Around a third of homes too cold in winter and too warm in summer

Data from the 2018 General Social Survey (GSS) shows a third of New Zealand homes are too cold in winter, and over a third are too warm in summer, Stats NZ said today.

As part of the year-long survey, Stats NZ took temperature measurements in approximately 6,700 homes.

“This is the largest-scale temperature measurement carried out in New Zealand to date and represents a snapshot at the time of each GSS interview,” wellbeing and housing statistics manager Dr Claire Bretherton said.

The average (mean) temperature recorded inside homes during a GSS interview was 21.4oC. Temperatures in winter, however, were colder, at 19oC. In contrast, the average temperature recorded in summer was 23.9oC. Indoor temperatures recorded during the survey ranged from near freezing in a small number of homes to over 30oC in others.

Temperature range Summer
0.7
16-17.9 0.7
18-19.9 4
20-24.9 58.4
25+ 36.2
0.2 1.2
0.3 1.1
2.9 5
55 61.7
33 39.5
Temperature range Autumn
3
16-17.9 5.4
18-19.9 13.9
20-24.9 63.6
25+ 14.1
2.1 4
4.1 6.7
11.7 16.1
60.9 66.3
11.6 16.7
Temperature range Winter
15.1
16-17.9 17.9
18-19.9 27.6
20-24.9 37.3
25+ 2.1
12.6 17.6
15.5 20.2
24.9 30.4
33.8 40.8
1.1 3.1
Temperature range Spring
3.5
16-17.9 9.5
18-19.9 22.5
20-24.9 60.5
25+ 4
2.5 4.5
7.9 11
19.3 25.7
56.9 64.2
2.9 5.2

“Most temperatures were recorded between late morning and late afternoon,” Dr Bretherton said.

“We measured temperatures where the interview took place, likely to be in a living room or kitchen, which are more commonly heated than bedrooms or other parts of the home.”

Housing in Southland was significantly cooler than the national average in summer (with a mean recorded temperature of 21.6oC), while Gisborne/Hawke’s Bay and Bay of Plenty, averaged over 25oC.

The Household Energy End-Use Project, a study by the Building Research Association of New Zealand, rated 20-25oC as a comfortable indoor temperature. Of all summer temperatures recorded by the GSS, 36 percent were 25oC or more.

“These high temperatures can make people uncomfortable,” Dr Bretherton said.

“However, of most concern is that in around a third of homes the recorded temperature in winter was under 18 degrees, which is below the World Health Organization’s minimum healthy indoor temperature.”

Lower recorded temperatures were also associated with other signs of cold. For people living in homes where the recorded temperature was lower than 16oC, 45 percent said they could see their breath inside during winter, and 36 percent rated their house as always or often cold.

“If the indoor temperature is 16 degrees or less, some people may need at least two or three layers of clothing, adding a singlet or a jersey to keep warm, if not both,” Dr Bretherton said.

“That’s especially so for the very young and very old.”

Housing quality measure Under 16 degrees Celsius
Can see breath inside 44.9
Cold always or often in winter 35.8
Damp always 10
37.2 52.5
29.9 41.6
6.5 13.4
Housing quality measure 16-17.9
Can see breath inside 30.7
Cold always or often in winter 27.7
Damp always 5.7
25.6 35.8
23.3 32.1
3.5 7.9
Housing quality measure 18-19.9
Can see breath inside 25.1
Cold always or often in winter 22.9
Damp always 4.9
21.7 28.5
19.9 26
3.4 6.4
Housing quality measure 20-24.9
Can see breath inside 15.8
Cold always or often in winter 17.9
Damp always 2.3
14 17.5
16.3 19.6
1.7 2.8
Housing quality measure 25+
Can see breath inside 15.1
Cold always or often in winter 21.3
Damp always 2.5
12.1 18
18 24.6
1.6 3.5
/Stats NZ Public Release. View in full here.