View inside the open-roof greenhouse with a chrysanthemum crop (August 2002).
More Pictures and a Slide Show
A MX-II style, open-roof greenhouse manufactured by Van Wingerden Greenhouse Company has been erected at the Horticultural Research Farm # 3 at Rutgers University. In recent years, many commercial growers have built various versions of the open-roof style greenhouse. It is the goal of this research project to learn as much as possible about the advantages and possible disadvantages associated with the commercial use of these structures.
The specific objectives of the open-roof greenhouse project are to investigate the effects of this new type of greenhouse design on inside environment (temperature, radiation, ventilation rate, etc.). In addition, an ebb and flood floor irrigation system and an in-floor hot-water heating system will be evaluated.
Dr. Sadanori Sase from the National Institute for Rural Engineering (NIRE) in Japan is collaborating with researchers at Rutgers University to develop a natural ventilation model for this type of greenhouse. The data collected at Rutgers University is used for calibration and validation of the model.
After completion of the greenhouse structure during the summer of 1999, the greenhouse was glazed with two layers of air inflated polyethylene film on the roofs and sidewalls. In the late fall of 1999, the exterior was refinished with acrylic panels. In the late fall of 2001, the polyethylene film on the roof segments was replaced with new polyethylene film material.
A new 100 amp electrical service and a water line have been brought inside the greenhouse. In addition, a computer control and data acquisition system (Argus Control Systems, Ltd.) has been installed to control the greenhouse environment as well as record environment parameters.
An outside weather station is recording parameters such as temperature, relative humidity, wind speed and direction, solar radiation (short wave), and PAR. Inside the greenhouse structure, temperature at three elevations, solar radiation (short wave), PAR, net radiation (250 to 60,000 nm range), and relative humidity data are collected at 15-minute intervals. Finally, the roof position (percent opening) of the roof sections is recorded.
To ensure the data collected is as accurate as possible, a careful calibration of the radiation sensors was completed in the spring of 2000, and the calibration of other sensors is performed regularly as required.
The floor heating system and the ebb and flood floor irrigation system were completed in early 2002. The first crop (chrysanthemum) was grown during the summer of 2002. During the fall of 2002, a crop of poinsettia was grown in the greenhouse. During 2003, an Easter Lily crop was grown in the spring, followed by a chrysanthemum crop during the summer, and a poinsettia crop during the fall.
The heating system has been fully operational since the fall of 2002. Research is under way to evaluate the operation and control of the floor heating system. In addition, the natural ventilation system is being analyzed and the results will be incorporated in a computer simulation model.