References
Albright, L.D.; Henderson, H.I., Jr. 1996
Air conditioning greenhouses to increase effectiveness of carbon dioxide enrichment
WHERE: ASAE paper 964007. ASAE, 2950 Niles Road, St. Joseph, MI 49085-9659. 15 p.
ABS: Greenhouse lettuce and other crops can benefit from supplemental lighting to enhance growth on dark days. When carbon dioxide is added during lighted hours, growth may be enhanced further. Unfortunately, heat added by lights may initiate venting and waste carbon dioxide. This paper presents a simulation model that suggests a modest degree of air conditioning may be economically beneficial in permitting carbon dioxide enrichment without venting to substitute for supplemental lighting to enhance g
rowth. The simulations suggest the savings of lighting costs may compensate for operating a simple air conditioning system during days of moderate cooling load and limited solar input.
Albright, L.D. 1995
Controlling greenhouse ventilation inlets by pressure difference
WHERE: HortTechnology 5(3): 260-264
ABS: Computerized control of the greenhouse climate has increased the importance of air distribution and mixing. This report reviews the fluid mechanics of air flow through ventilation inlets and external pressures imposed by winds and applies the analyses to suggest methods of inlet control that improve traditional greenhouse ventilation. The suggested improved control has been implemented in a five-section research greenhouse on the Cornell University campus and has improved climate control significantly during ventilation. Potential pitfalls in implementing the improved control methods are discussed.
Albright, L.D. 1995
Greenhouse lighting control to a daily PPF integral, with energy and cost consequences
WHERE: ASAE paper 954487. ASAE, 2950 Niles Road, St. Joseph, MI 49085-9659. 22 p.
ABS: A methodology is described and, from it, an accompanying computer model has been developed to calculate the yearly operating cost of a supplemental lighting system for commercial greenhouses based on reaching a prescribed daily integral of
PPF. The model is sensitive to time-of-day rates (including application of those rates to weekends and holidays), weather, greenhouse characteristics, luminaire characteristics, and greenhouse location.
Albright, L.D. 1994
Predicting greenhouse ventilating fan duty factors and operating costs
WHERE: ASAE paper 944576. ASAE, 2950 Niles Road, St. Joseph, MI 49085-9659. 20 p.
ABS: A methodology is described and, from it, an accompanying computer model has been developed to calculate the yearly operating cost of a mechanical ventilation system for commercial greenhouses having no installed evaporative (or other) cooling system. The model is sensitive to time-of-day rates (including application of those rates to weekends and holidays), thermal parameters, fan characteristics, environmental control set points, and weather.
Albright, L.D. 1994
Fan operating costs for controlled environment agriculture
WHERE: Proceedings of the 5th annual CAEP Agricultural Demand-Side Management Conference. Albany, NY. May 3-5, 1994. Northeast Regional Agricultural Engineering Service, Publication CAEP-1, Cornell Cooperative Extension, Ithaca, NY. pp. 51-60
Albright, L.D.; Both, A.J. 1994
Comparison of luminaires: efficacies and system design
WHERE: Proceedings of the International Lighting for Plants in Controlled Environments Workshop. University of Wisconsin, WI. March 27-30, 1994. NASA Conference Publication CP-3309. pp.281-297
ABS: The thrust of this report suggests supplemental lighting design processes might be used to achieve desired PAR levels and adequate uniformity over a lighted space. Measured PAR distribution patterns from eight commercially available 400 W HPS luminaires are used in three design examples, implemented through a commercially-available lighting design computer program. Results suggest that PAR uniformity within 110% is achievable at intensities of 200 and 300 micromol m-2 s-1 in
greenhouses and plant growth chambers. When PAR intensity is significantly lower (e.g., 50 micromol m-2 s-1), uniformity is more difficult to achieve. This study suggests the desirability of developing computer data file standards for PAR, rather than vision lighting, for commercial
luminaires, and obtaining a consensus data base of surface reflectance values for materials used in plant growth chambers and greenhouses. Results also suggest that luminaire selection can have a significant effect on lighting energy use and operating cost because of different numbers of various models of luminaires required to meet a design goal, not just luminaire-to-luminaire efficacy differences.
Both, A.J.; Albright, L.D.; Langhans, R.W.; Vinzant, B.G.; Walker, P.N. 1992
Research on energy consumption of HID Lighting
WHERE: Proceedings of the 4th National CAEP Agricultural Demand-Side Management Conference. Syracuse, NY. October 20-22, 1992. Northeast Regional Agricultural Engineering Service, Publication 65, Cornell Cooperative Extension, Ithaca, NY. pp. 125-134
Both, A.J. 1994
HID Lighting in Horticulture: a short review
WHERE: Greenhouse Systems, Automation, Culture and Environment. International Conference. Hyatt Regency Hotel, New Brunswick, NJ. July 20-22, 1994. Northeast Regional Agricultural Engineering Service, Publication 72, Cornell Cooperative Extension, Ithaca, NY. pp. 208-222
Both, A.J.; 1995
Dynamic simulation of supplemental lighting for greenhouse hydroponic lettuce production
WHERE: PHD Dissertation, Cornell University Libraries, Ithaca, NY. 172 p
ABS: During an eight month period, hydroponic lettuce growth experiments, consisting of 35 different supplemental lighting treatments, were conducted in five identical greenhouse sections in order to: (1) determine how supplemental lighting can be used to ensure consistent and timely year-round greenhouse lettuce production in New York State, and (2) provide greenhouse growers and researchers with a computer simulation program to study the effects of different daily integrated light levels, indoor temperature, and plant spacing on the growth and development of lettuce.
The daily integrated photosynthetically active radiation (PAR) was kept constant during each of the treatments by supplementing the solar PAR with PAR from 400 Watt high pressure sodium
(HPS) lamps. Among treatments, daily PAR varied between 4 and 22 mol m-2 d-1. The indoor greenhouse environment was computer controlled and carbon dioxide enrichment (up to 1000
ppm) was used during the light period, but only when no ventilation was needed to maintain the temperature set point. The temperature was maintained at 24 and 18.8 0C during the light and dark periods respectively.
During the first 11 days, the lettuce seedlings were kept in a growth chamber under fluorescent lamps. After transplant, the plants remained 24 days in the greenhouse. Maintaining a daily PAR of 17 mol m-2 d-1 in the greenhouse resulted in a marketable lettuce head with a fresh weight of 150 grams (nearly 7 grams of dry weight) at 35 days after seeding. Lettuce tipburn was prevented using an overhead fan which blew ambient air downward onto the lettuce plants.
The computer simulation program predicts dry weight production based on environment conditions in the greenhouse and plant parameters extracted from the literature. The universal crop growth model SUCROS87 was adjusted and incorporated in the simulation program. Using long-term average daily solar radiation data collected for Ithaca, NY, the simulation model successfully predicted dry weight production compared to plant dry weights measured during growth trials which were performed at Cornell University. The simulation program will be a helpful tool for commercial lettuce growers and future research.
Both, A.J.; Chou, C.A.; Albright, L.D.; Langhans, R.W. 1996
A microwave powered light source for plant irradiation
WHERE: Acta Horticulturae 418: 000-000. In press. 6 p
ABS: A new high intensity electrodeless light source, powered by two microwave generating units, was evaluated and compared with fluorescent and air- and water- cooled high pressure sodium
(HPS) lamps. Radiation measurements were taken in the following wavebands: 400-700 nm
(photosynthetically active radiation or PAR), 700-800 nm (far red), 800-2800 nm (near infrared) and 2800-50000 nm (far infrared), for all four light sources. The distribution of the radiation output of the microwave lamp over the various wavebands closely resembled the output of a water-cooled HPS lamp, although the microwave lamp was capable of delivering much higher light intensities. The relatively small amount of radiation emitted in the infrared waveband makes the microwave lamp a promising light source for plant irradiation in growth rooms
(phytotrons).
Both, A.J.; Albright, L.D.; Langhans, R.W.; Vinzant, B.G.; Walker, P.N. 1996
Electric energy consumption and PPFi output of nine 400 watt high pressure sodium luminaires and a greenhouse application of the results
WHERE: Acta Horticulturae 418: 000-000. In press. 8 p
ABS: The PPFi (instantaneous photosynthetic photon flux, in micromol m-2 s-1) output and electric energy consumption of nine different 400 watt high pressure sodium
(HPS) luminaires were measured at six mounting heights from 0.5 to 3.0 m in 0.5 m increments. Differences in luminaire efficacy and PPFi distribution patterns were found, but too few luminaires were tested to reach statistically valid conclusions. The most efficient luminaire proved 25% more energy efficient than the least efficient luminaire. PPFi data from one of the luminaires tested was used to design a research greenhouse which required uniform PPFi distribution patterns at various PPFi levels.
Both, A.J.; Albright, L.D.; Langhans, R.W.; Reiser, R.A.; Vinzant, B.G. 1996
Hydroponic lettuce production influenced by integrated supplemental light levels in a controlled environment agriculture facility: Experimental results
WHERE: Acta Horticulturae 418: 000-000. In press. 7 p
ABS: Bibb lettuce (Lactuca sativa L., cv. Ostinata) was grown in peat-vermiculite plugs placed in a recirculating hydroponic
(NFT) system. Supplemental lighting was used to reach different PPFtarget levels in each of 35 treatments. A second order exponential polynomial was developed to predict DW accumulation for PPFtarget levels between 8 and 22 mol m-2 d-1. Little difference in DW production was noted between lettuce grown under daytime and nighttime lighting. Tipburn was prevented using a fan blowing greenhouse air vertically down onto the lettuce plants. Marketable (150 g FW) lettuce heads were produced in 24 days after transplant while receiving an average PPFintegral of 17 mol m-2 d-1.
Both, A.J.; Goto, E.; Albright, L.D.; Langhans, R.W.; Leed, A.R. 1996
Controlling dissolved oxygen and temperature in floating hydroponics
WHERE: submitted for publication in Transactions of the ASAE
ABS: A control system for the dissolved oxygen (DO) concentration and temperature of the nutrient solution for floating hydroponic lettuce production is described. Sub-saturated, saturated and super-saturated DO concentrations are maintained continuously during a 24 day period the lettuce plants remain in a greenhouse to reach a fresh weight of 150 grams. Oxygen and nitrogen gas are used to increase or decrease the DO concentration in the nutrient solution respectively. Computer software is used to maintain the DO concentration to within plus or minus 0.1 mg/liter for set points between 2 and 16 mg/liter. A soil heating cable and a copper pipe filled with recirculating cold water are used to maintain a constant temperature of the nutrient solution. A separate computer control algorithm maintains the nutrient solution temperature within plus or minus 0.50C from the set point for solution temperatures between 15 and 300C. Controlling DO concentration and temperature of the nutrient solution while using a floating hydroponic system has both commercial and research applications.
Goto, E.; Both, A.J.; Albright, L.D.; Langhans, R.W.; Leed, A.R. 1996
Effect of dissolved oxygen concentration on lettuce growth in floating hydroponics
WHERE: Acta Horticulturae 440:205-210
ABS: Lettuce (Lactuca sativa L., cv. Ostinata) growth experiments were carried out to study the effect of dissolved oxygen (DO) concentration on plant growth in a floating hydroponic system. Pure O2 and N2 gas were supplied to the hydroponic system for precise DO control. The system allowed for DO concentrations above the maximum possible saturation concentration attainable when using compressed air. Eleven day old lettuce seedlings were grown for 24 days under various DO concentrations: sub-saturated, saturated, and super-saturated. There was no significant difference in fresh weight, shoot and root dry weight among the following DO concentrations: 2.1 (25% of saturated at 240C), 4.2 (50%), 8.4 (saturated), and 16.8 (200%) mg/L. The critical DO concentration for vigorous lettuce growth was considered to be lower than 2.1 mg/L. Neither root damage nor delay of shoot growth was observed at any of the studied DO concentrations.
Goto, E.; Albright, L.D.; Langhans, R.W.; Leed, A.R. 1994
Plant spacing management in hydroponic lettuce production
WHERE: ASAE paper 944574. ASAE, 2950 Niles Road, St. Joseph, MI 49085-9659. 13 p.
ABS: Three different spacing options were tested in a hydroponic lettuce production system. Two kinds of productivity and a growing area utilization efficiency factor were introduced to compare practical spacing management with idealized spacing management for individual days during a production period, and over the entire production.
Both, A.J.; Leed, A.R; Goto, E.; Albright, L.D.; Langhans, R.W. 1996
Greenhouse spinach production in a NFT system
WHERE: Acta Horticulturae 440: 187-192
