«How the combination of Geothermal System and Photovoltaic reduce energy consumption of a building to nearly zero»

The combination of Geothermal System and Photovoltaic they can turn a building into an NZEB i.e. a building with almost zero energy consumption. It is worth noting that both systems are part of the RES (Renewable Energy Sources) family.

But in a building these are used for a different purpose:

The Photovoltaic installation has the role of the electricity producer (Producer)

The Geothermal System has the role of the Heating/Cooling system (Consumer)

 At this point you raise the reasonable question “Since the Geothermal system consumes energy why does it belong to the RES family?”

The following tables give the answer to this question

Geothermal systems can be applied in any climate for heating or cooling systems, whereas other options have restrictions as to the optimal climatic conditions (Tables 1 & 2). What is more, Geothermal Systems can perform much more efficiently than all other systems and the equipment has a longer lifespan.

Table 1 of Performance for Cooling Systems
System	Climate	Performance	Lifespan
Geothermal	everywhere	350-500%	>24 years
Air Source Heat Pump	Normal	300%	10-15 years
A/C with split unit	Normal	300%	10-15 years

Table 2 of Performance for Heating Systems
System	Climate	Performance	Lifespan
Geothermal	everywhere	350-500%	>24 years
Air Source Heat Pump	Normal	300%	10-15 years
Oil Boiler	everywhere	85%	11-27 years
Gas Boiler	everywhere	100%	10-15 years

According to the above data, the Geothermal system:

1. With just 1Kw it returns 3.5-5Kw for Heating or Cooling. It is clarified that the range 3.5-5 is given due to the variation in undisturbed soil temperature which is a characteristic of each region (e.g. Greece 16-21^oC while Sweden 8-13^oC)

• It doesn’t change its performance as it is not affected by external conditions as is the case with Air Source Heat Pump or A/C . Therefore, Geothermal system performs the same in all climatic conditions (eg very high temperatures or very low).

• It reduces the required installed power and therefore the size-area of ​​the Photovoltaic system (solar).

Therefore the Geothermal system belongs to the family of RES (Renewable Energy Sources) because it takes advantage of the energy stored inside the Earth which is independent and naturally clean!