Some tips for building a small greenhouse include using standard designs and sizes, doubling the length over the width, choosing a good location and using pressure-treated wood. Because it is difficult to regulate the temperature of a small greenhouse, choose a site with southern or southeastern exposure for the best direct sunlight.
Along with choosing a good location to help regulate the temperature of a small greenhouse, paint the heat storage surface dark red or blue to better absorb light, while other surfaces need to be white or metallic for light reflection. Use double glazing or double-paned glass for the windows and insulate anything not made from double glazing.
Use standard designs and sizes for a small greenhouse where materials are more readily available in those shapes. Materials are usually sized in multiples of four such as a 2-inch by 4-inch board. Make the greenhouse into a rectangular shape, twice as long as it is wide, in order to conserve heat. Other than double-paned glass, use pressure-treated wood as another material. It works well for flooring or for walkways between benches and shelves.
When arranging shelves and plants, allow for plenty of airflow, especially important in a small area. Wire shelves help to facilitate airflow.