Greenhouse Structures and Systems ERT 352 What

Greenhouse Structures and Systems ERT 352

What is a greenhouse? • A greenhouse is an area designed to grow plants. • It is a controlled environment which allow optimum growth. • When several of these buildings are joined together they are often referred to as a greenhouse range. • A greenhouse at home is usually attached to the house or the garage.

Location • There are several factors to be considered in establishing a greenhouse range. • A. Room for expansion – 1. Land larger then immediate needs should be acquired. – 2. Area should be added to this figure to accommodate service buildings, storage, and access drivers.

• B. Topography – 1. The building site should be as level as possible to reduce the cost of grading. – 2. The site should be also well drained. Due to the vast amount of water in the green house it is always advisable to provide a drainage system. Try to select a site with deep, well drained loam, or sandy loam soil.

– 3. You should select a site with a natural wind break such as a tree line or a hill. • C. Land use Prediction – 1. Local zoning and tax laws are subject to change brought on by development pressures. Such changes have brought about the termination of many greenhouse business.

• D. Climate – 1. The greenhouse site should be selected with specific crops in mind. • E. Accessibility – 1. A site should be selected which has easily accessible shipping routes. – 2. Select a site that isn’t long distance. – 3. Site location is often the deciding factor in the type of fuel used.

Types of Greenhouses Even Span Uneven Span Lean-to Quonset Gothic Arch Curvilinear Dome Shaped

lean to even-span uneven-span ridge-and-furrow

Single Span Greenhouse

1. EVEN SPAN • Greenhouse with two roof slopes of equal pitch and width • Benefits: • Excellent light, ventilation, and temp control • Disadvantages: • Wasted heat air in the gables

EVEN SPAN

Even span gutter connected house.

2. GOTHIC ARCH • • POINTED ARCH ROOF TRUSSES HAVE BEEN ELIMINATED Not as popular today Can have sidewalls • Side walls are a short base wall of a solid material – often cinderblocks

GOTHIC ARCH

3. QUONSET • A greenhouse with a semicircular arch that starts at ground level or on top of a sidewall – (Half moon shape) • Benefits: – Less Expensive to construct – Few shadows • Disadvantage: – Cannot handle as much wind and snow

3. QUONSET

QUONSET QUONSET

QUONSET WITH TOP VENT

4. RIDGE AND FURROW • Several greenhouses connected along the length of the eaves • Benefits: – Large interior areas – Reduced heat loss – Less expensive construction • Disadvantages: – More difficult to control pest and temperature – Difficult snow removal

RIDGE AND FURROW

1. GLASS • ADVANTAGES: – Excellent Light Transmission – Available • DISADVANTAGES: – Breakable – High heat loss – Most Expensive

2. FLEXIBLE PLASTIC FILMS • EXAMPLES: – PVC- POLYVINYL CHLORIDE – PVF- POLYVINYL FLOURIDE FILM – POLYETHYLENE- Most Common • ADVANTAGES: – Inexpensive – Easy to Install • DISADVANTAGES: – Not as durable

3. RIGID PLASTIC SHEETS • EXAMPLES: – FIBERGLASS – ACRYLIC- PLEXIGLASS – POLYCARBONATE- LEXAN • ADVANTAGES: – Light weight – Most Durable • DISADVANTAGES: – More expensive than flexible plastic

Cooling and Ventilation Systems 1. 2. 3. 4. No Cooling NATURAL VENTILATION FAN & SHUTTER COOLING with SHADE CLOTH 5. Evaporative Cooling 6. Fan & Pad (Evaporative Cooling)

1. NO COOLING • 1. Inside temperature of greenhouse can exceed 140 degrees F. • 2. Plants will die within a short period of time.

NATURAL VENTILATION

FAN & SHUTTER COOLING

FAN & SHUTTER COOLING with SHADE CLOTH

Evaporative Cooling

EVAPORATIVE COOLING (Fan & Pad)

EVAPORATIVE COOLING (Fan & Pad) • Pad • Water Tank With pump

D. IRRIGATION 1. 2. 3. 4. 5. Drip irrigation Mist nozzles Fertilizer injectors Automatic Controls Solenoid valves

DRIP IRRIGATION (tubes)

MISTER (FOGGER)

FERTILIZER INJECTORS • SLOWLY ADD FERTILIZERS TO IRRIGATION WATER, AT A SET RATE

IRRIGATION CONTROLS • Solenoid Valves – Help control flow rate

Greenhouse Structural Components

Ridge-and-Furrow Greenhouses

Other structural components

Wooden framing.

Sawtooth Construction