Chapter 3

Greenhouse Curtain Systems

Types of Greenhouse Curtain Systems

Depending on greenhouse orientation, design and grower preferences, greenhouse curtain systems can operate from gutter-to-gutter or from truss-to-truss. For heat loss reduction, there is little advantage of one over the other. In a gutter-to-gutter system, the curtain panels are pulled flat across the width of the greenhouse at gutter height. In a truss-to-truss system, the panels are wide enough to travel the length of the greenhouse spanning the distance between one truss and the next. In either configuration, each panel of curtain material has a stationary edge and a moving edge.

Gutter-to-Gutter Curtain System

In a gutter-to-gutter curtain system, there is a single panel of fabric per house instead of multiple panels as in a truss-to-truss system (Figure 3.2). Unlike a truss-to-truss systems, if the single piece of fabric is damaged it will likely require replacement of the entire curtain. In a gutter-to-gutter curtain system, the curtain panels are pulled flat across the width of the greenhouse at gutter height. Though the volume of greenhouse space that is heated is minimized in this configuration, the amount of cold air above the system is maximized. This makes it harder to mix and reheat the air above the system when it uncovers in the morning. These systems require less installation labor than a typical truss-to-truss system, but gutter systems are not ideal for every greenhouse.

Truss-to-Truss Curtain System

The truss-to-truss type has a curtain section between each truss so for example a 100-foot (30m) long greenhouse with 10-foot truss spacing could have 10 curtain sections on (Figure 3.3). When the curtain is opened or closed each section moves at the same time and the same amount, covering the area between trusses. There are three types of configurations used for truss-to-truss curtain systems: flat at gutter height, slope-flat-slope, and slope-slope.

Flat at Gutter Height

Flat, at gutter height systems draw shade curtains from truss to truss at the height of the gutter. As with the gutter-to-gutter system, this configuration minimizes the volume of greenhouse space to be heated and is relatively easy to install.

Slope-Flat-Slope

Slope-flat-slope where the profile of the curtain system follows each slope of the roof part way up the truss, with a flat section at the top of the greenhouse joining the two sloped segments (Figure 3.4).

Slope-Slope

Slope-slope where the profile of the system parallels a line drawn from the gutter to the peak of the truss (Figure 3.5).

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