Search

Denne strategirapport for lavenergiløsninger til nye bygninger indeholder opdaterede resultaterne af en løbende strategiudvikling, der foregår i Innovationsnetværket LavEByg. LavEByg beskæftiger sig med integrerede lavenergiløsninger på bygningsområdet. Strategiudviklingen er en dynamisk proces, der foretages løbende og afspejler opbygningen af viden og udviklingen på området. Rapporten beskriver en samlet strategi for en ny bæredygtig energiløsning for hele energiforbruget i Danmark (Energi 2050), der er opdelt i en beskrivelse af en generel energiløsning/vision for hele energiforbruget i Danmark, der indebærer en udfasning af brugen af fossile brændsler i Danmark inden 2050, samt en beskrivelse af en energiløsning på bygningsområdet. Rapporten indeholder i forlængelse heraf en række detaljerede F&U strategier på forskellige faglige delområder: Hele bygningen, isoleret klimaskærm, energivinduer, glasfacader og -tage inkl. solafskærmninger og belysning, vandbåret opvarmning og køling, luftbårne systemer til ventilation, opvarmning og køling samt fjernvarme og solenergi.

Arcon Solvarmes HT solfangere, som benyttes i store solvarmecentraler, er blevet undersøgt med hensyn til effektivitet og ældning. To solfangere, som har været i drift i solvarmecentralerne i Ottrupgård og Marstal i henholdsvis 15 og 13 år, er udvalgt til undersøgelserne. Undersøgelserne viste, at solfangernes ydelser er blevet reduceret noget siden installationen. Årsagen til ydelsesreduktionen er teflonfoliens stand og opspænding. Teflonfolien er rynket og foldet og desuden så slap, at afstanden mellem teflonfolien og absorberen er blevet alt for lille. Bortset fra problemerne med teflonfolien er solfangerne i usædvanlig god stand. Det vurderes, at solfangernes levetid er ca. 30 år.

The aim of the project is to test marketed solar heating systems in a laboratory test facility and to establish contact between installers of solar heating systems and house owners wanting to install solar heating systems.Two small SDHW systems from Batec Solvarme A/S and from Velux Danmark A/S have been tested under realistic conditions side-by-side with a small solar combi system from Sonnenkraft Scandinavia A/S. The thermal performances of the systems have been measured for a long test period. Measured thermal performances have been compared to thermal performances calculated with detailed simulation models for a short period for the three systems. A goodagreement between measured and calculated thermal performances was achieved for all the systems.The yearly thermal performance for the three systems was calculated for different hot water consumptions based on the weather data from the Danish Test ReferenceYear. The thermal performances are compared to the thermal performances of earlier tested marketed solar heating systems.The thermal performances for the three tested systems are lower than the thermal performances of the most efficient of the earlier tested systems. The reason is that the three systems are high flow systems with a hot water tank with a built in heat exchanger spiral, which equalize temperature differences in the hot water tank during operation periods of the solar collector. Low flow systems with a highly thermal stratified hot water tank, such as a mantle tank, have higher thermal performances than high flow solar heating systems based on spiral tanks. Further, two of the tested systems are based on hot water tanks with pipe connections to the upper part of the tank. These pipe connections results in high thermal bridges and thereby in a low thermal performance of the solar heating system. It is recommended to use hot water tanks with no pipe connections and penetrations through the insulation in the upper part of the tank. The tests form a good basis for development of improved marketed systems.

Recently a number of Chinese companies started mass production of evacuated tubular solar collectors. Contrary to Europe, in China the evacuated tubular solar collectors have reached such a low price level that it has become normal to use these high-efficient solar collectors in many different types of solar heating systems. Four different evacuated tubular solar collectors produced by Chinese companies have been tested in a small solar domestic hot water test system. The test system has been tested under realistic conditions in a test facility for solar heating systems at DTU. By means of the tests a simulation model has been developed for each of the four solar collectors. With the developed models calculations of the yearly thermal performance of different Danish solar heating systems were carried out: Small and large solar domestic hot water systems, combined solar domestic hot water and space heating systems and solar heating plants. Calculations were carried out with the four investigated evacuated tubular solar collectors and with ordinary flat plate collectors. The investigations showed that the thermal performance of solar heating systems is increased by using evacuated tubular solar collectors instead of ordinary flat plate collectors and that the solar collector area of a solar heating system with a fixed thermal performance can be reduced considerably by using evacuated tubular solar collectors instead of ordinary flat plate collectors. The higher the solar fraction and the operation temperature are the greater the advantage of using the evacuated tubular solar collectors will be. For solar domestic hot water systems and for combined space heating and domestic hot water systems with typical solar fractions the solar collector area can be reduced about 2-3 times if the best suitable evacuated tubular solar collector is used instead of an ordinary flat plate collector. The price level of the Chinese evacuated tubular solar collectors that are exported to Europe is relatively high. With these prices it will be possible to improve the price/performance-ratios for solar heating plants with high operation temperatures. For the other solar heating systems it is not possible to improve the price/performance-ratios by using evacuated tubular solar collectors instead of flat plate collectors unless the solar fraction of the solar heating system is unusually high. As the prices of the solar collectors sold in China are very low, it is not unthinkable, however, that the prices of exported Chinese solar collectors can be reduced so that they can become attractive in several types of solar heating systems.