Active Ventilation System
Active Ventilation System |
Conditioned cultivation |
Conditioned cultivation
Conditioned cultivation is playing an increasingly important role in greenhouse horticulture because of the extra emphasis that is being put on sustainability and energy savings. Actively ventilating the greenhouse by drawing air from outside is a new, economically cost-effective application for this purpose. This process dehumidifies the greenhouse air because the outside air contains less moisture. This means that dehumidifying the greenhouse air by using a minimum pipe is no longer necessary.
In developing the Active Ventilation System (AVS) Van Dijk heating has created a system that makes it possible to dehumidify the greenhouse air with low costs. The system is based on actively ventilating the greenhouse air which is achieved by using high efficiency fans to draw in and distribute the outside air over the greenhouse. The system maintains circulation by having a small, forced air flow, which improves the greenhouse climate and saves energy.
Active ventilation, dehumidifying, cooling and heater with minimum energy consumption.
The temperature, humidity, and CO2 concentration in a greenhouse can be controlled with the Active Ventilation System which uses a minimum amount of energy and has very low investment costs. The outside air can be heated as required by:
a. mixing warm greenhouse air by having a mixing valve in the air flow, and/or
b. having a heat exchanger with a low value central heating system.
The system can also be used for cooling by combining the active ventilation with a water misting system. Because of the cooling system’s high COP value it is possible to achieve substantial cooling capacity using the lowest energy usage possible. Because of the low ventilation rate accompanied by this manner of cooling, the CO2 loss is minimised and the average CO2 concentration in the greenhouse with normal CO2 dosing increases.
Advantages of the Active Ventilation System in horticultural greenhouses
Energy savings due to:
- dehumidifying greenhouse air without adding heat (minimum pipe)
- keeping the screen closed for a longer time
- high COP value when used as a cooling system
- better utilisation of temperature integration
Climate improvement due to:
- the effects of actively ventilating the greenhouse air
- minimum temperature differences when recirculating
- a vertical flow of fresh air through the crop
- improvement to the microclimate around the plants
Improved returns due to:
- effective use of low value temperature systems
- better CO2 distribution
- higher CO2 concentration in the greenhouse
- reducing the disease pressure
Subsidies:
The AVS system in combination with a second energy screen has been included in the Dutch MEI subsidy 2010
The AVS has been included in the Dutch EIA (Energy Investment Deduction) 2010 energy list as number 220305
