An innovative use of renewable ground heat for insulation in low exergy building systems

Forrest Meggers, Luca Baldini, Hansjürg Leibundgut

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


Ground heat is a renewable resource that is readily available for buildings in cool climates, but its relatively low temperature requires the use of a heat pump to extract it for heating. We developed a system that uses low temperature ground heat directly in a building wall to reduce transmission heat losses. The Active Low Exergy Geothermal Insulation Systems (ALEGIS) minimizes exergy demand and maximizes the use of renewable geothermal heat from the ground. A fluid is pumped into a small pipe network in an external layer of a wall construction that is linked to a ground heat source. This decouples the building from the outside temperature, therefore eliminating large peak demands and reducing the primary energy demand. Our steady-state analysis shows that at a design temperature of -10 °C the 6 cm thick active insulation system has equivalent performance to 11 cm of passive insulation. Our comparison of heating performance of a building with our active insulation system versus a building with static insulation of the same thickness shows a 15% reduction in annual electricity demand, and thus exergy input. We present an overview of the operation and analysis of our low exergy concept and its modeled performance.

Original languageEnglish (US)
Pages (from-to)3149-3166
Number of pages18
Issue number8
StatePublished - Aug 2012
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Control and Optimization
  • Energy (miscellaneous)
  • Engineering (miscellaneous)
  • Energy Engineering and Power Technology
  • Electrical and Electronic Engineering
  • Building and Construction
  • Fuel Technology
  • Renewable Energy, Sustainability and the Environment


  • Buildings
  • Exergy
  • Geothermal
  • Ground heat
  • Heat pumps
  • Insulation


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