Regional heat pump energy loads. Ian Page Manager Economics. Lisa French Building Energy Scientist

E528 Regional heat pump energy loads Author: Ian Page Manager Economics Reviewer: Lisa French Building Energy Scientist Contact: BRANZ Limited Moonshine Road Judgeford Private Bag 598 Porirua City New Zealand Tel: +64 4 237 117 Fax: +64 4 237 1171 www.branz.co.nz Project Number: QC5118 Date of Issue:13th July 29 Page 1 of 71 Pages

Contents 1. CLIENT... 5 2. INTRODUCTION... 5 3. MAIN RESULTS... 5 4. METHOD... 1 5. SENSITIVITY RESULTS... 12 5.1 Heat pump uptake rates... 13 5.2 Heating and cooling temperatures... 16 5.3 Area of house conditioned... 17 5.4 Use of summer cooling.... 17 5.5 Heat pump efficiency changes... 18 5.6 Electric resistance heating temperatures... 18 5.7 Population growth rate changes... 18 6. MONTHLY ENERGY... 18 7. REFERENCES... 22 8. APPENDIX... 24 8.1 Housing energy use modelling...24 8.1.1 Population projections...24 8.1.2 Household formation and new house numbers... 25 8.1.3 Fuel mix... 26 8.1.4 Insulation retrofit... 35 8.1.5 Heat pump efficiencies... 35 8.1.6 Heating and cooling schemes... 37 8.1.7 Use percentage summer cooling... 37 8.2 Online survey on heat pumps... 38 8.3 Simulations... 39 8.3.1 Energy efficiency of houses... 39 8.3.2 Modelling Assumptions Heating Times, Temperatures... 4 8.3.3 Modelling Assumptions Heated areas... 4 8.3.4 Modelling Assumptions House Construction... 41 8.3.5 Modelling Assumptions Internal Loads...42 8.3.6 Modelling Assumptions Thermal Performance... 43 8.3.7 Weather files... 43 8.4 Sensitivity analysis... 45 8.4.1 Heating/ cooling regimes... 45 8.4.2 Conditioned house areas... 52 8.4.3 Use of heat pump for summer cooling... 54 Report Number: E528 Date of Issue: 13 July 29 Page 2 of 71 Pages

8.4.4 Heat pump efficiencies... 55 8.4.5 Winter electric resistance heating to 21/ 22 C... 57 8.4.6 High and low population growth scenarios... 58 8.5 Month energy volumes and percentages... 62 8.6 Hourly energy volumes... 7 TABLES Table 1. Base case energy use Summer cooling... 8 Table 2. Base case energy use Winter heating... 9 Table 3. HP % constant Summer cooling... 15 Table 4. HP % constant Winter heating... 16 Table 5. Population forecasts... 24 Table 6. Insulation retrofit for the existing housing stock... 35 Table 7. Heat pump efficiencies... 36 Table 8.Summer cooling proportions by region... 38 Table 9. No Insulation... 39 Table 11. New insulation regulations being introduced at present (27-28)... 39 Table 12. Potential building code insulation levels in 22 second option... 4 Table 14. Cooling schedules... 4 Table 15. Description of existing house models construction... 41 Table 16. Description of new house models construction... 42 Table 17. Existing house internal gains... 42 Table 18. New houses internal gains... 42 Table 19. Summer cooling Evening2... 46 Table 2. Summer cooling Day19... 47 Table 21. Summer cooling Day2... 48 Table 22. Winter heating Day22... 49 Table 23. Winter heating Evening21... 5 Table 24. Winter heating Evening22... 51 Table 25. Increased conditioned areas Summer cooling... 52 Table 26. Increased conditioned areas Winter heating... 53 Table 27. Summer cooling heat pump use held constant... 54 Table 28. Constant heat pump efficiencies Summer cooling... 55 Table 29. Constant heat pump efficiencies Winter heating... 56 Table 3. Electric resistance heating to 21/22 C... 57 Table 31. Summer cooling High population growth rate scenario... 58 Table 32. Winter heating High population growth scenario... 59 Table 33. Summer cooling Low population growth rate scenario... 6 Table 34. Winter heating Low population growth rate scenario... 61 Table 35. Monthly energy use. Cooling percent by month - 29... 62 Table 36. Monthly energy use. Cooling percent by month 226... 63 Table 37. Monthly energy use. Heating percent by month 29... 64 Table 38. Monthly energy use. Heating percent by month 226... 65 Table 39. Monthly energy use. Cooling volume by month 29... 66 Table 4. Monthly energy use. Cooling volume by month 226... 67 Table 41. Monthly energy use. Heating volume by month 29... 68 Table 42. Monthly energy use. Heating volume by month 226... 69 Report Number: E528 Date of Issue: 13 July 29 Page 3 of 71 Pages

FIGURES Figure 1. Summer energy use base case assumptions... 6 Figure 2. Winter energy use base assumptions... 7 Figure 3. Energy space conditioning model... 11 Figure 4. Heat pump uptake by region... 12 Figure 5. Compare peak energy with and without heat pump penetration Summer cooling 13 Figure 6. Compare peak energy with and without heat pump penetration Winter heating... 14 Figure 7. Monthly peak energy summer cooling - 29... 19 Figure 8. Monthly peak energy summer cooling - 226... 19 Figure 9. Monthly energy use summer cooling - 29... 2 Figure 1. Monthly energy use summer cooling - 226... 2 Figure 11. Monthly peak energy winter heating - 29... 21 Figure 12. Monthly peak energy winter heating - 226... 21 Figure 13. Monthly energy use winter heating 29... 22 Figure 14. Monthly energy use winter heating - 226... 22 Figure 15. Persons per household, selected regions.... 25 Figure 16. New housing numbers... 25 Figure 17. Housing demolitions... 26 Figure 18. Fuel type change by region Existing houses... 3 Figure 19. Fuel type change by region New houses... 34 Figure 2. Cooling use of heat pumps percentage use... 37 Figure 21: Climate map for HERS... 44 Figure 22 Hourly energy use. Auckland Cooling Even19.... 7 Figure 23 Hourly energy use. Auckland Cooling Day2.... 7 Figure 24 Hourly energy use. Auckland Heating Day21.... 71 Figure 25 Hourly energy use. Auckland Heating Even22.... 71 Report Number: E528 Date of Issue: 13 July 29 Page 4 of 71 Pages

REGIONAL HEAT PUMP LOADS 1. CLIENT Transpower New Zealand Ltd Transpower House 96 The Terrace Wellington 611 2. INTRODUCTION Transpower requested BRANZ to forecast by region the energy loads created by domestic space conditioning. This study has been initiated by the increasing uptake of air-to-air heat pumps, which are now in 21% of all households. Both summer cooling and winter heating loads are considered, and the energy demands and peak demands by the 16 regional councils were investigated. Existing house numbers were obtained from census data and Statistics New Zealand (SNZ) population forecasts were used to estimate new housing. Research was commissioned on the existing use of heat pumps by region and future rates of uptake. Energy modelling was undertaken on a number of typical houses using the SUNREL modelling package, and the results scaled up for the housing stock in each region. An earlier report, (Page, French 28) had energy volumes for Auckland, Canterbury and Otago. The values in this report are lower for a number of reasons including a change to smaller average house sizes and higher heat pump efficiencies in this report, compared to the earlier assumptions. 3. MAIN RESULTS The main results from the base case assumptions are shown graphically below for selected regions. The peak energy use and total energy use for summer cooling is shown in Figure 1. The results for winter heating are in Figure 2. Report Number: E528 Date of Issue: 13 July 29 Page 5 of 71 Pages

Energy use GWhe Peak Energy MW Summer cooling with Heat Pump: Conditioning area= const. Conditioning regime= Even19 Pop proj=m Partial HP cooling use 2 18 16 Auckland 14 12 Canterbury 1 Waikato 8 6 Wellington 4 Otago 2 BOP Year ending March Peak Demand Summer cooling with Heat Pump: Energy Use Conditioning area= const. Conditioning regime= Even19 Pop proj=m Partial HP cooling use 9 8 7 Auckland 6 Canterbury 5 4 Waikato 3 Wellington 2 Otago 1 BOP Year ending March Figure 1. Summer energy use base case assumptions The cooling peaks per house for Canterbury are higher than for Auckland, but the cooling volumes per house are lower. Hence total peak demand for Auckland and Canterbury are both quite high but the total energy use in Canterbury is lower than in Auckland. The lines for cooling peaks and total use are fairly flat in most places because the increased heat pump numbers are mostly off-set by insulation retrofit effects and improved heat pump efficiencies. The exception is Auckland where strong population growth over-rides most other factors. Report Number: E528 Date of Issue: 13 July 29 Page 6 of 71 Pages

Energy use GWhe Peak Energy MW Winter heating with Heat pump + Elect Resist Heater: Peak Demand Conditioning area= const. Conditioning regime= Day21. Resist. Heater 18DegC. Pop proj=m 35 3 Auckland 25 Canterbury 2 15 Waikato 1 Wellington 5 Otago BOP Year ending March Winter heating with Heat pump + Elect Resist Heater: Energy Use Conditioning area= const. Conditioning regime= Day21. Resist. Heater 18DegC. Pop proj=m 6 5 Auckland 4 Canterbury 3 Waikato 2 Wellington 1 Otago BOP Year ending March Figure 2. Winter energy use base assumptions Most of the lines for heating energy use are fairly flat. The reason for this is there is an approximate balance between rising house numbers and a switch from solid to electric fuel, off-set against more heat pumps compared to resistance heaters, improving heat pump efficiency, and more insulation retrofits. The energy totals and energy peaks are tabulated for all regions in Table 1 and Table 2. Note, winter heating includes electric resistance heaters, where the latter houses are assumed to be at 18 C, not 21 C as used for the heat pump houses. Report Number: E528 Date of Issue: 13 July 29 Page 7 of 71 Pages

Table 1. Base case energy use Summer cooling Summe r Cooling Ene rgy use Conditioning a re a = const. Conditioning re gime = e ve n19 Pop proj=m Pa rtia l HP cooling Northland Energy vol (GWh).5 1.1 2.9 4. 4.6 5.2 5.6 6. Energy peak MW 3.2 6.4 14.3 17.3 18. 18.9 19.1 19.3 Auckland Vol GWh 5.5 11.1 29.7 42.9 52.1 61.9 7.1 78.4 Peak MW 3.3 56.5 123.6 152.5 162.9 175.9 183.1 19.4 Waikato Vol GWh 2.1 3.8 7.9 1.2 11.5 12.7 13.7 14.6 Peak MW 17.9 28.2 51. 58.4 59.3 61.3 61.5 61.6 Bay of Plenty Vol GWh 1.2 2.2 6.1 8.6 1.3 12.1 13.5 15. Peak MW 6.4 1.9 25.1 31.2 33.4 36.1 37.5 38.9 Gisborne Vol GWh.2.3.6.8.9 1. 1.1 1.2 Peak MW 1.6 2.5 3.9 4.4 4.4 4.6 4.7 4.7 Hawkes Bay Vol GWh.5.9 1.8 2.3 2.6 2.9 3.1 3.4 Peak MW 6. 8.7 14.5 16.5 16.8 17.4 17.5 17.7 Taranaki Vol GWh.2.4.9 1.1 1.3 1.3 1.4 1.4 Peak MW 2. 3.7 8.1 9.6 9.7 1.1 1. 9.9 Man-Wang Vol GWh.3.7 1.8 2.3 2.6 2.9 3.1 3.3 Peak MW 3.8 7.3 15.6 18.6 19.2 2.2 2.4 2.6 Wellington Vol GWh 1.2 2.1 4.7 6.2 7.2 8.1 8.7 9.4 Peak MW 13.4 21.6 41. 48.2 5. 52.5 53.3 54.1 Tasman Vol GWh.1.3.7.9 1.1 1.3 1.4 1.6 Peak MW.7 1.5 3.3 4.1 4.3 4.7 4.8 5. Nelson Vol GWh.4.6 1. 1.3 1.5 1.6 1.8 1.9 Peak MW 2.7 3.8 5.5 6.1 6.3 6.5 6.6 6.7 Marlborough Vol GWh.4.6.9 1.2 1.3 1.4 1.6 1.7 Peak MW 2.9 3.8 5. 5.5 5.6 5.8 5.9 6. West Coast Vol GWh...1.1.2.2.2.2 Peak MW.2.6 1.5 1.9 1.9 2. 2. 1.9 Canterbury Vol GWh 5.3 7.3 11.6 13.9 15.3 16.8 17.9 19. Peak MW 79.3 11. 142.4 154.4 154.1 158.6 159.4 16. Otago Vol GWh 1. 1.4 2.4 2.9 3.2 3.6 3.8 4.1 Peak MW 12.9 17.4 26.2 29.2 29.7 31.1 31.7 32.3 Southland Vol GWh.1.1.3.4.4.4.4.4 Peak MW 3.7 5.5 1.2 11.3 11. 11.1 1.9 1.6 Report Number: E528 Date of Issue: 13 July 29 Page 8 of 71 Pages

Table 2. Base case energy use Winter heating W inte r He a ting Ene rgy use Conditioning a re a = const. Conditioning re gime = Da y21. Re sist. He a te r 18De gc. Pop proj=m Northland Energy vol GWh 25.5 26.9 31.5 31.8 31.2 32.5 33.2 33.5 Energy peak MW 12.4 16.5 25.4 26.8 25.9 26. 25.3 24.6 Auckland Vol GWh 49.9 47.6 434.9 432.6 429.6 46.1 486.6 52.1 Peak MW 165.6 197.1 275.3 291.4 288.7 299.2 34.5 35.7 Waikato Vol GWh 134.9 14.5 155.2 156.8 158. 168.8 177.2 182.3 Peak MW 53.9 66.9 93.1 96.6 93.1 93.9 92.7 91. Bay of Plenty Vol GWh 46.8 49.2 72.2 77.6 78.3 83.2 86.3 87. Peak MW 24.4 31.8 56.9 61.9 6.1 6.6 59.4 57.6 Gisborne Vol GWh 7.6 7.7 1.9 1.8 9.6 9.8 9.7 9.5 Peak MW 4. 5.2 7.3 7.3 6.5 6.3 6. 5.7 Hawkes Bay Vol GWh 39.9 4.8 5. 49.2 45.5 45.4 44.8 44.5 Peak MW 2.2 24.3 33.7 33.9 31.2 3.1 28.5 27.1 Taranaki Vol GWh 33.6 33.9 39.8 37.4 33. 32.9 32.1 31. Peak MW 11.2 14.5 22.7 23. 2.6 2. 18.9 17.7 Man-Wang Vol GWh 83.6 85.9 95.8 92.1 86.1 89.8 92.4 93.7 Peak MW 26.9 35.1 52. 52.5 48. 47.5 46. 44.4 Wellington Vol GWh 288.5 289.4 266.9 241.4 226.3 239.7 25.5 253.4 Peak MW 87.6 13.2 127.9 124.7 114.7 114.8 112.6 19.1 Tasman Vol GWh 3.5 4.3 8.9 1.2 1.1 1.7 1.9 11.2 Peak MW 2.3 3.8 7.3 8. 7.7 7.7 7.5 7.4 Nelson Vol GWh 1.7 11. 13.4 13.6 12.9 13.3 13.5 13.7 Peak MW 6.6 8. 1.1 1.2 9.6 9.4 9.1 8.9 Marlborough Vol GWh 9.3 9.7 11.8 11.9 11.2 11.3 11.3 11.4 Peak MW 7.5 8.9 1.3 1.1 9.3 9. 8.6 8.3 West Coast Vol GWh 9.7 11.1 14.5 14.3 13.1 13.1 12.8 12.2 Peak MW 2.1 3.3 5.9 6.2 5.6 5.5 5.2 4.8 Canterbury Vol GWh 471.7 481.5 491.6 473.5 455.6 471.9 48.8 483.8 Peak MW 185.7 28.4 243.9 237.1 218.3 213. 24.3 195.5 Otago Vol GWh 189.6 195.8 218.5 213. 21.5 25.6 27. 26.4 Peak MW 61.5 7.9 87.6 85.2 77.3 74.7 71. 67.4 Southland Vol GWh 56.1 6. 82.6 79.5 69.1 66.3 62.6 59.1 Peak MW 18.2 22.9 35.9 35.6 31.2 29.6 27.2 25.1 Report Number: E528 Date of Issue: 13 July 29 Page 9 of 71 Pages

4. METHOD The method used to calculate energy volumes is shown diagrammatically in Figure 3. It is driven by demographics, combined with the thermal modelling results. Household formation forecasts are based on SNZ scenarios, described further in Section 8.1.1. The existing housing stock numbers, by region, are obtained from the five-yearly census of population and dwellings. The amount of insulation in houses affects their demand for heating and cooling energy, and existing insulation levels are obtained from the BRANZ House Condition Survey (Clark et al, 25), and the Housing Energy End-use Project (HEEP; Isaacs et al, 26). Insulation retrofit of the existing stock will continue into the future and the model allows for these changes. The heating and cooling regimes and the space conditioning modelling of the houses is described later and the results of that work provides the total and peak energy demand for the different locations. Demolitions of the stock are included since their replacements will usually be houses with a higher insulation level and a different space conditioning energy performance. TNS Conversa carried out a survey of over 3,8 households to obtain data on heat pump incidence, likely future uptake rates, and heating and cooling regimes. This was used to select the thermal modelling regimes and estimate future numbers of heat pumps. The demand model does not have any price information inputs. Electricity price escalation is indirectly included as encouraging a steady increase in the proportion of the housing stock with heat pumps and insulation retrofits. The price of heat pumps is not expected to change significantly in real terms, though there is allowance for efficiency improvements. Report Number: E528 Date of Issue: 13 July 29 Page 1 of 71 Pages

ENERGY DEMAND MODEL Household Existing formation housing by region Demolition stock replacements New housing numbers BRANZ & TNS survey data Heat pump and resistant heater uptake rates Insulation retrofit rates Heating/ cooling regimes Heat pump efficiency trends New housing Existing stock energy use Summer cooling energy use SUNREL modelling percentage use SUNREL modelling Total energy demand and peak energy demand Figure 3. Energy space conditioning model The main variables set out in the brief relate to: Population (Low, Medium, High) Household formation (Medium) Heat pump Uptake (Static, Medium) Insulation (no change, retrofit). Conditioned areas (living only, whole house). COP/EER (constant, improving). Heating regime(4 schemes, including Day21 degc) Cooling regime (4 schemes, including Even19 degc). Use percentage (full summer, partial and increasing summer). The assumptions for the base forecasts are shown in bold above, and the shaded boxes in Figure 3 represent where the assumptions can be altered. The single most important variable is the uptake rate of heat pumps. A summary of the assumptions is shown in Figure 4 for the existing stock. By 241 the uptake is expected to be up to 6% of all houses in the North Island and 8% in the South Island. Report Number: E528 Date of Issue: 13 July 29 Page 11 of 71 Pages

Percent of houses Percent of houses 1 Heat pumps in existing stock - North Island 8 6 4 2 29 216 226 241 1 Heat pumps in existing stock - South Island 8 6 4 2 29 216 226 241 Figure 4. Heat pump uptake by region 5. SENSITIVITY RESULTS A number of the variables listed in Section 4 were changed: Heat pump uptake rate Heating and cooling temperatures Heated areas of the house Summer cooling use Heat pump efficiency changes Electric resistance heating temperatures Population growth rates. The effect of changes in these variables were examined as follows. The detailed tables for the sensitivity analyses are in the appendix. Report Number: E528 Date of Issue: 13 July 29 Page 12 of 71 Pages

Peak energy MW Peak energy MW 5.1 Heat pump uptake rates The fuel mix assumptions for the base case are shown in Figure 18 and Figure 19 in the appendix. These allow for the heat pump incidence to increase to up to 8% of all houses in some regions. The following sensitivity analysis assumes that the fuel mix is unchanged and remains at the 29 percentages into the future. The heat pump efficiencies are also keep constant. This is the so-called demographics only run and the results are in Figure 5 and Figure 6 for Auckland and Canterbury only. 2 18 16 14 12 1 8 6 4 2 Auckland Summer cooling - Peak energy Conditioning area= const. Conditioning regime= Even19 Pop proj=m Partial HP cooling use Increased HP % No change HP% Canterbury Summer cooling - Peak energy Conditioning area= const. Conditioning regime= Even19 Pop proj=m Partial HP cooling use 18 16 14 12 Increased HP % 1 8 No change HP% 6 4 2 Figure 5. Compare peak energy with and without heat pump penetration Summer cooling Figure 5 indicates the summer cooling peak energy in the Auckland region increases by approximately 8MW by 216, and 13MW in 241, comparing increased heat pump penetration with no further gains in the percentage of houses with heat pumps. In Canterbury the peak increases by 6MW in 216 and 6MW in 241. Figure 6 indicates the winter heating peak in the Auckland region increases by approximately 9MW by 216 allowing for heat pump penetration compared to no change in current market penetration. By 241 the peaks are similar as electric resistance heater numbers rise in the No change scenario. In Canterbury the peak Report Number: E528 Date of Issue: 13 July 29 Page 13 of 71 Pages

Peak energymw Peak energy MW heating lines are fairly flat because insulation retrofits offset the increase in new housing. 35 Auckland Winter heating- Peak energy Conditioning area= const. Conditioning regime= Day21. Resist. Heater 18DegC. Pop proj=m 3 25 Increased HP % 2 15 1 No change HP% 5 3 25 Canterbury Winter heating - Peak energy Conditioning area= const. Conditioning regime= Day21. Resist. Heater 18DegC. Pop proj=m 2 15 1 Increased HP % No change HP% 5 Figure 6. Compare peak energy with and without heat pump penetration Winter heating In Table 3 and Table 4 the energy volumes and peaks decline slightly with time for some regions (Gisborne, Taranaki, West Coast and Southland), and these are locations where the SNZ population projections are for a net loss in population. Report Number: E528 Date of Issue: 13 July 29 Page 14 of 71 Pages

Table 3. HP % constant Summer cooling Summe r Cooling Ene rgy use Conditioning a re a = const. Conditioning re gime = e ve n19 Pop proj=m Pa rtia l HP cooling use Northland Energy vol (GWh).5.6.8 1. 1.2 1.3 1.5 1.6 Energy peak MW 3.2 3.3 3.6 3.8 3.9 4.1 4.3 4.4 Auckland Vol GWh 5.5 6.1 9.5 13.1 16.7 2.2 23.8 27.4 Peak MW 3.3 3.8 34.4 38.2 42. 45.9 49.9 53.8 Waikato Vol GWh 2.1 2.6 3.6 4.6 5.6 6.6 7.5 8.3 Peak MW 17.9 18.5 2.1 21.5 22.9 24.5 25.9 27.3 Bay of Plenty Vol GWh 1.2 1.4 2.1 2.8 3.4 4.1 4.8 5.4 Peak MW 6.4 6.6 7.3 8.1 8.8 9.6 1.3 11. Gisborne Vol GWh.2.2.3.3.4.4.5.5 Peak MW 1.6 1.6 1.6 1.6 1.6 1.7 1.7 1.7 Hawkes Bay Vol GWh.5.7 1. 1.2 1.5 1.7 1.9 2.2 Peak MW 6. 6.1 6.6 6.9 7.3 7.6 8. 8.4 Taranaki Vol GWh.3.3.4.5.6.7.7.7 Peak MW 3. 3.1 3.3 3.4 3.5 3.6 3.7 3.8 Man-Wang Vol GWh.3.4.6.8.9 1.1 1.2 1.3 Peak MW 3.8 4. 4.4 4.7 5. 5.3 5.6 5.9 Wellington Vol GWh 1.2 1.3 1.8 2.3 2.7 3.1 3.5 3.8 Peak MW 13.4 13.6 14.4 15.2 16. 16.8 17.5 18.3 Tasman Vol GWh.1.1.2.3.4.5.5.6 Peak MW.7.7.9 1. 1.1 1.2 1.3 1.4 Nelson Vol GWh.4.4.6.7.8.9 1.1 1.2 Peak MW 2.7 2.7 2.9 3. 3.1 3.3 3.4 3.6 Marlborough Vol GWh.4.5.6.7.8.9 1. 1.1 Peak MW 2.9 2.9 3.1 3.2 3.3 3.4 3.5 3.6 West Coast Vol GWh.1.1.2.2.3.3.3.3 Peak MW.21.22.24.24.25.25.26.26 Canterbury Vol GWh 5.3 5.8 7.2 8.6 1. 11.4 12.7 13.9 Peak MW 79.3 79.9 82.5 84.9 87.2 91.4 95.2 98.5 Otago Vol GWh 1. 1.1 1.3 1.5 1.7 1.9 2.1 2.3 Peak MW 12.9 12.9 13.3 13.6 13.8 14.4 14.9 15.5 Southland Vol GWh.9.1.12.13.14.14.14.15 Peak MW 3.7 3.7 3.7 3.6 3.5 3.5 3.5 3.5 Report Number: E528 Date of Issue: 13 July 29 Page 15 of 71 Pages

Table 4. HP % constant Winter heating W inte r He a ting Ene rgy use Conditioning a re a = const. Conditioning re gime = da y21. Re sist. He a te r 18De gc. Pop proj=m Northland Energy vol (GWh) 25.5 26.1 27.9 29.5 3.9 33.6 36. 38.8 Energy peak MW 12.4 12.9 14.1 15.2 16.1 17.4 18.5 19.7 Auckland Vol GWh 49.9 41.3 423.6 449.2 476.4 533.3 591.5 65.1 Peak MW 165.6 166.1 185.7 26.5 227.8 255.7 284. 312.3 Waikato Vol GWh 134.9 139.6 153.4 166. 178.2 198.2 217.4 235.7 Peak MW 53.9 55.6 6.3 64.7 68.8 74.7 8.2 85.5 Bay of Plenty Vol GWh 46.8 48.1 57.9 67.9 77.9 9.3 12.5 114.7 Peak MW 24.4 25. 29. 32.9 36.9 41.5 46. 5.4 Gisborne Vol GWh 7.6 7.6 7.8 8. 8.2 9. 9.9 1.7 Peak MW 4. 4. 4. 4. 4. 4.2 4.4 4.6 Hawkes Bay Vol GWh 39.9 4. 4.7 41. 41. 43.5 46.3 49.5 Peak MW 2.2 2.2 2.3 2.3 2.1 2.7 21.4 22.1 Taranaki Vol GWh 33.6 33.4 31.8 29.8 27.5 28.4 29.1 29.6 Peak MW 11.2 11.2 1.8 1.4 9.9 1. 1.2 1.2 Man-Wang Vol GWh 83.6 83.5 83.9 83.6 82.7 89.9 97.1 14. Peak MW 26.9 27. 27.3 27.4 27.3 28.9 3.5 32. Wellington Vol GWh 288.5 285.1 286.9 287.7 288.3 318.5 348.1 376.7 Peak MW 87.6 87.1 88.5 89.5 9.4 97.2 13.7 19.9 Tasman Vol GWh 3.5 3.9 4.7 5.5 6.3 7.3 8.2 9.3 Peak MW 2.3 2.4 2.7 3. 3.3 3.6 4. 4.4 Nelson Vol GWh 1.7 1.6 1.6 1.6 1.6 11.5 12.3 13.1 Peak MW 6.6 6.6 6.6 6.7 6.6 6.9 7.2 7.4 Marlborough Vol GWh 9.3 9.3 9.6 9.9 9.9 1.6 11.4 12.2 Peak MW 7.5 7.5 7.6 7.6 7.5 7.7 7.9 8.1 West Coast Vol GWh 9.75 1.77 11.67 12.18 12.39 13. 13.49 13.77 Peak MW 2.5 2.24 2.43 2.55 2.61 2.71 2.78 2.82 Canterbury Vol GWh 471.7 47.2 483. 496.1 58.7 555.1 598.2 638.8 Peak MW 185.7 184.3 184.3 184.1 183.7 191.6 198.5 24.6 Otago Vol GWh 189.6 19.2 195.9 2.8 25.4 223.1 241. 258.5 Peak MW 61.5 61.1 6.7 6.2 59.5 61.8 63.9 66. Southland Vol GWh 56.11 57.57 58.45 57.45 54.93 55.57 56.5 57.74 Peak MW 18.2 18.3 18. 17.3 16.5 16.4 16.3 16.3 5.2 Heating and cooling temperatures The base case summer cooling regime is 19 C in the evening, and for winter heating it is 21 C during the day. These are the base cases as specified by the client. It should be pointed out that HEEP data shows that for winter heating it is evening heating that is more common than the day heating used in the base case. The tables for different cooling and heating regimes are in the Appendix. The summary results, compared to the base case, are: Summer cooling Evening 2 C peak MW energy decreases by between 9% and 18%, and the energy GWh total reduces by 3% to 4%, depending on the region (see Table 19). Summer cooling Day 19 C the peak energy decreases by between 3% and 5%, and energy totals increase by 7% to 12%, depending on the region (see Table 2). Report Number: E528 Date of Issue: 13 July 29 Page 16 of 71 Pages

Summer cooling Day 2 o C the peak decreases by between 4% and 6%, and energy totals increase by 1% to 4%, depending on the region (see Table 21). Winter heating Day 22 C peak and energy total volumes increase by between 6% and 14% depending on the region (see Table 22). Winter heating Evening 22 C the peak changes reduce by up to 1%, and energy totals increase by up to 1%, depending on the region (see Table 24). Winter heating Evening 21 C the peak decreases by between 1% and 2%, and energy totals reduce by 5% to 1%, depending on the region (see Table 23). Full details are in the appendix. These changes can be used to approximate the effect of climate change on space conditioning energy demand. Temperatures are expected to be approximately 1 C warmer, on average by 241 (see Bengtsson et al 27). The above indicates that going from 19 C to 2 C evening cooling reduces the energy use by about 3% to 4%. A 1 C temperature rise will increase energy demand and the temperature-energy relationship is approximately linear, for small changes in temperatures. So maintaining 19 C evening temperatures in summer in 241 will increase energy use by approximately 3% to 4%. The converse occurs with winter heating, where climate change will reduce energy demand. The base case is 21 C Day and a 22 C Day indoor temperature increases energy volumes by between 6% to 14%. So we can expect winter energy volumes to decrease by about 6% to 14% in 241 assuming the base case remains at 21 C. 5.3 Area of house conditioned The areas conditioned in the base case are the living areas and includes the kitchen and dining area connected to the living area in an open plan. Alternative thermal modelling was carried out using an increased house area to cover the bedrooms and hallways. The heating and cooling set points remained the same as the base case. Typically the conditioned area in the alternative modelling was two to three times larger than in the base case. The energy peaks were typically 27% to 3% above base case summer cooling peaks, and energy use was 18% to 25% higher. For winter heating the peaks were 2% to 26% higher than the base case, and the energy use was 12% to 21% above the base case. Full details are in the appendix. 5.4 Use of summer cooling. Not all heat pumps are used for summer cooling because it is believed most households purchase them for winter heating as the primary use. The TNS survey indicates about 64% of residential heat pumps nationwide are used for summer cooling, but overseas studies indicates the percentage rises over time. The regional cooling use percentage is shown in the appendix (see Table 8), based on results from the TNS survey. This indicates a regional variation of between 4% and 9% of heat pumps used in the summer at present and the percentage use is assumed to rise by Report Number: E528 Date of Issue: 13 July 29 Page 17 of 71 Pages

3% (to a maximum of 1%) in each region by 241. This rise in use is included in the base case. In this sensitivity analysis the summer use percentage was kept constant at the percentage for 29. The result is that summer energy peak and total use is about 2% to 4% lower, depending on the region, in 241 compared to the base case. This is because although heat pump numbers are increasing, the percentage used for cooling does not increase, as occurs in the base case. 5.5 Heat pump efficiency changes Heat pump efficiencies (also known as Coefficients of Performance, or COPs) are given in Table 7 in the appendix and are assumed to rise to between 4.2 and 5. by 241, the efficiency depending on the season and location. When these efficiencies are keep constant (i.e. there is no improvement in heat pump technology) the energy use in 241, both peak and volume, rises by about 25% to 6% in winter and 45% to 6% in summer, depending on the region. 5.6 Electric resistance heating temperatures In houses with electric resistance heaters winter temperatures levels are held at 18 C rather than the 21 C or 22 C level assumed for other fuels. This is the base case assumption for modelling, based on HEEP work that shows houses with electric resistance heaters have lower average winter temperatures than houses using other fuel types. However, in the sensitivity analysis we allow for electric resistance heated houses to achieve the same temperatures as houses heated with the other fuel types. This gives an energy volume up by about 1% to 35% compared to the base case. The peak demand is up about 3% in the early years but drops to about 1% in later years as the heat pump market penetration rises. 5.7 Population growth rate changes The demographic projections use a medium population growth scenario for the base case. The sensitivity analysis allows for high and low population growth scenarios. With the high scenario energy use is up about 4% on the base case by 241 and the peaks are about 15% higher than the base case. With the low population scenario the energy volumes are down about 4% and peaks down about 15% compared to the base case, summer and winter. 6. MONTHLY ENERGY Figure 7 to Figure 1 show energy use and peaks by month, for summer cooling at 29 and 226, for selected regions. The volumes are higher for the later year but the seasonal pattern is similar in 29 and 226, i.e. the peak month is February for cooling, though in Auckland and Wellington January is almost as high as February. Report Number: E528 Date of Issue: 13 July 29 Page 18 of 71 Pages

Peak energy MW Peak energy MW 9 Monthly energy peak. Summer cooling. Conditioning area = const Conditioning regime = even19 Pop proj= M Year = 29 8 7 6 5 4 3 2 1 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC Auckland Wellington Canterbury Figure 7. Monthly peak energy summer cooling - 29 2 18 16 14 12 1 8 6 4 2 Monthly energy peak. Summer cooling. Conditioning area = const Conditioning regime = even19 Pop proj= M Year = 226 Auckland Wellington Canterbury JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC Figure 8. Monthly peak energy summer cooling - 226 Report Number: E528 Date of Issue: 13 July 29 Page 19 of 71 Pages

Energy use GWh per year Energy use GWh per year 1.8 1.6 1.4 1.2 1..8.6.4.2. Monthly energy use. Summer cooling. Conditioning area = const Conditioning regime = even19 Pop proj= M Year = 29 Auckland Wellington Canterbury JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC Figure 9. Monthly energy use summer cooling - 29 18 16 14 12 1 8 6 4 2 Monthly energy use. Summer cooling. Conditioning area = const Conditioning regime = even19 Pop proj= M Year = 226 Auckland Wellington Canterbury JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC Figure 1. Monthly energy use summer cooling - 226 Monthly heating for winter is shown in Figure 11 to Figure 14. For peak energy (MW) June is the highest month for Auckland and Canterbury, and July for Wellington. For total energy use (GWh) July is the highest month for the three centres. Report Number: E528 Date of Issue: 13 July 29 Page 2 of 71 Pages

Peak energy MW Peak energy MW 2 18 16 14 12 1 8 6 4 2 Monthly energy peak. Winter heating Conditioning area = const Conditioning regime = Day21 Pop proj= M Year = 29 Auckland Wellington Canterbury JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC Figure 11. Monthly peak energy winter heating - 29 35 Monthly energy peak. Winter heating Conditioning area = const Conditioning regime = Day21 Pop proj= M Year = 226 3 25 2 Auckland Wellington 15 Canterbury 1 5 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC Figure 12. Monthly peak energy winter heating - 226 Report Number: E528 Date of Issue: 13 July 29 Page 21 of 71 Pages

Energy use GWh per year Energy use GWh per year 1. 9. 8. 7. 6. 5. 4. 3. 2. 1.. Monthly energy use. Winter heating Conditioning area = const Conditioning regime = Day21 Pop proj= M Year = 29 Auckland Wellington Canterbury JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC Figure 13. Monthly energy use winter heating 29 12. Monthly energy use. Winter heating Conditioning area = const Conditioning regime = Day21 Pop proj= M Year = 226 1. 8. 6. 4. Auckland Wellington Canterbury 2.. JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC Figure 14. Monthly energy use winter heating - 226 More details of the monthly volumes and percentages are in Section 8.5. 7. REFERENCES Bengtsson et al (27). Assessment of the need to adapt buildings in New Zealand to the impact of climate change. Study Report 179. BRANZ. Wellington. French L. (28). Active cooling and heat pump use in New Zealand Survey results. Study Report 186. BRANZ, Wellington. Clark S, Jones M, Page I. (25). New Zealand 25 House Condition Survey. BRANZ, Wellington Report Number: E528 Date of Issue: 13 July 29 Page 22 of 71 Pages

Page I, French L (28).Peak load and total energy use forecasting for heat pumps. BRANZ Report QC5112. For Transpower NZ. Isaacs et al (26). Energy use in NZ households Report on the year 1 analysis. BRANZ Study Report 155. BRANZ, Wellington. Mustard D, Mc Kibbin R. (29) Research on heat pump usage and incidence rates in New Zealand. TNS Conversa, Auckland. Report Number: E528 Date of Issue: 13 July 29 Page 23 of 71 Pages

8. APPENDIX This appendix consists of five main sections: Regional housing energy use modelling TNS survey results summary Space conditioning simulations Sensitivity analysis results Monthly energy volumes and percentages Hourly energy volumes 8.1 Housing energy use modelling The derivation of energy use by region follows the flow chart in Figure 3. 8.1.1 Population projections The base case used for population growth is the medium scenarios from Statistics New Zealand assuming 1, net migration inflows per year on average, and medium levels for mortality and fertility rates, based on recent trends. The usual residential population as at the 26 is the starting point. These numbers are slightly lower than the numbers used by SNZ for their population projections. SNZ use a 3 June date for their forecasts whereas the table below uses March censuses. The percentage change in five year increments from the SNZ population forecasts for each region were used to obtain the population numbers below. To derive new housing statistics the population forecasts are divided by the persons per household trends, see Table 5 and Figure 15. Table 5. Population forecasts Usual resident population At March 26 211 216 221 226 231 236 241 Northland 148,47 154,27 159,68 163,54 166,166 168,28 169,179 17,194 Auckland 1,33,68 1,49,84 1,518,44 1,626,56 1,733,52 1,836,556 1,936,273 2,3,574 Waikato 382,716 399,86 413,132 425,337 435,895 444,516 45,523 454,72 Bay of Plenty 257,379 271,543 284,349 296,88 36,953 316,461 324,263 33,358 Gisborne 44,499 44,983 45,176 45,273 44,983 44,499 43,78 42,836 Hawke's Bay 147,783 15,54 152,447 153,613 154,99 153,71 153,249 152,789 Taranaki 14,124 14,512 14,69 14,27 12,765 1,728 98,247 95,237 Manawatu-Wang 222,423 225,332 227,756 229,21 229,695 228,725 227,44 224,394 Wellington 448,959 464,845 478,614 49,745 51,143 59,327 515,242 518,827 Tasman 44,625 46,769 48,522 5,81 51,445 52,517 53,239 53,985 Nelson 42,888 44,243 45,45 46,373 47,148 47,729 48,72 48,49 Marlborough 42,558 44,22 45,193 46,72 46,462 46,56 46,653 46,746 West Coast 31,326 31,326 31,131 3,74 3,155 29,277 28,26 27,79 Canterbury 521,832 546,957 568,12 586,964 64,69 619,434 63,847 639,1 Otago 193,8 198,941 23,5 27,477 21,774 213,199 214,939 215,895 Southland 91,494 9,79 89,531 87,764 85,47 82,364 79,399 76,541 NZ 4,27,944 4,229,793 4,417,9 4,591,346 4,752,239 4,895,841 5,21,246 5,128,979 Report Number: E528 Date of Issue: 13 July 29 Page 24 of 71 Pages

Number per 5 year period 3. 2.9 2.8 2.7 2.6 2.5 2.4 2.3 2.2 2.1 2. Persons per household assumptions 26 211 216 221 226 231 236 241 Auckland Waikato Bay of Plenty Wellington Canterbury Otago Figure 15. Persons per household, selected regions. 8.1.2 Household formation and new house numbers The new housing numbers are obtained by dividing the population by the persons per household and these are shown in Figure 16. Auckland remains the major centre into the future followed by Canterbury and Wellington regions. 45 4 35 3 25 2 15 1 5 New housing - for selected regions 26 211 216 221 226 231 236 5 Years starting Auckland Waikato Bay of Plenty Wellington Canterbury Otago Figure 16. New housing numbers The housing stock is beginning to age and by about 221 houses from the 195s and 196s will require significant renovation to extend their life. It is likely some will be beyond repair/adaptation and will be demolished. These houses will be replaced with new housing and have been added to the numbers derived from population growth demand for houses. The net effect of these demolition replacements is that energy use is reduced because the new replacements have higher insulation levels, on average, than the demolished stock. Report Number: E528 Date of Issue: 13 July 29 Page 25 of 71 Pages

Demolitions in 5 year period 45 Housing demolitions - NZ total 4 35 3 25 2 15 1 5 26 211 216 221 226 231 236 Source:BRANZ Study Report 25 5 years starting Figure 17. Housing demolitions 8.1.3 Fuel mix The fuels for winter heating consist of four main types, electric resistance heaters, heat pumps, solid fuel heaters (i.e. wood, pellet and coal burners), and gas heaters (natural gas and LPG). The forecasts for fuel shares by region are shown in the following charts, see Figure 18. The starting point is the main heating fuel shares at present, by region, as revealed in the TNS survey (TNS Conversa, 29) (Q4) of approximately 3,8 households. To obtain the shares in 241 the answers to the question on heating replacement (Q6) were used to allocate the regions to one of three categories, namely a high, medium or low likelihood to purchase a heat pump. An increased share of 5%, 4% and 3% respectively (for high, medium and low likelihoods) was added to the 29 heat pump regional percentages, to represent the share for 241. Solid fuel use was assumed to reduce by 5% and gas use by 2% from current levels. The residual was electric resistance, with an assumed minimum of 5% share in all regions. The decline in solid fuel heating is assumed to be driven by clean air regulations, with most regional councils having air-shed pollution targets to achieve. The maximum share for heat pumps occurs in Canterbury, Otago and Southland, and the least in Northland, Gisborne, Tasman and the West Coast. A similar set of regional fuel types are shown below for new housing, see Figure 19. The current incidence by region is based on the BRANZ New Dwellings Survey, and the heat pump percentage in 241 is assumed to be between 1% and 2% higher than for existing houses at that time. As for existing houses, solid fuel use is assumed to decline by 5%, and gas use by 2%, through to 241. Report Number: E528 Date of Issue: 13 July 29 Page 26 of 71 Pages

Percentage Percentage Percentage Percentage 6 5 4 3 2 1 6 5 4 3 2 1 6 5 4 3 2 1 8 6 4 Northland - Fuel types Auckland - Fuel types Waikato - Fuel types BOP - Fuel types Heat pump Other Elect Solid fuel Gas Heat pump Other Elect Solid fuel Gas Heat pump Other Elect Solid fuel Gas Heat pump Other Elect Solid fuel Gas 2 Report Number: E528 Date of Issue: 13 July 29 Page 27 of 71 Pages

Percentage Percentage Percentage Percentage 6 5 4 3 2 1 8 6 4 Gisborne - Fuel types Hawkes Bay - Fuel types Heat pump Other Elect Solid fuel Gas Heat pump Other Elect Solid fuel Gas 2 6 5 4 3 2 1 6 5 4 3 2 1 Taranaki - Fuel types Manawatu-Wanganui - Fuel types Heat pump Other Elect Solid fuel Gas Heat pump Other Elect Solid fuel Gas Report Number: E528 Date of Issue: 13 July 29 Page 28 of 71 Pages

Percentage Percentage Percentage Percentage 6 5 4 3 2 1 8 6 4 Wellington - Fuel types Tasman - Fuel types Heat pump Other Elect Solid fuel Gas Heat pump Other Elect Solid fuel Gas 2 8 6 4 Nelson - Fuel types Heat pump Other Elect Solid fuel Gas 2 8 6 4 Marlborough - Fuel types Heat pump Other Elect Solid fuel Gas 2 Report Number: E528 Date of Issue: 13 July 29 Page 29 of 71 Pages

Percentage Percentage Percentage Percentage 6 5 4 3 2 1 8 6 4 West Coast - Fuel types Canterbury - Fuel types Heat pump Other Elect Solid fuel Gas Heat pump Other Elect Solid fuel Gas 2 8 6 4 Otago - Fuel types Heat pump Other Elect Solid fuel Gas 2 8 6 4 Southland - Fuel types Heat pump Other Elect Solid fuel Gas 2 Figure 18. Fuel type change by region Existing houses Report Number: E528 Date of Issue: 13 July 29 Page 3 of 71 Pages

Percentage Percentage Percentage Percentage 7 6 5 4 3 2 1 7 6 5 4 3 2 1 8 6 4 Northland - Fuel types Auckland - Fuel type Waikato - Fuel type Heat pump Other Elect Solid fuel Gas Heat pump Other Elect Solid fuel Gas Heat pump Other Elect Solid fuel Gas 2 8 6 4 BOP - Fuel types Heat pump Other Elect Solid fuel Gas 2 Report Number: E528 Date of Issue: 13 July 29 Page 31 of 71 Pages

Percentage Percentage Percentage Percentage 8 6 4 Gisborne - Fuel types Heat pump Other Elect Solid fuel Gas 2 1 8 6 Hawkes Bay -Fuel types Heat pump Other Elect Solid fuel Gas 4 2 8 6 4 Taranaki - fuel types Heat pump Other Elect Solid fuel Gas 2 8 6 4 Manawatu- Wanganui - Fuel types Heat pump Other Elect Solid fuel Gas 2 Report Number: E528 Date of Issue: 13 July 29 Page 32 of 71 Pages

Percentage Percentage Percentage Percentage 8 6 4 Wellington - Fuel types Heat pump Other Elect Solid fuel Gas 2 8 6 4 Tasman - Fuel types Heat pump Other Elect Solid fuel Gas 2 8 6 4 Nelson - Fuel type Heat pump Other Elect Solid fuel Gas 2 1 8 6 4 Marlborough - Fuel types Heat pump Other Elect Solid fuel Gas 2 Report Number: E528 Date of Issue: 13 July 29 Page 33 of 71 Pages

Percentage Percentage Percentage Percentage 6 5 4 3 2 1 1 8 6 West Coast - Fuel type Canterbury - Fuel type Heat pump Other Elect Solid fuel Gas Heat pump Other Elect Solid fuel Gas 4 2 1 8 6 Otago - Fuel types Heat pump Other Elect Solid fuel Gas 4 2 1 8 6 Southland - Fuel types Heat pump Other Elect Solid fuel Gas 4 2 Figure 19. Fuel type change by region New houses Report Number: E528 Date of Issue: 13 July 29 Page 34 of 71 Pages

8.1.4 Insulation retrofit Pre-1978 houses are unlikely to have wall or floor insulation, though most have some ceiling insulation. The BRANZ 24 House Condition Survey and HEEP provides data on the amount of ceiling and floor insulation in typical houses for a number of regions. These results are shown in Table 6, where nil/little insulation is defined as 5 mm of ceiling insulation or less. The assumptions on retrofit levels are in the table, and indicate that the pre -1978 housing stock (when insulation first became mandatory) will have been retrofitted to a reasonable level by 226. Many of the post-1978 houses would also have been upgraded by then to current insulation levels (28). Table 6. Insulation retrofit for the existing housing stock Insulation retrofit - selected regions Insulation Pe rce nt by sta nda rd a t level 29 226 241 Auckland Nil/Little 28 5 1978 7 54 4 28 2 42 6 1 1 1 Waikato Nil/Little 28 5 1978 7 54 4 28 2 42 6 1 1 1 BOP Nil/Little 24 5 1978 74 55 4 28 2 4 6 1 1 1 Wellington Nil/Little 3 1978 68 48 3 28 2 53 7 1 1 1 Canterbury Nil/Little 2 1978 78 48 2 28 2 52 8 Otago Nil/Little 21 1978 77 47 2 28 2 53 8 1 1 1 8.1.5 Heat pump efficiencies The technology for heat pumps is continually improving and it is assumed there will be efficiencies of COPs between 4.2 and 5., depending on location and season, in new heat pumps over the next 3 years. The assumptions are in Table 7 where lower efficiencies are used in cooler climates and for heating compared to cooling. These values are based on some research carried out by Nikki Buckett at BRANZ - see below. Report Number: E528 Date of Issue: 13 July 29 Page 35 of 71 Pages

Table 7. Heat pump efficiencies Heat pumps - COPs and EERs Se le cte d re gions COP or EER a t 29 226 241 Auckland Summer 3.4 4.2 5. Winter 3.2 4. 4.8 BOP Summer 3.4 4.2 5. Winter 3.2 4. 4.8 Wellington Summer 3.1 3.9 4.7 Winter 2.9 3.7 4.5 Canterbury Summer 2.8 3.6 4.4 Winter 2.6 3.4 4.2 Otago Summer 2.7 3.55 4.4 Winter 2.5 3.35 4.2 Comments from Nikki Buckett, Building Technologist, BRANZ, on heat pump efficiency trends. I ve done a bit of research into the efficiency of heat pumps in order to get a better idea of where their efficiency will be in about 2 years time. There is very little information available, especially regarding COPs of older units. I believe that a typical COP for early NZ models installed in the 9s was around the 2.5 mark although can t find any proof of this. Now, going through the EnergyWise database of heat pump units, the average COP over ALL sizes and heat pump types is 3.77 (124 entries). My data from May 7 (3576 entries) has an average COP over ALL sizes and heat pump types of 3.1. The maximum COP a heat pump can reach, or Ideal COP as it is known, = Output Temperature ( K)/Temperature differential ( K). So, if the external temperature is 7 C, and the heat pump is heating to 23 C, the equation is: 296.15 K/(296.15 K-28.15 K) = 18.5 (Ideal COP). See the attachment for a good explanation. However, the unit must also operate a fan and a pump for the refrigerant, display, fin direction etc, plus there are external factors such as humidity levels etc. Therefore the actual COP is never anywhere close to the Ideal COP, nor is it likely to be achieved. The maximum efficiency in the new energywise list is 5.22 (Panasonic CS-HE9GKE, under 4kW in output see http://www.panasonic.co.nz/heatpumps/heatpumps-products/heatpumps-home/cscuhe9gke.html). The maximum efficiency in the May 7 list was the Panasonic RAS-B1SKVP-E (no longer produced by the looks), non ducted single split system under 4kW in output. Also, see http://www.heatpumpcentre.org/about_heat_pumps/hp_performance.asp (last updated April 9) for a handy graph and tables they reckon maximum efficiency for an electric compressor-type heat pump is around 5. After looking at all of this, and acknowledging the slowing of efficiency improvements over the past few years, I d say the average COP for NZ air to air heat pumps in 2 years will be hovering around the 5 mark for all types as inverter technology is developed further and adopted for more types of heat pump applications. This does not include losses in efficiency due to ducting in the central heat pump systems. This gives manufacturers some room to improve a little on the current designs, but acknowledges the challenges they have in increasing the COP to closer to Ideal COP levels. Unless there is a radical change in technology, I think this will be about right. The heat pumps with the highest COPs (over 5) are all single split inverters from what I can see, which appeared on the market here about 2-3 years ago. CO2 heat pumps (manufactured in Japan under the name EcoCute ) are probably the next air to air heat pump technology that will be introduced to our market over the next few years. These have COPs of around 5. Report Number: E528 Date of Issue: 13 July 29 Page 36 of 71 Pages

8.1.6 Heating and cooling schemes There are four heating schemes for summer cooling and winter heating and these are described later in 8.3. 8.1.7 Use percentage summer cooling The TNS survey indicates that users do not all use their heat pump for summer cooling. The assumed track is as below for selected regions, see Figure 2 and Table 8. At present, according to the survey Waikato and Taranaki are the regions most likely to use heat pumps for cooling, followed by Auckland and Canterbury. The percentages are the proportion of houses that use their heat pumps for cooling; the others open windows, use fans or do not actively cool in summer. Heat pump summer cooling use 1% 9% 8% 7% 6% 5% 4% 3% 2% 1% % Auckland Waikato BOP Wellington Canterbury Otago Figure 2. Cooling use of heat pumps percentage use Report Number: E528 Date of Issue: 13 July 29 Page 37 of 71 Pages

Table 8.Summer cooling proportions by region Percentage use of heat pumps for summer cooling Northland 69 72 77 81 86 9 95 99 Auckland 67 7 74 79 83 88 92 97 Waikato 76 79 82 86 89 93 96 1 Bay of Plenty 52 55 59 64 68 73 77 82 Gisborne 5 53 58 62 67 71 76 8 Hawkes Bay 58 61 66 7 75 79 84 88 Taranaki 6 63 68 72 77 81 86 9 Man-Wang 5 53 58 62 67 71 76 8 Wellington 59 62 66 71 75 8 84 89 Tasman 5 53 58 62 67 71 76 8 Nelson 67 7 74 79 83 88 92 97 Marlborough 53 56 61 65 7 74 79 83 West Coast 5 53 58 62 67 71 76 8 Canterbury 64 67 72 76 81 85 9 94 Otago 4 43 48 52 57 61 66 7 Southland 58 61 66 7 75 79 84 88 Taranaki and Tasman had very high and very low cooling percentages, respectively, in the survey, and these were somewhat arbitrarily adjusted to align with the percentages in adjacent regions. 8.2 Online survey on heat pumps The primary goal of this survey was to calculate the incidence of heat pump ownership across New Zealand, with the aim of using this information to forecast the energy usage of heating devices. The survey was done at a regional level. TNS Conversa was contracted by BRANZ Ltd to complete the survey. The TNS Conversa report of this survey is provided as a separate document. Nationwide ownership of electric heat pumps is at the 21% level. The regions with significantly higher ownership levels are: Hawke s Bay, Marlborough, Canterbury and Otago. Heat pump ownership levels are significantly lower for: Northland, Auckland, Taranaki, Manawatu and Wellington. South Island has a higher penetration of heat pumps; but there are still regions in the South Island where enclosed woodburners are the norm. Auckland and Wellington use more forms of other electric heating devices. The average number of heat pumps among those who own a heat pump is 1.28 Household income affects heat pump ownership; families that earn more have higher ownership levels. People with heat pumps are extremely likely to continue using heat pumps; even if they were required to replace their existing form of heating, most would (re)purchase a heat pump. Heat pumps are primarily post 2 devices, located in lounges or family rooms. Report Number: E528 Date of Issue: 13 July 29 Page 38 of 71 Pages

If electricity prices increased, most people would not change their behaviour regarding the use of their heat pump. This is true for both heating and cooling usage. People tend to heat either the whole house, or just the lounge, with their heat pump. 8.3 Simulations Five houses have been modelled in SUNREL. Three existing houses from the HEEP database and two new houses from group builders. The newer houses tend to have a larger floor area and larger glazing area. All houses are one level except the existing large house, which is two levels with the living space being on the upper level. A range of assumptions is required to support the simulations; the following section describes the models and the key assumptions. 8.3.1 Energy efficiency of houses Three levels of insulation are used in the simulations, representing the two major changes in code requirements and before requirements were in place. The R-value of the insulation added to the floor, roof and walls are shown in Table 9 through to Table 12, including the glazing type. The lowest R-value insulation that meets code and is available commercially has been used. Table 9. No Insulation Component Insulation added (m² C/W) Zone 1&2 Zone 3 Roof - - Wall - - Floor - - Glazing Single Single Table 1. Insulation at 1978 code Component Insulation added (m² C/W) Zone 1&2 Zone 3 Roof 1.8 3.2 Wall 1.5 1.8 Floor - - Glazing Single Single Table 11. New insulation regulations being introduced at present (27-28) Component Insulation added (m² C/W) Zone 1&2 Zone 3 Roof 3.2 3.6 Wall 1.8 1.8 Floor - - Glazing Double Double Report Number: E528 Date of Issue: 13 July 29 Page 39 of 71 Pages