ECN publication
Monitoring KODI : energieheipalen als fundament onder een energiezuinig gebouw
Published by: Publication date:
ECN Energy in the Built Environment 1-7-2002
ECN report number: Document type:
ECN-C--02-035 ECN publication
Number of pages: Full text:
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The Kodi building in Heerhugowaard has been equipped with an energy-efftcientheating and cooling system, in which heat and cold are extracted from the soil underneath the building using 'energy-piles' (foundation piles with integrated heat exchangers). Relevant data, such as heat flows, electrical power of heat pumps and circulation pumps and temperatures have been collected from April 2000 to April 2001, and were analysed to assess the performance of the heating and cooling system. The main conclusions are:

  • The subsoil system has been functioning very well, in spite of the fact that the amount of heat extracted in wintertime appeared to be a factor of 10 higher than that injected in smnmertime. The imbalance could in theory result in 'thermal exhaustion' of the soil, but no such phenomenon has been observed in the measuring period. The average power of heat extracted in wintertime appeared to be 10 W/m (per m length of pile).
  • There has not been any danger of fieezing of the soil around the piles, since the fluid entering the piles had at al1 times been warmer than °C. The soil around the piles was a few degrees C warmer.
  • The performance of the heat pump appeared to be somewhat lower than expected, having a Carnot-efficiency of 35-40%. Year averaged values of COP (Coeffient Of Performance) and SPF (Seasonal Performance Factor) were 3.8 and 2.6 respectively.
  • The PER (Primary Energy Ratio) of the heating and cooling system as a whole has reached values of more than 100% during most of the measuring period. Improvements are possible by reducing the amount of auxiliary power.
  • When using open distributors to couple two hydraulic circuits, the flow rates in both circuits should be identical to avoid mixing of fluids of different temperatures, leading to exergy losses. Mixing also results in a higher than necessary temperature lift for the heat pump, resulting in lower values of the COP.
  • The second heat pump has been in operation for only 240 hours (85 equivalent full load hours) in the measuring period. From the point of investments, a simple gas-fired boiler would have been a better choice for peak heat demands.

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