Notes:
Scale of 1 to 5 with 1 as worst rating and 5 as best rating.
Even though some of the factors are more relevant to the user than others, all factors have been weighed equally due to the generic approach adopted. Weighed factors would impact those numbers in different ways.

Applications

The criteria for air conditioning selection vary with the type of application; here is a rundown of some of the most applied criteria per application type;

Apartments	Project References

Important criteria for apartment residents:

• Energy cost may become an important consideration, therefore conditioning occupied spaces rather than the whole flat may result in substantial operating savings. Certain systems are more adept at that than others

• Individual control is another parameter that apartment dwellers care for; Room-based controls and related system become thus the primary choice.

• Units are generally bulky, require space and need to conform to certain aesthetics and regulations; Based on these requirements, appropriate selections can ensue

• Apartments are usually located in urban environments with a high level of noise and pollution; systems need to cope with these 2 considerations effectively.  Thus systems that can effectively emit reduced sound levels and systems that have various filtering options are to be considered

• Electrical power can be a limiting factor in selecting the suitable equipment; In some cases for example, one is limited to single phase voltage or certain maximum amperage which in and by itself restrict the possible range of selections.

Villas	Project References

Besides the criteria found in apartments, there are some related notes that are to be accounted for as well;

Villas have generally more space to locate units thus certain systems can be morenaturally used; vertical discharge condensing sections become more acceptable.

Besides, people who own villas can possibly be less concerned about operating cost and more about maintaining comfort throughout; certain systems can cater better to this requirement than others by maintaining all spaces to required temperatures.

Commercial Centers	Project References

A wide variety of possibilities apply to those commercial centers;

• Strip malls (one or two-story buildings) are usually recommended with rooftop packaged units since the costs of installation and operation are reduced and the setup is simple.

• Forsaken is the multi-unit, multi-controls concept for the simpler sweeping single controllers.

• Depending on owner/tenant policies, energy bills may be passed on per usage rather than simply divided across the board. Accordingly, individual systems may be more appropriate since their energy use can be tagged on to the tenant’s overall bill.

• More elaborate malls usually rely on a comprehensive chilled water system that offers extreme flexibility especially when space remodeling and reconfiguration take place, a very common procedure.

Healthcare Facilities	Project References

Indoor Air Quality is one most important criterion (such as maintaining 100% fresh air in certain areas, or ensuring bacteria and particle free air to other patient care areas). Thus more sophisticated controls and more elaborate filtration devices are required to uphold those sanitary requirements. The best systems to cope with such requirements are of course chilled water systems and modular double-skin air handling units. Besides this, reliability, redundancy, and design flexibility further enforce the use of such systems.

 

Commercial Buildings	Project References

Low and high rise buildings alike are sophisticated breathing organisms that impose major requirements on the air conditioning system. Gone are the duct risers that become unsuited considering the limited space available ruling out the use of packaged rooftops. For mid to high rise buildings, gone are also any DX system considering that DX can only carry over a rise not exceeding 20-30 meters (depending if cool only or heat pump systems). The choices therefore become limited to either a floor-based system (DX system with condensing units located on the balcony or specially developed containment areas) or the more conventional chiller system. The latter can be configured as one main riser serving the many floors or it can be broken down per tenant to allow some level of independence. On the air side, the individual fan coils and air handlers ensure that the right quantity of air reaches the various spaces.

Showrooms	Project References

Similar to some extent to the strip malls, these open spaces with little to no partitions can have a number of units contributing to the requirements in airflow and cooling capacity. It could also mean that one large unit would also do the same trick. DX systems are quite cost effective and suitable for this type of application.

Industrial facilities	Project References

Usually requiring process cooling as well as climate control, these facilities require a flexible and reliable configuration that eliminates downtime, critical consideration for continuous running operations.

Places of worship	Project References

Spaces with large congregations of people demand a certain set of norms and systems to cope with the large number of occupants who require certain air properties and ratios and who are at the same time generating a lot of moisture, and bodily emanations. In order to cope with this sudden influx and high requirements, oversized equipment, noiseless air discharges, fresh air minimum, and filtration stages contribute to good environment and holy inspirations.

Product/Solutions

This most basic air conditioning “appliance” is considered simplest to purchase, ship, install and run. The smallest units can be hand-carried from the store, placed in your car and set-up and wired on the fly (assuming you have got a sized-up opening in the wall). You may want to ask your retailer to install the larger units (18,000 btuh and higher). Great value for the money, you get the cooling you need for your room with the least hassle possible.

Wall Type

Moving on up in style and functions, the wall type (a.k.a. minisplit) provides owners with such attributes as more aesthetics, smoother and quieter running operation, standard remote control, greater functionalities, smoother airflow as well as less discernible airflow variations. The unit has however some negatives such as the need for a qualified installer, external and internal piping, space for the outdoor condensing unit, lack of fresh air, and of course its physical attributes bearing on the living space.

Floor-Type

These units apply to large spaces usually commercial stores, small assembly halls, and spacious living room quarters. They are designed to have large airflows, they stand tall, are placed against the wall in a central manner to distribute the air evenly and with the throw large enough to reach the opposite wall. Though the units have become thinner over time (enhanced components and engineering design), they are still very much apparent (unless a closure is built around them) and have a difficult time being unnoticeable. Furthermore, the air draft grows as one comes closer to it since the air flows at the upper body level.

Concealed Type

Here is a room-based unit that resolves a couple of the issues that wall type and window-type units were facing but also picks a few more complications. Gone is the concern for looks since the unit is “concealed” that is that it is hidden behind the false ceiling or the partition. Reduced also is the possible airborne sound that motors and fans can generate since the unit has a duct that if correctly designed can further muffle these sound sources.  The concealed unit can also garner more functions and capabilities such as various filtration media, fresh air capability, and more flexible airflow patterns.  Their robust design makes them also  more reliable over their lifetime. On the other hand, this type of air conditioner requires technical expertise in selection and installation. It assumes that you have a location that is easily accessible and serviceable. It involves calling on a sheet metal team to connect the ducting and diffusers/grills to the unit.  Last but not least, these units are not readily available in a retail store and thus come generally with a higher price tag.

Central Split

Central splits are zone-based systems that serve a number of individual rooms/spaces. Generally controlled through a central thermostat, endowed with a single speed fan, requiring a servicing area and air conduits generally hidden above the false ceiling, the central split unit is made up of an indoor unit (blower/coil/filter) and a sizeable outdoor condensing unit which has a vertical discharge rather than the horizontal discharge outdoor units found in the smaller mini splits and concealed splits. While all benefits found in the concealed type apply for the central splits, the latter assume similar requirements and needs for all the individual spaces unless the potential owner requires room control add-ons. Since this situation usually applies to office spaces and similar functions for rooms (like single bedrooms), the central split is most appropriate. Considering that this system is more complex than single-room applications, and has certain limitations in terms of individual control, their use is primarily found in light commercial applications as well as larger residences and villas.

Packaged Rooftops

As the name indicates, these units are large self-contained boxes usually found on the roof of buildings. They contain all that is required to condition air and blow it into the needed spaces. While the packaged unit is similar in many ways to the central splits, it has the advantage of ease of service, accessibility and does not require service people to enter the premises. It can also be designed to further reduce any airborne sounds through well engineered ducting. Like its consumer counterpart (the window type), the packaged unit assumes an open space through which the air is brought indoors, accordingly packaged units may not be practical in multi-storey buildings due to the critical space risers may take up.

Chillers/Air handler/Fan Coils

Bridging the gap between all these systems is the complex system solution found with the chiller/air handling and fan coil units. More appropriate for large facilities, it can handle almost all types of configurations, restrictions and considerations. Where individual control is needed, fan coils are specified, and where large spaces and zones are sized up, larger air handling units are selected. All of these air moving products are selected appropriately for the task at hand and analysis, selection, installation are performed by industry professionals. What provides the cooling medium is of course the chiller; a unit located mostly outdoors (if air cooling condensers) or indoors (if water cooling condensers linked up to cooling towers). These units are complex and depending on size and operation mode may require technicians on hand.

Rating Parameters

Sound is carried through the air as well as across physical barriers. Sound and sound reduction are important considerations and in many cases stringent specifications are developed to ensure that occupants are least disturbed. There are sound norms that apply to each type of application with specific sound rating recommendations per application type (db for decibels). In addition, noise disturbance is further enhanced when equipments are turned on or off or when there are sudden changes in speed.

There are various ways one can deal with sound reduction such as sound attenuators in ducts, sound barriers to isolate the noise transmission, strategically locating the units, selecting units that have integrated sound solutions (such as double-skin air handlers), etc…

Appearance

All living quarters will be exhibiting one form or another of air distribution; be it grills or diffusers or actual units or apparent ducts or architecturally designed openings or having the actual unit in the space. Depending on stakeholders’ requirements, inclinations, or likings, such as the architect, the consultant/designer, and the owner/occupants, the suitable system that conforms most to the specifications can be selected.

Sometimes concerns over appearance go beyond the indoor units to include the outdoor units. Again depending on the system type one can put some distance between the occupied or visible quarters and the units. In certain cases, indoor chillers can be specified and in many cases mechanical rooms can be constructed to ensure adequate space for these units.

Indoor Air Quality

This issue is becoming more critical by the day as more pollutants are affecting the health of individuals and the concentration of building occupants can affect their well being. Standards have been created to ensure adequate flow of fresh and treated air (refer to ASHRAE.org website and standard 62). 

Fresh air is of course one contributor to good indoor air quality but there are more; such as filtration (different stages and types) to remove pollutants, Carbon dioxide sensors to ensure that critical concentrations are not reached, locating the intake units away from sources of pollutants, humidity control with special sections (such as spray humidifiers).

Installation

There are various considerations to take into account such as:

All equipments need to be serviced regularly otherwise they would operate less efficiently, could incur breakdowns, and possibly have a shorter life-cycle. Depending on the habits and requirements of the occupants, there can be various considerations: such as type of equipment, location of the indoor/outdoor units, technical expertise required, type of servicing such as preventive maintenance, or responding to service calls, or even performance contracting.

> Air Distribution

> Air Flow

> Temperature Control

> Humidity Control

> Efficiency

> Operation

> Scalability

> Availability

> Cost