Heat Losses for 96' and 144 foot long Gutter Connected Greenhouse Structures.

This is for double poly houses.

Infiltration rate based on 1 AC/hr on 8 foot height for area of building. Note: For gutter vented structures we would recommend providing approximately 5% more heat to take into account increased inflitration rates due to the nature of gutter vent systems. In high wind load areas you may wish to double the 5% factor.

This table is heating output requirements. Do not confuse this with input heating. Typically, if you do you will find yourself short heating. By about 20%.

Package size : example 2-21X96 refers to two bays of 21' gutter connects having a length of 96 feet.

A safety factor of 15% has been included since the U value of double poly will increase as it become aged. ( ie a holes etc. form and are unpatched. ) Double poly has an excellant U value, but it is dependant on maintaining a dead air space without to much loss or overinflation.

All temperatures are in deg F. Losses in BTU's/hr.

HEAT LOSSES
Outdoor Range			+20 to +10	+10 to 0	0 to -10	-10 to -20	-20 to -30
Outdoor			10	0	-10	-20	-30
Indoor			70	70	70	70	70
Delta T			60	70	80	90	100
safety factor			0.15	0.15	0.15	0.15	0.15
	Area
Package Size	sq. ft.		BTUs/hr	BTUs/hr	BTUs/hr	BTUs/hr	BTUs/hr
2-21X96	4032		318322.944	371376.768	424430.592	477484.416	530538.24
2-21X144	6048		451982.016	527312.352	602642.688	677973.024	753303.36
2-24X96	4608		355470.336	414715.392	473960.448	533205.504	592450.56
2-24X144	6912		504059.904	588069.888	672079.872	756089.856	840099.84
2-27 1/2X96	5280		393951.36	459609.92	525268.48	590927.04	656585.6
2-27 1/2X144	7920		557531.04	650452.88	743374.72	836296.56	929218.4
2-30X96	5760		437051.52	509893.44	573196.8	655577.28	728419.2
2-30X144	8640		615568.32	718163.04	820757.76	923352.48	1025947.2
3-21X96	6048		433766.016	506060.352	578354.688	650649.024	722943.36
3-21X144	9072		612395.424	714461.328	816527.232	918593.136	1020659.04
3-24X96	6912		489487.104	571068.288	652649.472	734230.656	815811.84
3-24X144	10368		690512.256	805597.632	920683.008	1035768.384	1150853.76
3-27 1/2X96	7920		547208.64	638410.08	729611.52	820812.96	912014.4
3-27 1/2X144	11880		770718.96	899172.12	1027625.28	1156078.44	1284531.6
3-30X96	8640		611858.88	713835.36	801504	917788.32	1019764.8
3-30X144	12960		857774.88	1000737.36	1143699.84	1286662.32	1429624.8
4-21X96	8064		549209.088	640743.936	732278.784	823813.632	915348.48
4-21X144	12096		772808.832	901610.304	1030411.776	1159213.248	1288014.72
4-24X96	9216		623503.872	727421.184	831338.496	935255.808	1039173.12
4-24X144	13824		876964.608	1023125.376	1169286.144	1315446.912	1461607.68
4-27 1/2X96	10560		700465.92	817210.24	933954.56	1050698.88	1167443.2
4-27 1/2X144	15840		983906.88	1147891.36	1311875.84	1475860.32	1639844.8

4-30X96	11520		786666.24	917777.28	1029811.2	1179999.36	1311110.4
4-30X144	17280		1099981.44	1283311.68	1466641.92	1649972.16	1833302.4
5-21X96	10080		664652.16	775427.52	886202.88	996978.24	1107753.6
5-21X144	15120		933222.24	1088759.28	1244296.32	1399833.36	1555370.4
5-24X96	11520		757520.64	883774.08	1010027.52	1136280.96	1262534.4
5-24X144	17280		1063416.96	1240653.12	1417889.28	1595125.44	1772361.6
5-27 1/2X96	13200		853723.2	996010.4	1138297.6	1280584.8	1422872
5-27 1/2X144	19800		1197094.8	1396610.6	1596126.4	1795642.2	1995158
5-30X96	14400		961473.6	1121719.2	1258118.4	1442210.4	1602456
5-30X144	21600		1342188	1565886	1789584	2013282	2236980
6-21X96	12096		780095.232	910111.104	1040126.976	1170142.848	1300158.72
6-21X144	18144		1093635.648	1275908.256	1458180.864	1640453.472	1822726.08
6-24X96	13824		891537.408	1040126.976	1188716.544	1337306.112	1485895.68
6-24X144	20736		1249869.312	1458180.864	1666492.416	1874803.968	2083115.52
6-27 1/2X96	15840		1006980.48	1174810.56	1342640.64	1510470.72	1678300.8
6-27 1/2X144	23760		1410282.72	1645329.84	1880376.96	2115424.08	2350471.2
6-30X96	17280		1136280.96	1325661.12	1486425.6	1704421.44	1893801.6
6-30X144	25920		1584394.56	1848460.32	2112526.08	2376591.84	2640657.6
7-21X96	14112		895538.304	1044794.688	1194051.072	1343307.456	1492563.84
7-21X144	21168		1254049.056	1463057.232	1672065.408	1881073.584	2090081.76
7-24X96	16128		1025554.176	1196479.872	1367405.568	1538331.264	1709256.96
7-24X144	24192		1436321.664	1675708.608	1915095.552	2154482.496	2393869.44
7-27 1/2X96	18480		1160237.76	1353610.72	1546983.68	1740356.64	1933729.6
7-27 1/2X144	27720		1623470.64	1894049.08	2164627.52	2435205.96	2705784.4
7-30X96	20160		1311088.32	1529603.04	1714732.8	1966632.48	2185147.2
7-30X144	30240		1826601.12	2131034.64	2435468.16	2739901.68	3044335.2

8-21X96	16128		1010981.376	1179478.272	1347975.168	1516472.064	1684968.96
8-21X144	24192		1414462.464	1650206.208	1885949.952	2121693.696	2357437.44
8-24X96	18432		1159570.944	1352832.768	1546094.592	1739356.416	1932618.24
8-24X144	27648		1622774.016	1893236.352	2163698.688	2434161.024	2704623.36
8-27 1/2X96	21120		1313495.04	1532410.88	1751326.72	1970242.56	2189158.4
8-27 1/2X144	31680		1836658.56	2142768.32	2448878.08	2754987.84	3061097.6
8-30X96	23040		1485895.68	1733544.96	1943040	2228843.52	2476492.8
8-30X144	34560		2068807.68	2413608.96	2758410.24	3103211.52	3448012.8
9-21X96	18144		1126424.448	1314161.856	1501899.264	1689636.672	1877374.08
9-21X144	27216		1574875.872	1837355.184	2099834.496	2362313.808	2624793.12
9-24X96	20736		1293587.712	1509185.664	1724783.616	1940381.568	2155979.52
9-24X144	31104		1809226.368	2110764.096	2412301.824	2713839.552	3015377.28
9-27 1/2X96	23760		1466752.32	1711211.04	1955669.76	2200128.48	2444587.2
9-27 1/2X144	35640		2049846.48	2391487.56	2733128.64	3074769.72	3416410.8
9-30X96	25920		1660703.04	1937486.88	2171347.2	2491054.56	2767838.4
9-30X144	38880		2311014.24	2696183.28	3081352.32	3466521.36	3851690.4
10-21X96	20160		1241867.52	1448845.44	1655823.36	1862801.28	2069779.2
10-21X144	30240		1735289.28	2024504.16	2313719.04	2602933.92	2892148.8
10-24X96	23040		1427604.48	1665538.56	1903472.64	2141406.72	2379340.8
10-24X144	34560		1995678.72	2328291.84	2660904.96	2993518.08	3326131.2
10-27 1/2X96	26400		1620009.6	1890011.2	2160012.8	2430014.4	2700016
10-27 1/2X144	39600		2263034.4	2640206.8	3017379.2	3394551.6	3771724
10-30X96	28800		1835510.4	2141428.8	2399654.4	2753265.6	3059184
10-30X144	43200		2553220.8	2978757.6	3404294.4	3829831.2	4255368

To select your heating output requirment select the outside temperature range range you wish to deal with. For input BTU's for natural gas add about 20%. Remeber most high efficiency gas fired equipment is 80 to 83% efficient.

Yes .... you can keep a lower space temperature to reduce your heating, but as many found out, in the 2001 season, reducing the space temp to conserve fuel costs certainly hurt crop quality. The heat is nice to have when you need it. So plan for it.