combined and laid out to meet the requirements of your air conditioning scene regardless of the capacity required or the volume of the space to be cooled. Another benefit is that you don't have to take into account the constraints that usually come with direct expansion air conditioning, e.g., height differences of components, length of refrigerant piping, limits in air volume or static pressure.