analysis of the influences of solar radiation and façade glazing ...

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Abstract Modern, urban multi-family buildings are characterized by large façade glazing areas. Under the perspective of ecology and the duty to design energy-efficient buildings, these market requirements are contributing to a technical conflict of goals. It is well known that large glazing openings are not only responsible for a large part of heat loss in cold periods, but can also help to collect a lot of energy for living rooms through the passive effect of solar radiation. The question is which opening sizes, which technical glazing properties and which directions support an optimal situation between thermal comfort and the use of primary energy. A qualified answer can only be found in an integrated approach with the application of modern and complex computer simulation programs which include all parameters of building geometry, building materials used and the interaction between all installed heating, cooling and ventilation systems. The aim of this work is to show new ways of designing modern, energy-efficient dwelling-houses taking solar radiation into special consideration. Three co-operative apartment houses, which are being built in Hannover in 2009, are the object of this dissertation. The detailed simulation method was chosen for the current work. The use of the EnergyPlus V3-0 simulation tool helped to combine heat and mass transfers, to simulate multi-zone airflow and to operate heating, cooling and ventilation systems for long periods. Special attention was focused on the heat transfer through windows. Twelve cases of fenestration products with different types of low-e-coatings and different configurations of optical filters on glass surfaces were examined. All relevant parameters of the developed glazing systems were determined with the help of the WINDOWS 5.2 computer program. Based on the above analysis, a general procedural method was presented to determine an optimal window-to-wall ratio (WWR) for any dwelling house. As it turned out in the investigated case, the annual heating energy consumption could be reduced by over 30 % when using the considered WWR optimization. The simulations were conducted with different weather profiles for several locations in Germany. Additionally, experimental investigations were carried out to determine the thermal performance of a considered external wall in solid construction and then to calibrate the building simulation software. Furthermore, the analysis of the influence of the glazing system area on the buildings´ energy demand showed that there is an approximate linear correlation between energy consumption for space heating and the WWR. Another aspect of the investigations was to determine the relationship between the energy demand for space heating and the windows´ height above ground level in different seasons. Simulation results indicated that the difference between the first and the last floor is high and equal to 31 % for balconywindows and up to 66 % for windows in winter. Large fenestration areas can generate overheating problems for living spaces during intensive solar radiation. Coupled with external shading devices, cooling through the use of ambient air driven by ventilation systems is an effective and energy-efficient solution if the ambient temperature is lower
than the inner air temperature. It was found that the amplitude between day and night internal air temperatures is significantly higher for apartments with variable air volume systems in comparison to constant air volume systems. The difference between the mean operative temperature reaches up to 4.4°C. Window shades with the highest reflective surface mounted outside and near the fenestration guarantee the best protection of gains from solar radiation. In order to compile the energy balance of the analyzed building, the operation of a solar domestic hot water system (SDHW) was investigated. Several tilt angles were tested for the solar collectors, whereas the simulation showed that an angle of 35° is optimal in summer time and an angle of 70°C is optimal for the cold period. If a fixed tilt angle of 45° is used throughout the year the absorbed solar energy varies only about 10 % maximum. It turned out that the solar conversion process is about ten times lower in winter than those during the summer time. Another important question in the design of a SDHW system is the optimal value of a stratified storage tank. Based on the analysis of the influence of the volume of accumulated water on the thermal performance of the SDHW system, it can be concluded that the recommended volume of the storage tank for the developed case is 4 m 3 . Results of the calculations showed that the temperature of storage water increased by over 50°C between April and September. Hereby it could be shown that the total designed area of solar collectors is too small to be an effective support of the heating system during the whole year.
Page 1: ANALYSIS OF THE INFLUENCES OF SOLAR
Page 5 and 6: 4.1 SUMMARY .......................
Page 7 and 8: Subscripts σ - Stefan-Boltzmann co
Page 9 and 10: 1.1 Introduction 9 Another problem,
Page 11 and 12: 1.2 Background and literature revie
Page 41 and 42: 2.1 Building energy simulation soft
Page 47 and 48: 2.2 Experimental research methods 4
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3.1 Building description 53 Fig. 3.
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3.1 Building description 55 All int
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3.1 Building description 57 Case B5
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3.1 Building description 59 Of cour
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3.1 Building description 61 Outside
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3.1 Building description 63 In orde
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3.2 Selection of the optimal glazin
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3.3 Estimation of thermal energy ga
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3.4 Testing of a building indoor en
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36 34 32 30 28 26 24 22 20 18 36 34
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3,00 2,50 2,00 1,50 1,00 0,50 0,00
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3.5 Optimization of a solar domesti
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4.1 Summary 99 4 Summary and conclu
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4.2 Comments and conclusions 101 So
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4.3 Future research 103 of the annu
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References 105 Beausoleil-Morrison,
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References 107 Hendron, R., et al.
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References 109 Rees, S. and Haves,
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References 111 Yohanis, Y.G., et al
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Appendix 1 113 Fig. A1.1 VASATI 2.0
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Appendix 2 123 !-Generator IDFEdito
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Appendix 2 125 0.035, !- Conductivi
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Appendix 2 127 , !- Zone Inside Con
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Appendix 2 129 Discrete; !- Numeric
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Appendix 2 131 Fraction, !- Schedul
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Appendix 2 133 Air Conditioner:Wind
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Appendix 2 135 , !- Sensible Heat F
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Appendix 2 137 281, !- Lighting Lev
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Appendix 2 139 OG2 InfilTRATION, !-
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Appendix 2 141 OG3, !- Zone Name 16
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Appendix 2 143 0.004, !- Zone Heati
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Appendix 2 145 Zone15WindACAirInlet
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Appendix 2 147 0, !- Maximum Flow R
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Appendix 2 149 Zone16WindACOAMixer,
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Appendix 2 151 Zone 9 Outlet Node;
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Appendix 2 153 Stand Alone ERV 16,
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Appendix 2 155 ZoneHVAC:WindowAirCo
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Appendix 2 157 ZoneHVAC:Baseboard:C
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Appendix 2 159 Zone Control Type Sc
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Appendix 2 161 WindACPLFFPLR, !- Pa
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Appendix 2 163 Stand Alone ERV Supp
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Appendix 2 165 0.03001, !- Maximum
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Appendix 2 167 0.81, !- Sensible Ef
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Appendix 2 169 !- == ALL OBJECTS IN
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