EXAMINING AC, LIFT & LIGHTING SERVICES

Examining AC, Lift & Lighting Services



Examining AC, Lift & Lighting Services

INTRODUCTION

The main objective of comfort air conditioning is to provide building occupants with a comfortable, safe and healthy indoor environment. The benchmark for comfort, safety, health and indoor air quality varies depending on the building use such as

Commercial: Office buildings, supermarkets, shopping malls, restaurants etc.

Institutional: Recreation centers, theaters, indoor stadia, schools, museums etc

Residential: Hotels, private homes, low or high rise residential buildings

Health Care Facilities: Hospitals, nursing homes etc

Though the design criteria for the above spaces show slight variations, the basic design principle remains as follows:

·         Consideration of air conditioning fundamentals

·         Cooling load calculations

·         Consideration of thermal distribution requirements

·         Concepts of equipment selection

Figure 1

As shown in Figure 1, an air conditioning system comprises an air conditioning plant and a thermal distribution system. For space cooling as shown, heat energy in the form of sensible heat and or latent heat has to be extracted (transferred) from the conditioned space. The thermal distribution system serves as an energy transfer medium between the air conditioning plant and the conditioned space. The thermal distribution system also acts to improve the air quality in the conditioned space by regulating the introduction of a design quantity of fresh air into the conditioned space. Generally the air conditioning system functions to:

Provide the required cooling and heating energy

Control and maintain the indoor environment parameters such as temperature, humidity, differential pressure between conditioned space and its surroundings, air movement, air quality and sound levels within specified limits.

Distribute the conditioned air to the conditioned space.

As facility developers, owners and users present varying requirements for the design, installation and operation of HVAC systems coupled with variations in building occupancies, location and outdoor conditions, HVAC systems now come in different types and configurations. A sound knowledge of the classification and the ability to distinguish one system from another is key on the part of the designer, to selecting an appropriate air conditioning system for the client.

This post takes a look into the types of air conditioning systems and the criteria for selecting a suitable air conditioning system. To get a good grasp of the discussion here, the reader should be familiar with some basic HVAC terminologies and principles. These include methods of HVAC design criteria, load calculations (sensible and latent heat loads, infiltration load, equipment and appliances load, ventilation requirements, etc), building solar orientation and heat transfer mechanisms through the building envelope, etc.

 

TYPES OF AIR CONDITIONING SYSTEMS

In considering air conditioning for large buildings, the space is divided into thermal zones. The movement of heat from one place to the other has led to the development of HVAC system variations. The classification of air conditioning systems is dependent on various factors. Air conditioning systems can be classified into comfort air conditioning systems and process (industrial) air conditioning systems according to their applications. Similarly, air conditioning systems can be classified according to construction and operating characteristics as:

Individual room air conditioning systems

Evaporative-cooling air conditioning systems

Desiccant-based ...