A heating, ventilation and air conditioning (HVAC) system is used to heat and cool a house. Many of these systems also draw fresh air in to ventilate the home, while exhausting stale air. Depending on the application, HVAC systems can be extremely complex, and must include a wide variety of components in order to function properly. HVAC design is typically performed by skilled mechanical engineers or HVAC contractors.
During the HVAC design process, engineers must balance the comfort of building occupants with the need for energy efficiency and safe indoor air quality. To accomplish this, HVAC engineering professionals look at factors such as the size of the building, the local climate, the amount of insulation in the building, and how much heat is escaping the home through uncontrolled means. By the end of the HVAC design process, the engineer will know what kind of heating and cooling equipment to use and how it should be installed for maximum effect.
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.
During HVAC design, engineers can calculate heating and cooling needs on a room-by-room basis or using a whole house approach. Designers select equipment, including grills and registers used to distribute the air. Total electrical loads of all HVAC equipment is calculated, and fresh air requirements are also included. The size and layout of ductwork is also included in the process. During the duct design process, engineers choose the best materials for each duct as well as the amount of insulation required around or inside the ductwork.
HVAC design can be performed manually using worksheets, or by computer. Many different software programs are available that can be used to design almost any type of HVAC system, large or small. Users simply input data related to building size, climate and layout and the software produces a final design that can be used during HVAC installation.
