14 Dunedin
A telephone survey of domestic heating methods and fuels for Dunedin was carried out by Digipoll in October 2004. This involved surveying 151 households within the 2001 census area unit (CAU) areas of:
- Fryatt
- Maori Hill
- Musselburgh
- Belleknowes
- High Street–The Oval
- Balmacewen
- Andersons Bay
- Kenmure
- High Street–Stuart Street
- Glenleith
- Vauxhall
- Caversham
- Stuart Street–Frederick Street
- North-East Valley
- Halfway Bush
- St Kilda Central
- Caledonian
- Pine Hill
- Brockville
- St Kilda East
- South Dunedin
- Woodhaugh
- Roslyn North
- Green Island Central
- Forbury
- North Dunedin
- Helensburgh
- Ravensbourne
- Corstorphine West
- Opoho
- Wakari
- St Kilda West
- Corstorphine East
- Roslyn South
- Abbotsford
- St Clair
- Otago University
- Mornington
- Concord
Survey details are shown in Table 14.1. Although the total number of respondents used in the analysis was 151, initial results were inconsistent with data for Dunedin on the proportion of rented versus owner-occupied dwellings (the original survey showed 20% of households were rented compared with a value of around 32% from census and other data). It is unclear whether the difference occurred as a result of sampling error or bias in non-respondents. Because of the significant difference, additional sampling was made for 44 respondents in rented accommodation. These data were used in place of the first 44 respondents for occupied dwellings.
The number of households for 2004 was estimated based on 2001 census data for occupied dwellings, extrapolated for 2004 based on Statistics New Zealand population projections. [New Zealand Statistics 2004, www.stats.govt.nz] The latter suggest a population increase for Dunedin of 4% by 2021. [High, medium and low population projections were estimated by Statistics New Zealand. The value used is the medium population projection.]
Table 14.1: Summary survey data, Dunedin
14.1 Home heating methods and fuels
The Digipoll survey was used to collect information on home heating methods and fuels for Dunedin. These data were collected for the purpose of evaluating the impact of variations in heating methods on air quality in Dunedin, in particular the extent of change required to achieve the national environmental standard for PM10. This section presents the results of the home heating survey for Dunedin largely in tabular form, in the expectation that these results will be of value in other assessments (eg, emission inventory studies).
Tables 14.2 and 14.3 show domestic heating methods and fuels used for main living areas in Dunedin houses, and seasonal variations in heating behaviour. The commonest method of heating the main living area in Dunedin homes was electricity, which was used by 77% of households. Many households used more than one method of heating in their main living area.
The main difference in home heating methods for Dunedin was the low use of solid fuel burning for domestic home heating. In particular, the use of wood burners was low at 14% of households compared to a national average of around 38%. Overall, 30% of households in Dunedin used wood and 12% used coal. This compares with national averages of 52% and 7%, respectively. One reason for the lower proportion of wood use is likely to be the higher proportion of dwellings in Dunedin that are rented as opposed to owner-occupied; as subsequent data show, wood burners are less common in rental accommodation in Dunedin. Although this may account for some of the difference, wood use among owner-occupied dwellings was also lower in Dunedin. The reasons for this are unclear.
Table 14.2: Domestic home heating methods and fuels, Dunedin
About 13% of the households using multi-fuel burners operated them during the summer months, generally burning seven days a week. Gas was also used for heating during the summer months by a small proportion of households using that method. However, the quantities of fuel used per day on multi-fuel burners was typically much less during the non-winter months than during winter (Table 14.4). Results for wood burners suggest high fuel use on average during non-winter months. This does not imply that households that heat their homes all year round burn more wood in the non-winter months. It is likely to occur because of the smaller sample size during the non-winter months. Data are not presented for all heating methods, because there was a high non-response rate for questions relating to seasonal variations for some heating types.
Table 14.3: Monthly variations in heating behaviour and fuel use, Dunedin
Table 14.4: Estimated daily fuel use, by season, Dunedin
14.2 Insulation, cost of heating, income, and house age and size
In addition to collecting data for the purpose of evaluating the impact of variations in heating methods on air quality, information was collected on a number of variables relevant to the Ministry for the Environment's Warm Homes Project. Relevant data for Dunedin are presented in this section.
Figure 14.1 shows that the proportion of households using gas systems that are properly flued in Dunedin is around 37%. This compares to a national average of around 24%.
The amount spent on heating for a winter month, by heating method, is shown in Table 14.5. In Dunedin, households heating using open fires and multi-fuel burners spend on average less per month (around $38 and $51, respectively) than those using other heating methods.
Figure 14.2 shows the average heating costs, home ownership, age of dwelling and number of bedrooms for households in Dunedin. Results indicate that some of the open fires were installed in new dwellings in Dunedin within the last 10 years. Open fires and wood burners were more common heating methods in owner-occupied houses than in rented accommodation.
One factor influencing the amount spent on different heating methods is the ability of households using solid fuel burners to obtain wood free of charge. Figure 14.3 shows that over 60% of the wood used on solid fuel burners and open fires in Dunedin is self-collected compared with around 40% for multi-fuel burners.
Figure 14.1: Distribution of flued versus unflued gas heating and age of wood burner, Dunedin
Text description of figure
There are two pie graphs. The first graph shows the distribution of flued and unflued gas heaters. Unflued gas makes up 63% of all gas heating and Flued gas makes up 37%.
The second graph is divided by the age of wood burners. Post-1999 wood burners make up 42%, 1994-99 wood burners make up 26% and the remaining 32% of wood burner are Pre-1994.
Table 14.5: Average monthly heating costs (winter), Dunedin
Figure 14.2: Domestic heating method, by average monthly heating expenditure, house ownership, house age and number of bedrooms, Dunedin
Average heating cost per month (winter)
House ownership
Age of dwelling
Number of bedrooms
Text description of figure
There are four bar graphs.
The first graph sets out the average heating cost per month in winter. Cost per month by heating methods are: electric $142, gas $87, open fire $38, wood burner $81 and multi-fuel $51.
The second graph sets out heating methods divided by home tenure. For households living in rentals 7302 use electric, 2712 use gas, 417 use open fire, 417 use wood burners, 0 use pellet burners, 209 use multi-fuel and 209 use oil. For households living in their own house 17107 use electricity, 3547 use gas, 3129 use open fires, 3964 use wood burners, 0 use pellet burners, 1669 use multi-fuel and 417 use oil.
The third graph sets out the age of a dwelling using a particular method of heating.
- Heating methods for houses under 10 years old are 9% electric, 7% gas, 10% wood burners, 11% multi fuel and 18% open fires.
- Heating methods for houses between 11 and 20 years old are 6% electric, 7% gas, 5% wood burners, 11% multi fuel and 0% open fires.
- Heating methods for houses between 21 and 40 years old are 19% electric, 33% gas, 14% wood burners, 11% multi fuel and 6% open fires.
- Heating methods for houses over 41years old are 62% electric, 43% gas, 67% wood burners, 67% multi fuel and 76% open fires.
The fourth graph sets out particular heating methods by the number of bedrooms.
- Heating methods for houses with one bedroom are 7% electricity, 0% gas, 5% wood burner, 0% multi fuel and 6% open fire.
- Heating methods for houses with two bedrooms are 24% electricity, 10% gas, 10% wood burner, 22% multi fuel and 6% open fire.
- Heating methods for houses with three bedrooms are 29% electricity, 43% gas, 24% wood burner, 11% multi fuel and 35% open fire.
- Heating methods for houses with four bedrooms are 18% electricity, 23% gas, 33% wood burner, 33% multi fuel and 12% open fire.
- Heating methods for houses with five bedrooms are 18% electricity, 17% gas, 19% wood burner, 33% multi fuel and 35% open fire.
- Heating methods for houses with six bedrooms are 3% electricity, 7% gas, 10% wood burner, 0% multi fuel and 6% open fire.
Figure 14.3: Proportions of fuel obtained free of charge versus bought, Dunedin
Text description of figure
This bar graph shows the amount of wood either bought or collected free of charge by three different types of heating.
Those using open fires bought 38% of their fuel, those using wood burners bought 32% of their fuel and those using multi-fuel burners bought 57% of their fuel.
Table 14.6: Type of electric heating, Dunedin
The most common types of electric heating used in the main living area in Dunedin houses were oil column heaters (Table 14.6). Radiant and fan heaters were also common. The proportion of houses using the more efficient heat pumps was 21%, which is higher than the national average (13%).
Data on home heating methods, by house ownership, are shown in Table 14.7.
Table 14.7: Home heating method, by house ownership, Dunedin
Household insulation types and heating methods are shown in Tables 14.8 and 14.9. Around 19% of households in Dunedin indicated that the house had no insulation. This compares with a national average of 10%. Table 14.10 shows household income, by heating method. The overall non-response rate was around 22%. This limits the interpretation of these data, because there may be an income bias in the non-respondents.
Table 14.8: House insulation summary statistics, Dunedin
Table 14.9: Degree of house insulation, by heating method, Dunedin
Table 14.10: Home heating method, by household income, Dunedin
Tables 14.11 and 14.12 show the relationship between heating methods and the age of the dwelling and number of bedrooms, respectively.
