Contract: EIE/07/069/SI Duration: October 2007 – March 2010Version: July 7, 2009 Calculation of the integrated energy performance of buildings EN 15316: Heating systems in buildings Method for calculation of system energy requirements and system efficiencies Part 2-3: Space heating distribution systems Laurent SOCAL Ediclima s.r.l. / Italy

slide 2 The EU CENSE project (Oct March 2010) Aim of the project: To accelerate adoption and improve effectiveness of the EPBD related CEN- standards in the EU Member States These standards were successively published in the years and are being implemented or planned to be implemented in many EU Member States. However, the full implementation is not a trivial task Main project activities: A.To widely communicate role, status and content of these standards; to provide guidance on the implementation B.To collect comments and good practice examples from Member States aiming to remove obstacles C.To prepare recommendations to CEN for a “second generation” of standards on the integrated energy performance of buildings

slide 3 Brief introduction A brief introduction to the CENSE project and the CEN-EPBD standards is provided in a separate presentation:

slide 4 More information More information and downloads: Disclaimer: CENSE has received funding from the Community’s Intelligent Energy Europe programme under the contract EIE/07/069/SI The content of this presentation reflects the authors view. The author(s) and the European Commission are not liable for any use that may be made of the information contained therein. Moreover, because this is an interim result of the project: any conclusions are only preliminary and may change in the course of the project based on further feedback from the contributors, additional collected information and/or increased insight.

slide 5 Fitting into the puzzle slide 5 EN EN HEATINGCOOLING VENTILATION EN EN EN EN15243 EN EN XXEN15243 LIGHTING EN EN15193 EN SERVICES BUILDING NEEDS TECHNICAL SYSTEMS DISTRIBUTION GENERATION OVERALL PERFORMANCE DHW EN EN EN

02/07/2016 Ing. SOCAL - Rendimenti impianti 6 Distribution system energy balance W H,dis,aux Auxiliary energy Losses Q H,dis,ls Q H,dis,in Q H,dis,out Useful effect COSTS Not useful effect

Available methods Heat losses –Detailed calculation § 7.2 and § 7.3 –Simplified calculation§ A3  s implified input to detailed method –Tabulated values § A4  nationally precalculated values, according to detailed method Auxiliary energy –Detailed calculation § 6.2 and § 6.3 –Simplified calculation § A1  simplified input to detailed method –Tabulated values § A2  nationally precalculated values, according to detailed method Water temperature calculation § 8 –To be connected to the calculation shown in the generation part slide 7

Energy recovery Auxiliary energy recovery § 6.6 –Recovery to heating medium –Recovery to heated space Heat recovery § –Holistic method: recoverable losses are calculated to be summed to recoverable losses from other subsystems –Simplified method: heat recovery is directly accounted for as a reduction of losses within the distribution subsystem slide 8

Heat recovery: holistic (explicit) slide 9

Heat recovery: simplified (implicit) slide 10 This is the most common option for tabulated values. Information on assumptions about heat recovery should be included when supplying tabulated values This is the most common option for tabulated values. Information on assumptions about heat recovery should be included when supplying tabulated values

Detailed calculation of losses, §7.2 The principle is to sum up all losses from pipe elements For each element the following data is needed: –L j pipe length in m; –Ψ j linear thermal transmittance (loss factor) in W/m·K –θ w,j temperature of water inside the pipe in °C; –θ e,j surroundings temperature in °C. Ψ j is calculated using basic physics formulae t op is the operation time slide 11

Linear transmittance § 7.3 slide 12  d int : insulation inner diameter in m (= pipe outer diameter)  d ext : insulation outer diameter in m (or d int + thickness of insulating layer);  λ D thermal conductivity of insulating layer in W/m·K;  α air external heat transfer coefficient in W/m²·K.

Simplified method for heat losses Simplified method (§ A.3) = Detailed method with simplified input PIPE LENGTH: L V = horizontal distribution L S = vertical distribution (shafts) L A = terminal connection pipes Length for each part is estimated according to the floor area and the external dimensions of the building with correlation formulae PIPE LINEAR TRANSMITTANCE Linear thermal transmittances are given in tables according to building age and type. slide 13

Simplified method for heat losses slide 14 Values Unit LV Distribution to the shafts LS Vertical shafts LA connection pipes Mean surrounding temperature °C13 respectively 2020 Pipe length in case of shafts in outside walls LiLi m2. L L + 0, L L. L W 2 0,025. L L. L W. h lev. N lev 0,55. L L. L W. N lev Pipe length in case of shafts inside the building LiLi m2. L L + 0,0325. L L. L W + 60,025. L L. L W. h lev. N lev 0,55. L L. L W. N lev L L = Length of the buildingh lev = floor heighth L W = Width of the building N lev = number of floors Default correlation table for pipe length

Tabulated method for heat losses slide 15 Example: Italian table of efficiencies There are other tables according to distribution type Values include recovered heat losses Values were calculated according to detailed method Example: Italian table of efficiencies There are other tables according to distribution type Values include recovered heat losses Values were calculated according to detailed method

Distribution auxiliary energy: detailed § 6.3 Starting point: required hydraulic energy P hydr,des P hydr,des [W]= 0,2778 ⋅ Δp des [kPa] ⋅ V’ des [m³/h] … then this is corrected by a series of multiplying correction factors  β takes into account part-load operation of the heating system  f S, takes into account supply flow temperature control (takes into account the presence or absence of outdoor temperature compensation)  f NET takes into account hydraulic networks (differentiates between ring line, star type or vertical column network) f SD takes into account any oversizing of the heat emitters;  f HB takes into account any hydraulic unbalance;  f GPM takes into account integrated management of the circulation pump within the heat generator;  f η takes into account pump mechanical efficiency;  f PL takes into account pump performance at part load;  f PSP takes into account correct selection of the pump compared to design requirement;  f C takes into account the type of pump control. slide 16

Distribution auxiliary energy: simplified Simplified method § A.1 –The number of correcting factors is reduced Tabulated method § A.2 Tables of precalculated values are given according to floor area or other relevant properties. slide 17 Example: tabulated values In the following table, distribution auxiliary energy (kWh/year) is given as a function of:  Floor area A H,z  Type of pump control Example: tabulated values In the following table, distribution auxiliary energy (kWh/year) is given as a function of:  Floor area A H,z  Type of pump control

02/07/2016 Ing. SOCAL - Rendimenti impianti 18 NOMINAL POWER 180 W DESIGN CONDITION 125 W AVERAGE OPERATION 50 W Auxiliary energy example

Calculation of network temperatures Calculation procedure (chapter 8) Emitter average temperature is calculated According to heat output and emitter size Distribution circuits analysis: Flow and return temperature are calculated taking into account control strategy The effect of mixing valves or any other control device is taken into account here Distribution collectors: Return temperature shall be averaged Generation circuits: The effect of the hydraulic connection of generators (direct/independent flow rate,…) is taken into account here (see and other) slide 19

Direct connection Direct connection of heat emitters to the boiler room collectors. Typical for thermostatic valves. Distribution network temperature is the same as emitters temperature Flow rate in the distribution network is the same as in the emitters. slide 20 Nominal 1 80/60 Nominal 1 80/60

Mixing valve connection Emitter connection through a mixing valve. Typical for central control or for lower temperature emitters. Distribution network temperature is the same as emitters temperature Flow rate before the mixing valve is less than in the emitters.. slide 21 Nominal 1 80/60 Nominal 1 80/60

By-pass connection Emitter connection with a by-pass Typical for the connection of HVAC hot heat exchanger or single pipe circuits. Distribution network losses increase when the emitter power is reduced. Flow rate in the network is greater than required by the emitters causing higher auxiliary energy needs. slide 22 Nominal 1 80/60 Nominal 1 80/60

Practical issues Distribution network calculation requires much care: Tabulated values –The correct tables shall be used –If all boundary conditions, also hidden ones, are not fulfilled then the detailed calculation should be used (see following example, tables would give ) Simplified method –Correlations are suitable only for simple building shapes and well defined network topology Detailed calculation method –Temperature shall be calculated consistently with operation time –Temperature hall be calculated according to hydraulic circuit type –Relative position of pipes and building insulation shall be taken into account slide 23

02/07/2016 Ing. SOCAL - UNI-TS Losses of a vertical shafts distribution network Vertical shafts are within external walls Distribution is operated at variable temperature: 27…49 °C Heat to distribution 2600 … kWh/month Distribution losses 1000…6000 kWh/month Net losses 240…1710 kWh/month Yearly efficiency 92%

02/07/2016 Ing. SOCAL - UNI-TS DISTRICT HEATING 40 FLATS NETWORK LOSSES 100 MWh/year i.e. 250 m³ natural gas for each flat Distribution efficiency 90…35% NETWORK LOSSES 100 MWh/year i.e. 250 m³ natural gas for each flat Distribution efficiency 90…35% Though well insulated, continuous 24/24 operation at high temperature causes very high yearly losses

slide 26 More information More information and downloads: Disclaimer: CENSE has received funding from the Community’s Intelligent Energy Europe programme under the contract EIE/07/069/SI The content of this presentation reflects the authors view. The author(s) and the European Commission are not liable for any use that may be made of the information contained therein. Moreover, because this is an interim result of the project: any conclusions are only preliminary and may change in the course of the project based on further feedback from the contributors, additional collected information and/or increased insight.