Applied Building Physics: Ambient Conditions, Building Performance and Material Properties

Bad experiences with construction quality, the energy crises of 1973 and 1979,complaints about 'sick buildings', thermal, acoustical, visual and olfactory discomfort, the need for good air quality, the move towards more sustainability - all these have accelerated the development of a field that, for a long time, was hardly more than an academic exercise: building physics. The discipline embraces domains such as heat and mass transfer, building acoustics, lighting, indoor environmental quality and energy efficiency. In some countries, fire safety is also included. Through the application of physical knowledge and its combination with information coming from other disciplines, the field helps to understand the physical phenomena governing building parts, building envelope, whole building and built environment performance, although for the last the wording 'urban physics' is used. Building physics has a real impact on performance-based building design. This volume on 'Applied Building Physics' discusses the heat, air and moisture performance metrics that affect building design, construction and retrofitting.

Table of Contents:
Preface  xv 0 Introduction 1 0.1 Subject of the book  1 0.2 Building physics vs. applied building physics  1 0.3 Units and symbols 2 Further reading 5 1 Outdoor and indoor ambient conditions 7 1.1 Overview 7 1.2 Outdoors  8 1.2.1 Air temperature 9 1.2.2 Solar radiation 12 1.2.2.1 Beam radiation  14 1.2.2.2 Diffuse radiation 16 1.2.2.3 Reflected radiation  17 1.2.2.4 Total radiation 17 1.2.3 Longwave radiation  18 1.2.4 Relative humidity and (partial water) vapour pressure 22 1.2.5 Wind 23 1.2.5.1 Wind speed 24 1.2.5.2 Wind pressure 24 1.2.6 Precipitation and wind-driven rain  26 1.2.6.1 Precipitation  27 1.2.6.2 Wind-driven rain 28 1.2.7 Microclimates around buildings 30 1.2.8 Standardized outdoor climate data  31 1.2.8.1 Design temperature 31 1.2.8.2 Reference years 31 1.2.8.3 Very hot summer, very cold winter day  31 1.2.8.4 Moisture reference years 31 1.2.8.5 Equivalent temperature for condensation and drying 34 1.2.8.6 Monthly mean vapour pressure outdoors  37 1.3 Indoors  37 1.3.1 Air temperatures 37 1.3.1.1 In general  37 1.3.1.2 Measured data 38 1.3.2 Relative humidity and vapour pressure 41 1.3.2.1 Vapour release indoors 41 1.3.2.2 Measured data 44 1.3.2.3 Indoor climate classes 47 1.3.3 Indoor/outdoor air pressure differentials 50 Further reading 51 2 Performance metrics and arrays 54 2.1 Definitions 54 2.2 Functional demands  54 2.3 Performance requirements  54 2.4 A short history 55 2.5 Performance arrays 56 2.5.1 Overview 56 2.5.1.1 The built environment 56 2.5.1.2 Whole buildings and building assemblies 57 2.5.2 In detail 57 2.5.2.1 Functionality 57 2.5.2.2 Structural adequacy 57 2.5.2.3 Building physics related quality 60 2.5.2.4 Fire safety 60 2.5.2.5 Durability  61 2.5.2.6 Maintenance 61 Further reading 62 3 Whole building level 63 3.1 Thermal comfort 63 3.1.1 General concepts 63 3.1.2 Physiological basis 63 3.1.2.1 Exothermic 63 3.1.2.2 Homoeothermic  65 3.1.2.3 Autonomic control system  65 3.1.3 Steady state thermal comfort, the physiology based approach 66 3.1.3.1 Clothing  66 3.1.3.2 Heat flow between body and ambient 66 3.1.3.3 Comfort equations 68 3.1.3.4 Comfort parameters and variables 69 3.1.3.5 Thermally equivalent environments and comfort temperatures  69 3.1.3.6 Comfort appreciation  71 3.1.4 Steady state thermal comfort, the adaptive model 72 3.1.5 Thermal comfort under non-uniform and under transient conditions 74 3.1.5.1 Refined body model  74 3.1.5.2 Local discomfort  76 3.1.5.3 Drifts and ramps 78 3.1.6 Standard-based comfort requirements 80 3.1.7 Comfort related enclosure performance  81 3.2 Health and indoor environmental quality 83 3.2.1 In general  83 3.2.2 Health 84 3.2.3 Definitions 85 3.2.4 Relation between pollution outdoor and indoors  85 3.2.5 Process-related contaminants  86 3.2.5.1 Dust, vapour, smoke, mist and gaseous clouds  86 3.2.5.2 Fibres  86 3.2.5.3 Ozone 87 3.2.6 Building, insulation and finishing material related contaminants  87 3.2.6.1 (Semi) volatile organic compounds ((S)VOCs)  87 3.2.6.2 Formaldehyde (HCHO)  88 3.2.6.3 Phthalates  89 3.2.6.4 Pentachlorinephenols  89 3.2.7 Soil-related radon as contaminant  89 3.2.8 Combustion related contaminants  91 3.2.8.1 Carbon monoxide 91 3.2.8.2 Nitrous dioxide (NO2) 91 3.2.9 Bio-germs 92 3.2.9.1 Viruses  92 3.2.9.2 Bacteria  92 3.2.9.3 Mould 92 3.2.9.4 Dust mites 95 3.2.9.5 Insects  95 3.2.9.6 Rodents  96 3.2.9.7 Pets 96 3.2.10 Human related contaminants 96 3.2.10.1 Carbon dioxide (CO2)  97 3.2.10.2 Water vapour 97 3.2.10.3 Bio-odours  97 3.2.10.4 Tobacco smoke 98 3.2.11 Perceived indoor air quality  99 3.2.11.1 Odour  99 3.2.11.2 Indoor air enthalpy  101 3.2.12 Sick building syndrome (SBS) 102 3.2.13 Contaminant control 103 3.2.13.1 Minimizing emission  103 3.2.13.2 Ventilation  103 3.2.13.3 Air cleaning and personal protective measures  109 3.3 Energy efficiency  110 3.3.1 In general  110 3.3.2 Some statistics 111 3.3.3 End energy use in buildings  112 3.3.3.1 Lighting and appliances  112 3.3.3.2 Domestic hot water 116 3.3.3.3 Space heating, cooling and air conditioning  116 3.3.4 Space heating  116 3.3.4.1 Terminology 116 3.3.4.2 Steady state heat balance at zone level 118 3.3.4.3 Whole building steady state heat balance 123 3.3.4.4 Heat gain utilization efficiency  123 3.3.4.5 Annual end use for heating  125 3.3.4.6 Protected volume as one zone  125 3.3.5 Residential buildings, parameters shaping the annual net heating demand 125 3.3.5.1 Overview 125 3.3.5.2 Outdoor climate  126 3.3.5.3 Building use  127 3.3.5.4 Building design and construction 135 3.3.6 Residential buildings, parameters fixing net cooling demand 144 3.3.7 Residential buildings, gross energy demand, end energy use  146 3.3.8 Residential buildings ranked in terms of energy efficiency 146 3.3.8.1 Insulated 146 3.3.8.2 Energy efficient  146 3.3.8.3 Low energy  147 3.3.8.4 Passive  147 3.3.8.5 Near zero energy  147 3.3.8.6 Net zero energy  147 3.3.8.7 Net plus energy  147 3.3.8.8 Energy autarkic  148 3.3.9 Non-residential buildings, net and gross demand, end and primary energy use  148 3.3.9.1 In general  148 3.3.9.2 School retrofits as an exemplary case 148 3.4 Durability  152 3.4.1 In general  152 3.4.2 Loads 153 3.4.3 Damage patterns 153 3.4.3.1 Decrease in thermal quality 153 3.4.3.2 Decrease in strength and stiffness  154 3.4.3.3 Stress, strain, deformation and cracking 154 3.4.3.4 Biological attack  158 3.4.3.5 Frost damage 160 3.4.3.6 Salt attack 163 3.4.3.7 Chemical attack 167 3.4.3.8 Corrosion  168 3.5 Economics 170 3.5.1 Total and net present value  170 3.5.2 Optimum insulation thickness 171 3.5.3 Whole building optimum  173 3.5.3.1 Methodology 173 3.5.3.2 Example  174 3.6 Sustainability  178 3.6.1 In general  178 3.6.2 Life cycle inventory and analysis 179 3.6.2.1 Definition  179 3.6.2.2 Some criteria 181 3.6.2.3 Whole energy use and minimal environmental load  181 3.6.2.4 Recycling  182 3.6.3 High performance buildings 182 Further reading 186 4 Envelope and fabric: heat, air and moisture metrics 195 4.1 Introduction 195 4.2 Airtightness 195 4.2.1 Air flow patterns  195 4.2.2 Performance requirements  197 4.2.2.1 Air infiltration and exfiltration  197 4.2.2.2 Inside air washing, wind washing and air looping  197 4.3 Thermal transmittance 198 4.3.1 Definitions 198 4.3.1.1 Opaque envelope assemblies above grade  198 4.3.1.2 Whole envelope  199 4.3.2 Basis for requirements 199 4.3.2.1 Envelope parts 199 4.3.2.2 Whole envelope  200 4.3.3 Examples of requirements 200 4.3.3.1 Envelope parts 200 4.3.3.2 Whole envelopes 200 4.4 Transient thermal response  204 4.4.1 Properties of importance  204 4.4.2 Performance requirements  206 4.4.3 Consequences for the building fabric 206 4.5 Moisture tolerance 208 4.5.1 In general  208 4.5.2 Construction moisture 208 4.5.2.1 Definition  208 4.5.2.2 Performance requirements  208 4.5.2.3 Consequences for the building fabric 209 4.5.3 Rain 210 4.5.3.1 The problem 210 4.5.3.2 Performance requirements  212 4.5.3.3 Modelling 213 4.5.3.4 Consequences for the building envelope 215 4.5.4 Rising damp  217 4.5.4.1 Definition  217 4.5.4.2 Performance requirements  217 4.5.4.3 Modelling 218 4.5.4.4 Avoiding or curing rising damp  221 4.5.5 Pressure heads 222 4.5.5.1 Definition  222 4.5.5.2 Performance requirements  223 4.5.5.3 Modelling 223 4.5.5.4 Protecting the building fabric 223 4.5.6 Accidental leaks  224 4.5.7 Hygroscopic moisture 224 4.5.7.1 Definition  224 4.5.7.2 Performance requirements  226 4.5.7.3 Modelling 226 4.5.7.4 Consequences for the building fabric 226 4.5.8 Surface condensation  226 4.5.8.1 Definition  226 4.5.8.2 Performance requirements  226 4.5.8.3 Modelling 227 4.5.8.4 Consequences for the envelope 228 4.5.9 Interstitial condensation  228 4.5.9.1 Definition  228 4.5.9.2 Modelling 229 4.5.9.3 Performance requirements  232 4.5.9.4 Consequences for the building envelope 233 4.5.9.5 Remark 234 4.5.10 All moisture sources combined 234 4.5.10.1 Modelling 234 4.5.10.2 Performance requirements  234 4.5.10.3 Why models still have limitations 236 4.5.10.4 Three examples where full models were hardly of any help 240 4.6 Thermal bridges  244 4.6.1 Definition  244 4.6.2 Performance requirements  245 4.6.3 Consequences for the envelope 245 4.7 Contact coefficients 245 4.8 Hygrothermal stress and strain  246 4.9 Transparent parts: solar transmittance 247 4.9.1 Definition  247 4.9.2 Performance requirements  247 4.9.3 Consequences for the envelope 248 Further reading 248 5 Timber-framed outer wall as an exemplary case 253 5.1 In general  253 5.2 Assembly  253 5.3 Heat, air, moisture performances  253 5.3.1 Airtightness 253 5.3.2 Thermal transmittance. 255 5.3.3 Transient response  257 5.3.4 Moisture tolerance 257 5.3.4.1 Construction moisture 257 5.3.4.2 Rain control 257 5.3.4.3 Rising damp  258 5.3.4.4 Hygroscopic moisture and surface condensation  258 5.3.4.5 Interstitial condensation  258 5.3.4.6 More advanced modelling 264 5.3.4.7 Thermal bridging  265 6 Heat-air-moisture material properties 266 6.1 Introduction 266 6.2 Dry air and water 267 6.3 Materials, thermal properties 268 6.3.1 Definitions 268 6.3.2 Design values 268 6.3.2.1 Non-certified materials (ISO 10456) 268 6.3.2.2 Design values (NBN B62-002 (2001))  272 6.3.3 Measured data 281 6.3.3.1 Building materials  281 6.3.3.2 Insulation materials  287 6.4 Materials, air-related properties 290 6.4.1 Design values 290 6.4.1.1 Measured values 291 6.5 Materials, moisture properties 304 6.5.1 Design values for the vapour resistance factor (ISO 10456)  304 6.5.1.1 Building and finishing materials  304 6.5.1.2 Insulation materials 309 6.5.2 Measured values 309 6.5.2.1 Building materials 310 6.5.2.2 Insulation materials 323 6.5.2.3 Finishes  324 6.5.2.4 Miscellaneous  326 6.5.2.5 Vapour retarders 327 6.6 Surfaces, radiant properties  328 Further reading 329 Appendix A: Solar radiation for Uccle, Belgium, 50° 51´ north, 4° 21´ east  331

About the Author :
Dr. Ir. Hugo S.L.C. Hens is an emeritus professor at the University of Leuven (KU Leuven), Belgium. Till 1972, he worked as a structural engineer and site supervisor at a mid-sized architectural office. In 1975, after defending his PhD-thesis, he started the research unit Building Physics within the Faculty of Engineering of the university. He taught Building Physics from 1975 till 2003, Performance Based Building Design from 1975 till 2005 and Building Services from 1975 till 1977 and 1990 till 2008. He authored and co-authored some 70 peer reviewed journal and 170 conference papers about the research done at the unit, helped man-aging hundreds of building damage cases and acted as coordinator of the CIB W40 working group on Heat and Mass Transfer in Buildings from 1983 till 1993. Between 1986 and 2008, he was operating agent of the Annexes 14, 24, 32 and 41 of the International Energy Agency`s EXCO on Energy in Buildings and Communities. He is a fellow of the American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE).