CombiSol project. Solar Combisystems Promotion and Standardisation. D4.4 : Comparison of results of all monitored plants.

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1 CombiSol project Solar Combisystems Promotion and Standardisation D4.4 : Comparison of results of all monitored plants Created by: Thomas Letz, Xavier Cholin, Guillaume Pradier (INES Education) Contributions from Chris Bales, Johan Heier (SERC), Alexander Thür, Johann Breidler (AEE Intec), Barbara Mette, Jens Ullmann (ITW) (2010) Date 2010/11/28 Version Final Revision 1 The sole responsibility for the content of this publication lies with the authors. It does not necessarily reflect the opinion of the European Union. Neither the EACI nor the European Commission are responsible for any use that may be made of the information contained therein.

2 CONTENTS Symbol list... 3 Table list... 3 Figure list... 4 Introduction Presentation of monitored plants List of monitored systems Location of monitored systems Statistics on monitored systems Monitoring equipment installed Irradiation meters Final energy meters Flow meters Temperature sensors Data loggers Extrapolation of measurements Results in Austria Location of monitored systems Energy balance of the heat water stores Annual results at the auxiliary heater outlet Thermal fractional energy savings Annual results at the auxiliary heater inlet Thermal fractional energy savings Extended fractional energy savings Results in France Location of monitored systems Energy balance of the heat water stores Annual results at the auxiliary heater outlet Thermal fractional energy savings Annual results at the auxiliary heater inlet Thermal fractional energy savings Extended fractional energy savings Results in Germany Location of monitored systems Annual results at the auxiliary heater outlet Thermal fractional energy savings Annual results at the auxiliary heater inlet Thermal fractional energy savings Extended fractional energy savings Results in Sweden Location of monitored systems Energy balance of the heat water stores Annual results at the auxiliary heater outlet Thermal fractional energy savings Annual results at the auxiliary heater inlet Parasitic electricity Results of Solcombi2 French project Location of monitored systems Energy balance of the heat water stores Annual results at the auxiliary heater outlet Thermal fractional energy savings Annual results at the auxiliary heater inlet Thermal fractional energy savings Extended fractional energy savings Energy produced by the solar loop and energy savings Synthesis D4.4: Comparison of results of all monitored plants page 2

3 7.... General comments Domestic Hot Water distribution temperatures Immersed DHW heat exchanger Tank in tank General considerations Results sorted by country Results sorted by manufacturer Results sorted by system type Comparison between compact systems and systems assembled on site Comparison between laboratory tests and on site monitoring Outcomes Bibliography Detailed results of monitored systems Symbol list Symbol Definition Unit A area m² Fsav fractional energy savings - FSC fractional solar consumption - Suffixes aux c ext auxiliary solar collector extended (thermal and electrical) Table list Table 1 : Number of monitoring equipments in operation (status on 2010, 30 th of November)... 5 Table 2 : Some statistics (37 systems, 2010 May)... 7 Table 3 : Main characteristics of monitored systems in Austria Table 4 : Storage (and pipe) losses of the Austrian monitored systems Table 5: Yearly indicators for monitored systems in Austria Table 6: Parasitic electricity for monitored systems in Austria Table 7 : Main characteristics of monitored systems in France Table 10: Parasitic electricity for monitored systems in France Table 11 : Main characteristics of monitored systems in Germany Table 12: Yearly indicators for monitored systems in Germany Table 13 : Main characteristics of monitored systems in Sweden Table 14 : Storage (and pipe) losses of the Swedish monitored systems Table 15: Yearly indicators for monitored systems in Sweden Table 16: Parasitic electricity for monitored systems in Sweden Table 17 : Characteristics of monitored houses (Manufacturer A) Table 18 : Characteristics of monitored houses (Manufacturer B) Table 19 : Comparison between indicators coming from laboratory tests and from on site monitoring D4.4: Comparison of results of all monitored plants page 3

4 Figure list Figure 1: Location of monitored systems in Austria, France, Germany and Sweden... 6 Figure 2: Typology of monitored systems... 7 Figure 3: Heated area of monitored houses... 8 Figure 4: Systems sizes (storage volume according to collector area)... 8 Figure 5: Auxiliary energy used in the monitored systems... 9 Figure 6: Type of DHW preparation... 9 Figure 7: Number of water stores Figure 8: Type of solar collector Figure 9: Number and type of space heating loops Figure 10: Location of monitoring equipment installed Figure 11: Evolution of extrapolated indicators (missing winter months) Figure 12: Evolution of extrapolated indicators (missing summer months) Figure 13: Location of monitored systems in Austria Figure 14: Yearly energy losses of water stores in Austria Figure 15: Monthly energy losses of water stores in Austria Figure 16: Thermal fractional energy savings (auxiliary heater outlet) versus FSC Figure 17: Thermal fractional energy (auxiliary heater inlet) savings versus FSC Figure 18: Thermal fractional energy (auxiliary heater inlet) savings versus FSC Figure 19: Extended fractional energy savings versus FSC Figure 20: Location of monitored systems in France Figure 25: Location of monitored systems in Germany Figure 26: Thermal fractional energy savings (auxiliary heater outlet) versus FSC Figure 27: Location of monitored systems in Sweden Figure 28: Yearly energy losses of water stores in Sweden Figure 29: Thermal fractional energy savings (auxiliary heater outlet) versus FSC Figure 30: Location of monitored systems in France (project Solcombi2) Figure 31: Yearly energy losses of water stores in France (project Solcombi2) Figure 32: Performances of monitored systems in France evaluated at the auxiliary heater outlet Figure 33: Performances of monitored systems in France evaluated at the auxiliary heater inlet Figure 34: Measured parasitic electricity used versus reference one Figure 35: Performances of monitored systems in France evaluated at the auxiliary heater outlet Figure 36: Specific solar contribution in the collector loop and specific auxiliary energy savings Figure 37: Solar contribution in the collector loop and auxiliary energy savings Figure 38: Evolution of tap water temperature (immersed heat exchanger, low demand) Figure 39: Evolution of tap water temperature (immersed heat exchanger, high demand) Figure 40: Evolution of tap water temperature (tank in tank, high demand) Figure 41: Results sorted by country Figure 42: Results sorted by manufacturer Figure 43: Results sorted by system type Figure 44: Compact systems compared to systems assembled on site Figure 45: Comparison between laboratory and on site monitoring results D4.4: Comparison of results of all monitored plants page 4

5 Introduction In four countries (Austria, France, Germany and Sweden), several Solar Combisystems (SCS) have been equipped with monitoring equipment described in D4.1: Specification for monitoring, collection and evaluation of results [1]. This report presents results obtained thanks to the methodology described in D4.2: Guidelines for calculation of savings indicators [2]. It gives as an output a value for the annual fractional energy savings F sav according to the Fractional Solar Consumption FSC [3]. This method is based on the evaluations of monthly balances based on energy measurements. F sav is evaluated by comparison between the auxiliary energy used by the SCS and the one used by a conventional system without solar collector, using the same energy. At the end of the project, results are not available for all monitored plants, because for some of them, the installation of the monitoring equipment has been delayed, due to the difficulty to identify volunteers, to have the installers working in due time and to some faulty installations of the monitoring equipment. But many valuable results have been obtained, and the main role of heat losses in different parts of the system has been pointer out. Annual indicators have been obtained for 31 of them (69 %). Results from a French evaluation project called Solcombi2 have been integrated in this report, because they give an overview of results reached with compact prefabricated systems. 1. Presentation of monitored plants 1.1. List of monitored systems The objective was to install 45 monitoring equipments on 45 systems. At the end of the project, it has been reached at 91 % (Table 1). Many different SCS concepts of 9 manufacturers have been equipped. Manufacturer Germany France Austria Sweden Total Manufacturer Manufacturer Manufacturer Manufacturer Manufacturer Manufacturer Manufacturer Manufacturer Manufacturer /11/ % 93 % 100 % 100 % 91 % Table 1 : Number of monitoring equipments in operation (status on 2010, 30 th of November) Monitored systems are factory made systems. That means that manufacturers sell all components necessary to build the system (solar collectors, water store(s), solar pump group, space heating pump group, fresh water unit, control devices and optionally auxiliary boiler). These prefabricated units are connected on site by the installer, who has to decide where these components will be placed, and who will realise all pipes connections between them. D4.4: Comparison of results of all monitored plants page 5

6 But none of the monitored systems is a compact system in the sense of what is described in report D2.4: Updated State of the Art Report of Solar Combisystems Analysed within CombiSol, from page 63 [1] Location of monitored systems Figure 1 shows the location of monitored systems at a European level. Figure 1: Location of monitored systems in Austria, France, Germany and Sweden 1.3. Statistics on monitored systems This paragraph presents some statistical elements on the monitored systems. Figure 2 shows the repartition of systems between the different categories of hydraulic diagrams described in [1]: In Sweden, all monitored systems have the same hydraulic scheme, with a special 4-way valve on the space heating loop, which allows taking heat from the store at different levels according to the temperatures in the different layers. In France, no systems with an external heat exchanger for DHW preparation have been measured. D4.4: Comparison of results of all monitored plants page 6

7 Type of system 120% 100% Percentage of Plants 100% 80% 60% 40% 43% Number of plants 40% 40% 33% 36% 33% 20% 0% 17% 14% 17% 10% 10% 7% A1 A2 B1 B2 B2 V4V C1 C2 Austria France Germany Sweden Figure 2: Typology of monitored systems Table 2 and figure 3 show the reached global data of the instrumented systems, compared with the initial objectives. minimum mean maximum Heated area (m²) : objectives Heated area (m²) Number of inhabitants 2 3,3 5 Total gross collector area (m²) : 8-30 objectives Total gross collector area (m²) 8,1 13,8 32,2 Total volume of the water store(s) Table 2 : Some statistics (37 systems, 2010 May) In France, the mean value is coherent with the objectives. In other countries, and especially in Sweden, monitored houses are quite big. In Germany and Austria, the mean heated area is near of the upper value of the objective range. In Sweden, the mean value is even higher than this limit. Considering the way the systems are dimensioned, it appears clearly that there is no real obvious link between the heated area, the climate and the solar collector size: figure 4 shows that Swedish systems have small collector area compared to Austrian ones, and even to French ones. This will be a reason for much lower fractional energy savings in Sweden compared to other countries. D4.4: Comparison of results of all monitored plants page 7

8 Heated area Objectives (m²) minimum mean maximum Austria France Germany Sweden Figure 3: Heated area of monitored houses Specific Storage Volume Objectives 3000 Storage (l) 100 ltr/m² 70 ltr/m² ltr/m² W 30 ltr/m² 500 Solar collector Area (m²) Austria France Germany Sweden Figure 4: Systems sizes (storage volume according to collector area) Figure 5 shows that most monitored systems use wood pellets as auxiliary energy. In Sweden, wood pellet is the only auxiliary energy used, sometimes with wood logs as complement. Natural gas is the second used energy, especially in France. D4.4: Comparison of results of all monitored plants page 8

9 Type of auxiliary energy used 120% Percentage of plants 100% 100% 80% 64% 60% 50% 40% 30% 33% 30% Number of plants 20% 20% 17% 14% 14% 10% 7% 10% 0% Wood pellets Fuel oil Heat pump Natural gas Propane District heating Austria France Germany Sweden Figure 5: Auxiliary energy used in the monitored systems Regarding the type of DHW preparation (figure 6), heat exchanger immersed in the main water store is the most common system. It is the case for all Swedish systems. Type of DHW preparation 120% 100% Percentage of Plants 100% 80% 60% 50% 50% 40% 43% 33% 40% 36% Number of plants 20% 10% 17% 7% 14% 0% Tank in tank External heat exchanger Immersed heat exchanger Tank-in-tank system + Separate DHW tank Immersed heat exchanger + Small separate DHW tank Austria France Germany Sweden Figure 6: Type of DHW preparation External heat exchangers for DHW preparation are not met in the monitored systems in France and Sweden. In France, some systems have an additional separate DHW tank. In one case, DHW is preheated by the auxiliary heat pump in a tank in tank device, and then heated up to the desired hot water temperature by an additional electrical tank. In another case, the main storage device is only heated up with solar energy. DHW is preheated with an immersed heat exchanger, and then heated up to the desired hot water temperature by an additional tank heated connected to the auxiliary gas boiler. Most systems have only one water store (figure 7). This is a favourable point toward the promotion of standardized systems, having less storage and pipes heat losses. D4.4: Comparison of results of all monitored plants page 9

10 120% Percentage of plants Number of Heat water stores incl. DHW tank 100% 100% 80% 70% 69% 70% 60% 40% 30% Number of plants 20% 19% 20% 13% 10% 0% Austria France Germany Sweden Figure 7: Number of water stores Almost all systems use flat plate collectors. Only in France six systems are equipped with vacuum tube collectors. One manufacturer developed a special control strategy to protect the collector against freezing, with no use of glycol mixture: during period with low ambient temperatures, the solar loop pump is started in order to send a little amount of heat from the water store to the collector and then prevent it for freezing. In order to decrease the volume of liquid in the solar collector, vacuum tubes are used. Four systems of this type are monitored in France. Type of solar collector 120% Percentage of Plants 100% 100% 100% 100% 80% 60% 57% 40% 43% 20% 0% Flat Plate Vacuum tubes Austria France Germany Sweden Number of plants Figure 8: Type of solar collector Almost half of systems are equipped with two space heating loops. Systems using low temperature space heating loops, like floor or wall heating, which are a favourable factor to increase efficiencies of solar heat collection, are a minority. D4.4: Comparison of results of all monitored plants page 10

11 Type of space heating loops 100% 90% 80% 70% Percentage of Plants 67% 80% 60% 50% 40% 40% 50% 30% 29% 20% 10% 20% 17% 14% 10% 10% 7% 17% 10% 20% 10% 0% Floor heating (1 loop) Radiators (1 loop) Floor heating (2 loops) Floor heating + radiators Radiators (2 loops) Austria France Germany Sweden Number of plants Figure 9: Number and type of space heating loops 1.4. Monitoring equipment installed Monitoring equipment described in [2] has been installed on all systems (figure 10). C5 Auxiliary boiler C1 C1' Domestic Hot Water θi Ic θe C3' Solar collector Space heating loops C4' C4'' C4 C3 C2 Controller Wsol C7 Swimming pool C6 Discharge loop ENERGY SUPPLY TRANSFER, STORAGE, CONTROL AND DISTRIBUTION Figure 10: Location of monitoring equipment installed LOAD D4.4: Comparison of results of all monitored plants page 11

12 A datalogger stores with a small time step (generally 1 minute to 6 minutes) temperatures, flows and energies calculated on the different loops, where meters described in the following list are mounted: C1 : oil-, gas- or electric meter C1' to 7 : heat meters Ic : irradiation θ i : inside temperature θ e : ambient temperature W sol : parasitic electricity Hereunder are given some examples of installed meters, sensors and data loggers, used in the different countries. Technical requirements of these devices are given in [2] Irradiation meters Final energy meters Irradiation sensor Spektron 300, TRITEC International AG Electrical meter DDS Electrical meter MCI Contax 32 A Gas meter Actaris Oil meter Sappel VZO Flow meters Ultrasonic flowmeter Sharky FS 474 Volumetric flowmeter Sensus 620 C Turbine flowmeter Hydrometer E-THXKA/444 High temperature turbine flowmeter SENSUS AN 130 D4.4: Comparison of results of all monitored plants page 12

13 Temperature sensors Indoor temperature sensors Prosensor Hobo PT1000 temperature sensors HTF, RTF1, ATF1 S+S Regeltechnik Data loggers Data logger NAPAC Rio Data logger ENNOVATIS Smartbox 1.5. Extrapolation of measurements In the D4.2 document [3], a procedure is described that allows to extrapolate yearly indicators (FSC and F sav,th ) from a shorter monitoring period, provided that this period includes at least three months with space heating. Real values 0,80 0,70 0,60 0,50 0,40 0,30 0,20 0,10 0,00 M onitoring period Fractional Solar Consumprion Thermal fractional energy savings Jun/ Oct M ay/ Oct M ar/oct Feb/Oct Jan/Oct Dec/ Oct Year 10 0 % 90% 80% 70% 60% 50% 40% 30% 20% 10 % 0% Thermal fractional energy savings Thermal fractional energy savings Range of properly working sytems FSC 0,0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1,0 Figure 11: Evolution of extrapolated indicators (missing winter months) Figure 11 shows the evolution of yearly indicators extrapolated from a period shorted than one year, compared to the real yearly values. For the two first evaluation periods (Jun/Oct and May/Oct), there are too few months with space heating, so the extrapolated results are far from the real one. At the opposite, figure 12 shows that with a few missing months in summer period, but with a longer measurement period in winter, extrapolated indicators are quite near to the real ones. D4.4: Comparison of results of all monitored plants page 13

14 Real values 0,40 0,35 0,30 0,25 0,20 0,15 0,10 0,05 0,00 M onitoring period Fractional Solar Consumprion Thermal fractional energy savings Nov/M ar Nov/Apr Nov/M ay Nov/Jun Nov/Jul Nov/Aug Nov/Sep Year 10 0 % 90% 80% 70% 60% 50% 40% 30% 20% 10 % 0% Thermal fractional energy savings Thermal fractional energy savings Range of properly working sytems FSC 0,0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1,0 Figure 12: Evolution of extrapolated indicators (missing summer months) 2. Results in Austria 2.1. Location of monitored systems Figure 13: Location of monitored systems in Austria In Austria, monitored systems are mostly gathered in the region of Graz (Styria), where AEE Intec has its office building. Table 3 shows the main characteristics of Austrian monitored systems. System Heated Auxiliary Solar collector Storage Space heating loop N type area energy area Tilt angle Orientation volume Space heating loop 1 2 (m²) (m²) ( ) ( ) (l) 1 A2 110 district heating 18, , 0, radiators radiators 2 C2 220 natural gas 20, floor heating floor heating 3 C2 300 air heat pump floor heating 4 B2 180 wood pellets 16, radiators 5 6 C2 180 natural gas 20, radiators + floor heating C1 100 fuel oil 20, radiators floor heating 7 C2 300 wood pellets (15)/-20(3) 1000 floor heating radiators 8 B2 140 wood pellets 18, radiators radiators 9 10 B2 270 natural gas 32, wall- and floor heating B2 270 geothermal heat pump 24, wall- and floor heating radiators Table 3 : Main characteristics of monitored systems in Austria D4.4: Comparison of results of all monitored plants page 14

15 2.2. Energy balance of the heat water stores Heat losses of the water store are evaluated with following energy balance, taking the numbers of heat meters in figure 10: Equation 1 Heat losses of the water store =C1' + C4 C2 C3 C3' C5 These losses also include all losses of pipes located between the tank and the heat meters. In some cases, when pipe design is not optimized, the length of all pipes can exceed several tens of meters! Figure 14 and table 4 show the measured heat losses of the water store compared to the reference losses. It must be pointed that some figures are given for periods shorter than one year. The ratio between the measured losses and the reference ones is very high, except for systems n I9, II7 and III1 using wood pellets as auxiliary energy. In these cases, the volume of the reference water store is larger than the one for other energies (natural gas, oil, etc ). Analysis period Heat losses of the water store (incomplete year) ratio number of beginning end monitored reference monitored / rooms n Auxiliary reference I5 District heating Dec 2009 Nov I7 Natural gas Mar 2010 Nov I8 Air Heat Pump + Electrical heater Feb 2010 (outlet) Apr 2010 (inlet) Nov I9 Wood boiler (pellets) Apr 2010 Nov II1 Natural gas Dec 2009 (outlet) Jan 2010 (inlet) Nov II5 Fuel oil Dec 2009 Nov II7 Wood boiler (pellets) Dec 2009 Nov III1 Wood boiler (pellets) Dec 2009 Nov III2 Natural gas Dec 2009 Nov III3 Geothermal heat pump Feb 2010 Nov Table 4 : Storage (and pipe) losses of the Austrian monitored systems The ratio is very high for two reasons: in summer time, the total volume of the storage is very hot, due to large solar gains, but also to all losses of pipe connections, thermal bridges etc (see D5.4 report [5]). the volume of the storage is generally much larger than the one of the reference system, and consequently the heat losses area (except systems I9, II7, III1) kwh monitored reference ratio monitored / reference ratio months 10 months 8 months 10 months 2 0 I5 I7 I8 I9 II1 II5 II7 III1 III2 III3 Figure 14: Yearly energy losses of water stores in Austria 0 D4.4: Comparison of results of all monitored plants page 15

16 Figure 15 shows a deeper look in heat losses of water stores: for systems using short running time auxiliary heater (I5, II1, II5, III2), heat losses are much higher in summer, because very high temperatures are brought by solar energy in the whole tank, while in winter time, only the upper part of the tank is heated by auxiliary energy at a lower temperature. I5 (District heating) : Reference and real losses II1 (Natural gas) : Reference and real losses reference reference kwh real ratio ratio kwh real ratio Dec 09 Jan 10 Feb 10 Mar 10 ratio Apr 10 May 10 Jun 10 Jul 10 Aug 10 Sep 10 Oct 10 Nov 10 Dec 09 Jan 10 Feb 10 Mar 10 Apr 10 May 10 Jun 10 Jul 10 kwh Aug 10 Sep 10 Oct 10 Nov II5 (Fuel) : Reference and real losses reference real ratio ratio kwh II7 (Pellets boiler) : Reference and real losses reference real ratio Dec 09 Jan 10 Feb 10 Mar 10 Apr 10 May 10 Jun 10 Jul 10 Aug 10 Sep 10 Oct 10 Nov 10 Dec 09 Jan 10 Feb 10 Mar 10 Apr 10 May 10 Jun 10 Jul 10 Aug 10 Sep 10 ratio Oct 10 Nov III1 (Pellets boiler) : Reference and real losses reference real ratio III2 (Natural gas) : Reference and real losses reference real ratio kwh ratio kwh ratio Dec 09 Jan 10 Feb 10 Mar 10 Apr 10 May 10 Jun 10 Jul 10 Aug 10 Sep 10 Oct 10 Nov 10 Dec 09 Jan 10 Feb 10 Mar 10 Apr 10 May 10 Jun 10 Jul 10 Aug 10 Sep 10 Oct 10 Nov 10 Figure 15: Monthly energy losses of water stores in Austria At the opposite, for systems where the tank is more or less also used as a buffer for the auxiliary heater (II7 and III1 with pellet boilers), monthly losses are more or less regular in the whole year or even far more important in winter than in summer. However, it must be pointed out the even in winter time, heat losses of the water store are much higher than the reference ones, and that a significant part of them is compensated by auxiliary energy, because solar gains are usually low at this period with less irradiation on the collector areas Annual results at the auxiliary heater outlet Table 5 shows the yearly indicators obtained for the ten systems in Austria. D4.4: Comparison of results of all monitored plants page 16

17 Beginning End n Auxiliary FSC Fsav,th Fsav,ext FSC Fsav,th Fsav, ext FSC Fsav,th FSC Fsav,th I5 District heating Dec 2009 Nov ,54 24% I7 Natural gas Mar 2010 Nov ,67 22% 0,97 36% 36% 0,72 16% 1,00 30% I8 Air Heat Pump + Electrical resistance Feb 2010 (outlet) Apr 2010 (inlet) Nov ,65 7% 0,92 28% NA 0,42-2% 0,55 1% I9 Wood boiler (pellets) Apr 2010 Nov ,56 21% 0,88 39% II1 Natural gas Analysis period Dec 2009 (outlet) Jan 2010 (inlet) For 1 year (extrapolation if needed) Analysis intlet For analysis period if < 1year For 1 year (extrapolation if needed) Nov ,55 7% 0,63 11% 11% 0,57 4% II5 Fuel Dec 2009 Nov ,59 21% 30% 0,59 21% II7 Wood boiler (pellets) Dec 2009 Nov ,33 6% III1 Wood boiler (pellets) Dec 2009 Nov ,54 18% III2 Natural gas Dec 2009 Nov ,24 12% 11% 0,25 9% Analysis outlet For analysis period if < 1year III3 Geothermal Heat Pump Feb 2010 Nov ,87 55% 0,93 61% NA 0,57 26% 0,70 32% Table 5: Yearly indicators for monitored systems in Austria Thermal fractional energy savings Figure 16 shows the fractional energy savings evaluated at the auxiliary heater outlet, according to the FSC value. 3 systems have results in the range of properly working systems, 4 are not far from this range, but 3 are quite low. For these 3 systems, the evaluations made have shown bad quality of insulation and/or many thermal bridges and connection pipes not insulated. They have also the worst ratio between monitored and reference heat losses (figure 14). On the diagram are shown some points obtained with a measurement period shorter than one year (blue points) and the corresponding points extrapolated to one year, according the extrapolation procedure described in [3]. The extrapolated points have lower values for FSC and F sav,th because some winter months are missing in the monitoring period. But the yearly extrapolated points have a relative position compared to the range of properly working systems nearly identical to the one for the incomplete year of measurements. 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% Fsav,th outlet Full year Extrapolation Incomplete year range of properly working systems 0% FSC -10% 0,0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1,0 Figure 16: Thermal fractional energy savings (auxiliary heater outlet) versus FSC 2.4. Annual results at the auxiliary heater inlet D4.4: Comparison of results of all monitored plants page 17

18 Thermal fractional energy savings Figure 17 shows the fractional energy savings evaluated at the auxiliary heater inlet, according to the FSC value. It is possible to determine this value only for systems where a reference can be defined. Therefore there are no points in the diagram for systems with wood pellets or district heating as auxiliary energy. 100% 90% 80% 70% Fsav,th inlet Full year Extrapolation range of properly working systems Incomplete year 60% 50% 40% 30% 20% 10% 0% -10% 0,0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1,0 Figure 17: Thermal fractional energy (auxiliary heater inlet) savings versus FSC Figure 18 shows the indicators at the auxiliary heater outlet and at the auxiliary heater inlet, sorted by type of auxiliary heater. The relative position of the points versus the range of properly working systems does not change much, except for the systems using a heat pump as auxiliary heater. The system using a ground coupled heat pump (III3) gets better results compared to the one using an air heat pump (I8). Detailed results show a seasonal performance factor between 4 and 4.5 (Annex 10:Detailed results of monitored systems). FSC 100% 90% Fsav,th outlet Natural gas Fuel oil I7 100% 90% Fsav,th inlet Natural gas Fuel oil I7 80% Heat Pump I8 80% Heat Pump I8 70% 60% II1 70% 60% II1 50% 40% II5 50% II5 30% 20% III2 40% 30% III2 10% 0% -10% 0,0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1,0 FSC III3 Range of properly working sytems 20% 10% FSC 0% 0,0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1,0 Figure 18: Thermal fractional energy (auxiliary heater inlet) savings versus FSC III3 Range of properly working sytems Extended fractional energy savings Extended fractional energy savings illustrate the global behaviour of the system, taking into account the parasitic electricity consumed by the system and evaluated at the primary energy level (electricity is weighted by the ratio primary energy/final energy equal to 2,5). Table 6 shows the measured values of parasitic electricity, and figure 34 gives the extended fractional energy savings versus FSC. There is no definition available to calculate reference parasitic electricity for systems using district heating and wood pellets boiler. D4.4: Comparison of results of all monitored plants page 18

19 For systems III2 and II1, reference values are very closed, but there is a larger difference between the measured values. System II5 has two space heating loops, and reference parasitic electric is consequently increased. Measured value is much lower. n Auxiliary Analysis period Parasitic electricity beginning end monitored reference number of space heating loops (kwh/year) Parasitic electricity I5 District heating Dec 2009 Nov NA 2 II1 Natural gas Dec 2009 Nov monitored reference II5 Fuel Dec 2009 Nov II7 Wood boiler (pellets) Dec 2009 Nov NA 2 III2 Natural gas Dec 2009 Nov I5 II1 II5 II7 III2 Table 6: Parasitic electricity for monitored systems in Austria 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% Fsav,ext Full year range of properly working systems 0% FSC -10% 0,0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1,0 Figure 19: Extended fractional energy savings versus FSC 3. Results in France 3.1. Location of monitored systems Table 7 shows the main characteristics of French monitored systems. N System type Heated area Auxiliary energy Solar collector area Tilt angle Orientation Storage volume Space heating loop 1 Space heating loop 2 (m²) (m²) ( ) ( ) (l) 1 B2 150 Wood pellets 16, Floor heating Radiators 2 B2 160 Natural gas 14, Floor heating Radiators 3 B2 140 Wood pellets 16, Floor heating 4 B2 120 Natural gas 12, Floor heating Radiators 5 B2 270 Heat pump Floor heating Towel dryer 6 A1 120 Propane 13, Floor heating 7 A2 138 Heat pump 12, Floor heating Floor heating 8 A1 170 Natural gas Floor heating Radiators 9 B1 180 Natural gas 8, Floor heating Air convectors 10 B1 120 Natural gas 10, Floor heating Radiators 11 A1 100 Natural gas Radiators 12 A1 90 Natural gas 9, Radiators 13 A1 235 Natural gas 10, Radiators 14 A1 180 Natural gas 10, Radiators Table 7 : Main characteristics of monitored systems in France D4.4: Comparison of results of all monitored plants page 19

20 In France, monitored systems are mostly gathered in the region of Chambery (Rhône-Alpes), where INES Education has its office building. Figure 20: Location of monitored systems in France Up to now, due to monitoring difficulties at the beginning of the project, results are available for 10 systems (1 with a complete year of measurements, 9 with the extrapolation procedure). Monitoring will continue in 2011, in order to achieve one year of measurements for 14 systems Energy balance of the heat water stores Figure 21 and table 8 show the measured heat losses of the water store, evaluated as described in paragraph 2.2, compared to the reference losses. For systems I-2 and I-3, the flow measured at the auxiliary boiler outlet is very variable, and the measurements done at this place are therefore not reliable. Losses are not presented in table 8. Analysis period Heat losses of the water store (incomplete year) ratio number of beginning end monitored reference monitored / n rooms Auxiliary reference I-1 Jun 10 Dec I-2 Jun 10 Dec 10 4 I-3 Natural gas Mar 10 Dec 10 5 I-4 Mar 10 Dec III-1 Dec 2009 Sep III-4 Heat pump Jun 10 Dec IV-3 HP + electrical boiler Jul 10 Dec IV-4 Jan 10 Dec V-1 Natural gas Apr 10 Dec V-2 Apr 10 Dec Table 8 : Storage (and pipe) losses of the French monitored systems The ratio between the measured losses and the reference ones is very high for two reasons: in summer time, the total volume of the storage is very hot, due to large solar gains, but also to all losses of pipe connections, thermal bridges etc (see D5.4 report [5]). D4.4: Comparison of results of all monitored plants page 20

21 the volume of the storage is generally much larger than the one of the reference system, and consequently the heat losses area monitored reference kwh ratio ratio monitored / reference I-1 I-2 I-3 I-4 III-1 III-4 IV-3 IV-4 V-1 V-2 0 Figure 21: Yearly energy losses of water stores in France 3.3. Annual results at the auxiliary heater outlet Table 9 shows the yearly indicators obtained for two systems in France. Analysis period Analysis intlet Analysis outlet For 1 year For 1 year For analysis period Beginning End For analysis period if < 1year (extrapolation if needed) (extrapolation if if < 1year n Auxiliary FSC Fsav,th Fsav,ext FSC Fsav,th Fsav, ext FSC Fsav,th FSC Fsav,th I-1 juin-10 déc-10 0,31 13% 0,31 17% 18% 0,34 9% 0,29 10% I-2 juin-10 déc-10 0,23 10% 0,20 12% 14% I-3 Natural gas mars-10 déc-10 0,27 12% 0,35 16% I-4 juil-10 dec 10 0,26-4% 0,21-4% -2% 0,28-5% 0,20-6% III-1 déc-09 sept-10 0,44 14% 0,42 15% 9% 0,45 10% 0,41 10% III-4 Heat pump juin-10 déc-10 0,59 35% 0,46 33% 0,34 6% 0,25 8% IV-3 Heat pump + electrical heater juil-10 déc-10 0,77 25% 0,73 29% 0,57 6% 0,45 5% IV-4 janv-10 déc-10 0,35 21% 18% 0,36 8% V-1 Natural gas avr-10 déc-10 0,22 1% 0,30 8% 10% V-2 avr-10 déc-10 0,38 26% 0,47 39% 33% 0,41 16% 0,46 24% Table 9: Yearly indicators for monitored systems in France Thermal fractional energy savings Figure 22 shows the fractional energy savings evaluated at the auxiliary heater outlet, according to the FSC value. On the diagram are shown some points obtained with a measurement period shorter than one year (blue points) and the corresponding points extrapolated to one year, according the extrapolation procedure described in [3]. Two systems have results far from the range of properly working systems: that indicates a non optimized valorisation of solar energy by the system due to heat losses, control strategy,. Others have their representative point either in the range of properly working systems, or not too far from it. D4.4: Comparison of results of all monitored plants page 21

22 100% 90% 80% 70% 60% 50% 40% 30% 20% Fsav,th outlet Full year Extrapolation range of properly working systems Incomplete year 10% FSC 0% 0,0-10% 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1,0 Figure 22: Thermal fractional energy savings (auxiliary heater outlet) versus FSC 3.4. Annual results at the auxiliary heater inlet Thermal fractional energy savings Figure 23 shows the fractional energy savings evaluated at the auxiliary heater inlet, according to the FSC value. It is possible to determine this value only for systems where a reference can be defined. 100% 90% 80% 70% 60% 50% 40% 30% 20% Fsav,th inlet Full year Extrapolation range of properly working systems Incomplete year 10% FSC 0% 0,0-10% 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1,0 Figure 23: Thermal fractional energy (auxiliary heater inlet) savings versus FSC Six systems are in the range of properly working systems, or very close of it. Two systems are under the range, but still providing energy savings compared to the corresponding reference systems. But two present poor results, with no savings or even negative fractional energy savings. As for Austrian systems, there is a clear correlation between fractional energy savings and thermal losses of the water store: each kwh wasted in thermal losses in winter time, when auxiliary energy is used, is a kwh missing in savings! D4.4: Comparison of results of all monitored plants page 22

23 Extended fractional energy savings Extended fractional energy savings illustrate the global behaviour of the system, taking into account the parasitic electricity consumed by the system and evaluated at the primary energy level (electricity is weighted by the ratio primary energy/final energy equal to 2,5). Table 10 shows the measured values of parasitic electricity, and figure 29 gives the extended fractional energy savings versus FSC. For systems III-1, IV-4, V-1 and V-2, the reference values are quite high, because it is calculated taking into account two space heating loops. Measured values are lower than this reference value for four systems, but for three others, they are similar or even higher than reference values: that indicate that the systems are not optimize in terms of the parasitic energy consumption, e.g. running times of pumps, efficiency the pump or control strategy. System III-1 is from the same manufacturer as the Austrian III-2 system (table 6) and shows the same overconsumption of parasitic electricity (it seems that it is linked to the pump of the boiler running during all the heating period). Analysis period Parasitic electricity number of beginning end monitored reference space heating n Auxiliary loops I-1 juin-10 déc (kwh/year) Parasitic electricity monitored reference I-2 juin-10 déc I-4 juil-10 déc III-1 Natural gas déc-09 sept IV-4 janv-10 déc V-1 avr-10 déc I-1 I-2 I-4 III-1 IV-4 V-1 V-2 V-2 avr-10 déc Table 10: Parasitic electricity for monitored systems in France In figure 29, only one system can be represented, because only this system has a complete year of measurements, and there exists no extrapolation procedure for parasitic electricity consumption. 100% 90% 80% 70% 60% Fsav,ext IV-4 Range of properly working sytems 50% 40% 30% 20% 10% FSC 0% 0,0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1,0 Figure 24: Extended fractional energy savings versus FSC 4. Results in Germany D4.4: Comparison of results of all monitored plants page 23

24 4.1. Location of monitored systems In Germany, monitored systems are mostly gathered in the region of Stuttgart (Baden Württemberg), where ITW, University of Stuttgart has its office building. Figure 25: Location of monitored systems in Germany Due to the difficulties to find solar combisystems for the on site monitoring, measurement results are only available for four systems (for one system results of one year measurements are available, for three systems an extrapolation of the measurement results have to be performed). Up to now (November 2010) three more systems have been equipped with measurement instruments. As the time period of measurement was too short, these results could not be evaluated within the Combisol project. The monitoring will continue in 2011, so that at least one year measurement results will be available for all 7 systems Table 11 shows the main characteristics of German monitored systems. N System type Heated Auxiliary Solar collector Storage area energy area Tilt angle Orientation volume Space heating loop 1 (m²) (m²) ( ) ( ) (l) Space heating loop A1 100 natural gas 9, floor heating B1 280 wood pellets (oil shut off) 12, floor heating radiators 3 B2 210 fuel oil 15, radiators 4 B1 180 natural gas 9, radiators 5 C2 240 natural gas 15, radiators 6 C2 220 fuel oil 15, radiators Table 11 : Main characteristics of monitored systems in Germany 4.2. Annual results at the auxiliary heater outlet Table 12 shows the yearly indicators obtained for four systems in Germany. D4.4: Comparison of results of all monitored plants page 24

25 Analysis period Beginning End n Auxiliary FSC Fsav,th Fsav,ext FSC Fsav,th Fsav, ext FSC Fsav,th FSC Fsav,th I1 Natural gas Janv 2010 Nov ,42 20% 0,45 21% I2 Natural gas June 2010 Nov 2010 II1 Natural gas Nov 2010 Nov 2010 II2 Oil Nov 2010 Nov 2010 For 1 year (extrapolation if needed) Analysis intlet For analysis period if < 1year For 1 year (extrapolation if needed) Analysis outlet For analysis period if < 1year III1 Wood boiler (pellets) May 2010 Nov ,53 12% 0,67 31% III2 Oil Dec 2009 Nov ,48 15% III3 Natural gas June 2010 Nov ,24 0% 0,49 23% Table 12: Yearly indicators for monitored systems in Germany Thermal fractional energy savings Figure 26 shows the fractional energy savings evaluated at the auxiliary heater outlet, according to the FSC value. On the diagram are shown some points obtained with a measurement period shorter than one year (blue points) and the corresponding points extrapolated to one year, according the extrapolation procedure described in [3]. 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% Fsav,th outlet Full year Extrapolation Incomplete year range of properly working systems 0% FSC -10% 0,0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1,0 Figure 26: Thermal fractional energy savings (auxiliary heater outlet) versus FSC One system has a complete year of data available. The corresponding point is located a little below the range of properly working systems. Only one month is missing for system I1 to have a complete year of measurements. The point is located in the range of properly working systems, for the monitoring period and for the extrapolated value. The two other points have a shorter monitoring period, with few months where space heating is used. Therefore extrapolation is more hazardous, and has to be checked Annual results at the auxiliary heater inlet D4.4: Comparison of results of all monitored plants page 25

26 Thermal fractional energy savings No data of the auxiliary energy used at the auxiliary inlet (gas, oil consumption, ) are available. The main reason for this is that the measurement equipment has not been installed in time. Furthermore, some of the measurement equipment did not work properly and the measurement results could not be used for the analysis Extended fractional energy savings For none of the system, the parasitic energy used was measured for a complete year, so that the extended fractional energy savings cannot be calculated. 5. Results in Sweden 5.1. Location of monitored systems In Sweden, monitored systems are mostly gathered in the region of Borlänge, where SERC has its office building. Figure 27: Location of monitored systems in Sweden D4.4: Comparison of results of all monitored plants page 26

27 System Heated Auxiliary Solar collector Storage Space heating loop N type area energy area Tilt angle Orientation volume Space heating loop 1 2 (m²) (m²) ( ) ( ) (l) 1 B2 V4V 240 wood pellets 10, radiators 2 B2 V4V 214 wood pellets 10, radiators 3 B2 V4V 300 wood pellets 10, radiators 4 B2 V4V 390 wood pellets 14, radiators + heat coil 5 B2 V4V 150 wood pellets 8, radiators 6 B2 V4V 176 wood pellets 8, radiators wood logs and B2 V4V wood pellets 9, radiators radiators 8 B2 V4V 120 wood pellets 9, radiators 9 B2 V4V 290 wood pellets 10, radiators + floor heating 10 B2 V4V 300 wood pellets 10, radiators Table 13 : Main characteristics of monitored systems in Sweden Due to monitoring difficulties, three systems could not produce valuable data. Analysis will be made on seven systems, which have all the same hydraulic scheme and the same type of auxiliary heater (wood pellet boiler) Energy balance of the heat water stores Figure 28 and table 14 show the measured heat losses of the water store, evaluated as described in paragraph 2.2, compared to the reference losses. The ratio between the measured losses and the reference ones is very high, except for systems n 1 and 5. Analysis period Heat losses of the water store n Auxiliary beginning end monitored reference ratio monitored / reference sb1 Sep 2009 Aug ,4 sb2 Oct 2009 Sep ,1 sb3 Oct 2009 Sep ,4 sb4 Wood boiler (pellets) Oct 2009 Sep ,6 sb5 Oct 2009 Sep ,4 sb6 Oct 2009 Sep ,1 sb10 Oct 2009 Sep ,8 Table 14 : Storage (and pipe) losses of the Swedish monitored systems The ratio is very high for two reasons: in summer time, the total volume of the storage is very hot, due to large solar gains, but also to all losses of pipe connections, thermal bridges etc (see D5.4 report [5]). the volume of the storage is generally much larger than the one of the reference system, and consequently the heat losses area D4.4: Comparison of results of all monitored plants page 27

28 6000 kwh monitored reference 3, ratio monitored / reference 3, ,5 2, ,5 ratio , ,5 0 sb1 sb2 sb3 sb4 sb5 sb6 sb10 Figure 28: Yearly energy losses of water stores in Sweden 0, Annual results at the auxiliary heater outlet Table 15 shows the yearly indicators obtained for seven systems in Sweden. Analysis period Analyse outlet beginning end Full year n name Auxiliary FSC Fsav,th Fsav,ext 1 sb1 Sep 2009 Aug ,17 6% 2 sb2 Oct 2009 Sep ,27 4% 3 sb3 Oct 2009 Sep ,27 5% 4 sb4 Wood boiler (pellets) Oct 2009 Sep ,28 0% NA 5 sb5 Oct 2009 Sep ,28 6% 6 sb6 Oct 2009 Sep ,16-6% 10 sb10 Oct 2009 Sep ,20 7% Table 15: Yearly indicators for monitored systems in Sweden Thermal fractional energy savings Figure 29 shows the fractional energy savings evaluated at the auxiliary heater outlet, according to the FSC value. 2 systems have results in the range of properly working systems, 3 are not far from this range, but 2 are quite low. These 2 systems have also the worst ratio between monitored and reference heat losses (figure 28). D4.4: Comparison of results of all monitored plants page 28

29 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% Fsav,th outlet sb1 sb2 sb3 sb4 sb5 sb6 sb10 0% -10% 0,0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1,0 FSCrange of properly working systems Figure 29: Thermal fractional energy savings (auxiliary heater outlet) versus FSC Since monitored houses have large heated area and consequently large space heating loads, while installed solar collector areas are quite small, FSC cannot reach high values (highest values are 0.28). Fractional energy savings are therefore limited. Theoretically, values up to 0.15 should be observed, but in reality, due to the large heat losses of the water store, no value reaches Annual results at the auxiliary heater inlet For the ten systems monitored, auxiliary energy used is wood pellet, which is not easy to measure. Some device exist, such a weighing machine under the pellet water store, but this is very expensive and could not be used in the project. For this reason, no extended fractional energy savings could be assessed Parasitic electricity Table 16 shows the measured values of parasitic electricity. There is no definition available to calculate reference parasitic electricity for systems using wood pellets boiler. Some characteristics of the installed systems give tendencies to explain the very different values observed: First reason is the differences in the type of pellets ignition device: some of the systems (SB1, SB2, SB3 and SB6) have an electrical heater used to ignite for a cold start, otherwise pellets are kept burning for start-ups. Other systems (SB5, SB10) use only an electric heater for ignition, and use therefore more electricity than the previous ones. No information on that topic has been found for SB4. An other reason for the differences observed is linked to the number of pumps and the efficiency of those in the system. Some systems include a pump for DHW circulation (SB4, SB10). SB10 includes also an additional pump for an extra heating circuit. SB1 has a single space heating circuit, but connected to 2 houses (one guest house apart from the main building). It may require a larger pump or a higher pump setting than for the other systems. For system SB3, some of the pumps used are new and more efficient. That might explain a lower parasitic electricity consumption compared with SB1 or SB2, which have the same type of pellet boiler ignition. D4.4: Comparison of results of all monitored plants page 29

30 Analysis period Parasitic Number of space electricity heating loops name Auxiliary beginning end sb1 Sep 2009 Aug sb2 Oct 2009 Sep sb3 Wood Oct 2009 Sep sb4 boiler Oct 2009 Sep sb5 (pellets) Oct 2009 Sep sb6 Oct 2009 Sep sb10 Oct 2009 Sep (kwh/year) Parasitic electricity sb1 sb2 sb3 sb4 sb5 sb6 sb10 Table 16: Parasitic electricity for monitored systems in Sweden 6. Results of Solcombi2 French project Between 2007 and 2010, 20 SCS of 2 manufacturers have been monitored in France, using the same methodology as in the Combisol project ([2] and [3]), with support of ADEME, EDF and GDF-Suez. The systems installed are mainly compact factory made systems, with the same hydraulic concept for all systems of each manufacturer. Systems differ only with regards to the auxiliary energy used Location of monitored systems Figure 30: Location of monitored systems in France (project Solcombi2) Main characteristics of monitored houses are given in table 17 and table 18. Houses for manufacturer A are older than those for manufacturer B. Location is shown in figure 30. N Heated area (m²) Auxiliary energy Solar collector area (m²) Tilt angle Orientation Year of house constrcution Known thermal retrofit work Table 17 : Characteristics of monitored houses (Manufacturer A) Floor heating Radiators B1 131 Natural gas 9,4 45 South 1970 insulation + double glazing X X B2 300 Natural gas 11, West new part insulation of the new part X B4 100 Natural gas 9, East 1980 X X B5 130 Natural gas 9,4 50 South 1980 X B6 120 Natural gas 7, East 1980 X B7 150 Natural gas 7, East zones B8 140 Natural gas 7, West 2006 X B9 125 Natural gas 7, East 1900 insulation ceiling and walls X B Oil 9,4 45 South 1999 X X B Natural gas 14,1 45 South 1999 X D4.4: Comparison of results of all monitored plants page 30

31 N Heated area (m²) Auxiliary energy Solar collector area (m²) Tilt angle Orientation Year of house constrcution Floor heating Radiators Propane 17,8 35 South oct-04 2 zones Oil 12,7 45 South Automne 2004 X X Propane 13,7 26 South août-05 X Natural gas 10,3 67 South sept-05 X Oil 16, South West Eté 2005 X Electricity 17,8 30 South zones Electricity (HP) 16,4 30 South sept-06 2 zones Natural gas 16,1 45 South zones Propane 16,4 35 South 2 zones Wood pellets 22,0 55 South zones Table 18 : Characteristics of monitored houses (Manufacturer B) 6.2. Energy balance of the heat water stores Figure 31 shows the measured heat losses of the water store, evaluated as described in paragraph 2.2, compared to the reference losses. Except for one system, the measured values for the water store heat losses are smaller than 2500 kwh, a figure much lower then those observed in the Combisol project (figure 14, figure 21 and figure 28). This is obviously related to the compactness of the systems (short connection pipes) and the small storage volumes kwh 7 Measured losses (Manufacturer A) Reference losses (Manufacturer A) ratio Measured losses (Manufacturer B) Reference losses (Manufacturer B) ,4 11,8 9,4 9,4 7,1 7,1 9,4 7,1 14,1 12,7 13,6 10,3 16,2 17,8 16,3 16,0 Solar collector area (m²) 1 0 ratio monitored / reference Figure 31: Yearly energy losses of water stores in France (project Solcombi2) 6.3. Annual results at the auxiliary heater outlet Since houses for manufacturer A are generally older than those for manufacturer B, and locater in less sunny climates (North East of France for some of them), while solar collector areas are much smaller, the FSC values for A are generally much smaller than those of B Thermal fractional energy savings Due to this difference in the FSC values, very different fractional energy savings are observed. These values are evaluated at the boiler outlet that is without taking into account the efficiency of the auxiliary heater. Systems of manufacturer B are more efficient than those of manufacturer A: for this last one, almost half of the points are located below the range of properly working systems, mainly due to a too small specific storage volume D4.4: Comparison of results of all monitored plants page 31

32 100% 90% 80% 70% 60% 50% 40% 30% Fsav,th Manufacturer A 1 storage 2 storage tanks Manufacturer B Range of properly working sytems 20% 10% FSC 0% 0,0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1,0 Figure 32: Performances of monitored systems in France evaluated at the auxiliary heater outlet (project Solcombi2) 6.4. Annual results at the auxiliary heater inlet Thermal fractional energy savings Taking into account the efficiencies of the auxiliary heater, all representative points are located in the range of properly working systems (figure 33). In this range, the upper curve has been obtained in Task 26 of the IEA for a system using a condensing boiler, while the lower curve is derived from a system with a conventional boiler. All systems of manufacturer A use condensing gas boiler as auxiliary. 5 systems of manufacturer B use the same type of boiler (4 with gas and 0ne with oil). Condensing boilers clearly provide an additional gain. For manufacturer A, there is no clear gain using two water stores: it can be assumed that the additional gain in solar heat recovery is more or less compensated by additional storage and pipe losses. 100% 90% 80% 70% Fsav,th inlet Manufacturer A 1 storage t k 2 storage tanks 60% 50% 40% 30% 20% 10% FSC 0% 0,0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1,0 Manufacturer B Condensing gas Condensing oil Fuel oil Electrical boiler HP + electrical boiler Figure 33: Performances of monitored systems in France evaluated at the auxiliary heater inlet (project Solcombi2) For manufacturer B, the system with a heat pump and electric boiler shows very poor performances. Very close to 0, it means that the monitored system consumes almost as much electricity as the reference system. In fact, by analyzing its operation more closely, it appears that the electric boiler operates more D4.4: Comparison of results of all monitored plants page 32

33 than it should only for the auxiliary energy needed for DHW preparation, and that substantial consumption is used for space heating. In fact, solar gains are lost by a malfunction of the auxiliary device Extended fractional energy savings This indicator takes into account the parasitic electricity used. Figure 34 shows the parasitic electricity used compared to the reference one. All systems where this parameter could be measured show better performances than the reference values. This explains why the representative points in figure 35 are located higher in the range of properly working systems than in figure Measured parasitic electricity (kwh) Manufacturer A Manufacturer B Reference parasitic electricity (kwh) Figure 34: Measured parasitic electricity used versus reference one (project Solcombi2) 100% 90% Fsav,ext Range of properly working systems Manufacturer A 1 storage tank 80% 2 storage tanks 70% Manufacturer B 60% condensing gas 50% condensing oil 40% oil 30% electrical boiler 20% 10% 0% 0,0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1,0 Figure 35: Performances of monitored systems in France evaluated at the auxiliary heater outlet (project Solcombi2) FSC D4.4: Comparison of results of all monitored plants page 33

34 6.5. Energy produced by the solar loop and energy savings Energy measured on the solar loop gives an indication on how this part of the system works. Energy savings can be quite different, because they take into account the behaviour of the whole system (storage and pipe losses, auxiliary heater efficiency, etc ) Figure 36 shows the specific solar contribution and the specific energy savings (solar energy produced in the solar loop and energy savings divided by the solar collector area) for the two manufacturers. Savings can be higher than solar gains when an efficient auxiliary heater is used, with a higher efficiency than the one of the reference auxiliary boiler. For manufacturer A, there is a clear difference between both figures: the specific storage value is quite low, and solar heat cannot be stored in an efficient way in some periods where the space heating load is low and the solar irradiation high. Specific energy savings are in the same range for the two manufacturers, but systems of the second one have much larger solar collector areas. Figure 37 shows the absolute figures of solar energy produced in the solar loop and energy savings: a clear difference in solar gains and energy savings can be stated between the two manufacturers, once again linked with the typical size of solar collectors they offer in their systems (kwh/m².year) Collector loop (Manufacturer A) Energy savings (Manufacturer A) Collector loop (Manufacturer B) Energy savings (Manufacturer B) ,4 11,8 9,4 9,4 7,1 7,1 7,1 9,4 7,1 14,1 17,8 12,7 13,6 10,3 16,2 17,8 16,3 16,0 21,8 Solar collector area (m²) Figure 36: Specific solar contribution in the collector loop and specific auxiliary energy savings (project Solcombi2) (kwh/year) Collector loop (Manufacturer A) Energy savings (Manufacturer A) Collector loop (Manufacturer B) Energy savings (Manufacturer B) ,4 11,8 9,4 9,4 7,1 7,1 7,1 9,4 7,1 14,1 17,8 12,7 13,6 10,3 16,2 17,8 16,3 16,0 21,8 Solar collector area (m²) Figure 37: Solar contribution in the collector loop and auxiliary energy savings (project Solcombi2) D4.4: Comparison of results of all monitored plants page 34

35 6.6. Synthesis Systems measured in this Solcombi2 project are compact factory made systems. They show generally better results than systems where components are prefabricated and then build-in together on site, like in the Combisol project. 7. General comments 7.1. Domestic Hot Water distribution temperatures The different types of DHW preparation do not provide the same comfort. Systems with instantaneous heat exchanger have a limited power. Hereunder are shown some diagrams obtained with a detailed one minute time step data recording. The volume of the draw-off is put on the X-axis. The temperature measured with the warm temperature sensor of heatmeter C2 in figure 10 is plotted on the Y-axis. Each blue line shows the evolution of the temperature of the hot water according to the volume consumed. The red line is an envelope curve that indicates the ability of the system to deliver hot water more or less quickly at the required setpoint temperature Immersed DHW heat exchanger In these systems, the DHW heat exchanger is a tube with a power linked to its size and the set point temperature of the water store. According to the value of the draw-off, the temperature remains stable (figure 38) for small draw-offs or not (figure 39 for larger draw-offs. Reached DHW temperature vs draw off 80 Temperature ( C) Max draw off = 4,4 l/min, min cold water temperature = 8 C, power = 18 kw 30 DHW draw off (l) Figure 38: Evolution of tap water temperature (immersed heat exchanger, low demand) D4.4: Comparison of results of all monitored plants page 35

36 60 Temperature ( C) Reached DHW temperature vs draw off Draw off = 9 l/min, power = 20 kw Draw off = 14 l/min, power = 30 kw DHW draw off (l) Figure 39: Evolution of tap water temperature (immersed heat exchanger, high demand) Tank in tank In these systems, a DHW tank is immersed in the main water store. A larger amount of DHW can be drawn off, according the size of this DHW tank. In figure 40, the volume of the DHW tank (180 l) is much larger than the maximum draw off. So the DHW temperature remains stable during the whole draw-off. Reached DHW temperature vs draw off Temperature ( C) Draw off = 14 l/min, cold water temperature = 6 C, power = 35 kw DHW draw off (l) Figure 40: Evolution of tap water temperature (tank in tank, high demand) 7.2. General considerations In this chapter, all results from the different countries are presented together, in order to analyse if some tendencies can be observed. Four sets of diagrams are presented hereunder, each set showing evaluations at the auxiliary heater outlet and at the auxiliary heater inlet. At the auxiliary boiler outlet, the thermal fractional energy savings is related to the way solar energy will decrease the need of auxiliary energy, taking into account the quality of the "solar part" of the system: heat storage, hydraulic scheme, control strategy. D4.4: Comparison of results of all monitored plants page 36

37 At the auxiliary boiler inlet, the thermal fractional energy savings include the quality of the auxiliary heater, of its connection to the "solar part" of the system, and its control strategy Results sorted by country Figure 41 shows results sorted by country. Three zones can be observed, related to the size aspects of the systems: In Sweden, small collector areas (mean value : 9 m²) are installed in big houses, with high space heating loads: lowest values for FSC and Fractional energy savings are observed In Austria, large collector areas (mean value : 18 m²) are installed: highest values for FSC and Fractional energy savings are observed In France and Germany, intermediate collector areas are installed (mean value: 10 m² for France, 12 m² for Germany): points are located between in the middle of the diagram. 100% 90% 80% 70% Thermal fractional energy savings Auxiliary heater outlet Range of properly working systems Austria France Germany Sweden 100% 90% 80% 70% Thermal fractional energy savings Auxiliary heater inlet Range of properly working systems Austria France 60% 50% 40% 30% 20% 60% 50% 40% 30% 20% 10% 10% FSC 0% 0% FSC -10% -10% 0,0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1,0 0,0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1,0 Figure 41: Results sorted by country Results sorted by manufacturer Figure 42 shows results sorted by manufacturer. No clear tendency can be observed, especially for manufacturers having systems installed in several countries (Austria, Germany and France). The case of Sweden is particular, since Swedish systems are only distributed in Sweden. 100% 90% 80% 70% 60% 50% 40% Thermal fractional energy savings Auxiliary heater outlet Range of properly working systems Manufacturer A Manufacturer B Manufacturer C Manufacturer D Manufacturer E Manufacturer F Manufacturer G Manufacturer H Manufacturer I 100% 90% 80% 70% 60% 50% 40% Thermal fractional energy savings Auxiliary heater inlet Range of properly working systems Manufacturer A Manufacturer B Manufacturer D Manufacturer E Manufacturer F Manufacturer G 30% 30% 20% 20% 10% FSC 0% -10% 0,0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1,0 10% FSC 0% -10% 0,0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1,0 Figure 42: Results sorted by manufacturer Results sorted by system type Figure 43 shows results sorted by system type, according to figure 2. No clear tendency can be observed, especially for manufacturers having systems installed in several countries (Austria, Germany and France). Once again, the case of Sweden is particular, since Swedish systems use a special hydraulic diagram with a 4-way valve. D4.4: Comparison of results of all monitored plants page 37

38 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% -10% Thermal fractional energy savings Auxiliary heater outlet Range of properly working systems A1 A2 B1 B2 B2 V4V C1 C2 0,0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1,0 FSC 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% -10% Thermal fractional energy savings Figure 43: Results sorted by system type Auxiliary heater inlet Range of properly working systems A1 A2 B1 B2 C1 C2 0,0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1,0 FSC Comparison between compact systems and systems assembled on site In Figure 44, results of the Combisol project are compared with results of the French Solcombi2 project (paragraph 6). As already mentioned, this last project shows better results than the Combisol project, because systems measured for the two manufacturers were homogeneous compact factory made systems, with few hydraulic connections between different subparts of the system, no unused pipes connection without insulation. However, some points are located under the range of properly working systems, due to a non optimised water store device in term of heat capacity (left diagram). 100% 90% 80% 70% Thermal fractional energy savings Auxiliary heater outlet Range of properly working sytems Combisol: systems assembled on site Solcombi2: compact systems good acceptable bad 100% 90% 80% 70% Thermal fractional energy savings Auxiliary heater inlet Range of properly working sytems Combisol: systems assembled on site Solcombi2: compact systems good acceptable bad 60% 60% 50% 50% 40% 40% 30% 30% 20% 20% 10% 0% -10% 0,0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1,0 FSC 10% 0% -10% 0,0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1,0 Figure 44: Compact systems compared to systems assembled on site Compact systems evaluated in the Solcombi2 project use mainly efficient auxiliary heaters as condensing boilers. Therefore, all representative points except one (see paragraph 6.4.1) are located in the range of properly working systems. For assembled on site systems, performances lie at a lower level, with some systems not working at all. FSC 7.3. Comparison between laboratory tests and on site monitoring Some monitored systems have also been evaluated in laboratory test rigs, according test procedures elaborated within "WP3: Laboratory determination of primary energy savings". Table 19 shows the main parameters of three different systems that have been evaluated in laboratory, and where on site monitoring results are available. For manufacturer 1, two monitoring results are available, but for one of them, the really installed hydraulic scheme differs from the one tested in the laboratory, because an additional Domestic Hot Water store has been installed after the immersed heat exchanger in the main water store. Therefore it has not been considered for the comparison. D4.4: Comparison of results of all monitored plants page 38

39 Solar collector area System type Space Climate heating DHW load Total load load FSC Fsav (m²) (kwh) (kwh) (kwh) Manufacturer 1 B ,52 30% Lab tests Manufacturer 2 16,0 C2 Zürich ,54 20% Manufacturer 3 A ,53 28% Manufacturer 1 10,0 B1 Lyon ,38 26% On site monitoring Manufacturer 2 18,6 C1 Graz ,59 21% Manufacturer 3 9,3 A1 Stuttgart ,42 20% Location of auxiliary energy evaluation Auxiliary heater inlet Auxiliary heater inlet Auxiliary heater outlet Table 19 : Comparison between indicators coming from laboratory tests and from on site monitoring Climate of the locations of monitored systems are continental climates, similar to the Zürich climate use for testing. For manufacturers 1 and 3, real loads are similar to test loads. System 2 has a smaller load compared to the test load. 100% 90% 80% 70% 60% 50% 40% 30% 20% Thermal fractional energy savings Lab tests Range of properly working systems Manufacturer 1 Manufacturer 2 Manufacturer 3 In situ tests 10% 0% Auxiliary heater outlet 0,0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1,0 Figure 45: Comparison between laboratory and on site monitoring results Figure 45 shows thermal Fractional Energy Savings vs FSC value, for laboratory and on site results. Following observations can be made: Results of on site measurements are consistent with those obtained from laboratory test, because for each manufacturer, the line between both points has a similar slope compared to the range of properly working systems. For systems of manufacturers 1 and 3, real points have smaller values for FSC and Fractional Energy Savings, mainly linked to smaller collector areas, since loads and irradiation available are similar. For systems of manufacturer 2, it is the opposite: the real point has higher values for FSC and Fractional Energy Savings, linked simultaneously to slightly larger collector areas, but mainly to a smaller load. This comparison shows a good correlation between the results coming from testing in the lab and those coming from on site monitoring, what in fact is a proof of the validity of the FSC approach used to evaluate the thermal efficiency of solar combisystems. It also shows that within the lab test, the annual thermal performance of the system can be very well predicted from a short (12 days) testing period. FSC D4.4: Comparison of results of all monitored plants page 39

40 8. Outcomes Monitoring equipments installed on the different systems have allowed putting figures on what was more or less known, but not clearly measured. Main outcomes of this work are given hereunder: The main parameter driving the final yearly savings is the thermal losses of the whole systems. To minimize these losses, several characteristics are required : o o o Use one large water store instead of two smaller ones with the same whole capacity. Minimize the length of pipes between the different components: from this point of view, compact systems with all components except the solar collectors prefabricated in a single unit are much more effective than several units connected on site. If a system with separate units is installed, the location of components must be chosen in order to minimize the length of connection pipes. All pipes must be insulated very carefully, without any gap between insulation pieces. All unused connections on the water store must be insulated. o If this points are not well addressed, yearly solar gains can be smaller than yearly thermal losses of water stores and pipes Second important point is the quality of the auxiliary heater. A solar combisystem is a complete system, including the auxiliary heater. For new systems, high efficiency boilers as for example condensing boilers or ground coupled heat pumps must be selected. For SCS installed in existing houses, the boiler must be changed if it is too old and it has a low efficiency. Low temperature space heating loop allows the solar collector to work with lower temperatures and a increased efficiency. Parasitic electricity can vary in a large range: best systems use less than 500 kwh electricity a year, since systems where this point is not really optimised can use up to three times more electricity. In order to have efficient systems, all topics described before must be addressed in a homogeneous way: if not, the weakest point will push performances to the bottom. 9. Bibliography [1]: THÜR A., BREIDLER J., KUHNESS G. and all, 2010, D2.4: Updated State of the Art Report Of Solar Combisystems analysed within CombiSol, technical report of the Combisol project, 85 p [2]: LETZ T. and all, 2010, D4.1: Specification for monitoring, collection and evaluation of results, technical report of the Combisol project, 17 p [3]: LETZ T. and all, 2010, D4 2: Guidelines for calculation of savings indicators, technical report of the Combisol project, 34 p [4]: LETZ T. and all, 2010, D4.3: Software for quick delivery of yearly indicators, technical report of the Combisol project, 12 p [5]: THÜR A. and all, 2010, D5.4: Main conclusions and resulting in general recommendations for the industry, technical report of the Combisol project, xx p 10. Detailed results of monitored systems D4.4: Comparison of results of all monitored plants page 40

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