Tag: johnbartok

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Step Controllers Optimize Greenhouse Energy Use

This is a four-step controller with a solar sensor shield and shielded shielded cable, suitable for greenhouse use.

A step controller is an advanced electronic device that controls conditions in a greenhouse better than a mechanical thermostat and can save money in the long run. It uses a solid-state integrated circuit to monitor environmental data in the greenhouse and create output signals that activate equipment based on a set of internal programmed instructions. The microprocessor is a simple, low-cost device …

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Root Zone Heating Systems for Greenhouses

Root zone heating is an effective option for greenhouses that provides heat directly to the growing media rather than heating the air of the greenhouse. This approach provides a triple benefit for greenhouse growers: faster production, higher quality crops and energy savings. If the root zone temperature is maintained at the optimum, air temperature in the greenhouse can be lowered 5 to 10 degrees F., reducing heat loss to the outside and therefore, reducing energy consumption. This is possible because …

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Greenhouse Ventilation

Good temperature control is vital for a productive high tunnel greenhouse, and this in turn means that the ventilation system needs to be effective and efficient. Regardless of whether a grower uses fans or “natural ventilation,” it is important to make sure that the system is designed properly and working well. Here are a few pointers that will help you improve your system.

Natural Ventilation

The concept of cooling a greenhouse with thermal buoyancy and wind goes back to the …

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Wood Heat for Greenhouses

Outdoor wood boilers are increasingly subject to state and local and regulations aimed at minimizing air pollution. Photo courtesy of Vern Grubinger

 

Introduction

Wood is an attractive alternative fuel for greenhouse heating – it is renewable, locally produced, and usually less expensive than other fuels. While wood is not for everyone, an increasing number of growers are turning to it as an economical heating alternative for their facilities. Fuel wood, waste wood and biomass are all potential sources of heat …

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Fuels and Alternate Heat Sources for Commercial Greenhouses

corn boiler
Corn furnace with fuel. Photo by Vern Grubinger, University of Vermont Extension, Creative Commons

Which fuel is best for heating a greenhouse? The right answer depends on price, convenience, and availability. Some fuels have more “heat per dollar” and some heating units have a greater efficiency. Others are especially easy to use. All of these factors need to be considered when deciding what fuel to use. The most common fuels for greenhouse heating are natural gas, propane, and fuel oil, …

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Insulation Know-How

With volatile energy costs, a good return on investment may be obtained by adding insulation to homes, offices, farm shops and other heated buildings such as greenhouse headhouses or boiler rooms. Insulation can provide benefits in winter by keeping expensive heat in and in summer by keeping unwanted heat out.

Although all building materials have some insulation value, the term “insulation” usually refers to materials with a relatively high resistance to heat flow that are designed specifically for that purpose. …

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Horizontal Air Flow is Best for Greenhouse Air Circulation

Before Horizontal Air Flow (HAF) systems were developed, it was common to find 10°F to 15°F difference in nighttime temperature between the opposite ends of a greenhouse. Plant growth and quality often reflected this unevenness. Today with a properly installed HAF system, there should be no more than 2°F difference anywhere in the greenhouse.

Understanding the basics

Horizontal air flow fans maintain good air circulation in this greenhouse full of vegetable seedlings. The first fan should be placed about 10′
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Introduction to Greenhouse Efficiency and Energy Conservation


Contents

Greenhouses do their job most successfully using designs and siting for energy efficiency and maximum light transmission. Greenhouses must optimize crop growth and energy use by allowing sunlight in during the day, retaining as much heat as possible during cold weather, and providing sufficient ventilation to …

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Geothermal Heat for Greenhouses

Soil and water below ground contain a vast reservoir of thermal energy. Geothermal heating systems recover this energy and convert it to heat that can be utilized in greenhouses and other buildings. Geothermal heat resources can be classified into three categories: low, medium, and high temperature.

Types of Geothermal Resources

  • Low temperature (50°F +/-). The soil temperature at the surface varies considerably over the year and closely follows the air temperature. At the 5 to 6 foot depth, the
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Natural Ventilation in High Tunnels

Roll-up sides and drop-down curtains are low-cost vent systems that can be installed in most high tunnels. These systems operate on the principle that heat is removed by a pressure difference created by wind gradients, so no energy is required to operate fans to move air. A wind speed of 2-3 miles per hour is adequate to force cool air in the windward sidewall. The air traveling over the high tunnel creates a vacuum on the leeward side to pull …

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