12th International Symposium on District Heating and Cooling

DATA AND VALUESIn the spring of 2009, the authors, both being lecturersat Halmstad University in Sweden, initiated a pre-studyto be carried out by two Bsc-students at theirdepartment [4]. The study was two-fold in regard ofgathered data. Partly it delivered previously assembledand crucial data on plot ratios, land areas and trenchlengths in 39 detached house districts heating schemesin Sweden [5], allowing estimations of effective widthsin these districts, see Figure 2, and partly own collecteddata.Effectivewidth (w)[m]250200150100500y = 27,802x -0,37310,0 0,1 0,2 0,3 0,4Plot ratio (e)DetachedhousesPower(Detachedhouses)Figure 2. Effective width as a function of plot ratio in 39district heating schemes in detached house districts inSweden. Source: [5]The own collected data of the study refers to data from34 district heating schemes in multi-family housingdistricts in the Swedish cities of Halmstad andGothenburg, see Figure 3.Effectivewidth (w) [m]400350300250200150100500y = 56,622x -0,410 0,5 1 1,5Plot ratio (e)MultifamilyhousesPower(Multifamilyhouses)Figure 3. Effective width as a function of plot ratio in 34district heating schemes in multi family housing districts inSweden. Source [4]On the basis of these results, and when combined inone common graph, see Figure 4, a power functionwere established and presented in [2]. Note that (e)refers to plot ratio values, not to the natural logarithmbase (e);0.15w 61.8 e[m] (9)As can be seen in Figure 4, the graph suggests aconvergence at effective width values at 60 meters forThe <strong>12th</strong> <strong>International</strong> <strong>Symposium</strong> on District Heating and Cooling,September 5 th to September 7 th , 2010, Tallinn, Estonia130plot ratio values above 1. This would indicate that therelationship between high dense inner city land areasand the length of the required piping grid in such areasis constant.Still, if plotted explicitly, the function does not convergeat any effective width value, no matter how far the plotratio value is extended, but the rate of divergencedecreases with higher plot ratio values. Since plotratios values above 3 are considered extremely rare,effective width values within high dense inner city areas(plot ratio values above 0.5) can be anticipated to befound in the interval of 50 < w < 60 meters.Effectivewidth (w) [m]400350300250200150100500y = 61,838x -0,14950 0,5 1 1,5Plot ratio (e)Detachedand MFhousesPower(Detachedand MFhouses)Figure 4. Effective width as a function of plot ratio,combination of 39 district heating schemes in detachedhouse districts and 34 in multi family housing districts inSweden. Datapoints merged from figure 2 and 3.EffectiveWidth (w) [m]1401301201101009080706050400 0,5 1 1,5 2 2,5 3Plot Ratio (e)Figure 5. Effective width as a function of plot ratio by useof eq. (9).For plot ratio values below 0.5, on the other hand(outer city area and park areas), the relationship is byno means constant, but diverges rapidly with increasedeffective width values as a consequence. At a plot ratiovalue of 0.04 the effective width reaches a value of 100meters, and the curve reveals that the increase ofeffective width values at even lower plot ratio valuesbelow 0.04 renders values above 100 meters andbeyond.The graph characteristics of Figure 5 has significancefor estimations of district heat distribution capital cost