Luckily, the answer is simple: root zone heating.
There are three reasons why root zone heating is easily the most efficient way to heat a greenhouse in winter for commercial growers.
- The soil and water in hydronic piping becomes a heat sink. The easiest and most common way to even out the temperature in a greenhouse is to utilize a thermal mass called a heat sink to maintain warm temperatures overnight when the sun isn’t fighting the cold. Soil, concrete, and water are some of the best heat sinks, which means that adding a heat source within the floor or beds allows you to store even more of the sun’s natural energy. This means that even less additional heat-- and associated energy-- is needed later
- When a plant’s root zone is warm, they can grow at their peak in cooler air temperatures. When it comes to peak growth, the roots are the most vital part of the plant to keep warm. If ground temperatures drop below the ideal, the plant will simply slow growth and achieve lower yields overall. Warm roots, however, can negate cool winter temperatures more quickly than any other solution. In fact, when the root temperature of a plant is kept at the ideal, the air temperature needed to sustain peak growth is about 5 to 15 degrees Fahrenheit lower, depending on the plant and stage in the growth cycle. This costs less to achieve all winter long.
- Root zone heating directs 95% of heating energy first at the plants and their needs. The goal of heating a greenhouse isn’t to keep the building nice and toasty to work in. The goal is to keep the plants at their ideal temperature for growth. Unfortunately, with forced air heating, much of the heat dissipates into the atmosphere before even reaching the plants, warming the greenhouse as a whole and leaving only 40-60% of the heat to the plants. Root zone heating, on the other hand, transfers 95% of the heat directly to the plants first. Heat dissipates throughout the rest of the greenhouse only after being transferred first to plants.