Assessing the impact of energy efficiency measures on load diagram shape—a case study in the Portuguese residential sector

This paper intends to address the effect of energy efficiency and load management measures on load diagrams. In order to assess this specific impact, diagrams of load variations caused by energy efficiency measures are proposed. A case study is used to illustrate the effects of energy efficiency measures implemented under the Portuguese plan for the promotion of efficient electricity use (PPEC). The diagrams of load variations were estimated for measures targeting the residential sector which were approved in the six PPEC editions launched until presently. The measures were grouped according to the targeted energy service. The results of this case study indicate that energy distribution operators can change their load diagram by implementing energy efficiency measures in consumer dwellings, with demand reduction at critical periods. It is shown that energy efficiency in lighting measures can help smoothen the evening demand peak at 10 p.m. On the other hand, the effect of hot water measures, although beneficial in terms of energy saving, may increase the negative power gradient occurring at 9 a.m. due to photovoltaic generation under clear sky conditions. Diagrams of load variations can help to estimate the impact of energy efficiency measures on the network load diagram and can give important information for decision support to the distribution system operator, the utilities, and the energy regulator.