A greenhouse having glass panels that is designed to capture and retain warmth in the colder months may be totally unsuitable for use in the warmer months as the conditions inside may be too hot. And conversely, for a structure designed to keep plants cooler during hot weather. This invention provides a building or structure that can easily be modified to provide improved growing conditions for plants in a range of seasons. This is made possible by a construction that facilitates easy removal and replacement of the major panels of the building, for example glass panels can quickly be replaced with shade panels when the seasons change from cold to hot. The top rails of the structure include a removal section providing access to remove both side wall panels and roofing panels. In addition, the panels are secured to the frames with a friction fit sealing arrangement which aids quick replacement, and enhances the structural rigidity of the greenhouse when fitted.
