System-based design is a technique which considers specific air-handling system features when performing load estimating and system sizing calculations. This is important because many systems have unique features which require special sizing procedures. For example, consider Single Zone CAV, Multizone, VAV, and Fan Powered Mixing Box systems. All contain different components and operate in different ways. To provide high quality system sizing data, the special features of each must be considered.
In the past, HVAC load estimating programs calculated room loads and airflow rates, and system airflow rates and coil loads without considering system specifics. This data is useful for general studies and for preliminary design when the system type is not known. System Design Load still offers these capabilities, but also provides the option of going a step further to tailor system sizing data to specific air handling designs and controls.
In System Design Load, general load estimating and system-based design start with the basics. Access to design weather data for hundreds of cities is at your fingertips. The ability to define specific wall, roof, and window constructions. Features for defining building design, layout, and operation in as much or as little detail as necessary. The process then continues by allowing the user to specify the type of system and controls used to deliver cooling and heating to the building. As much or as little detail as desired can be used. Sizing procedures then are tailored to the system choice to provide high-quality output listings for room loads and airflow rates, system coil loads and fan airflow rates, and component load details.