Heating, ventilation, and air conditioning

Heating, ventilation, and air conditioning (HVAC) is the use of various technologies to control the temperature, humidity, and purity of the air in an enclosed space.Its goal is to provide thermal comfort and acceptable indoor air quality.HVAC system design is a subdiscipline of mechanical engineering based on the principles of thermodynamics,fluid mechanics, and heat transfer."Refrigeration" is som" is som Etimes is added to the abbreviation of the field as hvac & r or hvacr, or "Ventilation" is removed, as in HACR (as in the name of a HACR rated circuit breaker).HVAC is an important part of residential structures, such as single-family homes, apartment buildings, hotels, and senior living facilities; medium and large industrial and office buildings, such as skyscrapers and hospitals; and transportation vehicles, such as automobiles, trains, airplanes, ships, and Submarines; in marine environments, safe and healthy building conditions are regulated in terms of temperature and humidity, using fresh air from outside.Ventilation or ventilation (the "V" in HVAC) is the process of exchanging or replacing air in any space to provide high indoor air quality, including temperature control, oxygen supplementation, and removal of moisture, odors, smoke, heat, dust, airborne bacteria, carbon dioxide and other gases. Ventilation removes bad odors and excess moisture, brings in outside air, maintains air circulation inside buildings, and prevents stagnation of indoor air. Ventilation methods for buildings are divided into mechanical/forced and natural types.

Overview

The three interrelated functions of heating, ventilation and air conditioning are especially required to provide thermal comfort and acceptable indoor air quality within reasonable installation, operation and maintenance costs.HVAC systems are used in both domestic and commercial environments.HVAC systems provide ventilation and maintain pressure relationships between spaces.The way air is delivered and removed from a space is called room air distribution.

Individual systems

In modern buildings, the design, installation and control systems for these functions are integrated into one or more HVAC systems. For very small buildings, contractors typically estimate the capacity and type of system required, then design the system, selecting the appropriate refrigerant and the various components required.For larger buildings, building services designers,mechanical engineers, or building services engineers analyze, design, and specify HVAC systems.Specialized mechanical contractors and suppliers then fabricate, install and commission the system.Building permits and code compliance checks for installations are generally required for buildings of all sizes.

Regional network

Although HVAC is performed in a single building or other enclosed space such as NORAD's underground headquarters, in some cases the equipment involved is a larger district heating (DH) or district cooling (DC) network Or combine extensions of the DHC network. In this case, operational and maintenance aspects are simplified and there is a need for metering of energy consumed and, in some cases, billing of energy returned to the larger system.For example, at a given time, one building might be using cold water for air conditioning, and the warm water it returns might be used to heat another building, or for the overall heating portion of the DHC network (possibly adding energy to increase the temperature).Basing the HVAC on a larger network helps to provide economies of scale, which are often not possible for individual buildings, to take advantage of renewable energy sources such as solar thermal,winter cold.The cooling potential of natural cooling in parts of lakes or seawater, and the enabling function of seasonal heat storage.By utilizing the natural resources available for HVAC systems,it can have a huge impact on the environment and help expand the knowledge of using different methods.