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Title: Influence of greenhouse design and cooling systems on temperature and energy requirements
CITATION THUMBNAILS PAGE IMAGE ZOOMABLE
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00065917/00001
 Material Information
Title: Influence of greenhouse design and cooling systems on temperature and energy requirements
Series Title: ARC-A research report
Physical Description: 8 p. : ; 28 cm.
Language: English
Creator: Conover, Charles Albert, 1934-
Poole, R. T ( Richard Turk )
Agricultural Research Center (Apopka, Fla.)
Publisher: University of Florida, Agricultural Research Center-Apopka
Place of Publication: Apopka FL
Publication Date: 1977
 Subjects
Subject: Greenhouses -- Design and construction -- Florida   ( lcsh )
Greenhouses -- Heating and ventilation -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
 Notes
Statement of Responsibility: Charles A. Conover and Richard T. Poole.
General Note: Caption title.
 Record Information
Bibliographic ID: UF00065917
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 70669484

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Full Text





HISTORIC NOTE


The publications in this collection do
not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
research may be found on the
Electronic Data Information Source
(EDIS)

site maintained by the Florida
Cooperative Extension Service.






Copyright 2005, Board of Trustees, University
of Florida






L /

INFLUENCE OF GREENHOUSE DESIGN AND COOLING SYSTEM .,
ON TEMPERATURE AND ENERGY REQUIREMENTS.*

Charles A. Conover and Richard T. Poole M r?0
Agricultural Research Center Apopka
University of Florida
ARC-A Research Report RH-77-3 .

Greenhouses presently available to growers of plants in warm climates are
designed for more northernly locations. Therefore, little is known about heat
loads generated under subtropical and tropical conditions and heat dissipation
by various ventilation systems. Factors of major importance include light inten-
sity, humidity and air movement.
Investors and growers must make decisions without adequate knowledge on types
of greenhouses to erect. At present most decisions are based on structure longev-
ity, upkeep and initial cost. However, increased costs for energy now provide
another factor for consideration.
Since information on temperatures under various types of structures was lacking,
this survey was conducted throughout an entire year to determine the annual energy
requirements of six types of structures.
The six greenhouse structures selected for study were all within five miles
of Apopka, FL with shade levels maintained at 3000 + 250 foot-candles when full sun
light intensity was 13,000 foot-candles. Greenhouse types selected were as follows:
1. Four wide-span, high profile, curved steel frame, fiberglass covered
greenhouses, gutter connected and with fan and pad cooling. These
units covered 24,000 sq ft and were constructed by IBG. The green-
houses were located on the crest of a hill where there was good air-
flow on one side the other side being next to other greenhouses.
Hoghair bristle pads were installed on this unit (see Table 1 for
specifications).
2. Six wide-span, high profile steel frame fiberglass covered greenhouses,
gutter connected with fan and pad cooling. These units covered 22,464
sq ft and were constructed by Imperial. The greenhouses were located
in an area where airflow was limited. Aspen pads were installed about
six weeks prior to the beginning of data accumulation (see Table 1 for
specifications).
3. Six low profile curved steel frame fiberglass covered greenhouses,
gutter connected and with fan and pad cooling. These units covered
approximately 16,000 sq ft and were constructed by Stuppy. The








greenhouses were located in an open field near the top of a rise
where there was considerable air movement. Aspen pads were re-
placed about two months before the experiment began (see Table
1 for specifications).
4. Twelve narrow-span, low profile, steel-frame and glass greenhouses,
gutter connected with fan and pad cooling. The unit covered 38,000
sq ft and was constructed by V & V Nordland. New aspen pads were
installed approximately 30 days before the experiment began. The
unit was in an open field where there was air flow (see Table 1
for specifications).
5. Eight wide-span steel-frame glass greenhouses, gutter connected with
single ridge ventilators and 2 side ventilators. The unit covered
40,000 sq ft, was near the crown of a hill, but had some air flow
restriction due to nearby buildings. This was a Lord and Burnham
unit about 20 years old (see Table 1 for specifications).
6. Single wide-span steel-frame and glass greenhouse with double ridge
and side vents. The unit covered 20,000 sq ft but air flow was some-
what restricted because of nearby buildings. This was a Lord and
Burnham pipe frame greenhouse about 40 years old (see Table 1 for
specifications).
Data were collected weekly from two temperature recording units located in the
center of each unit (as measured from the sides) and 1/3 and 2/3's of the length
of the greenhouse as measured from the pad area if present. Units were placed 12
inches above bench height, and data collected from the two units averaged. Units
were calibrated two times weekly, once when the seven day charts were collected
on Monday, and again each Thursday. Each unit having fans and pads had two or
more electric meters installed into the energy supply. This was necessary because
all units had sequential fans and some had the pad pump on a separate circuit.
All electric meters were new at installation time and had been calibrated for
accuracy. The data provided in Table 2 include the average weekly minimum and
maximum temperatures from the average of the two recorders in each unit, plus
the average number of hours each day that temperatures were above 90 and 950F.
Total number of watts per sq ft on a weekly basis was obtained by dividing the
wattage used by the number of sq ft in the unit. At the end of the experiment,
the total annual wattage for each of the energy consuming units was totaled
(Table 2). Total radiant energy was also measured on a daily basis and converted








to calories/sq centimeter/minute. These data provide information on the vast
difference between radiant energy in summer versus winter.
Observation of the summer period in greenhouses numbers five and six with
ventilators indicates that daily temperatures commonly reached 900 or more for
several hours. Although this did not seem to influence plant quality, it may
have reduced employee output.
Greenhouse number one had very high temperatures even though it had fan and
pad cooling. Since the grower realized the inefficiency of the hog bristle pads,
he allowed temperatures to run as high or higher than those found in the ventilated
greenhouses, while using 444.4 watts/sq ft/yr. Plant material in this greenhouse,
especially during the spring of 1976 appeared to be of poor quality, because of the
high temperature.
Greenhouses numbers two, three and four were all fan and pad cooled greenhouses
and were maintained near the same average temperatures. The energy requirement for
the curved Stuppy low profile structure was higher than the Dutch glass or Imperial
fiberglass design by slightly over 30%. The average annual cost of cooling the
Stuppy house was 4.5 cents a sq ft/yr, while the Dutch glass house was 3.4 cents
and the Imperial fiberglass house 3.1 cents based on electrical cost of .07 cents
per kilowatt hour. Plant growth in the three houses was similar.
These data indicate that under the Florida conditions listed, for a 12 month
period, that electrical energy costs averaged 3 to 4.5 cents per sq ft/yr for
greenhouses shaded to provide 3000 foot candles on a maximum light intensity day
and maintained near 900F by fan and pad cooling. These annual costs would be in
addition to maintenance costs on the fan and pad system as well as the initial
capital costs. Ridge ventilated greenhouses provided acceptable growing conditions,
but would have had capital costs about equal to the greenhouses with fan and pad
systems installed. The major cost differences would have been the annual energy
costs and upkeep, which would probably have made the ventilated greenhouses about
8 to 10 cents a sq ft lower in annual operating costs.


*This survey was supported in part by a Grant-in-aid from Lord & Burnham, Division


Burnham Corporation, Irvington-On-Hudson, NY 10533.









Table 1. Specifications of the 6 greenhouses utilized in this temperature survey.

Greenhouse No.
Specifications 1 2 3 4 5 6


Width (ft)
Length (ft)
Size of vents top (ft)
Number of vents top
Size of vents side (ft)
Number of vents side
Distance from pad to fan (ft)
Size of pads (ft)
Greenhouse orientation
Height ground to peak (ft)
Fan size (ft) and motor size (HP)
Number fans


126
204
NA
NA
NA
NA
130
10 x 168
N-S
18
4 3/4
12


210
124
NA
NA
NA
NA
124
5 x 210
E-W
15
4 3/4
10


140
100
NA
NA
NA
NA
100
4 x 140
N-S
13
4 3/4
8


252
150
NA
NA
NA
NA
150
7 x 252
N-S
12
4 3/4
12


180
260
2 x 260
1 on E
3 x 254
1 each side
NA
NA
N-S
15
NA
NA


60
400
2 x 400
2
2.3 x 400
1 each side
NA
NA
N-S
20
NA
NA




Table 2-- GREENHOUSE ENERGY STUDY -
-' No. 1 IBG Arch No. 2 Imperial
II Fiberglass Fiberglass pads
(24,000 ft2) (22,464 ft2)
Daily Daily
Week of Temp. F Hrs. above Watts/ Temp. F Hrs. above Watts/
1975-76 Min. Max. 90F 950F ft2 Min. Max. 900F 950F ft2


July 7
July 14
July 21
July 28
Aug. 4
Aug. 11
Aug. 18
Aug. 25
Sept. 1
Sept. 8
Sept. 15
Sept. 22
Sept. 29
Oct. 6
Oct. 13
Oct. 20
Oct. 27
Nov. 3
Nov. 10
Nov. 17
Nov. 24
Dec. 1
Dec. 8
Dec. 15
Dec. 22
Dec. 29
Jan. 5
Jan. 12
Jan. 19
Jan. 26
Feb. 2
Feb. 9
Feb. 16
Feb. 23
Mar. 1
Mar. 8
Mar. 15
Mar. 22
Mar. 29
Apr. 5
Apr. 12
Apr. 19
Apr. 26
May 3
May 10
May 17
May 24
Jun. 1
Jun. 7
Jun. 14
Jun. 21
Jun. 28
Total


70 100
69 95
71 95
69 94
71 96
71 94
71 93
73 98
71 93
65 98
58 95
69 94
70 92
67 92
65 90
70 86
68 92
65 98
64 94
66 98
66 98
65 94
70 90
66 89
65 90
64 90
61 89
60 90
63 92
62 91
65 86
62 91
60 92
63 96
62 95
60 98
56 100
58 95
56 100
62 100
58 100
62 100
62 100
64 101
68 100
66 98
67 100
70 98
70 98
72 100
70 100
71 100


4
1
3
2
3
1
3
4
2
2
2
3
2
2
0
0
4
6
4
6
6
2
2
1
1
2
1
2
2
3
2
3
4
4
4
3
2
1
4
4
3
4
5
4
4
4
4
3
3
4
4
4


1
0
0
0
1
0
0
3
0
1
0
0
0
0
0
0
2
3
3
3
3
1
0
0
0
0
0
0
1
1
0
1
1
2
2
1
1
0
2
3
2
3
3
3
2
2
2
2
2
3
2
2


17.8
17.6
7.6
6.8
11.2
13.8
8.4
9.4
9.4
14.4
10.2
8.4
17.8
11.8
14.4
13.4
10.2
8.4
7.2
8.4
10.6
5.8
9.0
3.2
7.2
2.4
3.2
4.0
6.2
3.6
8.0
13.6
0.8
6.0
9.6
13.2
16.0
11.0
3.4
4.0
3.2
6.0
6.2
5.6
7.0
8.6
7.8
7.2
6.0
7.8
5.4
6.2
444.4


70
70
71
79
74
75
75
75
61
60
72
68
80
74
74
54
71
73
72
68
68
72
72
73
72
72
69
68
70
69
70
68
70
70
70
68
68
70
70
70
68
68
66
68
70
66
68
70
72
74
70
72


1
0
0
0
3
0
3
0
0
0
0
0
4
0
4
0
4
5
4
6
5
3
2
1
3
2
0
1
1
1
2
2
3
3
2
0
0
0
0
0
0
0
0
0
0
0
0
0
2
2
1
2


0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
3
2
3
2
1
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0


13.8
13.6
18.3
14.2
16.4
18.0
15.4
17.6
20.3
14.8
17.9
13.4
12.1
14.2
14.2
7.9
3.8
3.1
3.3
2.9
2.6
2.6
7.6
0.3
0.9
0.0
0.2
0.2
1.1
0.7
1.1
0.8
3.5
1.9
1.5
9.6
12.1
5.0
5.3
9.9
4.7
7.8
14.0
15.1
2.4
13.9
8.8
12.6
6.0
10.2
8.8
9.2
438.2




ble 2-- CONTINUED


ek of
75-76
ly 7
ly 14
ly 21
ly 28
g. 4
g. 11
g. 18
g. 25
pt. 1
pt. 8
pt. 15
pt. 22
pt. 29
t. 6
t. 13
t. 20
t. 27
. 3
. 10
17
24
1
8
.15
22
29
5
12
19
n. 26
b. 2
b. 9
b. 16
b. 23
r. 1
r. 8
r. 15
r. 22
r. 29
. 5
. 12
19
26
3
10
17
24
1
7
14
21
28


Temp.
Min.
68
67
70
70
72
69
70
69
66
65
75
76
71
66
65
72
70
68
67
67
69
72
72
69
70
72
68
72
70
70
68
72
71
71
72
70
70
70
70
64
62
64
64
64
68
68
68
70
70
70
68
70


No. 4 Gutter connected
Dutch glass-pads
(38,000 ft2)


oF
Max
92
9C
91
91
95
92
93
92
91
91
9C
95
97
86
87
89
90
93
90
85
86
90
92
87
86
87
86
90
87
85
83
86
88
88
89
90
90
92
92
90
88
90
92
94
90
92
90
93
90
94
92
93


No. 3 Stuppy low
Profile fiberglass
(16,000 ft2)
Daily
Hrs. above
. 900F 950F
2 0
0 0
3 0
2 0
3 0
3 0
3 0
2 0
2 0
3 0
0 0
2 0
4 3
0 0
0 0
0 0
2 0
5 3
4 0
0 0
1 0
2 0
3 1
1 0
1 0
1 0
1 0
3 0
2 0
0 0
0 0
1 0
3 0
3 0
4 0
0 0
0 0
1 0
1 0
0 0
0 0
0 0
1 0
1 0
0 0
1 0
0 0
1 0
0 0
2 0
1 0
1 0
6


Watts/
ft2
15.3
15.8
19.5
15.9
21.9
25.0
21.0
17.9
20.2
19.8
21.0
17.2
13.8
14.9
14.8
18.0
6.3
5.2
4.9
4.3
7.8
3.1
0.4
0.6
4.1
0.0
1.8
1.2
5.3
7.1
2.7
5.7
8.8
7.2
8.0
7.4
11.2
9.0
12.4
15.0
9.2
12.9
15.9
18.2
21.4
23.2
12.5
22.4
19.1
20.5
15.4
20.5
i42.7


Temp.
Min.
70
68
75
69
69
70
74
74
68
65
71
73
70
68
70
75
70
65
64
66
67
64
62
61
62
53
60
62
61
60
60
60
63
63
64
64
56
62
64
62
66
66
64
62
66
68
68
70
70
72
70
71


oF
Max.
92
89
89
90
93
90
91
88
87
81
80
86
82
81
86
90
90
88
89
88
84
85
82
83
80
91
88
89
86
83
86
90
92
92
93
88
89
90
92
90
92
94
92
94
92
90
92
94
93
94
93
93


Daily
Hrs. above
900F 950F
1 0
0 0
0 0
0 0
2 0
0 0
3 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
2 0
3 0
4 0
4 0
0 0
0 0
0 0
0 0
0 0
2 1
2 0
2 0
1 0
0 0
1 0
3 0
4 1
4 1
5 2
0 0
0 0
0 0
1 0
0 0
2 0
2 0
1 0
1 0
1 0
0 0
1 0
2 0
2 0
3 0
2 0
2 0


Watts/
ft2
15.0
10.7
16.2
11.7
16.2
19.4
15.6
14.2
18.3
15.1
10.6
9.2
3.3
8.3
7.2
9.6
6.3
3.6
2.8
3.2
2.4
1.4
1.0
1.6
4.4
0.5
0.0
1.5
2.5
3.2
3.9
7.9
6.6
9.7
8.1
10.2
12.1
16.4
8.7
19.7
9.4
12.0
14.4
13.6
18.4
9.9
10.6
11.8
12.3
13.8
12.6
12.2
489.3




-7-
T e.2-- CONTINUED
No. 5 Gutter connected No. 6 Single glass
glass-no pads no pads
(40,000 ft2) (20,000 ft2)
Daily Daily
Week of Temp. OF Hrs. above Watts/ Temp. OF Hrs. above Watts/
1975-76 Min. Max. 90aF 950F ft2 Min. Max. 900F 950F ft2


July 7
July 14
July 21
July 28
Aug. 4
Aug. 11
Abg. 18
Aug. 25
Sept. 1
Sept. 8
Sept. 15
Sept. 22
Sept. 29
Oct. 6
Oct. 13
Oct. 20
Oct. 27
Nov. 3
Nov. 10
Nov. 17
Nov. 24
Dec. 1
Dec. 8
Dec. 15
Dec. 22
c. 29
;'an. 5
Jan. 12
Jan. 19
Jan. 26
Feb. 2
Feb. 9
Feb. 16
Feb. 23
Mar. 1
Mar. 8
Mar. 15
Mar. 22
Mar. 29
Apr. 5
Apr. 12
Apr. 19
Apr. 26
May 3
May 10
May 17
May 24
Jun. 1
Jun. 7
Jun. 14
Jun. 21
Jun. 27


69
70
69
67
68
70
70
69
66
71
73
71
74
70
69
71
69
67
68
67
67
68
66
63
64
65
61
63
62
61
64
60
62
65
64
62
58
64
60
60
66
64
64
64
66
66
68
70
70
70
68
70


95
96
98
99
100
100
99
96
96
96
97
97
94
96
95
95
93
92
92
90
90
92
94
89
87
89
90
91
90
88
90
95
92
96
94
97
95
95
93
95
92
98
100
100
98
100
100
98
100
98
100
100


0 0
4 1
4 2
3 2
3 2
4 2
6 3
4 2
3 2
4 3
4 3
3 2
3 0
4 2
3 0
3 0
4 2
5 2
3 2
5 3
5 0
4 1
2 1
2 0
4 0
3 0
2 0
3 1
2 0
2 0
3 0
5 3
4 2
4 2
4 3
2 1
1 0
1 0
1 0
1 0
1 0
3 1
3 1
2 1
3 2
3 1
3 2
3 2
2 1
2 1
3 1
3 1


0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0


70
67
71
74
73
74
76
76
62
66
64
64
67
64
61
57
60
62
60
62
64
65
63
62
62
63
57
54
57
60
58
63
65
64
62
55
56
56
54
58
60
62
62
62
70
70
70
72
70
72
72
72


95
100
97
95
96
95
95
95
93
96
94
92
96
97
94
90
95
97
95
94
95
97
98
93
91
88
100
98
100
101
96
95
98
97
99
100
94
98
100
98
100
102
100
102
100
100
102
102
100
100
102
101


3 0
3 1
5 1
2 0
2 1
3 0
6 0
4 0
3 0
3 2
4 0
4 0
2 1
4 2
3 0
0 0
4 2
6 3
6 4
5 2
5 2
4 1
4 2
2 1
2 1
2 0
3 2
3 2
5 2
4 2
5 3
5 3
5 3
5 4
6 4
3 1
1 0
2 1
4 3
4 2
3 2
4 3
4 3
5 3
4 3
4 2
4 3
3 2
3 2
5 3
4 3
4 2


0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0


Total 0 0





Table 2-- CONTINUED


Week of
1975-76
July 7
July 14
July 21
July 28
Aug. 4
Aug. 11
Aug. 18
Aug. 25
Sept. 1
Sept. 8
Sept. 15
Sept. 22
Sept. 29
Oct. 6
Oct. 13
Oct. 20
Oct. 27
Nov. 3
Nov. 10
Nov. 17
Nov. 24
Dec. 1
Dec. 8
Dec. 15
Dec. 22
Dec. 29
Jan. 5
Jan. 21
Jan. 19
Jan. 26
Feb. 2
Feb. 9
Feb. 16
Feb. 23
Mar. 1
Mar. 8
Mar. 15
Mar. 22
Mar. 29
Apr. 5
Apr. 12
Apr. 19
Apr. 26
May 3
May 10
May 17
May 24
Jun. 1
Jun. 7
Jun. 14
Jun. 21
Jun. 27


ARC-Apopka
Wx. Station
Temp. F
Min. Max.
72 91
72 90
69 89
71 91
71 93
74 92
73 92
72 92
72 92
72 91
72 89
72 81
72 84
69 89
68 86
68 88
68 85
67 83
53 70
50 70
50 68
50 68
47 67
41 64
41 59
46 69
43 64
49 65
40 70
37 61
39 66
35 72
54 80
49 69
56 81
52 77
50 77
64 77
57 82
54 75
60 77
60 86
60 84
60 86
66 86
64 84
64 83
66 88
66 84
68 89
68 93
69 90


Full sun
Radiant energy
(cal/cm2/min)
1.203
1.108
.935
1.073
1.117
.935
1.114
1.049
1.096
1.034
1.009
1.020
.967
.954
.911
.929
.816
.797
.872
.756
.722
.870
.791
.795
.680
.760
.779
.238
.309
.316
.387
.458
.529
.600
.671
1.086
1.108
1.064
1.019
1.122
1.075
1.079
1.052
1.114
.987
1.129
1.016
1.093
1.060
1.115
1.132
1.120


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