12th International Symposium on District Heating and Cooling

The <strong>12th</strong> <strong>International</strong> <strong>Symposium</strong> on District Heating and Cooling,September 5 th to September 7 th , 2010, Tallinn, EstoniaFigure 4 shows the energy consumption in relation tothe outdoor temperature during week long periods withand without heat load reductions implemented as LC.The squares are from periods without LC and thetriangles are from periods with LC. LC in this regardmeans that temporary heat load reductions are beingperformed in recurring sets throughout the week aslong as the thermal inertia of the building allows it, i.ewithout jeopardizing the indoor climate. In this examplethe energy usage is about 8.2% lower during periods ofheat load reductions.Figure 6 shows recurring heat load reductions insteadof single long ones. It is clear that the building is able torespond to the control scheme in this example also.The largest heat load reduction during the recurringscheme is about 25%.Figure 6: Heat load reductions shown 24 hours withoutreductions (black), 24 hours with reductions (dark grey)and control scheme for reductions (light grey)Figure 4: Energy usage in relation to outdoor temperature.The squares are values during periods without LC, andtriangles show periods with LCFigure 7 shows a range of indoor temperature readingsduring periods with heat load reduction (triangles) andduring periods without (squares). The averagedeviation during heat load reduction is about 0.29 whilethe average deviation during periods without reductionsis about 0.19.Figure 5 shows the heat load (kW) during 24 hourswhen using reductions compared to not usingreductions. The control scheme is also added to thefigure in order to show when the reduction wasperformed.Figure 5: Heat load showing 24 hours without reductions(black), 24 hours with reductions (dark grey) and controlscheme for reductions (light grey)Figure 5 clearly shows that the reduction in heat loadclosely follows the control scheme. The largest heatload reduction is about 30% in this example.247Figure 7: Indoor temperature during periods with heatload reductions (squares) and during periods withoutheat load reductions (hourglass)Figure 8 shows readings from two different outdoortemperature sensors during a time period of two days.The graph shows the outdoor temperature sensorwhich is connected to the actual consumer sub-stationin the building (black line). Normally these sensors areplaced somewhat in the shadow to avoid largefluctuations due to solar radiation. We added anothertemperature sensor (grey line) in order to estimate the