IT Workshop for IEA-HPT ExCo Meeting
November 11th, 2021

Heat pumps in the context of the energy performance of buildings

Roberto Nidasio
Comitato Termotecnico Italiano (CTI)2

CTI – ITALIAN THERMOTECHNICAL COMMITTEE
Who we are:
• A standardization body (federated with UNI)
• Developing standards in the thermotechnical field• Both nationally (UNI) and internationally (CEN – ISO)
What we do:• Normative activity• Technical support to the regulatory bodies and public authorities• Research activity• Training activity• Communication and dissemination activity

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CTI – ITALIAN THERMOTECHNICAL COMMITTEE
Thematic areas:• Energy management and energy audits• Energy performance of buildings• Renewable energy souces and sustainability• Energy measurement• Heating systems• Cooling and ventilation systems• Process safety in industrial plants• Systems under pressure• Traditional energy sources

AREAS

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ENERGY PERFORMANCE OF BUILDINGS
Actual framework:
Regulations

Directive 2010/31/UE
Directive 2018/844/UE

D.Lgs 192/05 e s.m.i.
+ Ministerial Decree

EN standards developed
under Mandate M/480

UNI/TS 11300 series

Technical Standards

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HEAT PUMPS ENERGY PERFORMANCESIn the framework of energy performance of buildings, for the heat pumps:«system» standards
UNI EN 15316-4-2 Energy performance ofbuildings - Method for calculation of systemenergy requirements and system efficiencies Part 4-2: Space heating generation systems,
heat pump systems, Module M3-8-2, M8-8-2
UNI/TS 11300-4 Energy performance ofbuildings - Part 4: Renewable energy and othergeneration systems for space heating anddomestic hot water production
Note: both of these standards are currently
under review!

«product» standards

UNI EN 14825 Air conditioners, liquidchilling packages and heat pumps, withelectrically driven compressors, forspace heating and cooling - Testing andrating at part load conditions andcalculation of seasonal performance6HEAT PUMPS ENERGY PERFORMANCES IN DETAIL
The energy performance of heat pumps, in particular the COP, depends on three main factors:• the temperature of the cold source;• the temperature of the hot sink;• the load factor (Capacity Ratio, CR) of the machine.

The technical specification UNI / TS 11300-4 takes into account all three of these factors as follows:• by first, identifying the fully loaded COP, by interpolation or extrapolation between the fully loaded COP
data declared by the suppliers. These data are determined in correspondence with pairs of predefinedvalues of the temperatures of the cold source and the hot well according to the specific application;• then, applying a correction factor of the COP at full load, which is considered fixed and independent of thetemperatures of the cold source and of the hot sink.

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HEAT PUMPS ENERGY PERFORMANCES IN DETAILThe UNI / TS 11300-4 technical specification allows you to determine the COP correction factor at partial
loads in different ways:a)According to the data that suppliers publish in compliance with UNI EN 14825 on the basis of four work
points A, B, C and D defined as follows:(A) -7 °C,(B) 2 °C,(C) 7 °C,(D) 12 °C.

a)According to a simplified method, which consists of a fixed correlation;b) Using a correlation declared by the manufacturer (for absorption heat pumps).

8HEAT PUMPS ENERGY PERFORMANCES IN DETAIL
An important clarification (using the 14825 data in the 11300-4):
The technical specification UNI/TS 11300-4 specifies the data required for the calculation of the COP
correction factor as a function of the partial load, if provided by the manufacturers data according to UNI EN
14825 used for the calculation of seasonal performance (SCOP, Seasonal COP). Among the requests, it isspecified that the temperature of the hot sink must be constant, in particular equal to 35 ° C or 45 ° C.

The UNI EN 14825 standard, on the other hand, allows to determine the COP at partial loads both withconstant delivery temperature (“fixed outlet” option), and with variable delivery temperature. The secondcase (variable temperature) is allowed when the machine regulation system is able to manage a variable
delivery temperature according to the external temperature (point 6.4.1).

9HEAT PUMPS ENERGY PERFORMANCES IN DETAIL
Capacity Ration (CR) and Intermittent Ration (IR):It is important to distinguish between fixed power on / off heat pumps and stepped or inverter modulatingheat pumps. UNI EN 14825 allows to use the performance of the machine in correspondence with the steps
closest to the required load conditions. So, for example, in the case of heat pumps with inverters that are
working below the minimum continuous operation power (lower end of the modulation range), thereference point on which to calculate the load factor in intermittent operation on / off and consequently theCOP correction factor is that of the minimum power in modulation.
In these cases, therefore, to better represent the on / off cycling condition between the machine off and themachine in conditions of minimum modulation, it is useful to refer to a value that can be defined as IR(Intermittency Ratio), in addition to the CR (Capacity Ratio) value.

10HEAT PUMPS ENERGY PERFORMANCES IN DETAIL
In conclusion:• for on / off heat pumps, the IR value always coincides with the CR value, therefore when calculating thecorrective factor it is always necessary to refer to the maximum power of the heat pump for eachtemperature condition;• for inverter heat pumps in conditions for which the machine load factor CR is above the minimum
modulation range of the machine, the IR value is equal to 1 and the COP is the one defined by the supplieraccording to the data collected or calculated with the simplified method by applying the corrective factor
equal to 1;• for inverter heat pumps in conditions for which the machine load factor CR is below the minimum
modulation range of the machine, the IR value is always less than 1 and is calculated with respect to theminimum modulation step.

11HOW TO PARTICIPATE

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