The Department of Horticulture and Landscape Architecture at Purdue University brought on-line a new, world-class 31,400 ft2 plant growth facility during March 1998 valued at $7.2 M. Seventy-year old wood and glass greenhouses were razed to make way for a facility consisting of 24 greenhouses, two growth rooms, 5 walk-in refrigeration units, 6 reach-in growth chambers, and headhouse space for office, potting areas, and a tissue culture lab. The greenhouses are Nexus-built, ridge and furrow design with 80-cm wide glass glazing. Each 108 m2 (1200 ft 2) greenhouse is controlled using Priva Computers, Inc. sensors, microprocessors, weather station and Priva's QNX-based Precision II (version 1.9) software. Aspirated dry bulb and wet bulb thermometers measure temperature and humidity continuously and log data points every 10 minutes. Weather station data of light (Licor Quantum LI-190SB), temperature, humidity, rain, wind speed and wind direction allow the microprocessors to anticipate heating and cooling requirements. This anticipatory logic function gives accurate temperature control while minimizing equipment cycling. The greenhouses are heated with hot water and cooled using active ventilation and evaporative cooling. No vents are present in the ridge or sidewalls (other than fan shutters), allowing for a better seal, reduced maintenance, and reduced insect pressure. Clear water and fertilizer solution are independently plumbed into each greenhouse, and reverse-osmosis purified water plumbed into nearly half of the greenhouses. Compressed air for aeroponic/hydroponic culture and computer ports for specialized equipment are also available in each greenhouse. The computer ports can be linked to Purdue's server network, allowing investigators to log and examine data remotely using dial-in access. Approximately 30% of crops are irrigated automatically using drip tubes or dribble rings. In the future, Priva software will trigger on irrigation systems' solenoids based on timeclock, accumulated sunlight, moisture sensors or a combination of these factors. The mist system will be similarly controlled. The computer will also allow for proper ventilation of a greenhouse or growth room following pesticide application, ensuring the proper number of air exchanges prior to re-entry.

Within the 4500 ft 2 headhouse, two 81 m2 (900 ft2) growth rooms have control features similar to the greenhouses including compressed air, clear water, purified water, and fertilizer solution and environmental monitoring. Fifty-four metal halide and 36 high-pressure sodium lamps (400-watts each) distribute 350 µmol/m2/s of PAR at bench top level. Chilled water exchangers are used to cool the room and for dehumidification, and a minimum 15% fresh air is added with each air exchange. A five-compartment walk-in refrigeration unit was installed in July. Each compartment of 8.1 m2 (90 ft2) is controlled independently and alarmed both at the unit and remotely. Units are air-cooled, semi-hermetic, and supplied with electronic thermostats, timeclocks, solenoids, crankcase heaters and condensing units. Six reach-in Conviron growth chambers of .72 m2 (8 ft2) were also installed in July. Several larger Conviron units will be installed following completion of remodeling project of the old 8000 ft2 headhouse. All chambers will be linked to a common interface for monitoring and control similar to the greenhouse system. The growth chambers are part of a decentralized multi-user facility obtained through a $450 K National Science Foundation MRI grant plus equivalent matching funds from Purdue University. The HLA Plant Growth Facilities Manager will manage the multi-user facility. Future construction will include a set of poly-film quonset greenhouses fully equipped and computer-controlled.