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 ±10% 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 C 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 0.5C from the set point for solution temperatures between 15 and
30C. 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 24C),
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
