Leafy offices cost ratepayers $48,000
Christchurch City Council may be breathing the freshest office air in the city, but it comes at a cost.
The council spends $48,000 a year on the 2445 plants in its civic offices in Hereford St - equating to two plants for each employee.
Other Canterbury public sector organisations including police, the Canterbury Earthquake Recovery Authority (Cera) and the Canterbury District Health Board (CDHB) go without, saying employees bring in their own.
Statistics New Zealand's latest income survey shows the average annual Kiwi salary is $41,912. Council corporate support manager Sue Chappell said the greenery was part of the council's "green-star rating" and the annual maintenance cost included a 20 per cent replacement allowance. None of the plants was fake, she said.
The New Zealand Green Building Council green star indoor guidelines require one plant per 15 square metres for its 5-star and 6-star ratings.
The plants must be in 15cm or 30cm pots respectively.
The council's civic building has a 6-star rating.
Green Building Council chief executive Alex Cutler said indoor plants were included in the rating because they filtered carcinogenic compounds from the air and provided "a green indoor environment".
However, University of Canterbury biological sciences lecturer Grant Pearce said proper ventilation was more important for office workers' physical wellbeing than plants. "[Plants] will provide a little more oxygen and use up some of the carbon dioxide, but it would be fairly negligible," he said.
A more likely benefit from indoor plants was regular watering would increase humidity - "rather than a dry, stuffy environment", he said.
A 2010 Sydney University of Technology study found office plants reduced a group of workers' "negative mood states" by 30 to 60 per cent during a three-month period leading up to Christmas. The control group, who did not have office plants, reported increases in bad moods of 20 to 40 per cent.
A Cera spokeswoman said all the plants in its office were personally owned. These were seven plants, 18 fake flowers and six vegetable seedlings.
The building's body corporate managed several outdoor planter boxes, but this did not create a cost for Cera, she said.
A police spokesman said Canterbury stations did not have any commercial contracts for the supply, hire or maintenance of plants and did not hold any counts of plants in police facilities.
Environment Canterbury could not provide its plant budget yesterday.
A CDHB spokeswoman said the board did not have an annual plant maintenance budget, but some staff brought in their own plants.