Design and Construction of Bioclimatic Wooden Greenhouses, Volume 1

Gian Luca Brunetti is an Associate Professor of Building Technology at the Polytechnic University of Milan, Italy. His research focuses on the topics of bioclimatic design, sustainable construction technologies, lowcost construction techniques suited to self-building and design-applied optimization.

Foreword ix
Remo DORIGATI

Introduction xvii

Chapter 1 Basic Concepts 1

1.1 What a greenhouse usually is -- and what it could be 1

1.2 The historical trajectory of greenhouses 3

1.3 The main design factors: shape, orientation and envelope characteristics, in the context of local microclimates 28

1.3.1 Climate analysis 31

1.3.2 Site analysis 33

1.4 Solar gains and air retention as conditions for the greenhouse effect 40

1.5 Solar gains and thermal losses 42

1.5.1 Facts common to all kinds of solar gains 45

1.5.2 Factors influencing the solar gains on surfaces 46

1.6 Thermal storage 51

1.6.1 Charging the thermal masses by direct radiation 54

1.6.2 Loading the thermal masses by reflected radiation 58

1.6.3 Loading the thermal masses by convection 59

1.6.4 Phase-change materials 60

1.6.5 Natural convection -- thermosyphoning 62

1.6.6 Further information on the solar utilization of directly radiated thermal masses 72

1.7 Passive ventilative cooling 81

1.7.1 Indoor air movements 81

1.7.2 Thermal buoyancy ventilation 84

1.7.3 Sound absorption for sound insulation when combined with ventilation strategies 86

1.7.4 Quantity of air changes 86

1.8 Dissipation of heat towards the sky 87

1.9 Dependence of solar control on the radiation type 90

1.9.1 Techniques and indicators for checking solar access 91

1.9.2 General shading strategies 111

1.9.3 Horizontal shading devices 114

1.9.4 Vertical shading devices 122

1.9.5 Horizontal shading devices for east and west exposures 124

1.9.6 Horizontal shading devices for south-east and south-west exposures 126

1.9.7 Grid-like shading devices (egg crates, brise soleils) 126

1.9.8 Frontal shading devices 128

1.9.9 "Green" shading devices: vegetation as a shading device 130

Chapter 2 Fundamental Relations Between Greenhouse Features and Climatic Factors 139

2.1 General considerations 139

2.1.1 On shape, with regard to solar radiation 140

2.1.2 On shape, as regards ventilation 144

2.1.3 Acoustics in greenhouses 148

2.2 Greenhouses for cold, cool and temperate climates 151

2.2.1 Additional information about the relations between greenhouse shape and climate 151

2.2.2 About the slope of the frontal transparent envelope 153

2.2.3 Relations between the character of daylight and the slope of the transparent enclosures 154

2.2.4 About east and west enclosures 156

2.2.5 About roofs 156

2.2.6 Ventilation openings 158

2.2.7 Solid thermal masses 158

2.3 Considerations on greenhouses for cold climates 164

2.4 Framing the theme of greenhouses for hot climates 165

2.5 Shadehouses and nethouses 166

Chapter 3 Fundamental Complements for Solar Greenhouse Design 173

3.1 On passive heating of greenhouses 173

3.2 On the role of solar gains 174

3.3 On the main passive heat transfer strategies in solar greenhouses 174

3.3.1 On the heat transfer by conduction between greenhouse masses and greenhouse indoor environments 175

3.3.2 On the heat transfer by conduction between attached greenhouse and building 177

3.3.3 On the heat transfer by convection between attached greenhouses and buildings 178

3.3.4 On the types of thermal masses within greenhouses 181

3.4 On the role of thermal masses for passive greenhouse heating 182

3.4.1 On the combination of heat transfer by convection and conduction in attached greenhouses 182

3.4.2 On the thermal masses loaded by direct radiation 183

3.4.3 On the thermal masses loaded by reflected radiation 183

3.4.4 On the thermal masses loaded by convection 183

3.5 Passive cooling of greenhouses 184

3.5.1 The role of thermal masses in the passive cooling of greenhouses 185

3.5.2 Thermal mass for thermal inertia 185

3.5.3 Thermal mass for coolth storage via "night flushing" 186

3.5.4 Natural ventilation 188

3.5.5 Wind-driven ventilation 189

3.5.6 Criteria for predicting wind flows by means of streamlines 192

3.5.7 Stack-effect ventilation 196

3.5.8 Mixed -- wind-driven and stack-effect -- ventilation 196

3.6 Evaporative cooling 208

3.6.1 Direct evaporative cooling 211

3.6.2 Indirect evaporative cooling 213

3.6.3 Evaporative cooling from still water under still air 213

3.6.4 Evaporative cooling with still water and air moving over it 213

3.6.5 Evaporative cooling with water in movement in a container or channel, possibly on corrugated surfaces 214

3.6.6 Evaporative cooling via water sprinkled by pressure as droplets through nozzles, or falling by gravity 214

3.6.7 Evaporative cooling by wetting surfaces and transferring the coolth by convection or conduction 215

3.6.8 Downdraught cooling 218

3.6.9 Radiative cooling 223

3.6.10 Heating and cooling through seasonal storage strategies involving thermal exchange with the ground 225

3.6.11 Layout of cooling strategies in bioclimatic charts 226

3.7 Greenhouse features deriving from use and typology 229

3.7.1 Agricultural greenhouses 229

3.7.2 Specificities of inhabitable attached greenhouses 234

3.7.3 Stand-alone solar greenhouses 235

3.7.4 Lean-to, attached solar greenhouses 240

Chapter 4 Advanced Complements for Solar Greenhouse Design 249

4.1 Considerations related to shape 249

4.1.1 On the symmetry between solar aperture and heat-loss aperture 249

4.1.2 On the optimal tilt of front façades 250

4.1.3 On the greenhouse "thickness" 251

4.1.4 On the greenhouse width 252

4.1.5 On the greenhouse height 252

4.2 Considerations combining shape and construction 253

4.2.1 On gable enclosures 253

4.2.2 On roofs 254

4.2.3 On the greenhouse "knees" 257

4.2.4 Rainwater catchment and collection 258

4.2.5 Floors 260

4.2.6 Additional considerations about the shared wall between the greenhouse and the building 267

4.2.7 Stack-effect-driven heat exchange with the ground during daytime 276

4.3 Ventilative considerations related to shape 278

4.3.1 Openings on the greenhouse and the building as regards wind-driven ventilation 278

4.3.2 Directionality control for wind-driven ventilation 279

4.3.3 Openings in the shared wall with respect to wind-driven ventilation, with the greenhouse front in pressure 281

4.3.4 Openings in the shared wall as regards wind-driven ventilation, with the greenhouse front in depression 282

4.3.5 Openings in the shared wall as regards wind-driven ventilation, with the wind direction parallel to the fronts 283

4.3.6 Combination of stack-effect and wind-driven ventilation using the openings in the shared wall 284

4.3.7 Ventilation openings on the greenhouse façades and the roof 284

4.4 Position of the shading devices 285

4.4.1 External shading devices 287

4.4.2 Internal shading devices 293

4.5 Movable thermal insulation 294

4.6 Microclimates in solar greenhouses 295

4.6.1 Cold-sink pits 298

4.6.2 Human thermal comfort in solar greenhouses 299

4.7 Walkways, in growing greenhouses 301

Conclusion 303

References 305

Index 329

Summaries of other volumes 333