1 INTRODUCTION 1

[Figures and illustrations]

Figure 1: Map of New Zealand showing HEEP monitoring locations  2

Figure 2: A power station was hiding in the wood shed  3

Figure 3: Theme illustrations from the HEEP Year 10 celebration  4

Figure 4: Electricity use per household 1946-2005  8

Figure 5: Electricity uses 1971/72 8,400 kWh pa  9

Figure 6: Electricity uses HEEP 7,240 kWh pa  9

Figure 7: Energy use distribution – all fuels  10

Figure 8: Energy use distribution – electricity  12

Figure 9: Energy use distribution – gas (natural gas & large bottle LPG)  12

Figure 10: Energy use distribution – LPG (small bottles)  12

Figure 11: Energy use distribution – Solid fuel  12

Figure 12: Regional patterns of energy end-uses  13

Figure 13: Total energy use by fuel type  15

Figure 14: Total energy use by end-use  15

Figure 15: Space heating gross energy by fuel  16

Figure 16: Space heating delivered energy by fuel  16

Figure 17: Energy use by end-use and month  17

Figure 18: Electric appliances  20

Figure 19: Average monthly lighting power – all NZ  21

Figure 20: Fuels all end-uses (Dec yr 2004)  22

Figure 21: Fuels all end-uses (Sept yr 2005)  22

Figure 22: Participation rate of households taking part in HEEP  25

Figure 23: Regional participation rate by urban level  26

Figure 24: Schematic of HEEP data processing  33

Figure 25: A section of a prepro file  33

Figure 26: Sample EDA plots for two temperature sensors  36

Figure 27: HEERA modelling framework  55

Figure 28: HEERA flow diagram with representative tables, algorithms and forms  55

Figure 29: Contribution of new dwellings to the stock of dwellings  60

Figure 30: Net dwelling stock growth over the period 1850 to 2070  64

Figure 31: Building consents (1974 to 2003) compared to vintage stock model  64

Figure 32: New dwelling survival function  65

Figure 33: Probability of new dwelling stock retirement function  65

Figure 34: National dwelling stock by insulation level  68

Figure 35: Mean winter evening living room and ambient temperature by Regional Council 71

Figure 36: Mean winter night time bedroom temperature by Regional Council  72

Figure 37: Distribution of winter evening living room temperatures  72

Figure 38: Living room daytime heating by region and weekday/weekend  74

Figure 39: Heating index by region  74

Figure 40: Bedroom overnight heating by region and weekday/weekend  74

Figure 41: Living room 24 hour heating by region  75

Figure 42: Reported heating season start and finish  77

Figure 43: Length of reported heating season  77

Figure 44: Example – LPG heater use  79

Figure 45: Example – solid fuel use  79

Figure 46: Non-hot water electricity use for one house  80

Figure 47: Months of heating – start and finish  81

Figure 48: Length of heating season  81

Figure 49: External temperature and energy use during heating season  82

Figure 50: Average external temperature for heating season  83

Figure 51: External temperatures of heating start and finish months  83

Figure 52: Living room evening temperature by location and most used heating fuel  85

Figure 53: Winter evening living room temperatures by year built  86

Figure 54: Regional living room temperature differences by insulation requirements  87

Figure 55: Regional bedroom temperature differences by insulation requirements  88

Figure 56: Relationship between temperature difference from the high and low loggers and the difference between outside and inside (linear fit line)  90

Figure 57: Mean living room temperatures  92

Figure 58: Time spent at given temperature ranges  93

Figure 59: Living and bedroom temperature distribution for morning and day  94

Figure 60: Time of maximum living room temperature by Regional Council  95

Figure 61: Maximum living room temperature by Regional Council  96

Figure 62: Mean living room daytime temperatures by Regional Council  97

Figure 63: Summer temperatures by house age  98

Figure 64: Mean living room temperature by airtightness  100

Figure 65: Glazing to wall area ratio by decade house built  100

Figure 66: Solar glazing ratio vs Auckland living room temperatures  101

Figure 67: Palmerston North House  103

Figure 68: Measured parameters  104

Figure 69: Average daily profile  105

Figure 70 Vertical temperature stratification, 1999 (living room south-east corner)  106

Figure 71: Vertical temperature profile, 2000 (living room south-east corner)  107

Figure 72 Hamilton pensioner family room evening temperatures  110

Figure 73 Hamilton non-pensioner family room evening temperatures  110

Figure 74: HEEP and 2001 Census and 2006 Household Composition  113

Figure 75: Age of youngest HEEP household member  114

Figure 76: Equivalised HEEP household income by youngest household member  115

Figure 77: Total fuel use by age of youngest household member HEEP households  120

Figure 78: Winter evening living room average temperature distribution  124

Figure 79: Household composition – HEEP & 2001 Census  127

Figure 80: Age of youngest household member – all & Māori HEEP households  128

Figure 81: Equivalised household income – all & Māori HEEP households  129

Figure 82: Winter evening living room temp – all & Māori HEEP households  130

Figure 83: Total gross annualised energy use for all & Māori HEEP households  131

Figure 84: Total gross annualised heating energy use for all & Māori HEEP households  132

Figure 85: Energy Use Groups vs Dwelling Size  151

Figure 86: Test calibration of gas heated house – House 1  156

Figure 87: Solid fuel calibration graphs (House 2)  157

Figure 88: Equation 15 heat output  159

Figure 89: HEEP estimates and Equation 15  159

Figure 90: LPG heaters per household in city and small town/rural areas  163

Figure 91: Gross energy output for each setting for radiant non-thermostat LPG heaters  165

Figure 92: LPG setting determination for one heater  165

Figure 93:LPG heater use by time of day & day of year (Houses 2 & 4)  168

Figure 94: LPG heater use by time of day & day of year (Houses 1 & 5)  169

Figure 95: Histogram of hours of use LPG heaters (winter months)  171

Figure 96: Histogram of the energy use for LPG heaters (winter months)  171

Figure 97: Proportion of the time spent in the primary settings for LPG heater  171

Figure 98: Expected gas consumption for the 'on' setting for each LPG heater  171

Figure 99: Energy used by each setting for heaters with winter usage  172

Figure 100: Time in each setting for heaters with winter usage  172

Figure 101: Cumulative plot of the energy used by each LPG heater  172

Figure 102: Wintertime LPG heater energy use (in kWh per week) for a number of areas around New Zealand  173

Figure 103: Total house heat loss for pre- and post-1978 houses  176

Figure 104: Heat loss per m² for pre- and post-1978 houses  176

Figure 105: Fitted model plots  184

Figure 106: STEM model results  186

Figure 107: Long-term stock levels of home entertainment appliances  193

Figure 108 Fridge power use histogram  197

Figure 109: Breakdown of standby energy per house by appliance group  200

Figure 110: 10 minute time series of refrigeration appliance power  205

Figure 111: Faulty freezer – 10 minute time series  206

Figure 112: Fridge freezer 10 min time series – cycles <20 min but not faulty  207

Figure 113: Energy use of new frost-free fridge freezers 1980-2006  212

Figure 114: Power factors for monitored houses - Hamilton, Wanganui and Wellington  214

Figure 115: Load curves for different HEEP locations  214

Figure 116: Household daily average real and reactive power and power factor  217

Figure 117: Histograms of the 10 minute power factors by household  217

Figure 118: Mean real and reactive components for each household  218

Figure 119: Real vs reactive power by household  218

Figure 120: House 1 summer day – real & reactive power, power factor  219

Figure 121: House 6 summer day – real & reactive power, power factor  219

Figure 122: Average daily profiles by house – real and reactive power, power factor  220

Figure 123: Examples of hot water cylinders  223

Figure 124: Residential use of storage electric hot water systems  225

Figure 125: Selected nations - electric hot water cylinders by capacity  227

Figure 126: DHW Fuels  228

Figure 127: Variation in proportions of energy end-uses  229

Figure 128: Variation in energy end-uses  229

Figure 129: DHW Energy use distribution – all fuels  230

Figure 130: DHW electricity distribution  232

Figure 131: DHW gas distribution  232

Figure 132: DHW Wetback distribution  232

Figure 133: Average DHW energy profiles  232

Figure 134: Monthly hot water energy profiles  232

Figure 135: National Hot Water Energy Use by Month  233

Figure 136: DHW Energy use by month  233

Figure 137: DHW Energy Use by Month for Houses with that fuel  234

Figure 138: Changing estimates of NZ residential energy end-uses  235

Figure 139: Energy consumption and standing losses by system type  238

Figure 140: Hot water systems – by type and houses  242

Figure 141: Cylinder volumes  245

Figure 142: Cylinder size by region  246

Figure 143: Cylinder size by age  246

Figure 144: NZ Sales by capacity of electric DHW cylinders 2004/5  247

Figure 145: System pressure by region  248

Figure 146: Pressure by house decades  248

Figure 147: Pressure by cylinder decades  248

Figure 148: System age by location  250

Figure 149: 135 and 180 litre cylinders by decade of manufacture  251

Figure 150: Cylinder manufacture compared to house construction decade  251

Figure 151:Total hot water volume vs floor area  253

Figure 152: Total hot water volume vs number of occupants  253

Figure 153: Single electric DHW systems – litres per person  253

Figure 154: Use of baths and showers 1971/72  255

Figure 155: Use of baths and showers HEEP  255

Figure 156: Household DHW volume 1971/72  256

Figure 157: Household DHW volume HEEP  256

Figure 158: Self-reported shower duration – histogram  257

Figure 159: Tap temperature by system type  261

Figure 160: Distribution of hot water tap temperature by electric cylinder volume  262

Figure 161: Variation between thermostat setting & delivered water temperature  264

Figure 162: Adult skin (full thickness) epidermal burn time  266

Figure 163: Hot water temperature vs occupant average age  267

Figure 164: Thermostat setting distribution  267

Figure 165: Tap temperature distribution  267

Figure 166: Thermostat setting vs tap hot water temperature  268

Figure 167: Negawatt cylinder wrap  270

Figure 168: Examples of electric hot water cylinder wraps  275

Figure 169: ALF3 screen image  279

Figure 170: Daily profile of inside temperatures and energy use – weekend  281

Figure 171: Daily profile of inside temperatures and energy use – weekday  281

Figure 172: Winter temperature profiles for Christchurch HEEP houses  282

Figure 173: HEEP sample mean average winter evening temperatures  283

Figure 174: Histogram of living room evening temperatures in selected sample  284

Figure 175: Cumulative frequency of living room temperatures in selected sample  284

Figure 176: Wind exposure classes  287

Figure 177: Percentage versus modelled heated zone methods  289

Figure 178: Average living room temperatures during heating times  292

Figure 179: ALF3 vs reality – 20% lines  293

Figure 180: ALF3 vs reality – 2000 kWh lines  293

Figure 181: Average house temperatures during measured heating times  294

Figure 182: ALF3 vs reality – 20% lines  295

Figure 183: ALF3 vs reality – 2000 kWh lines  295

Figure 184: NZ Census 1945-1996 Domestic Hot Water by fuel type  319

Figure 185: NZ Census 1945-1996 % Dwellings with no DHW  319

Figure 186: NZ Census 1976-1996 Dwellings with only one DHW fuel  320

Figure 187: 1981 Census DHW Fuels  321

Figure 188: 1996 Census DHW Fuels  321

Figure 189: Changes in reported DHW fuel by region  321

Figure 190: First Class Hotel 1899  322

Figure 191: 1930s Laundry Copper  324

Figure 192: Chip heater  324

Figure 193: Push-through water heater  324

Figure 194: Low pressure household hot water system (1923)  325

Figure 195: “An Improved Electrical Water Heater” (1923) NZ Patent 51131  327

Figure 196: “Domestic Boiler System” (1926) US Patent 1,612,270  327

Figure 197: 1888 Lighting Fuel Cost Comparison  329

Figure 198: 1930s ‘Mercer’ Gas Storage Water Heater  331

Figure 199: 1930s ‘Champion’ Gas Cooker, Water heater & rubbish destructor59  331

Figure 200: Standing losses as function of tap temperatures  338

Figure 201: Average daily hot water energy use  340

Figure 202: Leaking cylinder - only turns off during ripple control  342

Figure 203: Cylinder that recharges occasionally  344

Figure 204: Cylinder that rarely turns off  344

Figure 205: Night-rate hot water cylinder  345

Figure 206: Example of a vacancy period  346

Figure 207: Example of a vacancy period for a ‘Night rate’ hot water system  346

Figure 208: Solid fuel burner output vs rate of change of cylinder temperature  347

Figure 209: Solid fuel burner output vs rate of change of cylinder temperature  348

Figure 210: Combined electric and wet-back water heating energy  349

[Tables]

Table 1: Location, count and year monitored for HEEP houses  2

Table 2: Fuel use – top and bottom 20%  11

Table 3: Energy end-use by fuel for houses with that end-use  13

Table 4: Total annual energy consumption – all fuels  14

Table 5: Total annual energy consumption per person – all fuels  14

Table 6: Total annual energy consumption – electricity only  14

Table 7: Total annual energy consumption per person – electricity only  15

Table 8: Appliance groups  18

Table 9: Average appliance electricity consumption per household  19

Table 10: Average electricity consumption per appliance  19

Table 11: Average appliance category proportion of electricity  20

Table 12: Lighting power by region  21

Table 13: Participation rate  25

Table 14: Participation rate of households asked to participate in the HEEP study  26

Table 15: What did HEEP record and measure?  28

Table 16: Appliance database  29

Table 17: HEEP people  30

Table 18: Estimated distance travelled by HEEP download staff  30

Table 19: Monitoring equipment  31

Table 20: Logger electrical energy measurement units  34

Table 21: Summary of missing data by circuit  37

Table 22: Summary of missing data by House  37

Table 23: Missing data by year of monitoring  37

Table 24: Missing data - Regional Council  37

Table 25: Missing data - SAMs versus circuit monitoring  38

Table 26: Missing data - Tinytag versus BRANZ temperature loggers  38

Table 27: Missing data – TML  38

Table 28: Circuits missing  38

Table 29: The most common reasons for missing data  39

Table 30: HEERA 16 regions – Regional Councils and Territorial Authorities  59

Table 31: Basic dwelling types for categorising New Zealand dwelling stock  66

Table 32: Extended dwelling types used for categorising the NZ dwelling stock  67

Table 33: HEEP and 1971 descriptive temperatures by region  70

Table 34: Mean temperatures: living room, bedroom and ambient  73

Table 35: Reported evening, all day and no heating by region  75

Table 36: Percentage of houses on various heating schedules  76

Table 37: Pre- and post-1978 heating schedule  76

Table 38: Reported heating season  77

Table 39: Average heating season by region (from north to south)  78

Table 40: Heating start and end month by region  81

Table 41: External temperatures over heating season  82

Table 42: Winter living room evening temperatures by heater type  84

Table 43: Living room winter evening temperature distribution  84

Table 44: Winter temperatures by insulation level  86

Table 45: Regional living room temperatures by insulation requirements  87

Table 46: Temperature difference between upper & lower logger by regional council  89

Table 47: Most used heater type and temperature difference  89

Table 48: Mean temperature during time periods  93

Table 49: Temperatures during afternoon solar gains and evening heating  107

Table 50: Average monthly living room evening temperatures in Hamilton houses (°C)  109

Table 51: Bedroom overnight temperatures in Hamilton houses (°C)  109

Table 52: Income, living room temperature and energy use descriptive statistics  117

Table 53: Correlations equivalised income and energy use variables  117

Table 54: Paired model summaries equivalised income and energy variables  118

Table 55: Household size, living room temperatures and energy use statistics  118

Table 56: Correlations equivalised income and energy use variables  119

Table 57: Paired model summaries household size, occupancy and energy variables  119

Table 58: Frequency table of the life stage variable  121

Table 59: Correlations life stage and energy use variables  121

Table 60: Paired model summaries for life stage and energy variables  121

Table 61: Multiple regression analysis for social dynamics variables and energy use  122

Table 62: HEEP equivalised income quintiles  124

Table 63: Equivalised income by at-risk mean temperatures  124

Table 64: Socio-demographic variables and winter evening living room at-risk (<16ºC) mean temperature  125

Table 65: HES average weekly expenditure by income group of household  125

Table 66: Equivalised income quintiles by winter energy expenditure – HEEP households 126

Table 67: Number of bedrooms for Māori & all HEEP households  129

Table 68: Age of house for Māori & all HEEP households  129

Table 69: Roofing insulation status of house for Māori & all HEEP households  130

Table 70: Winter evening living room temperatures for all & Māori HEEP households  131

Table 71: Winter evening living room temp by fuel for all & Māori HEEP households  131

Table 72: Main heating fuel – 1961 to 1971 Censuses & HEEP  134

Table 73: Heating fuels – 1971/72 Electricity Survey, Censuses & HEEP  134

Table 74: Availability of solid fuel appliances in HEEP households  134

Table 75: Solid fuel appliance types in HEEP households (observed data)  135

Table 76: Availability of solid fuel appliances by location  135

Table 77: Availability of solid fuel appliances by climate zone  135

Table 78: Availability of solid fuel appliances by urban/rural area  136

Table 79: Availability of solid fuel appliances by age of house  136

Table 80: Availability of solid fuel appliances by size of house  136

Table 81: Availability of solid fuel appliances by life stage  136

Table 82: Solid fuel appliance type by use in HEEP households (observed data)  137

Table 83: Use of solid fuel appliances by mix of heating fuels for HEEP households with a solid fuel appliance  137

Table 84: House areas heated by solid fuel appliances for HEEP households using a solid fuel appliance (self-reported data)  138

Table 85: Winter evening living room temperatures by heating fuel type for most used heating appliances  138

Table 86: Winter evening living room temperatures by available solid fuel appliance type for households using solid fuel  138

Table 87: Gas Hot Water Heating, Location and Income Characteristics  142

Table 88: Gas Hot Water Heating, Household Size, Composition, Tenure and Life Stage Characteristics  143

Table 89: Hot water cylinder characteristics by type of hot water heating  144

Table 90: Annualised Gross Energy Use and Annualised Gross Energy Use for Hot Water144

Table 91: Average Summer and Winter Fuel Bills for all energy use  145

Table 92: Key Water Use Patterns  146

Table 93: Number of Showers by Household Size by Type of Hot Water Heating  146

Table 94: Bedrooms and Rooms in Private Occupied Dwellings – 2006 Census  148

Table 95: The Size of HEEP Dwellings  149

Table 96: Estimated Typical Monthly Winter Energy Costs by the Size of HEEP Dwellings 150

Table 97: Estimated Typical Monthly Winter Energy Costs by Dwelling and Household Size150

Table 98: Total Energy Annual Use by the Size of HEEP Dwellings  150

Table 99: Total Annual Energy Consumption by HEEP Dwelling and Household Size  152

Table 100: Calibration slopes  156

Table 101: Assumed efficiencies of solid fuel burners  158

Table 102: Annual gross energy input by appliance type  160

Table 103: Variation of gross annual solid fuel energy consumption by location  160

Table 104: HES Household Heating Appliances  162

Table 105: Ownership of LPG heaters in the HEEP sample  163

Table 106: Gross energy output for each heater setting of the non-thermostatically controlled heaters  164

Table 107: Setting assignment errors for one heater  166

Table 108: Usage of LPG heaters from the processed HEEP LPG sample  170

Table 109: Mean LPG heater duration and energy consumption  170

Table 110: Mean energy consumptions for each setting  172

Table 111: Ownership of LPG heater and dehumidifier  173

Table 112: Heat losses for pre-and post-1978 HEEP houses  176

Table 113: Average winter temperatures by heating type  176

Table 114: Comparison of winter temperatures and Heat Index  177

Table 115: Comparison of space heating energy  177

Table 116: Mainly electrically heated houses space heating energy and temperatures  179

Table 117: Summary of model results  181

Table 118: Comparison of STEM and ALF U-value and thermal mass estimates  187

Table 119: Summary of the appliance ownership models  192

Table 120: Summary of the appliance energy models  192

Table 121 Top five appliances by standby power and energy  199

Table 122 Standby energy per house by appliance group  200

Table 123: Heated towel rail average power use  201

Table 124: New Zealand standby and baseload  202

Table 125: Breakdown of faulty appliances by type  208

Table 126: Breakdown of refrigeration appliances by decade  208

Table 127: Performance of algorithm at threshold of 07  209

Table 128: Performance of algorithm at threshold of 09  210

Table 129: Ownership of refrigeration appliances  216

Table 130: Average fraction of reactive energy from constant load  220

Table 131: Hot water cylinder characteristics by type  222

Table 132 Regional annual hot water energy use by fuel (kWh/house with fuel)  222

Table 133: Building Regulations 1992 Clause G12 – Objective  223

Table 134: Building Regulations 1992 Clause G12 – Performance (hot water)  224

Table 135: NZBC G12/AS1 – Water Temperature & Control (3rd Edition 2006)  224

Table 136: DHW fuels – international comparison  225

Table 137: Average DHW energy use by capacity  228

Table 138: Energy & proportion of main end-uses  230

Table 139: DHW Fuel use – top and bottom 20% of houses  231

Table 140: Hot water energy use by number of occupants  235

Table 141: Electric hot water cylinder standards  236

Table 142: Electric storage cylinder standing losses by size and grade  237

Table 143: Total energy consumption and standing losses by HEEP system type  237

Table 144: Household hot water energy use by system type  238

Table 145: Comparison gas & non-gas water heater households  239

Table 146: Regression model for hot water energy use  239

Table 147: Life stage by water heating fuel  240

Table 148: Linear model application – non-gas and gas water heating  241

Table 149: HEEP hot water systems  241

Table 150: Hot water adequacy by fuel type for randomly selected houses  242

Table 151: Hot water adequacy by system pressure  243

Table 152: Wetback use by region  244

Table 153: Cylinder volume range  245

Table 154: Hot water systems by fuel source and cylinder volume  245

Table 155: System pressure by fuel type  248

Table 156: HEEP random electric and gas cylinder descriptive statistics  250

Table 157: House and cylinder age comparison  252

Table 158: Life expectancies of cylinder types  252

Table 159: Hot water requirements for baths and showers  254

Table 160: Self reported bathing times  257

Table 161: Self reported shower duration by time of day per house  257

Table 162: Shower flow ratings  258

Table 163: HEEP shower flow by water pressure and temperature  259

Table 164: Maximum & minimum water flows  259

Table 165: HEEP Shower warm flow rates by WMCS rating  259

Table 166: Effect on average flows from retrofitting ‘low flow’ shower heads  260

Table 167: Auckland water costs (1 Sept 2006)  260

Table 168: High tap temperatures by system type  261

Table 169: HEEP 135 and 180 litre cylinder statistics  262

Table 170: Count of thermostat setting vs tap hot water temperature  268

Table 171: Tap Temperature and use of tempering valve  269

Table 172: Count of cylinder grade by house decade of construction  272

Table 173: Cylinder wrap cost benefit by cylinder grade  273

Table 174: Some alternative measures for D grade 180 litre retrofit  274

Table 175: Methods to reduce hot water emissions  275

Table 176: Length of Heating season  280

Table 177: ALF3 heating schedules  281

Table 178: Mean heating times on winter evenings  282

Table 179: Average heating temperatures in selected houses  283

Table 180: Wall and roof construction  285

Table 181: Construction R-value with no insulation  285

Table 182: Air leakage rates  287

Table 183: Climate locations  288

Table 184: Weighting of spaces for heating  293

Table 185: Standby power and energy for all measured appliances  310

Table 186: Average annual total energy use per house by fuel  311

Table 187: Average annual hot water energy use per house by fuel  311

Table 188: Average annual space heating energy use per house by fuel  311

Table 189: Average annual energy use per house for selected end-uses  311

Table 190: Christchurch Gas Company - Gas cost £ per 1,000 ft³  330

Table 191: Average gas by end-use: projected 1976 use & HEEP use  332

Table 192: NZ Censuses historical summary 1945-2001 – hot water questions  333

Table 193: NZ Censuses 1945-1996 – text of hot water questions  333

Table 194: North America – shower water use  335

Table 195: Australia – shower water usage  335

Table 196: Perth – shower water use  335

Table 197: Hot water energy comparison  337

Table 198: Hot water systems – comparison of properties  337

Table 199: Wetback heat output percentages  350

Full story including links for full report download (BRANZ) and online viewing.