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, Estoniabuilding mass will start to interact with the air mass andthus stabilizing the continuing temperature drop, i.e. thelong time constant [10].The influence of external and internal free heat is largeenough that when these heat sources interact withother parts of the thermal process it hides shorter heatload reductions in the ambient temperature. This canbe seen in Figure 7 where it is shown that although theaverage indoor temperature is not noticeably affectedthere is still a somewhat larger deviation in the indoortemperature which implies that there is indeed a higherlevel of temperature flux within the air mass and thatthis is triggered by the heat load reductions. Thecontrol policies used during this work obviously set ahigh bar for the control system to handle, but as theaverage hardware develops it should be possible toimplement such techniques on a larger scale.Figure 8 gives another clear indication of just howsubstantial such sources of free energy can be. Thisextra heating due to solar radiation through thewindows directly interacts with the mass of air insidethe building, thus raising the temperature.In addition to being able to help save energy usage in abuilding temporary heat load reductions also form thebackbone of DSM and LC, in which the goal is tomanage the heat load (kW) rather than the energyusage (kWh).FUTURE WORKIn the future we plan to further develop models in orderto dynamically estimate the temperature flux withinbuildings and develop theoretical and practicalinterfaces for incorporating this data dynamically intothe control systems.ACKNOWLEDGEMENTThis work has been financed by Blekinge Institute ofTechnology and NODA Intelligent Systems AB.REFERENCES[1] N. Björsell, Control strategies for heating systems,University-College of Gävle-Sandviken.[2] F. Wernstedt, P. Davdisson and C. Johansson,―Demand Side Management in District HeatingSystems‖, in Proc. Of Sixth <strong>International</strong>Conference on Autonomous Agents and MultiagentSystems, Honolulu, Hawaii, USA, 2007.[3] L. Jensen. ―Nattsänkning av temperatur I flerbostadshus‖,R64:1983, Byggforskningsrådet, 1983(In Swedish).[4] H. Lindkvist and H. Wallentun. ―Utvärdering av niofjärrvärmecentraler i Slagsta‖ Report ZW 04/05,ZW Energiteknik, 2004 (In Swedish)[5] F.B. Morris, J.E. Braun and S.J. Treado ―Experimentaland simulated performance of optimalcontrol of building thermal storage‖, ASHRAETransactions, Vol. 100, No. 1, 1994[6] E. Isfält and G. Bröms. ―Effekt- och energibesparinggenom förenklad styrning och drift avinstallationssystem I byggnader‖, ISRN KTH/IT/M--22--E. Institutionen för Installationsteknik. KungligaTekniska Högskolan, 1992. (In Swedish)[7] S. Ruud. ―Energimyndighetens program förpassivhus och lågenergihus‖ Remissversion 2009-03-10. Forum för Energieffektiva byggnader, 2009.(In Swedish)[8] F. Wernstedt and C. Johansson. ―Demonstrationsprojektinom effekt och laststyrning‖. ISBN 978-91-7381-041-8, The Swedish District HeatingAssociation, 2009. (In Swedish)[9] J. Skoog, ―PM avseende komfort‖, ÅF-InfrastrukturAB, 2005. (In Swedish)[10] C. Norberg. ―Direktverkande elradiatorers regleringoch konstruktion‖ Vattenfall Utveckling AB, Rapportnr F-90:5, Älvkarleby, 1990. (In Swedish)[11] L. Olsson Ingvarsson, S. Werner. ―Building massused as short term heat storage‖ in Proceedings ofThe 11th <strong>International</strong> <strong>Symposium</strong> on DistrictHeating and Cooling. Reykjavik, Iceland, 2008.249