A telephone survey of domestic heating methods and fuels for Kaiapoi was carried out by Digipoll in January 2005. This involved surveying 150 households within the 2001 census area unit (CAU) areas of Kaiapoi North, Kaiapoi South and Kaiapoi West.
Survey details are shown in Table 22.1. 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 the Waimakarari District of 36% by 2021. [High, medium and low population projections were estimated by Statistics New Zealand. The value used is the medium population projection.] This population increase is assumed to apply to the town of Kaiapoi.
Table 22.1: Summary survey data, Kaiapoi
22.1 Home heating methods and fuels
The Digipoll survey was used to collect information on home heating methods and fuels for Kaiapoi. These data were collected for the purpose of evaluating the impact of variations in heating methods on air quality in Kaiapoi, 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 Kaiapoi largely in tabular form, in the expectation that these results will be of value in other assessments (eg, emission inventory studies).
Tables 22.2 and 22.3 show domestic heating methods and fuels used for the main living areas in Kaiapoi houses, and seasonal variations in heating behaviour. The main methods of heating the main living area in Kaiapoi were electricity (48%) and wood burners (49%). Many households used more than one method of heating in their main living area.
Table 22.2: Domestic home heating methods and fuels, Kaiapoi
Around 3% of households using gas heat their homes during the summer months (Table 22.3). The proportion is higher in November and December, when a small proportion of households using wood burners also heat their homes. Table 22.4 shows that while the amount of fuel used on a wood burner is less on average during the non-winter months, households using open fires and multi-fuels during non-winter months burn more fuel per day than in winter months. It is likely that these households also use more fuel than average during the 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 22.3: Monthly variations in heating behaviour and fuel use, Kaiapoi
Table 22.4: Estimated daily fuel use, by season, Kaiapoi
22.2 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 Kaiapoi are presented in this section.
Figure 22.1 shows that the proportion of households using gas systems that are properly flued in Kaiapoi is around 31%. This compares to a national average of 24%.
The amount spent on heating for a winter month, by heating method, is shown in Table 22.5. In Kaiapoi less was spent per month on multi-fuel burners ($37) than on other heating methods, on average.
Figure 22.2 shows the average heating costs, home ownership, age of dwelling and number of bedrooms for households in Kaiapoi. Only a small proportion (10%) of the respondents in Kaiapoi were living in rental accommodation. This compares with a national average of around 20%.
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 22.3 shows that over 60% of the wood used on solid fuel burners in Kaiapoi is self-collected.
Figure 22.1: Distribution of flued versus unflued gas heating and age of wood burner, Kaiapoi
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 69% of all gas heating and Flued gas makes up 31%.
The second graph is divided by the age of wood burners. Post-1999 wood burners make up 19%, 1994-99 wood burners make up 36% and the remaining 45% of wood burners are Pre-1994.
Table 22.5: Average monthly heating costs (winter), Kaiapoi
Figure 22.2: Domestic heating method, by average monthly heating expenditure, house ownership, house age and number of bedrooms, Kaiapoi
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 $83, gas $74, open fire $0, wood burner $113, pellet burner $0, multi-fuel $37 and oil $0.
The second graph sets out heating methods divided by home tenure. For households living in rentals 193 use electric, 97 use gas, 24 use open fire, 193 use wood burners, 0 use pellet burners, 0 use multi-fuel and 0 use oil. For households living in their own house 1545 use electricity, 748 use gas, 169 use open fires, 1593 use wood burners, 48 use pellet burners, 145 use multi-fuel and 24 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 47% electric, 34% gas, 23% wood burners, 0% multi fuel and 0% open fires.
- Heating methods for houses between 11 and 20 years old are 18% electric, 6% gas, 18% wood burners, 0% multi fuel and 13% open fires.
- Heating methods for houses between 21 and 40 years old are 19% electric, 29% gas, 26% wood burners, 50% multi fuel and 0% open fires.
- Heating methods for houses over 41 years old are 15% electric, 31% gas, 31% wood burners, 33% multi fuel and 75% open fires.
The fourth graph sets out particular heating methods by the number of bedrooms.
- Heating methods for houses with one bedroom are 6% electricity, 0% gas, 0% wood burner, 0% multi fuel and 0% open fire.
- Heating methods for houses with two bedrooms are 19% electricity, 26% gas, 12% wood burner, 33% multi fuel and 13% open fire.
- Heating methods for houses with three bedrooms are 46% electricity, 51% gas, 59% wood burner, 50% multi fuel and 50% open fire.
- Heating methods for houses with four bedrooms are 24% electricity, 14% gas, 22% wood burner, 17% multi fuel and 25% open fire.
- Heating methods for houses with five bedrooms are 6% electricity, 3% gas, 3% wood burner, 0% multi fuel and 0% open fire.
- Heating methods for houses with six bedrooms are 0% electricity, 6% gas, 3% wood burner, 0% multi fuel and 0% open fire.
Figure 22.3: Proportions of fuel obtained free of charge versus bought, Kaiapoi
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 40% of their fuel, those using wood burners bought 32% of their fuel and those using multi-fuel burners bought 25% of their fuel.
Table 22.6: Type of electric heating, Kaiapoi
The commonest types of electric heater used in the main living area in Kaiapoi houses were heat pumps (Table 22.6). A number of houses used more than one type of electric heater in their main living area.
Data on home heating methods, by house ownership, are shown in Table 22.7.
Table 22.7: Home heating method, by house ownership, Kaiapoi
Household insulation types and heating methods are shown in Tables 22.8 and 22.9. Most houses (88%) had ceiling insulation and around 74% had wall insulation. Around 37% of houses had at least three types of insulation.
Table 22.10 shows home heating method, by household income. The overall non-response rate was around 29%. This limits the interpretation of these data because there may be an income bias in the non-respondents.
Table 22.8: House insulation summary statistics, Kaiapoi
Table 22.9: Degree of house insulation, by heating method, Kaiapoi
Table 22.10: Home heating method, by household income, Kaiapoi
Tables 22.11 and 22.12 show the relationship between heating methods and the age of the dwelling and number of bedrooms, respectively.
Table 22.11: Home heating method, by age of dwelling, Kaiapoi
Table 22.12: Home heating method, by number of bedrooms, Kaiapoi
22 Kaiapoi
November 2005
© Ministry for the Environment