A performance case study

of energy pile foundation

at Rosborg Gymnasium (Denmark)

12th REHVA World Congress Clima 2016, Aalborg, May 2016

Maria Alberdi -Pagola, Aalborg University (mapa@civi l .aau.dk)

Rasmus Lund Jensen, Aalborg Univers i ty

Søren Erbs Poulsen, VIA Univers i ty Col lege

The ground below the building is used as a heating/cooling source.

Solar energy

99%

Geothermal flux

1%

Energy piles Description of the site Results & Discussion Conclusions

South extension

4000 m2 area

200 kW heat pump

200 energy piles, heating demand

Fully monitored

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Energy piles Description of the site Results & Discussion Conclusions

House loop

Indoor temp.

Installation scheme & sensor network

Ground loop

Energy piles Description of the site Results & Discussion Conclusions

0 m

Heating & free cooling supply, 345-day period

Heat extraction = 70 MWhTotal heating = 100 MWhMax extraction rate = 50 W/m (1.2h) Average extraction rate = 13 W/m (3400h)

Heat injection = 8.5 MWhMax. injection rate = 50 W/m (0.15h) Average injection rate = 1 W/m (800h)

Energy piles Description of the site Results & Discussion Conclusions

Performance factors: improvement after summer due to adjustments in circulation pumps

Energy piles Description of the site Results & Discussion Conclusions

Hourly performance

Energy piles Description of the site Results & Discussion Conclusions

Ground loop temperatures: return brine temperature does not go below 5.5oC

Energy piles Description of the site Results & Discussion Conclusions

Thanks

?Maria Alberdi-Pagola (mapa@civil.aau.dk)

Energy piles Description of the site Results & Discussion Conclusions

The heat extraction from the ground can be further increased

The installation is over-sized in terms of thermal performance and capacity

Storage tank too small + heat pump too big Reason for heat pump running cycles

Building and soil interaction aim to more optimised systems

New strategies

- Supply the ventilation by GSHP

- Use more free cooling to balance ground use

- Better adjust circulation pumps