Workshop « Commissioning and auditing of buildings and HVAC systems » Brussels, January 28th, 2008 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

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

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

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

Comité de suivi IEA 48 Namur - 10/01/2008 General objective To quantify the heat recovery and/or the chiller reversibility potential in a given (office) building 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 identify the feasible technologies in that building To assess the energy, environmental (and economical) performance of a selected technology in a given 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 Survey of technologies Reversibility of the chiller Reversibility of the chiller Heat pump: connection of the building demand on the condensor sideHeat pump: connection of the building demand on the condensor side Heat pump: connection of the evaporator to some cold source:Heat pump: connection of the evaporator to some cold source: Ambient Ambient Air extracted from the building Air extracted from the building Ground Ground

Comité de suivi IEA 48 Namur - 10/01/2008 Survey of technologies Heat recovery Heat recovery Heat recovery on condensing loopHeat recovery on condensing loop With heat exchanger With heat exchanger Parallel auxiliaryParallel auxiliary Series auxiliarySeries auxiliary Without heat exchanger Without heat exchanger Heat pumping between condensing loop and heating system (templifier)Heat pumping between condensing loop and heating system (templifier) Water-loop heat pump systemsWater-loop heat pump systems Floating condensingFloating condensing CombinationCombination

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

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

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

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

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

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

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

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

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

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

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

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

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

Comité de suivi IEA 48 Namur - 10/01/2008 Typology of Buildings Health care buildings Health care buildings Type 1: Large hospital 40% ~ m² Type 2 : Rest home 60% ~4 000 m² bedrooms courtyard Operations room Circulations courtyard Laboratories bedrooms 46,1 m5 m25,7 m10,2 m 25,7 m5 m5,2 m5,4 m 4 m 3,2 m 46,8 m 138,5 m 4 m 9,3 m 20,8 m 6,6 m 9,3 m 4 m

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

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

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

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

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

Comité de suivi IEA 48 Namur - 10/01/2008 Heat recovery: Monthly evaluation MonthI m (i) January 0.19 February 0.28 March 0.65 April 0.74 May 0.23 June 0.11 July 0.06 August 0.04 September 0.07 October 0.29 November 0.59 December ……………………………………… 1 Reversibility Recovery Estimation in terms of heating/cooling demand: Objective : to identify the most interesting months

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

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

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

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

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

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

Comité de suivi IEA 48 Namur - 10/01/2008 From performance index to energy savings (recovery) Limited to heat demand! MonthI m (i)Heating demand kJ Cooling demand kJ P heat effective Potential heat recovery fraction January E E E February E E E March E E E April E E E May E E E June E E E July E E E August E E E September E E E October E E E November E E E December E E E

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

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

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

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