PhD Thesis - Energy Systems Research Unit - University of Strathclyde

In the table, the low and high efficiency fabric scenarios for the 3 household building(Scenario 1 Low and Scenario 1 High ) and the 6 household building (Scenario 2 Low andScenario 2 High ) are compared between one another, whilst the remaining scenarioswhich include the scenarios with a modified plant configuration are compared withScenario 2 High , which in this case is being used as the reference scenario.As can be expected there is a direct correlation between the fuel consumption and theoperating hours of the CHP unit. Both can be used to quantify how energy intensivea scenario is. The higher the values obtained for either criterion, the more energyintensive a specific case is.Despite the fact that the shoulder months have the highest number of days (151 dayscompared to the 92 and 122 days of the heating and cooling seasons respectively), ona seasonal basis the absence of a space heating or cooling demand, resulted in theCHP unit operating for a very short time period: out of the possible 3,720 hours forthe shoulder season, the average number of operating hours for all scenariosinvestigated was about 494 hours, resulting in an operating load factor of 13%. Theaverage daily fuel consumption was of 5 kg of LPG. In comparison the CHP unitoperated for 27% and 43% of the total time during the heating and cooling seasonrespectively. The corresponding daily average fuel consumption for all scenarios forthe heating and cooling season was approx. 10 and 16 kg of LPG respectively. Thecooling season was as expected the most energy intensive season. This is animportant consideration as it provides further evidence of how in warm climatesreasonable operating load factors, which can make the system technically viable, canonly be achieved if the micro-cogeneration system is complemented with theaddition of thermally activated cooling device to provide cooling during summer.Comparing the results obtained for the cases in Scenario 1 with those obtained forthe case in Scenario 2, it can be observed that when the trigeneration system wasconnected to the larger 6 household building the resulting increase in thermaldemand (heating, cooling and domestic hot water) resulted in an increase inoperating hours and fuel consumption of the CHP unit of around 34%. This is also an176