A Dutch tomato glasshouse optimised for energy efficiency is using less heat despite maintaining a slightly higher temperature than an adjacent control glasshouse.
The structure of the ID Glasshouse at Duijvestijn Tomatoes near Delft has been optimised for the use of insulating glass, with panes left in the standard manufactured size to reduce costs. It also features integrated thermal screens and a novel ventilation system incorporating large heat exchangers.
Now in its second year of cultivation, temperatures are kept 1-2 degsC higher than the reference house, yet energy consumption "could be" below 20cu m of gas per square metre per year, according to a report by Wageningen UR researcher Dr Wouter Verkerke for the government-backed Kas Als Energiebron (Glasshouse as Energy Source) project.
"In 2015 that is not yet the case, simply because the focus at the beginning of the year was all on the crop and cultivation," he said. "However, the potential is there to make (energy) savings of 35-40 per cent."
He added: "The required pipe temperature was only above 40 degsC for 500 hours and almost never above 45 degsC. This was an important design goal because the ID Glasshouse was intended to be heated as much as possible with water returned from other glasshouses, and that has been achieved."
The goal in the year ahead will now be to step up energy efficiency with greater use of screening and higher humidity without impacting the crop, he explained.
The glasshouse was set up by a consortium of Duijvestijn, Technokas, Boal, Scheuten Glass and Bode Project & Engineering.
A new 10ha tomato glasshouse being built in the north Holland province by Hortilux for Greenco will incorporate reflectors beside the main concrete path to ensure that light is not wasted on the path but redirected into the crop.