Workshop New Generation of Solar Thermal Systems, June 21, 2007 Experiences with Solar Combisystems in Multi-Family Buildings in Austria

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1 Experiences with Solar Combisystems in Multi-Family Buildings in Austria Dagmar Jaehnig AEE - Institute for Sustainable Technologies (AEE INTEC) A-8200 Gleisdorf, Feldgasse 19 AUSTRIA

2 Market Potential for Large-Scale Solar Thermal Systems

3 Multi-Family Buildings OPTISOL project 10 buildings, 370 apartments heat distribution via 2-pipe networks total collector area: m² (812 kw th ), total storage volume: 102 m³ average solar fraction approx.: 15 bis 20% (hot water & space heating)

4 Hydraulics: 2-pipe distribution network as standard Collector Field Heat Store Hot Water Cold Water Boiler Hot Water Cold Water Hot Water Cold Water Solar thermal system: Low-flow operation with single storage tank Heat distribution via 2-pipe network Hot domestic hot water generated in the flats by apartment heat transfer units

5 Advantages of Solar Assisted 2-Pipe Networks return temperatures of 30 C ensure an efficient operation of the solar thermal system distribution losses are reduced to a minimum, leading to highest possible system efficiencies (total heating system) the solar thermal system supplies inherently the space heating system improved comfort, no limit of hot water consumption and individual temperature control of each flat Hygienic domestic hot water generation (no legionella problem)

6 Optimization Phase

7 Optimization Phase Example 1 Problem: Return temperature from store to auxiliary boiler higher than necessary T_VL_Kessel T_RL_Kessel 70 Temperature [ C] :

8 Optimization Phase Example 2 Problem: Too much of the storage tank was kept at a high temperature by auxiliary heating T_Speicher_unten T_bottom T_Speicher_mitte T_middle T_Speicher_oben T_top Umstellung der Speichertemperatur Temperature [ C] [ C] : : : : :

9 Optimization Phase Example 3 Problem: Solar loop heat exchanger with manufacturing error (also when heat exchanger is too small). Systemtemperatur [ C] Vorlauf Primärkreis [ C] Rücklauf Primärkreis [ C] Vorlauf Sekundärkreis [ C] Rücklauf Sekundärkreis [ C] Durchfluss Primärkreis [l/h] Durchfluss Sekundärkreis [l/h] Before exchange of heat exchanger Vor Austausch des Wärmetauschers After exchange of heat exchanger Nach Austausch des Wärmetauschers Zeit Durchfluss [l/h]

10 Optimization Phase Example 4 Problem: Return temperature from heat distribution network too high (missing adjustment of radiators in common spaces) Flow temperature [ C] Return temperature [ C] Temperature [ C]

11 Measured Temperatures in Heat Distribution Net Flow and return temperatures in 8 demonstration systems C Temperature [ C] C Return temperatures around 30 C are the basis for an efficient operation of the solar thermal system!

12 Optimization Phase Example 5 Problem: Speed control of solar loop pump didn t work properly So So So So Solar Primärkreis Vorlauf [ C] Solar Primärkreis Rücklauf [ C] Solar Sekundärkreis Vorlauf [ C] Solar Sekundärkreis Rücklauf [ C] 70 Temperature [ C] Datum Datum

13 Eggenberger Allee Guaranteed Solar Results spez. measured Koll. Ertrag Messwert spez. simulated Koll. Ertrag simuliert Spec. coll. yield [kwh/(m² a)] spezifischer Kollektorertrag [kwh/m²a]. Feistritzer Nittnergasse Eggersdorf Seiersberg Schwarzer Weg Guaranteed value: 350 kwh/(m²a)

14 Legislative Framework in Austria Housing sector: funding by the provinces direct subsidies of 12 to 30% of investment costs improved subsidies for construction of apartments Province of Styria: Solar thermal system is mandatory Hotel/Industry/Trade: funding by the government direct subsidy of 30% of investment costs two provinces grant additional 10 16%

15 Economics Substitution of Fuel Oil Dynamic calculation of pay-back time Subsidies, provice of Styria + local authority Subsidies, Austrian average + local authority Dynamic pay-back time Average pay-back time: 12 to 14 years

16 Factors of Success: 1. Integral Approach for Planning and Realization Planning team Housing society, architects, building physicist Technicians, plant operator, property management Aesthetic and cost efficient integration of solar thermal components into the building Holistic heat supply concept Detailed planning Operation management Awarding of contracts and realization

17 Factors of Success: 2. Documented Commissioning of the Entire Heat Supply System by the Installer

18 Factors of Success: 3. Readjustment During the First Few Weeks of Operation Optimization Phase Systemtemperaturen [ C] Energie [kwh] Netzvorlauf Netzrücklauf Solarsekundärkreis - VL 90 Solarsekundärkreis - RL Energiespeicher unten Nachheizung - VL 90 Energiespeicher oben Wärmemenge - Solar Wärmemenge - Nachheizung :00 04:00 06:00 08:00 10:00 12:00 14:00 16:00 18:00 20:00 22:

19 Factors of Success: 4. Coupling of solar thermal system to the computeraided system control and to annual maintenance contracts of the conventional heating system

20 Factors of Success: 5. Contracts to Guarantee Minimum Solar Yields and Definition of Responsibilities Guaranteed solar yields in Austria normally 350 kwh/(m²a), verified by a heat meter. Return temperatures from distribution network (max. 40 C) can be part of guarantee contracts. 450 M a rkt H artm an nsd orf M essw e rte [kw h /m ²] M arkt H artm annsdorf G arantiew ert [kw h/m ²a] Sim ulierter spezifischer Jahreskollektorertrag: 383 kw h/m ² spezifischer Kollertorertrag in einem Jahr in kwh/m² Feb.04 Apr.04 Mai.04 Jun.04 Jul.04 Aug.04 Sep.04 Okt.04 Nov.04 Dez.04 Feb.05

21 Factors of Success: 6. Well Educated Players (Planners, Installers, Plant Operators etc.) Austrian national training program solarwärme, training courses to become a Certified solar thermal planner or Certified solar thermal installer (8 days, 64 course units) Approx. 350 people have passed the final exams, 100 people have been certified

22 Thank You for Your Attention!