Component sizing based on the actual load

For many electrical systems, the load profile determines what is the most energy efficient design, making each case unique. Failing to take this into account can lead to over or under-dimensioning, resulting in additional energy losses and a sub-optimal life cycle cost of the equipment.

• If energy saving measures are carried out downstream from the energy flow, the upstream devices risk becoming over-dimensioned. For example, adding thermal insulation to a building will reduce the heating and cooling system load. And installing a waste water heat recovery (WWHR) system will reduce the heating load of a domestic hot water boiler. Apart from the unnecessary financial cost of over-dimensioning, some devices will also have reduced energy efficiency when working at less than their nominal load. This is the case with electric motors, for instance.
• The energy efficiency of electrical conductors depends on the load profile. A higher load can be compensated by increasing the cross-section of the conductor. Consequently, an estimation of the future load profile is required when optimizing the energy efficiency of wires, cables, connectors and transformers. For example, when dimensioning cables in non-residential buildings based on safety regulations only, there is a high risk they will be substantially under-dimensioned from an energy efficiency point of view.

A systems approach will always take the interactions between the different components of the system into account. This includes making a reasonable approximation of future load profiles and energy flows to avoid equipment over-dimensioning and under-dimensioning.