Solar Technologies for Buildings

Ursula Eicker is a physicist who carries out international research projects on solar cooling, heating, electricity production and building energy efficiency at the University of Applied Sciences in Stuttgart. She obtained her PhD in amorphous silicon thin-film solar cells from Heriot-Watt University in Edinburgh and then worked on the process development of large-scale amorphous silicon modules in France. She continued her research in photovoltaic system technology at the Centre for Solar Energy and Hydrogen Research in Stuttgart. She set up the Solar Energy and Building Physics Research Group in Stuttgart in 1993. Her current research emphasis is on the development and implementation of active solar thermal cooling technologies, low-energy buildings and sustainable communities, control strategies and simulation technology, heat transfer in façades, etc. Since 2002 she has been the scientific director of the research centre on sustainable energy technologies (zafh.net) in BadenWürttemberg. She also heads the Institute of Applied Research of the University of Applied Sciences in Stuttgart, where building physicists, geoinformation scientists, mathematicians, civil engineers and architects cooperate. During the last 10 years Professor Eicker has coordinated numerous research projects on sustainable communities with renewable energy systems and highly efficient buildings. The largest projects include the European Integrated POLYCITY Project, a demonstration project on sustainable buildings and systems in Germany, Italy and Spain, and the European PhD school CITYNET on information system design for sustainable communities.

"...balances the physics and engineering background of solar heating, cooling and building integrated photovoltaics with practical applications..." (Bulletin, Vol 94(24/25), 2003)

• Preface ixAbbreviations in the text xi1 Solar energy use in buildings 11.1 Energy consumption of buildings 11.1.1 Residential buildings 21.1.2 Office and administrative buildings 41.1.3 Air conditioning 61.2 Meeting requirements by active and passive solar energy use 91.2.1 Active solar energy use for electricity, heating and cooling 91.2.2 Meeting heating energy requirements by passive solar energy use 122 Solar irradiance 132.1 Extraterrestrial solar irradiance 132.1.1 Power and spectral distribution of solar irradiance 132.1.2 Sun–Earth geometry 162.1.2.1 Equator coordinates 172.1.2.2 Horizon coordinates 202.1.2.3 Sun-position diagrams 222.2 The passage of rays through the atmosphere 242.3 Statistical production of hourly irradiance data records 262.3.1 Daily average values from monthly average values 272.3.2 Hourly average values from daily average values 312.4 Global irradiance and irradiance on inclined surfaces 342.4.1 Direct and diffuse irradiance 342.4.2 Conversion of global irradiance to inclined surfaces 352.4.2.1 An isotropic diffuse irradiance model 352.4.2.2 Diffuse irradiance model based on Perez 362.4.3 Measurement techniques for solar irradiance 392.5 Shading 393 Solar thermal energy 453.1 Solar-thermal water collectors 453.1.1 Innovations 453.1.2 System overview 463.1.3 Thermal collector types 473.1.3.1 Swimming pool absorbers 473.1.3.2 Flat plate collectors 473.1.3.3 Vacuum tube collectors 483.1.3.4 Parabolic concentrating collectors 483.1.4 System engineering for heating drinking-water 493.1.4.1 The solar circuit and hydraulics 493.1.4.2 Heat storage 553.1.4.3 Piping and circulation losses 603.1.5 System technology for heating support 613.1.6 Large solar plants for heating drinking water with short-term stores 633.1.6.1 Design of large solar plants 663.1.7 Solar district heating 683.1.8 Costs and economy 713.1.9 Operational experiences and relevant standards 733.1.10 Efficiency calculation of thermal collectors 743.1.10.1 Temperature distribution of the absorber 753.1.10.2 Collector efficiency factor F' 793.1.10.3 Heat dissipation factor FR 793.1.10.4 Heat losses of thermal collectors 833.1.10.5 Optical characteristics of transparent covers and absorber materials 923.1.11 Storage modelling 973.2 Solar air collectors 1033.2.1 System engineering 1053.2.2 Calculation of the available thermal power of solar air collectors 1073.2.2.1 Temperature-dependent material properties of air 1073.2.2.2 Energy balance and collector efficiency factor 1083.2.2.3 Convective heat transfer in air collectors 1093.2.2.4 Thermal efficiency of air collectors 1173.2.3 Design of the air circuit 1203.2.3.1 Collector pressure losses 1203.2.3.2 Air duct systems 1214 Solar cooling 1234.1 Open cycle desiccant cooling 1254.1.1 Introduction to the technology 1254.1.2 Coupling with solar thermal collectors 1284.1.3 Costs 1284.1.4 Physical and technological bases of sorption-supported air-conditioning 1294.1.4.1 Technology of sorption wheels 1294.1.4.2 Air-status calculations 1304.1.4.3 Dehumidifying potential of sorption materials 1324.1.4.4 Calculation of the sorption isotherms and isosteres of silica gel 1354.1.4.5 Calculation of the dehumidifying performance of a sorption rotor 1404.1.5 The technology of heat recovery 1434.1.5.1 Recuperators 1434.1.5.2 Regenerative heat exchangers 1484.1.6 Humidifier technology 1524.1.7 Design limits and climatic boundary conditions 1534.1.7.1 Demands on room temperatures and humidities 1534.1.7.2 Regeneration temperature and humidity 1534.1.7.3 Calculation of supply air status with different climatic boundary conditions 1544.1.7.4 Limits and application possibilities of open sorption 1554.1.8 Energy balance of sorption-supported air-conditioning 1564.1.8.1 Usable cooling power of open sorption 1564.1.8.2 Coefficients of performance and primary energy consumption 1584.2 Closed cycle adsorption cooling. 1624.2.1 Technology and areas of application 1624.2.2 Costs 1634.2.3 Operational principle 1634.2.4 Energy balances and pressure conditions 1654.2.4.1 Evaporator 1664.2.4.2 Condenser 1684.2.4.3 The adsorption process 1694.2.4.4 Heating phase 1724.2.4.5 The desorption process 1724.2.4.6 Cooling phase 1744.2.5 Coefficients of performance 1754.3 Absorption cooling technology 1774.3.1 The absorption cooling process and its components 1784.3.1.1 Double-lift absorption cooling process 1814.3.1.2 Evaporator and condenser 1824.3.1.3 Absorber 1834.3.1.4 Generator 1854.3.2 Physical principles of the absorption process 1854.3.2.1 Vapour pressure curves of material pairs 1854.3.3 Refrigerant vapour concentration 1894.3.4 Energy balances and performance figures of an absorption cooler 1904.3.4.1 Ideal performance figures 1904.3.4.2 Real performance figures and enthalpy balances 1914.3.5 Absorption technology and solar plants 2005 Grid-connected photovoltaic systems 2015.1 Structure of grid-connected systems 2015.2 Solar cell technologies 2035.3 Module technology 2035.4 Building integration and costs 2045.5 Energy production and the performance ratio of PV systems 2055.5.1 Energy amortisation times 2065.6 Physical fundamentals of solar electricity production 2075.7 Current-voltage characteristics 2095.7.1 Characteristic values and efficiency 2095.7.2 Curve fittings to the current-voltage characteristic 2105.7.2.1 Parameter adjustment from module data sheets 2165.7.2.2 Full parameter set calculation 2205.7.2.3 Simple explicit model for system design 2215.7.3 I-V characteristic addition and generator interconnecting 2235.8 PV performance with shading. 2255.8.1 Bypass diodes and backwards characteristics of solar cells 2255.9 Simple temperature model for PV modules 2285.10 System engineering 2315.10.1 DC connecting 2315.10.1.1 Cable sizing 2315.10.1.2 System voltage and electrical safety 2325.10.1.3 String diodes and short-circuit protection 2325.10.2 Inverters 2345.10.2.1 Operational principle 2345.10.2.2 Electrical safety and mains monitoring 2355.10.2.3 Inverter efficiencies 2355.10.2.4 Power sizing of inverters 2386 Thermal analysis of building-integrated solar components 2436.1 Empirical thermal model of building-integrated photovoltaics 2446.2 Energy balance and stationary thermal model of ventilated double facades 2466.2.1 Heat transfer coefficients for the interior and facade air gap 2506.3 Building-integrated solar components (U- and g-values) 2546.4 Warm-air generation by photovoltaic facades 2577 Passive solar energy 2607.1 Passive solar use by glazings 2607.1.1 Total energy transmittance of glazings 2617.1.2 Heat transfer coefficients of windows 2637.1.3 New glazing systems 2657.2 Transparent thermal insulation 2657.2.1 Operational Principle 2667.2.2 Materials used and construction 2707.2.2.1 Construction principles of TWD systems 2707.3 Heat storage by interior building elements 2717.3.1 Component temperatures for sudden temperature increases 2747.3.2 Periodically variable temperatures 2817.3.3 Influence of solar irradiance 2868 Lighting technology and daylight use 2888.1 Introduction to lighting and daylighting technology 2888.1.1 Daylighting of interior spaces 2898.1.2 Luminance contrast and glare 2918.2 Solar irradiance and light flux 2918.2.1 Physiological–optical basics 2928.2.2 Photometric radiation equivalent 2928.2.3 Artificial light sources. 2948.3 Luminance and illuminance 2958.3.1 Luminance and adaptation of the eye 2998.3.2 Distribution of the luminous intensity of artificial light sources 3008.3.3 Units and definitions 3038.4 Sky luminous intensity models 3048.5 Light measurements 3078.6 Daylight distribution in interior spaces 3088.6.1 Calculation of daylight coefficients 311References 316Index 320