Design criteria for a modern commercial greenhouse facility-3

Heating Greenhouses:
The selection of the appropriate greenhouse heating system should be determined by factors such as crops to be grown, etc. The initial cost of the greenhouse heating system is usually still the most important consideration. This may, however, not always be the best way the choose a greenhouse heating system, as factors such as the ability to control the greenhouse environment properly and efficiently, the running cost of the system, the cost of maintaining the system, etc. should also be taking into consideration.

Piped hot water heating systems, while more expensive to install, are ultimately a better choice than unit heaters in most cases. These systems do provide for more accurate control of the greenhouse temperature as well as the ability to ensure much improved distribution of the heat. The pipe/rail heating system in vegetable greenhouses are also used to facilitate crop maintenance work and harvesting.

Natural gas, LP gas and heating oil are most commonly used to heat greenhouses. Fuels such as coal, wood chips, sawdust, may in some cases be an alternative. The development of affordable combined heat and power (CHP) units may in the future provide another alternative. This may become especially important when grow lights are being used.

Energy retention and Greenhouse shade curtain systems:
It is essential that the Commercial greenhouse structure is prepared for the inclusion of energy retention/shade or black-out curtains at a later stage if these systems are not included in the initial construction. Care must be taken that heating and irrigation pipes, electrical wiring, VAF fans, etc. do not obstruct the installation of the curtains. Alterations to these installations tend to be very expensive and time consuming.

An extensive selection of curtains is now available, including several flame retardant types.

Greenhouse Irrigation systems:
There are several types of greenhouse irrigation systems available. When selecting a system, or a combination of systems, it is important to consider the type of crops to be grown and the source and quality of the irrigation water. The overall layout of the system(s) should be carefully designed. Pipe sizes should be determined with possible future expansion in mind. A good quality filtration system should be included in the greenhouse irrigation design.

Fertilizer injection systems are an integral part of the irrigation system and it is important to select a system that is the correct one for the crops that will be grown in facility. The selection should be based on various factors, but the most important one is the ability of the user to operate, maintain and calibrate the equipment properly. Many systems do not meet expectations because the operator does not know how to work with the equipment or the equipment is unsuitable for the greenhouse irrigation system it serves.

With the availability of quality irrigation water and the increase in the cost of fertilizers becoming major factors in the future, recirculation of the irrigation water is becoming more prevalent. In that case appropriate sterilization equipment must be included in the design of the irrigation system.

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