The term HVAC control refers to a system of automated climate control in buildings. HVAC is an acronym for heating, ventilation, and air conditioning, and encompasses the complete internal climate manipulation of any building or space. HVAC control systems typically consist of computerized networks in large buildings and stand alone, single controller systems in homes or smaller venues. 

A lot of detail goes into ductwork design. It is usually necessary to consult guidelines from the ACCA or seek help from HVAC trade contractors to select the right duct supplies and ensure proper installation. In addition, the location of utilities such as plumbing, communications, and electrical lines, and space requirements for access, must be taken into account when considering ductwork design criteria. When configured properly, an HVAC duct system performs efficiently and quietly.

There are other systems today that offer additional controls and options for managing variable air volume within a given space. With these options, the ventilation system may be configured with multiple points of entry and exit, creating a more efficient flow of air to and from various points within the space. Many of these types of systems today are operated with the use of software technology, making it possible to alter the flow of air from specific vents as well as adjust the temperature of the air flow at different points within the space. This can be especially important in a manufacturing setting, where the temperature near one area of the floor may need to be different from the temperature at the opposite end of the space, owing to machinery or computer equipment that is placed within the area.

Traditionally, HVAC and sheet metal contractors have used a mechanical device called a nomoraph to establish duct sizing. It is easy to use and provides a quick calculation of the optimal dimensions for either round or rectangular ducts. Software, however, gives the designer more real-world methods of calculating optimal duct sizing and routing, and can produce an estimate of material and labor costs. When airflow problems arise with an HVAC system, some software can analyze and recommend modifications to the existing duct layout by simulating the current system.

More advanced duct layout software is capable of importing data from Computer-Aided Design (CAD) drawings, thus minimizing the data that needs to be entered into the duct sizing and layout software. Most publishers of the software make the programs compatible with autoCAD-based design programs. It should be noted that, although CAD programs can assist with the design of the overall HVAC system, they are no substitute for experience and the judgment of an HVAC designer or engineer.

 

Throughout much of North America, the most widely used HVAC design standards are those developed by the American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE). ASHRAE Manual J provides standards for sizing HVAC equipment, while a number of additional ASHRAE publications are used to guide engineers through the design process.

The Air Conditioning Contractors of America (ACCA) is another organization that has developed its own HVAC design standards. ACCA standards are most commonly used by designers in the residential market, though the organization also produces commercial guidelines. In the UK, the Chartered Institution of Building Services Engineers (CIBSE) has developed its own line of standards similar to those created by ASHRAE and ACCA.