PhD Thesis - Energy Systems Research Unit - University of Strathclyde

In terms of the daily electrical energy consumption, it can be observed that for allhouseholds and for the characteristic days shown, improving the energy-efficiency ofelectrical appliances results in an overall reduction in the range of 30% to 40%. Asexpected therefore, improving the energy-efficiency of appliances substantiallyreduces the electrical energy demand.With regards to the daily peak demand however, although generally a reduction isobserved, it can be seen that at this low level of aggregation (single household orsmall aggregation of households) the daily peak demand appears to be highlydependent on the time-of-use and the individual aggregation of individual applianceloads. For example, the results obtained for the daily peak demand in February showthat, whereas increasing the electrical efficiency of appliances results in a reductionin the daily peak demand of each individual household, the aggregated daily peakdemand for the entire building was slightly increased. Similarly for individualhouseholds the daily peak demand of household 3B was higher for the high electricalefficiency scenario compared to the current efficiency scenario. Likewise, in terms ofthe load duration curves, Figure 5.1 shows that although the average daily loaddecreases rather substantially, the variability inherent to this low level of aggregationresults in a situation where even when using high electrical efficiency appliances, theinstantaneous demand may be similar (if not higher) to that obtained with the ‘low’efficiency appliances.The results indicate that a changeover to more energy-efficient appliances may notalways be successful in reducing the daily peak electrical demands of an individualhousehold or a small aggregation of households; this also indicates that the dailypeak demands are due to the coincidence of multiple loads rather than to individuallarge loads.Table 5.4 shows the equivalent key features calculated for the electrical demandprofiles modelled to represent the current and high electrical efficiency demandprofiles of the different floors in the 6 household building used in scenarios 2, 3, 4and 5. Recalling that in this case each floor was modelled to represent two171