The company features a state-of-the-art wood burner built in Austria, shipped to the nursery in containers and replaces the coal-fired burner previously used. The owners, Ian Kempthorne and Paul Loader, are keeping two houses warm, one is 3,300 square metres full of rose plants the other is 4,000 metres square and full of gerbera plants.

The unit is housed in a purpose-built block building, with the burner and associated systems about the size of two containers stacked one on top of the other. As well as being an impressive piece of equipment, there is a dazzling array of probes, sensors and systems, all controlled from a computer in the office or, if required, can also be controlled by the engineers in Austria who built it.

The system includes feeding and unwanted solids removal; delivery of primary air for three uses, 65% to pre-drying of the wood chips, 30% to combustion in the furnace and 5% to reburning ash. There is an ‘overheat suppression system’ which uses flue gases over the top of the primary air flow in the furnace; there is also an ‘emergency’ fire suppression system in the case of burning back into the wood supply; all coupled with a sophisticated feed system and water heating storage and circulation system with hot water coming out at 90 degrees Celsius. The furnace burns at temperature from 600 to 1,000 degrees Celsuis.

How did these guys come to spend mega bucks on this classy Austrian equipment? Loader explained that the pair also run a couple of florist shops in Christchurch malls which gives them excellent feedback as to customer wants and attitudes. He adds that sustainability is strong with customers, and in seeking a point of difference for their product, they decided to pursue this. Burning wood not only reduces their carbon footprint but because of the better fuel economics it enables them to prevent the greenhouses from ever reaching the critical humidity which triggers disease infection, thereby reducing spraying.

Insect pests are dealt with by using various forms of insect predators. Customers also express a desire to buy NZ-grown flowers and produce, confirming the consensus at the AGM meeting that people, especially young people, now want to support and invest in local communities.

Currently, most of the fuel is from chipped trees that were flattened on the Canterbury Plains during the storm of 2012, but also they can are able to dry and burn unwanted gerbera/rose plants, leaves and roots.

Kemptorne explained that Austria is a small country similar to NZ and it also has a lot of trees, the difference being NZ exports 70% of its timber whereas the Austrians burn 70% of their timber in wood burners, so they have become very skilled in the manufacture of such sophisticated equipment.

K&L’s burner consumes about 10 tonnes of wood chips daily depending on factors like air temperature, moisture content of the wood stock. It is kept burning 24 hours per day all year round and, in summer, the heat is transferred to a 400,000 litre body of water for storage.

Despite many, many challenges during setup and commissioning both Kempthorne and Loader said they were very pleased with their new greenhouse heating system.