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Identification of Heat Recovery on Chiller Condenser and Reversible Air Conditioning Opportunities in Office Buildings

This presentation discusses a method for identifying the potential for heat recovery and chiller reversibility in office buildings, along with the assessment of feasible technologies and their energy, environmental, and economical performance.

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Identification of Heat Recovery on Chiller Condenser and Reversible Air Conditioning Opportunities in Office Buildings

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  1. Identification of heat recovery on chiller condenser and reversible air conditioning opportunities in office buildings Philippe ANDRE, Stéphane BERTAGNOLIO – ULg Laurent SARRADE – CEA INES Pascal STABAT – Ecole des Mines de Paris Workshop « Commissioning and auditing of buildings and HVAC systems » Brussels, January 28th, 2008

  2. Presentation overview • Introduction • Specifications of the identification method • Methodology • Development of the method • Validation Comité de suivi IEA 48 Namur - 10/01/2008

  3. Introduction Comité de suivi IEA 48 Namur - 10/01/2008

  4. Background: • “Heat pumping”: one of quickest and safest solutions to save energy and reduce CO2 emission • Attractive opportunities exist in air-conditioned buildings: • Chiller condenser heat recovery (« recovery ») • Chiller used in heat pump mode (« reversibility ») Comité de suivi IEA 48 Namur - 10/01/2008

  5. General objective • To quantify the heat recovery and/or the chiller reversibility potential in a given (office) building • To identify the feasible technologies in that building • To assess the energy, environmental (and economical) performance of a selected technology in a given building Comité de suivi IEA 48 Namur - 10/01/2008

  6. Survey of technologies • Heat recovery • Heat recovery on condensing loop • With heat exchanger • Parallel auxiliary • Series auxiliary • Without heat exchanger • Heat pumping between condensing loop and heating system (templifier) • Water-loop heat pump systems • Floating condensing • Combination Comité de suivi IEA 48 Namur - 10/01/2008

  7. Heat exchanger on condensor loop – Series auxiliary Disadvantages: - reduction of supply temperature in heating system - possible losses from auxiliary To ambient (through dry cooler) Comité de suivi IEA 48 Namur - 10/01/2008

  8. Heat exchanger on condensor loop: parallel auxiliary Disadvantages: - reduction of supply temperature in heating system Comité de suivi IEA 48 Namur - 10/01/2008

  9. Direct connection of condensor loop – Parallel auxiliary Disadvantages: condensing temperature might be too high Comité de suivi IEA 48 Namur - 10/01/2008

  10. Floating condensing temperature Comité de suivi IEA 48 Namur - 10/01/2008

  11. Heat recovery + floating condensing Comité de suivi IEA 48 Namur - 10/01/2008

  12. Specifications of the identification tool Comité de suivi IEA 48 Namur - 10/01/2008

  13. Purposes of heating/cooling demands identification • Identify chiller reversibility potential • When demands are NOT simultaneous • When temperature levels are adequate (condensing temperature ./. Heating setpoint) • Identify condensor heat recovery potential • When demands are (partly) simultaneous • When temperature levels are adequate(condensing temperature ./. Heating setpoint) Comité de suivi IEA 48 Namur - 10/01/2008

  14. Reversibility potential • Methodology Comité de suivi IEA 48 Namur - 10/01/2008

  15. Recovery potential • Methodology Comité de suivi IEA 48 Namur - 10/01/2008

  16. How to assess this potential?Development of an identification method Comité de suivi IEA 48 Namur - 10/01/2008

  17. Possible sources of information • Measurements • Most often available: • Monthly bills of gas consumption • Monthly bills of TOTAL electricity consumption • Identification of heating and cooling demands from that information may be difficult -> use of a global index • Simulation results -> detailed assessment Comité de suivi IEA 48 Namur - 10/01/2008

  18. Principle of the method • Starts with rough (annual) information, then progressively refines the potential identification when more data are available or can be generated Heat pumping Global Assessment Detailed Monthly Daily Hourly Yearly Comité de suivi IEA 48 Namur - 10/01/2008

  19. Detailed assessment • Definition of typical buildings corresponding to the buildings stock (in France) • Detailed hourly simulations to calculate heating and cooling demands • Calculation of reversibility potentials Comité de suivi IEA 48 Namur - 10/01/2008

  20. Typology of Buildings • Office buildings Type 1 a 14% Type 1 67% 15 000 m² Type 1 b 20% Type 1 c 33% Type 2 8% 5 000 m² Type 3 25% 1 000 m² Comité de suivi IEA 48 Namur - 10/01/2008

  21. 138,5 m bedrooms 4 m Circulations 9,3 m courtyard Operations room courtyard 6,6 m 46,8 m Laboratories 20,8 m 9,3 m 3,2 m bedrooms 4 m 4 m 5,4 m 5,2 m 5 m 25,7 m 46,1 m 5 m 25,7 m 10,2 m 10,2 m Typology of Buildings • Health care buildings Type 1: Large hospital 40% ~30 000 m² Type 2 : Rest home 60% ~4 000 m² Comité de suivi IEA 48 Namur - 10/01/2008

  22. Climatic zones Comité de suivi IEA 48 Namur - 10/01/2008

  23. Example of results: Heating & Cooling demands in different climatic zonesOffices – Type 1A – Low solar factor – Low ventilation rate – 5 climatesConsoclim simulations Comité de suivi IEA 48 Namur - 10/01/2008

  24. Global assessment: definition of a « performance index » • Fundamental index:« ratio of heating and cooling demands » • Can be evaluated on different time bases • Standardisation: Min (|heating|, |cooling|) I = e [0,1] Max (|heating|, |cooling|) Comité de suivi IEA 48 Namur - 10/01/2008

  25. Annual evaluation • Estimation in terms of peak power(installed, sized, measured) 0 ……………………. 1 • Estimation in terms of yearly integrated demands No potential Iy Good potential Objective :to fixe the upper bound of the performance Comité de suivi IEA 48 Namur - 10/01/2008

  26. Two options • Assessment of reversibility: • Assessment of heat recovery Comité de suivi IEA 48 Namur - 10/01/2008

  27. Heat recovery: Monthly evaluation Estimation in terms of heating/cooling demand: 0 ……………………………………… 1 Recovery Reversibility Comité de suivi IEA 48 Namur - 10/01/2008 Objective :to identify the most interesting months

  28. Chiller reversibility assessment Comité de suivi IEA 48 Namur - 10/01/2008

  29. Reversibility: seasonal evaluation • Required for further reversibility assessment • Estimation in terms of heating/cooling demand • Computes if level of demands is worth reversibility • 00.51 Ideal for reversibility Comité de suivi IEA 48 Namur - 10/01/2008 Objective :to determine if the seasonal balance of demands is adequate

  30. Modified seasonal evaluation • Objective: to remove « parasitic » (non seasonal) heating and cooling demands in order to better approach the reversibility « target » Comité de suivi IEA 48 Namur - 10/01/2008

  31. Modified seasonal demands Comité de suivi IEA 48 Namur - 10/01/2008

  32. Comparison of global abd detailed assessments New indexes: Comité de suivi IEA 48 Namur - 10/01/2008

  33. Correlation reversibility potential – combined index Comité de suivi IEA 48 Namur - 10/01/2008

  34. Heat Recovery potential assessment Comité de suivi IEA 48 Namur - 10/01/2008

  35. From performance index to energy savings (recovery) Limited to heat demand! Comité de suivi IEA 48 Namur - 10/01/2008

  36. Heat recovery vs heat demand Comité de suivi IEA 48 Namur - 10/01/2008

  37. Heat recovery index vs potential heat recovery fraction Comité de suivi IEA 48 Namur - 10/01/2008

  38. Next step • Integration of technological constraints • Feasible technologies • Temperature levels Comité de suivi IEA 48 Namur - 10/01/2008

  39. Conclusions • Heat recovery and chiller reversibility are two options to be considered to reduce energy consumption and environmental impact of air-conditioned buildings • Global assessment not straightforward • Hourly simulation, even on a simplified basis, helps a lot Comité de suivi IEA 48 Namur - 10/01/2008

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