In most of North America , growing year-round in a greenhouse requires substantial heating and cooling . Glass and thin plastic are horrible insulators , making traditional greenhouses notoriously inefficient structures . Even though greenhouses collect vast amounts of solar energy during the day — usually too much — they lose all heat very quickly at night due to the lack of insulation . Thus , an unheated greenhouse will normally dip down to the outdoor temperature at night . In climates with freezing winters , that makes growing difficult , if not impossible . With more interest in producing local food , growers are looking for ways to do it sustainably by reducing the fossil fuels that it takes to grow year-round . Net-zero energy greenhouses , which produce as much or more energy than they consume , could be the solution . The first step in creating an independent and abundant year-round greenhouse is to design an energy-efficient structure . Passive solar greenhouse design is the typical go-to strategy for those looking to grow more sustainably year-round . Passive solar greenhouses incorporate a series of design principles that aim to maximize the use of free solar energy and reduce the reliance on fossil fuels .
Elements of a Passive Solar Greenhouse
Passive solar greenhouses have been around , growing abundantly , for several decades . They vary in almost every way imaginable , but they do share some basic principles . The first is to orient most of the glazing materials ( translucent materials like glass or plastics ) toward the sun .
“ Growers can also become more creative , integrating a range of sustainable systems that provide fossil-free heating and cooling .”
Net-zero greenhouses have most of their glazing materials oriented toward the sun . grow cycle 41