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, EstoniaCONSIDERATIONS AND CALCULATIONS ON SYSTEM EFFICIENCIES OF HEATINGSYSTEMS IN BUILDINGS CONNECTED TO DISTRICT HEATINGMaria Justo Alonso 1 , Rolf Ulseth 2 and Jacob Stang 11SINTEF Energy Research, Department of Energy Processes2NTNU, Faculty of Engineering Science and Technology,Department of Energy and Process EngineeringABSTRACTIn order to harmonize the implementation of the ECDirective on the energy performance of buildings(EPBD) [1], and to provide guidelines and commoncalculation tools, several technical standards havebeen worked out by CEN in accordance with amandate from the EC. This paper focuses oncalculating system efficiencies of hydronic heatingsystems by using the standards EN 15316-x-x [4], [5],[6].The paper has been written in order to ease anddiminish the time consuming process of interpretingdetails in the standards such as the numbered EN15316-x-x, and with the goal to enlighten main parts ofthese standards.To exemplify some results, an apartment building of1000 m 2 floor area located in a climate like Oslo ischosen. In the base case, the design distributiontemperatures in the building are 80/60. The differentefficiency figures applying for this case are calculatedefficiency values for the production of the heat, for itsdistribution through the building and its emission in theroom. The room efficiency is the one that has thebigger influence on the total system efficiency.INTRODUCTIONThe Directive on the energy performance of buildings iscarried out in order to be used together with a numberof EN-standards. The main goal of the Directive is topromote the improvement of the energy performance ofbuildings within the Community, taken into accountoutdoor climatic and local conditions as well as indoorclimate requirements and cost-effectiveness. The mainfocus is on reducing the primary energy use and theassociated CO 2 emission of buildings.Figure 1 shows how the Primary energy use iscalculated based on all the steps where the energy ischanging its nature from the source to the end use. Inthe current case, the energy calculations are performedfor the systems within the building to be able tocalculate the delivered energy to the building. Thismeans that the building substation with the heatexchangers and tap water storage are included.In the current scenario, all the losses before the heat isdelivered to the building are included in the primaryenergy factor (PEF) for the delivered heat. In case ofconsidering the complete scenario, the boundaries forthe energy performance indicators are the wholeenergy chain from the source to the end use. In thiscase, if a CHP plant is represented, the ―power bonusmethod‖ (EN 15316-4-5) should be used. This methodis giving the produced district heat a bonus for theelectricity produced assuming that this electricityreplaces electricity production with a high PEF-value.According to the implementation of EPBD, it is crucialthat the system borders are clearly defined so that thedelivered energy is doubtlessly defined.Calculation of Primary Energy use according to EPBD and mandated EN-standardsPrimary energy use = DEdh • PEFdh (f (x,y,z)) +DEel • PEFel (f (x,y,z)) = (Weighted delivered energy indicator (kWh/m 2 )) • A CDelivered Energy (DE)dh +el(PEF might be PEF R or PEF T depending on purpose)( A C = conditioned floor Area )Net energy demandPrimary energy use calculated by PEF(x,y,z)ElectricityHot tap waterAir and room +heating systemDH substationEnd usedemand !HeatingsystemsDistribution andTransmission(el)Delivered energy (el)Delivered energy (dh)Distribution andTransmission (dh)•CHP-plantHeat boilersStorageGenerationTransformationEnergy carrier (z)Energy carrier (y)Energy carrier (x)TransportationWaste coll.LoggingExtractionProcessingStorage2010/ 04/RUCalculating end use and losses by ENstandards worked out according to mandate from the EU CommissionHeating systems efficiencyCalculating directionSystem border for the energy performance indicators is the whole energy chain from the source to the end useFigure 1.- Sketch of the calculation of Primary Energy use according to EPBD and mandate EN-standardsFigure 1 Sketch of the calculation of Primary Energy Use according to EPBD and mandate EN-standards238