BPS and IDA ICE Encyclopedia
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Why do BPS?
Dimensioning
When dimensioning, the BPS user deals with the required size, shape and type of building and system components, usually for the cost estimate, the tendering or the implementation planning. Many studies have already shown that the savings of such simulations exceed their costs many times over. Depending on the application, this factor can be 10 or even 100.
Of course, one can regard the optimization of window size or insulation thickness as dimensioning. But in practice, it's all about power demand in a heating or cooling load calculation when we talk about dimensioning. In a first general such load calculation, it will be about the power that is generally needed to be supplied to the individual zones of a building.
For more specific and detailed load calculation, we will look at specific local heating and cooling units and size them by heat and cold supply power at certain design conditions (e.g. water supply and room air temperature), while the real supply power under simulation can differ from this input depending on the real, simulated conditions varying over time.
In the specific heating and colling load calculations, we also distribute the loads across several systems, which primarily involves heat transport via the ventilation system and waterborne room supply units. It may also be the case that several heating/cooling units (e.g. a slowly reacting basic supply system via high construction masses and a fast convective system to compensate for rapidly changing boundary conditions) are to be installed in the same room. In these specific load calculations, we can also take latent heat supply and removal into account.
When it comes to the dimensioning of central (both air handling unit and plant) systems and sizing its components, it can be important to consider both the simultaneity of the room requirements and the tolerance of temporary undersupply situations. This underlines how complex simulated systems can get, If the aim of dimensioning is not limited to sufficient safety, but also emphasizes maximum cost savings.