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, EstoniaDISTRICT HEATING AS PART OF THE ENERGY SYSTEM:AN ENVIRONMENTAL PERSPECTIVE ON ‘PASSIVE HOUSES’AND HEAT REPLACING ELECTRICITY USEMorgan Fröling 1,2 and Ingrid Nyström 31Engineering and Sustainable Development, Mid Sweden University, Östersund, Sweden2 Chemical Environmental Science, Chalmers University of Technology, Göteborg, Sweden3 CIT Industriell Energianalys, Göteborg, SwedenABSTRACTEnergy use for space heating, hot tap water and otherheat use at comparatively low temperature levelsrepresent a substantial part of the total energy use inSweden and countries with similar climate. It is thus ofimportance to meet this demand in a way generating assmall environmental impact as possible. However, it ispossible to create a system with higher environmentalimpacts with energy efficient buildings compared toless energy efficient buildings through choice of lessgood energy carriers. It is not enough that theindividual parts of a system are good and efficient togive a low environmental impact; the parts must beconnected into the system in a good way.From environmental perspective energy efficientbuildings and district heating don‘t oppose each other– good parts connected in a good system will give anoptimal. The results from the study of the three items ofhousehold equipment show possibilities for districtheating to be an alternative with good environmentalperformance, but not under all heat generationregimes.INTRODUCTIONIt is of importance to meet for space heating, hot tapwater and other heat use at comparatively lowtemperature levels in a way generating as smallenvironmental impact as possible. This can be done byincreasing the efficiency in the use phase and in theheating systems of buildings as well as through heatgeneration systems with low environmental impact.During recent years there has been a focus on houseswith low need of space heating, low energy houses or―passive houses‖. In such buildings the heat from theincoming sun radiation together with body heat frompeople living in the houses and different householdequipment will cover the whole or at least substantialparts of the space heating need over a year (extraheating might be needed during the coldest days of ayear). Hot tap water still need to be heated. For parts ofthe year this can be achieved by solar panels, but thereis a need for extra heating during winter. This mightresult in the extra heating demand being covered byelectricity, directly or indirectly.Increased energy efficiency is in itself a desirable goalfor a society – it increases the robustness of the energysystem and the possibilities for a resource efficient andmore sustainable energy system in the long run.However, it is possible to create a system with higherenvironmental impacts with energy efficient buildingscompared to less energy efficient buildings throughchoice of less good energy carriers. It is not enoughthat the individual parts of a system are good andefficient to give a low environmental impact; the partsmust be connected into the system in a good way.Thus it is important to identify system solutions thatavoids sub optimization and gives us energy efficientbuildings and an efficient energy system with goodenvironmental performance.In a synthesis studies within the framework ofChalmers Energy Center [1] the role of district heatingin a future society with more energy efficient buildingshave been investigated. Here we report on generalfindings of this study with a special focus on theenvironmental performance of the possibility to convertsome household electricity use into district heating - forthe use in dish washers, washing machines and tumbledriers [2]. The environmental performance is studiedusing life cycle assessment methodology and differentassumptions regarding electricity and district heatinggeneration.DISTRICT HEATING – DEMAND SIDEThere are today several drivers in the direction of lowertotal heat market for district heating in future [1].Among possible such drivers in Sweden are:Warmer climate (due to climate change)Higher energy pricesIncreased environmental awarenessIncreased energy efficiency of existing buildingstockLimited amounts of new housingNew housing more energy efficientHowever, there are also possible drivers for a largerheat market in future, e.g.:Increased wealth giving larger living space perperson and higher demands on comfort202