Greenhouse Cooling Systems & Chillers by Enerdes®

At Enerdes we can identify the ideal cooling system for your specific greenhouse using Computational Fluid Dynamics modelling. We compare different scenarios between evaporative cooling and active cooling with chillers and optimize the benefit of both. Sometimes this will lead to an efficient combination of both methods, lowering operational costs and giving extra cooling capacity when needed. 

Enerdes is part of the Reinders Corporation and has been developing and producing climate control systems since 1910.

11 Semi-closed greenhouse_Enerdes_Greenhouse climate control

The Enerdes expertise

Advantages of Greenhouse Cooling Systems by Enerdes®

At Enerdes we have decades of experience in the agriculture and horticulture industry. Our greenhouse cooling systems and chillers are market-leading and our engineers are the most experienced out there to develop the ideal system for your individual location and crop.

Advantages of greenhouse cooling systems by Enerdes:

  • Computational Fluid Dynamics modelling (CFD)
  • Very precise temperature control
  • Healthy plants and higher yields
  • Custom-made to your greenhouse
  • Low operational costs
  • Long product lifetime
  • Minimum maintenance required

Enerdes – experts in creating the perfect air conditions in greenhouses.

The Right Greenhouse Cooling Method

There are 3 methods available to cool an industrial greenhouse:

  1. Ventilation & Shading
  2. Evaporative Cooling
    1. Cooling Pads
    2. Adiabatic Cooling
  3. Active Cooling with Chillers

At Enerdes, we know exactly how to develop a greenhouse cooling system for your individual needs that operates with minimal energy consumption and low costs. 

Based on the following factors, Enerdes determines the heating and cooling demand for your greenhouse and what methods are most suitable to achieve the desired temperature:

  • Outdoor climate in all seasons over the last few years
  • Desired indoor climate
  • Plant type and plant evaporation production
  • Heat production by lights and other machines
  • Type of greenhouse, volume, area, roof and wall type

It is also possible to combine several systems to get optimal temperature results. For example a chilled water system during humid months with an evaporative cooling system that is active in less humid periods and a heating system for cooler months

Enerdes can advise you on which climate control installation is most suitable for you and what capacity you will need. We make sure you have sufficient cooling and heating capacity without making unnecessary investments.

1. Ventilation and Shading

To cool a greenhouse, the first measures are ventilation and shading. Ventilation can be achieved by creating air circulation with greenhouse fans and opening roof vents and shutter vents. 

However, these solutions may not be sufficient or not desired for many reasons such as:

  • It is desired to keep ventilation minimal
  • The outdoor climate is too hot
  • Sunlight is needed for plant growth

For big buildings like offices, mechanical refrigeration can be used, also referred to as air conditioning. However, the amount of heat that needs to be removed from greenhouses is so much bigger, air conditioning with mechanical refrigeration is not an economically feasible option.

2. Greenhouse Evaporative Cooling

When ventilation and shading are not sufficient, greenhouse temperatures can be controlled by means of evaporative cooling, also referred to as swamp cooling. 

How does it work?
When water evaporates in the air, energy is needed. This energy comes from heat which is dissipated from the hot air. The more water can evaporate in the air, the more heat is dissipated and thus the more the greenhouse is cooled. The initial temperature and the initial relative humidity of the air determine how much water can be evaporated and thus what the cooling capacity is and how much the greenhouse temperature can drop.

Two types of greenhouse cooling systems are available of which the working principles are based on evaporative cooling:

  • Cooling pads: The fan and pad cooling system 
  • Adiabatic cooling with a fogging system or misting system

Advantages of evaporation cooling in greenhouses:

  • Application of Computational Fluid Dynamics modelling (CFD)
  • 70% less costs to operate
  • No use of CFC’s or HCFC’s
  • Especially effective in dryer climates

2.1 Cooling Pads: Fan and Pad Cooling System

When the recirculation of air in the greenhouse is not enough to create a perfect climate for the crop, air from the outside is required. When outside air is drawn in, the use of cooling pads is the most efficient way to cool the greenhouse. By using cooling pads, the ambient temperature can be significantly lowered.

Advantages of Enerdes Cooling Pads:

  • Long product lifetime
    Enerdes has found a solution to increase the firmness of cooling pads and thus to extend their lifetime.
  • Use of frames to increase stability
    Enerdes cooling pads are fitted with frames. That way the cooling pads easily stay in place and are less sensitive to external influences and construction.
  • Universally applicable
    Both the cooling pads and the frames are custom-made and are therefore available in different sizes. 
  • Low maintenance
    Our cooling pads require a minimum amount of maintenance
  • Environmentally friendly
    Enerdes cooling pads are not harmful to the environment and water can be reused

The quantity and size of the cooling pads that you will need, depend on:

  • The optimal growing temperature
  • Outdoor climate
  • The kind of crop 
  • Environmental conditions

How does an Enerdes cooling pad work?

  1. Above the cooling pads is a water supply to distribute water onto the pads. 
  2. On top of the cooling pad is a glued distribution pad which spreads the water evenly across the pad. 
  3. That way, the cooling pad is evenly moistened. Water drips down through the honeycomb structure of the cooling pads. 
  4. The hot outside air flows through the cooling pads and is cooled down by the wet surface
  5. Hereafter the cooled air enters the greenhouse. 
  6. Under the cooling pads is a drain which collects the water and makes it suitable for reuse. 

A “wet wall greenhouse” is created, but no water is wasted in Enerdes climate systems!

The cooling pads with frames are sold separately for existing greenhouses, but also with water distribution units.

Pad Cooling System Lifetime

There are several factors that affect the lifetime of cooling pads, including 

  • Water treatment (pH and EC value)
  • Wind influences
  • Cleaning cycle
  • Drying after use
  • Intensity of use

Cooling pads can warp by these influences or fall out of the wall. Enerdes cooling pads are constructed for long product life time and we can advise you on how to sufficiently cool your greenhouse, while maintaining your cooling pads in a good condition.

2.2 Adiabatic cooling: Greenhouse Fogging System

How does adiabatic cooling work?
The evaporation of a crop requires energy. This energy is withdrawn from the greenhouse air. The energy in the form of heat is converted into water vapor. The energy is still there, but does not feel as heat. The crop can be helped in the conversion of sensible heat to water vapor using fogging. This is also known as adiabatic cooling.

Enerdes fogging systems consist of high-pressurized lines hung at the top of the greenhouse. The stainless steel high-pressure line has a branch every 2 to 3 meters with a special high pressure nozzle which will atomize the water to a very fine mist. Our systems are custom made and thus tailored to your requirements. 

Two systems are available:

  • Greenhouse high pressure fogger or high pressure misting system
  • Greenhouse low pressure fogger or sprayer

Advantages of adiabatic cooling:

  • Extremely energy efficient
    The air in the greenhouse is cooled down by the evaporation of water. The lower the relative humidity, the higher the efficiency of the cooling process.
  • Cooling the greenhouse without CO2 loss
    As fogging allows for cooling the air, the air windows can be opened partially. This allows the CO2 level in your greenhouse to remain higher.

A fogging system may also be referred to as a misting system or a spraying system.

3. Active Cooling: Chilled Water Cooling in Greenhouses

Many greenhouses revert to ventilation and evaporative cooling to achieve the desired temperature. However, in warm and humid climates, it is not possible to cool down the greenhouse sufficiently with evaporative cooling. Other technology must be used, namely, active cooling. This cooling technology can be compared with air conditioning, but on a really big scale. It requires a chiller to provide the water and an air handling unit to cool and dehumidify the air.

Active cooling system in a greenhouse can be based on

  • Water cooling
    This will provide chilled water with a minimal temperature of 4°C
  • Glycol solution
    This solution can be cooled to temperatures far below 0°C! 

The choice and the design will be based on the cooling demand and the energy costs.

Advantages of active greenhouse cooling using chillers:

  • Precise temperature control
  • Precise humidity control, moisture removal from the air
  • Suitable for any outdoor climate
  • Separate temperature and humidity zones
  • Minimal to no introduction of external air

How does a chiller work?

A chilled water cooling installation consists of a chiller and a piping network. Chilled water is transported throughout the greenhouse in a loop to provide cooling. The process during which water is used as the heat-transfer medium is called hydronics, in this case to provide cooling. 

Using valves, the piping network can be divided into several groups, so the greenhouse can be segregated in several areas in which the temperature is controlled separately. Individual temperature zones are assigned in the greenhouse. The air handling units together with the chiller provide optimal greenhouse temperature and humidity conditions.

In the air handling unit, a fan draws warm and humid air past a heat exchanger with the chilled water, the cooling coils. The air is cooled and the moisture condenses. Cool and dry air is spread into the greenhouse. The temperature in the cooling coils is regulated with temperature sensors and valves and variable fan power influences the amount of air that is cooled. This allows precise climate control in the greenhouse.

Greenhouse coolings pads Enerdes 3
Greenhouse cooling pads Enerdes 2
wrong constructed Greenhouse coolings pads

Precise Greenhouse Cooling Control

A chilled water cooling installation for greenhouses offers very precise control over your greenhouse temperature and growing conditions. Enerdes can also provide well designed control technology that contains robust control PID, that will smoothly operate all components in the installation in order to achieve the perfect greenhouse climate. 

Components that are monitored and controlled are:

  • Chiller power and output temperature
  • Temperature and RH sensors in the greenhouse
  • Greenhouse piping and valves
  • Air handling units and their fans
  • Temperature sensors in the piping and air handling units

By meticulously controlling the valves and fans, the desired greenhouse temperature and humidity can be achieved to a very accurate level and the automated control allows energy and cost savings.

Customized Enerdes Greenhouse Cooling solutions

Enerdes optimizes every greenhouse cooling installation to the unique requirements and conditions of the customer’s greenhouse. Together we will look into how we can achieve a robust climate control solution that will provide your greenhouse with appropriate cooling with minimal operating costs. 

Enerdes can provide you with a complete climate control system, or selected parts of it, such as:

  • Chilled water cooling installation
  • Greenhouse chiller
  • Greenhouse cooling piping
  • Greenhouse cooling pumps
  • Greenhouse valves
  • Air handling units for cooling a greenhouse
  • Greenhouse fans for cooling
  • Climate control sensors
  • Control technology for greenhouse cooling
  • Air distribution hoses

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