"Soil energy system certificate prevents people from tinkering around"

The BRL6000-21 certificate gives Bosman Van Zaal the authority to design and install the above-ground part of a soil energy system. The certification, required by the Dutch government, must guarantee the quality of soil energy systems.

"It prevents people from tinkering around," says Engineer Gerben van der Knaap, who works in the Climate Installations department at Bosman Van Zaal. "The soil and groundwater must be handled carefully to prevent undesirable effects" 

What are soil energy systems?
Soil energy is the storage of heat and cold in the soil to a depth of approximately 200 metres. These can be open or closed systems. In open systems, groundwater is pumped from one source, which is passed through an above-ground heat exchanger for heat/cold transfer, and then injected back into the other underground source.

The direction of flow usually changes twice a year, i.e. from a cold source to a hot source and vice versa. Gerben's experience is that "open systems can deliver large capacities, which can be interesting for certain horticultural companies". With closed systems, there is no displacement of groundwater, but heat/cold transfer via hose loops installed in the soil. The so-called soil changers. The power to be supplied is limited, which is why it is often used in homes and smaller utility buildings.

Heat/cold soil energy system

What makes a soil energy system sustainable?
A soil energy system is sustainable because it can store the solar heat that you harvest in the summer in the soil and the same heat can be used in the winter to heat the greenhouse with the heat pump. "The cold that is released in the process is put back into the soil, which is useful in the summer to cool the greenhouse or to harvest heat. This way of long-term storage ensures that as little (residual) energy as possible is thrown away and a considerable reduction in primary energy consumption compared to traditional heating and cooling. In addition, soil energy systems are almost always combined with a heat pump system. This makes it possible to 'get rid of the gas', because everything is electric after all".

Which soil energy systems have been realised?
Bosman Van Zaal has its own soil energy system for heating and cooling its premises. The building is heated in the winter by heat pumps. The (residual) cold produced by the heat pumps at that time is stored in the soil, which is used in the summer to cool the offices.

Bosman Van Zaal has also installed soil energy systems at various customers, such as for Van der Hoorn Orchids in Ter Aar and at GreenBalanz in Kudelstaart. This enables these growers to grow in a greenhouse without gas.