Doc. CEN/TC 228 N553 CEN/TC 228

Transcription

1 oc. CEN/TC 228 N553 CEN/TC 228 ate: CEN/TC 228 WI 030 CEN/TC 228 Secretariat: S Heating systems in buildings - Method or calculation o system energy requirements and system eiciencies - art 2-3: Space heating distribution systems Einührendes Element Haupt-Element Teil 2-3: Ergänzendes Element Systèmes de chauage dans les bâtiments Élément central artie 2-3 : Élément complémentaire ICS: escriptors: ocument type: European Standard ocument subtype: ocument stage: Formal Vote ocument language: E

2 Contents age Foreword...3 Introduction Scope Normative reerences Symbols units and indices rinciple o the method and deinitions Electrical energy demand Auxiliary energy demand General esign Hydraulic power etailed Calculation Method Input- / Output data Calculation Method Correction actors Expenditure energy actor Intermittent operation eviations rom the detailed calculation method Monthly energy demand Recoverable auxiliary energy Heat emission o distribution systems General etailed Calculation Method Input- / Output data Calculation method Heat emission o accessories Recoverable and non-recoverable heat emission Total heat emission Calculation o linear thermal transmittance (W/mK): Calculation o mean part load o distribution per zone Calculation o supply and return temperature depending on mean part load o distribution Annex A (inormative) reerred procedures A.1 Simpliied Calculation Method o annual electrical auxiliary energy demand A.1.1 Input- / Output data A.1.2 Calculation method A.1.3 Correction actors A.1.4 Expenditure energy actor A.1.5 Intermittent operation A.2 Tabulated calculation method o annual electrical auxiliary energy demand A.2.1 Tabulated calculation o annual electrical auxiliary energy demand A.3 Simpliied Calculation Method o heat emission A.3.1 Input- / Output data A.3.2 Approximation o the length o pipes per zone in distribution systems A.3.3 Approximation o U-Values A.3.4 Equivalent length o valves A.4 Tabulated Calculation Method o annual heat emission A.5 Tabulated calculation o annual heat emission A.6 Example

3 Foreword This document (pren :2005) has been prepared by Technical Committee CEN/TC 228 Heating systems in buildings the secretariat o which is held by S. The subjects covered by CEN/TC 228 are the ollowing: - design o heating systems (water based electrical etc.); - installation o heating systems; - commissioning o heating systems; - instructions or operation maintenance and use o heating systems; - methods or calculation o the design heat loss and heat loads; - methods or calculation o the energy perormance o heating systems. Heating systems also include the eect o attached systems such as hot water production systems. All these standards are systems standards i.e. they are based on requirements addressed to the system as a whole and not dealing with requirements to the products within the system. Where possible reerence is made to other European or International Standards a.o. product standards. However use o products complying with relevant product standards is no guarantee o compliance with the system requirements. The requirements are mainly expressed as unctional requirements i.e. requirements dealing with the unction o the system and not speciying shape material dimensions or the like. The guidelines describe ways to meet the requirements but other ways to ulil the unctional requirements might be used i ulilment can be proved. Heating systems dier among the member countries due to climate traditions and national regulations. In some cases requirements are given as classes so national or individual needs may be accommodated. In cases where the standards contradict with national regulations the latter should be ollowed. 3

4 Introduction In a distribution system energy is transported by a luid rom the heat generation to the heat emission. As the distribution system is not adiabatic part o the energy carried is emitted to the surrounding environment. Energy is also required to distribute the heat carrier luid within the distribution system. In most cases this is electrical energy required by the circulation pumps. This leads to additional thermal and electrical energy demand. The thermal energy emitted by the distribution system and the electrical energy required or the distribution may be recovered as heat i the distribution system is placed inside the heated envelope o the building. This standard provides three methods o calculation. The detailed calculation method describes the basics and the physical background o the general calculation method. The required input data are part o the detailed project data assumed to be available (such as length o pipes type o insulation manuacturer's data or the pumps etc.). The detailed calculation method provides the most accurate energy demand and heat emission. For the simpliied calculation method some assumptions are made or the most relevant cases reducing the required input data (e.g. the length o pipes are calculated by approximations depending on the outer dimensions o the building and eiciency o pumps are approximated). This method may be applied i only ew data are available (in general at an early stage o design). With the simpliied calculation method the calculated energy demand is generally higher than the calculated energy demand by the detailed calculation method. The assumptions or the simpliied method depend on national designs. Thereore this method is part o Annex A. The tabulated calculation method is based on the simpliied calculation method with some urther assumptions being made. Only input data or the most important inluences are required with this method. The urther assumptions depend on national design also. Thereore the tabulated method is part o Annex A also. Other inluences which are not relected by the tabulated values shall be calculated by the simpliied or the detailed calculation method. The energy demand determined rom the tabulated calculation method is generally higher than the calculated energy demand by the simpliied calculation method. Use o this method is possible with a minimum o input data. The general calculation method or the electrical energy demand o pumps consists o two parts. The irst part is calculation o the hydraulic demand o the distribution system and the second part is calculation o the expenditure energy actor o the pump. Here it is possible to combine the detailed and the simpliied calculation method. For example calculation o pressure loss und low may be done by the detailed calculation method and calculation o the expenditure energy actor may be done by the simpliied calculation method (when the data o the building are available and the data o the pump are not available) or vice versa. In national annexes the simpliied calculation method as well as the tabulated calculation method could be applied through a. o. relevant boundary conditions o each country thus acilitating easy calculations and quick results. In national annexes it is only allowed to change the boundary conditions. The calculation methods must be used as described. The recoverable energy o the auxiliary energy demand is given as a ixed ratio and is thereore also easy to determine. 4

5 1 Scope This standard provides a methodology to calculate/estimate the heat emission o water based distribution systems or heating and the auxiliary energy demand as well as the recoverable energy. The actual recovered energy depends on the gain to loss ratio. ierent levels o accuracy corresponding to the needs o the user and the input data available at each design stage o the project are deined in the standard. The general method o calculation can be applied or any time-step (hour day month or year). ipework lengths or the heating o decentralised non-domestic ventilation systems equipment are to be calculated in the same way as or water based heating systems. For central non-domestic ventilation systems equipment the length is to be speciied in accordance with its location. NOTE: It is possible to calculate the heat emission and auxiliary energy demand or cooling systems with the same calculation methods as shown in this standard. Speciically determination o auxiliary energy demand is based on the same assumtions or eiciency o pumps because the standard curve is an approximation or inline and external motors. It has to be decided by the standardisation group o CEN i the extension or cooling systems should be made in this standard. This is also valid or distribution systems in HVAC (in ducts) and also or special liquids. 2 Normative reerences The ollowing reerenced documents are indispensable or the application o this document. For dated reerences only the edition cited applies. For undated reerences the latest edition o the reerenced document (including any amendments) applies. EN Heating systems in buildings - Method or calculation o the design heat load EN ISO Thermal perormance o buildings - Calculation o building energy demand or heating (ISO 13790: 2004) 3 Symbols units and indices For the purposes o this standard the symbols units and indices given in Table 1 apply. Table 1 Symbols units and indices A Heated loor in the zone [m²] B Building width [m] c Speciic heat capacity [kj/kg K] e Expenditure energy actor or operation o circulation pump [-] d e S Correction actor or supply low temperature control [-] Correction actor or hydraulic networks (layout) [-] NET Correction actor or heating surace disign [-] S HB Correction actor or hydraulic balance [-] Correction actor or generators with integrated pump management [-] G M Correction actor or partial load characteristics [-] Correction actor or control o the pump [-] C Correction actor or selection o design point [-] S Correction actor or dierential temperature dimensioning [-] ϑ 5

6 q & Correction actor or surace related heating load [-] η Correction actor or eiciency [-] Building length [m] max Maximum length o pipe [m] m ratio o low over the heat emitter to low in the ring [-] n exponent o the emission system [-] n G Number o loors [-] Δ p ierential pressure at design point [ka] Δ p HS ierential pressure o heating suraces [ka] Δ p CV ierential pressure o control valves or heating suraces [ka] Δ p ZV ierential pressure o zone valves [ka] Δ p G ierential pressure o heating supply [ka] Δ p FH ierential pressure o loor heating systems [ka] Δ p A ierential pressure o additional resistances [ka] hydr Hydraulic power at design point [W] ump Actual power input [W] ump re Reerence power input [W] & N design heating load [kw] d r w d r a Recoverable energy into heating water [kwh/timstep] Recoverable energy into surrounding air [kwh/timstep] R ressure loss in pipes [ka/m] t H Heating hours per year [h/year] U linear thermal transmittance [W/mK] V & Flow in design point [m³/h] V & minimum volume low [m³/h] min W Electrical energy demand [kwh/year] d e W Electrical energy demand (tabulated) [kwh/year] d e W d e M Monthly total electrical energy demand [kwh/month] W d hydr Hydraulic energy demand [kwh/year] z Resistance ratio o components [-] α time actor [-] α set back time actor [-] setb ϑ HK Δ imensioned heating system temperature dierence [K] η Eiciency o pump at design point [-] β Mean part load o the distribution [-] ρ Speciic density [kg/m³] ϑ i surrounding temperature [ C] ϑ mean medium temperature [ C] m ϑ temperature in unheated space [ C] u 6

7 ϑ s supply temperature [ C] ϑ r return temperature [ C] ϑ design supply temperature [ C] sa ϑ design return temperature [ C] ra 4 rinciple o the method and deinitions The method allows the calculation o the heat emission and the auxiliary energy demand o water based distribution systems or heating circuits (primary and secondary) as well as the recoverable energy. As shown in Figure 1 a heating system can divided in three parts emission and control distribution and generation. An easy heating system has no buer-storage and no distributor/collector and also only one pump. arger heating systems have more then one heating circuits with dierent emitters as so called secondary heating circuits. Mostly such heating systems have also more than one heat generator (individual or equal) with so called primary heating circuits (in igure 1 only one primary circuit is shown). The subdivision in primary and secondary circuits is given by any hydraulic separator which can be a buer-storage with a large volume or a hydraulic separator with a small volume. Anyhow the calculation method is valid or a closed heating circuit and thereore the equations have to used or each circuit taking into account the corresponding values. Figure 0 - Scheme distribution and deinitions o heating circuits 7

8 Key 1 Next heating circuit 2 pump 3 room 4 emission 5 buer-storage 6 pump 7 generator 8 generation 9 distribution 10 primary heating circuits 11 secondary heating circuits Controls in distribution systems are thermostatic valves at the emitter which throttles the low or room thermostats which shut on/o the pump. Only i the low is throttled the control o the pump (speed control) is valid. 5 Electrical energy demand Auxiliary energy demand 5.1 General The auxiliary energy demand o hydraulic networks depends on the distributed low the pressure drop and the operation condition o the pump. While the design low and pressure drop is important or determining the pump size the part load actor determines the energy demand in a time step. The hydraulic power at the design point can be calculated rom physical basics. However or calculation o the hydraulic power during operation this can only be achieved by a simulation. Thereore or the detailed calculation method in this standard correction actors are applied which represent the most important inluences on auxiliary energy demand such as part load controls design criteria etc. The general calculation approach is to separate the hydraulic demand which depends on the design o the network and the expenditure energy or operation o the pump which take into account the eiciency o the pump in general. However or calculation o the expenditure energy during operation the knowledge o the eiciency o the pump at each operation point is required Thereore or the detailed calculation method in this standard correction actors are applied also which represent the most important inluences an expenditure energy such as eiciency part load design point selection and control. All the calculations are made or a zone o the building with the ailiated area length width height and levels. 5.2 esign Hydraulic power For all the calculations the hydraulic power and the dierential pressure o the distribution system at the design point are important. The hydraulic power is given by: hydr = Δp V& [W] (1) where: V & Δp Flow at design point [m³/h] ierential pressure at design point [ka] 8

9 The low is calculated rom the heat load design temperature dierence Δ o the heating system ϑ HK & N o the zone (design heat load according to EN 12831) and the & V& 3600 = c ρ Δϑ N HK [m³/h] (2) where: c ρ Δϑ HK Speciic heat capacity [kj/kg K] ensity [kg/m³] esign temperature dierence [K] The dierential pressure or a zone at the design point is determined by the resistance in the pipes (including components) and the additional resistances (the most important are listed below): ( + z) R + ΔpHS + ΔpCV + ΔpZV + ΔpG + ΔpA Δp = 1 [ka] (3) max where: z Resistance ratio o components [-] R ressure loss per m [ka/m] max p HS Maximum pipe length o the heating circuit [m] Δ ierential pressure o heating surace [ka] Δ p CV ierential pressure o control valve or heating surace [ka] Δ p ZV ierential pressure o zone valves [ka] Δ p G ierential pressure o heat supply [ka] Δ p A ierential pressure o additional resistances [ka] 5.3 etailed Calculation Method Input- / Output data The input data or the detailed calculation method are listed below. These are all part o the detailed project data. hydr Hydraulic power at the design point or the zone [in W] calculated by the knowledge o & N esign heat load o the zone according to EN Δ ϑ HK esign temperature dierence or the distribution system in the zone [K] max Maximum pipe length o the heating circuit in the zone [m] Δ p ierential pressure o the circuit in the zone [ka] β Mean part load o the distribution [-] t H Heating hours per year [h/year] Correction actor or supply low temperature control [-] S Correction actor or hydraulic networks [-] NET 9

10 S Correction actor or heating surace dimensioning [-] HB Correction actor or hydraulic balance [-] ump control e d e Expenditure energy actor or operation o the circulation pump [-] calculated by this standard using: η Correction actor or eiciency [-] Correction actor or part load [-] S Correction actor or design point selection [-] Correction actor or control o the pump [-] C esign temperature level emitter type Intermittent operation The output data are: W Total electrical energy demand [kwh/year] d e W d e M d r w d r a Monthly total electrical energy demand [kwh/month] Recoverable energy to the water [kwh/timstep] Recoverable energy to the surrounding air [kwh/timstep] Calculation Method The electrical energy demand or circulation pumps or water based heating systems is calculated by: where W d e Wd hydr ed e = (4) W Electrical energy demand [kwh/year] d e W Hydraulic energy demand [kwh/year] d hydr e Expenditure energy actor or operation o circulation pump [-] d e The hydraulic energy demand or the circulation pumps in heating systems is determined rom the hydraulic power at the design point ( hydr ) the mean part load o the distribution ( β ) and the heating hours in the time step ( t H ): where: = β (kwh/year) (5) 1000 hydr W d hydr th S NET S HB G M hydr Hydraulic power at design point [W] 10

11 β Mean part load o the distribution [-] t H Heating hours per year [h/year] Correction actor or supply low temperature control [-] S Correction actor or hydraulic networks [-] NET Correction actor or heating surace dimensioning [-] S HB Correction actor or hydraulic balance [-] Correction actor or generators with integrated pump management [-] G M The correction actors S NET and S include the most important parameters related to dimensioning o the heating system. The actor HB take into account the hydraulic balance o the distribution system. The correction actor G M or generators with integrated pump management take into account the reduction o operation time in relation to the heating time Correction actors The correction actors are based on a wide range o simulations o dierent networks. Some o the correction actors can not changed without changing the method. Correction actors which are based on assumptions can be changed on national requirements (see Annex A.1.3) Correction actor or supply low temperature control S = 1 or systems with outdoor temperature compensation S S see Figure 1 or systems without outdoor temperature compensation (i.e. constant low temperature) or very much higher low temperature than necessary 11

12 Key 1 Correction actor S [-] 2 Ground plan A N [m²] 3 Flow temperature characteristics Figure 1 Correction actor Correction actor or hydraulic networks NET S or constant low temperature and very much higher low temperature = 1 or a two-pipe ring line horizontal layout (on each loor) NET see Table 2 or other types o layout NET Table 2 Correction actors or hydraulic network Network design One amily house wellings 2 pipe system Ring line Ascending pipe Star-shaped The star-shaped network design is also valid or loor heating systems. 12

13 For one-pipe heating systems the correction actor NET is given by where: NET = 8 6 m + 07 (6) m ratio o low over the heat emitter to low in the ring [-] Correction actor or heating surace dimensioning S = 1 or dimensioning according to design heat load S = 096 in case o additional over-sizing o the heating suraces S Correction actor or hydraulic balance HB See Annex A Correction actor or generators with integrated pump management G M See Annex A Expenditure energy actor For assessment o partial load conditions and control perormance o the circulation pump the expenditure energy actor is determined by: e d e = η S C (7) where η Correction actor or eiciency [-] Correction actor or part load [-] S Correction actor or design point selection [-] Correction actor or control [-] C With these our correction actors the expenditure energy actor take into account the most important inluences on the energy demand representing the design the eiciency o the pump the part load and the control. The physical relations are shown in Figure 2. 13

14 Key 1 ressure Head H [m] 2 ower 1 [W] 3 Flow rate [m³/h] 4 H 0max 5 H pump 6 H Ausl 7 H 8 hydr 9 10 pump 11 pumpmax 12 C 14

15 13 pumpre 14 V & 15 V & 16 C = 17 S = pump pump re 18 = pump re η 19 hydr = β pump Figure 2 Expenditure energy - physical interpretation o the correction actors Correction actor or eiciency η The correction actor or eiciency is given by the relation between the reerence power input at the design point and the hydraulic power at the design point. = ump re η (8) hydr The reerence power input is calculated by means o the pump characteristic line: Correction actor or part load ump re = hydr (9) hydr The correction actor or part load take into account the reduction o pump eiciency by partial load. It also take into account the hydraulic characteristics o non-controlled pumps. The impact o the partial load on the pipe system and thus on the hydraulic energy demand is taken into account by the mean part load o the distribution β according to Figure 3 shows the correction actor or part load o the pump depending on the mean part load o the distribution. 15

16 Key 12 Correction actor [-] 13 Mean part load o distribution ß 14 Mean part load Ratio (R) Figure 3 Correction actor or part load o the pump Correction actor or design point selection S The correction actor or design point selection S is given by the relation between the actual power input o the pump and the reerence power input at the design point: S ump = (10) ump re where ump actual power input o pump at design point [W] ump re reerence power input o pump at design point [W] Correction actor or control o the pump C = 1 or non-controlled pumps C C see Figure 4 or controlled pumps 16

17 Key 1 Correction actor or control o the pump C [-] 2 pumpmax / pump 3 Δ pconst - control 4 Δ p var i - control 5 ump control Figure 4 Correction actor or control o the pump The constant pressure dierence control o the pump keeps the pressure dierence o the pump within the whole low area constant at the design value. The variable pressure dierence control varies the pressure dierence o the pump rom the design value at design low to mostly the hal o the design value at zero low. I a wall hanging generator with integrated pump management has a modulation control o the pump depend on the temperature dierence between supply and return then the correction actor or Δ is valid. p var i Intermittent operation For intermittent operation there are three dierent phases (see Figure 5): set back mode; 17

18 boost period; regular mode. Key 1 Room temperature 2 time 3 Set back 4 boost 5 Regular mode 6 Set back Figure 5 Intermittent operation phases The total electrical energy demand or intermittent operation is given by the sum o energy demand or each phase: W d e Wd e reg + Wd e setb + Wd e boost = (11) For the the regular mode operation the energy demand is determined by multiplication with a time actor or the proportional time o regular mode operation α : r W d e reg r Wd hydr ed e = α (12) For the set back operation it is necessary to distinguish between: 18

19 turn o mode or which the energy demand o the pump is zero - 0 W d e setb = set back o supply temperature and minimum speed o the pump. When the pump is operated at minimum speed the power is assumed to be constant as ollows: = (13) ump setb 0 3 umpmax and the electrical energy demand is determined by multiplication with a time actor or the proportional time o set back operation α : setb W ump setb d e setb = α setb th (14) set back o supply temperature. I thermostatic valves in this mode are not set back the low compensates the lower supply temperature and the energy demand is not reduced. The energy demand or set back operation can be calculated as or the regular mode operation. The correction actor or control is C = 1 in case o room temperature control with constant value (no changes between regular mode and set back mode) and in case o room temperature control with set back C depends on the type o pump control (see igure 4). For the boost mode operation the power boost is equal to the power ump at the design point. The electrical energy demand or the boost mode operation is determined by multiplication with a time actor or the proportional time o boost mode operation α : W b 1000 ump boost d e booth = α b th (15) 1000 The time actors can be calculated as relations o time periods. α r expresses the number o hours o regular mode operation t r per total The regular mode time actor number o hours per time period t (period could be day week month or year): = t r α r (16) t The boost mode time actor α b expresses the number o hours o boost mode operation per total number o hours per time period t. The number o hours o boost mode operation is typically one or two hours per day as an average over the year or can be calculated in accordance to EN ISO 13790: The set back mode time actor t = number o hours per time period t and is determined rom boost α b (17) t α setb expresses the number o hours o set back mode operation per total α setb r α r and b α b : = 1 α α (18) 19

20 5.4 eviations rom the detailed calculation method For some applications deviations rom the detailed calculation method are taken into account: One-pipe heating systems The total low in the heating circuit and in the pump is constant. The pump is always working at the design point. The mean part load o distribution is = 1 β Overlow valves Overlow valves are used to ensure a minimum low at the heat generator or a maximum pressure dierence at the heat emitter. The unction o the overlow valve is given by the interaction between the pressure loss o the system the characteristics o the pump and the set point o the overlow valve. The inluence on hydraulic energy demand can be estimated by applying a corrected mean part load o distribution where: β : & min V β = β + ( 1 β ) (19) V& β V & mean part load o distribution design volume low [m³/h] V & min minimum volume low [m³/h] The minimum volume low take into account the requirements o the heat generator or the maximum pressure loss o the heat emitter. 5.5 Monthly energy demand The detailed calculation method as well as the simpliied and tabulated calculation methods determines an annual energy demand. Where necessary the monthly energy demand is calculated by: W d e M = W d e Y β β M Y t t H M H Y (20) where: β M mean part load o distribution or the month β Y mean part load o distribution or the year t heating hours per month H M t heating hours per year H Y Calculation o β is given in 7. 20

21 5.6 Recoverable auxiliary energy For pumps operated in heating circuits part o the electrical energy demand is converted to thermal energy. art o the thermal energy is recovered as heat transerred to the water and another part o the thermal energy is recoverable as heat transerred to the surrounding air. This both parts are partially recoverable: Recovered energy to the water: d r w rec Wd e = (21) Recoverable energy to the surrounding air: d r a ( 1 rec) Wd e = (22) Values rec see Annex A Heat emission o distribution systems 6.1 General The heat emission o a distribution system depends on the mean temperature o the supply and return and the temperature o the surroundings. Also the kind o insulation has an important inluence on the heat emission. 6.2 etailed Calculation Method Input- / Output data The input data or the detailed calculation method are listed below. These are all part o the detailed project data: length o pipes in the zone U linear thermal transmittance in W/mK or each pipe in the zone ϑ m mean medium temperature in the zone in C ϑ i surrounding temperature in the zone (unheated and heated space) in C t H heating hours in the time step in h/(time step) Number o valves and hangers taken into account The output data are: d r Total heat emission o the distribution system in the zone [kwh/year] Recoverable energy in the zone [kwh/timstep] Unrecoverable energy in the zone [kwh/timstep] d u Calculation method The heat emission or the sum o the pipes j in a time step is given by = U j ϑ j ( m i j ) j th ϑ (23) 21

22 where: U linear thermal transmittance in W/mK ϑ mean medium temperature in C m ϑ surrounding temperature in C i j length o the pipe Index or pipes with the same boundary conditions t H heating hours in the time step in h/(time step) For parts o the distribution system with the same linear thermal transmittance the same mean medium temperature and the same surrounding temperature the heat emission is given by a shorter term: = q& t (24) j j The mean medium temperature o heating circuits with outdoor temperature compensation o the supply temperature depends on the mean part load o distribution and the temperature dierence between mean emission system design temperature and room temperature. Calculation o the mean medium temperature is given in 7. Thereore the heat emission per length in a space with surrounding temperature ϑ i depends on the mean part load o distribution and is given by: For distribution systems with: constant supply temperature ( β ) = U ϑ ( β ) j H ( ) & (25) q j j m ϑ i j ϑ m not depending on the mean part load o distribution. a temperature dierence between a heated and an unheated space ϑ = ϑ ϑ Δ (26) U i u the linear thermal transmittance respectively per length or pipes in heated and unheated spaces U U U the heat emission in unheated spaces is given as a unction o the heat emission in heated spaces (so that the heat emission o the pipes has to be calculated only once or parts with the same boundary conditions): U U Δϑ U u ( β ) = q& ( β ) + U U U ( ) (27) q& β q& The expression in the brackets o equation (34) can be written as a actor U u U U = + U U U ΔϑU q& ( β ) (28) and the heat emission in unheated spaces depends only on the heat emission in heated spaces and a actor which contains the relation between the dierent U-Values per length and the temperature dierence in heated and unheated spaces: 22

23 Given the sum o pipe length values o linear thermal transmittance part o the heat emission is given by: u H in heated spaces and ( β ) = q& ( β ) U q& (29) U in heated spaces and U - or parts o the distribution system with the same U U in unheated spaces the recoverable a n = H U + U U U H ΔϑU 1+ ϑm ( β ) ϑa (30) Heat emission o accessories The heat emission o a distribution system is not only given by the emission o the pipes. The heat emission o accessories such as valves and hangers is also taken into account. To take the heat emission o hangers into account an additional equivalent length o 15 % could be used as an approximation. I special insulated pipe hangers are used with their thermal resistance equal to the one o the pipe insulation the additional heat emission due to the hangers should not be taken into account. The equivalent length o valves including langes is given in Annex A Recoverable and non-recoverable heat emission In heated rooms the heat emission o the pipes is a part o useul heat demand. So this part o heat emission is recoverable. In uncontrolled or unheated rooms the heat emission o pipes is not recoverable. Given the sum o pipe length recovered is calculated by: r j in heated space the heat emission o the time step r r = q r j r t & j H (31) j which may be Given the sum o pipe length u i in uncontrolled or unheated space the heat emission o the time step which can not be recovered is calculated by: u = q u j u t & j H (32) j u Total heat emission The total heat emission is the sum o the recoverable heat emission in heated spaces an the non-recoverable heat emission in unheated spaces: r + u = (33) 6.3 Calculation o linear thermal transmittance (W/mK): The linear thermal transmittance or insulated pipes in air with a total heat transer coeicient including convection and radiation at the outside is given by 23

24 U = 1 2 λ π d ln d a i 1 + α d a a (34) where: d i d a inner diameter (without insulation) outer diameter o the pipe (with insulation) (m) α a λ outer total heat transer coeicient (convection and radiation) (W/m²K) thermal conductivity o the insulation (material) (W/mK) For embedded pipes the linear thermal transmittance is given by U em = λ d ln d a i + π 1 4 ln λ d E z a (35) where: z λ E depth o pipe rom surace thermal conductivity o the embedded material (W/mK) For non-insulated pipes the linear thermal transmittance is given by U non = π 1 d p a ln 2 λ d p i 1 + α d a p a (36) where: d p i d p a λ inner diameter outer diameter o the pipe (m) thermal conductivity o the pipe (material) (W/mK) As an approximation the linear thermal transmittance or non insulated pipes is given by U non = a π d p a α (37) For heating systems the inner total heat transer coeicient must not be taken into account. 7 Calculation o mean part load o distribution per zone The mean part load o distribution is given by: 24

25 em in β = (38) & N th where: em in Energy including emission and control per time step & N design heat load per zone t H heating hours in the zone per time step 8 Calculation o supply and return temperature depending on mean part load o distribution For heating systems with supply temperature control depending on the outdoor temperature the supply temperature ϑ s and the return temperature ϑ r as well as the mean emission system temperature ϑ m are given as unctions o the mean part load o distribution in each process area: m ( β ) n i = Δϑa β i i ϑ + ϑ 1 (39) s 1 ( β ) n i = ϑsa ϑi ) βi i ϑ + ϑ r ( (40) ( β ) n i = ϑra ϑi ) β i i ϑ + ϑ 1 ( (41) where: β i ϑ a mean part load o distribution in the process area Δ temperature dierence in C between mean emission system design temperature and room temperature ϑsa + ϑra Δϑa = ϑi 2 n exponent o the emission system (standard value = 133 or radiators 11 or loor heating systems) ϑ design supply temperature in C sa ϑ design return temperature in C ra ϑ room temperature in C i (42) For heating circuits between a hydraulic decoupling system or a storage vessel the temperature is sometimes not inluenced by outside temperature control. For heating systems where the temperature o the decoupling system or a storage vessel does not depend on the supply temperature o the emission system the heat emission o the pipes between the heat generator and the storage vessel has to be calculated with the ixed temperature given by the heat generator i.e. non gas- or oil ired burner. 25

26 Annex A (inormative) reerred procedures A.1 Simpliied Calculation Method o annual electrical auxiliary energy demand For the simpliied calculation method some assumptions are made or the most relevant cases reducing the required input data (e.g. the length o pipes are calculated by approximations depending on the outer dimensions o the building and eiciency o pumps are approximated). This method may be applied i only ew data are available (in general at an early stage o design). The assumptions in A.1.2 can be changed on national requirements but the calculation method must be used as described in A.1.3 A.1.4 and A.1.5. A.1.1 Input- / Output data The input data or the simpliied calculation method are listed below. These are all part o the detailed project data. hydr Hydraulic power at the design point or the zone [in W] calculated by the knowledge o & N design heat load according to EN o the zone Δ ϑ HK design temperature dierence [K] or the distribution system in the zone max Maximum pipe length o the heating circuit [m] in the zone Δ p ierential pressure o the circuit in the zone [ka] simpliied calculated β Mean part load o distribution [-] t H Heating hours per year [h/year] Correction actor or hydraulic networks [-] NET HB Correction actor or hydraulic balance [-] ump control e d e Expenditure energy actor or operation o circulation pump [-] simpliied calculated by this standard esign temperature level emitter type Intermittent operation The output data are: W Total electrical energy demand [kwh/year] d e W d e M d r w d r a Monthly total hydraulic energy demand [kwh/month] Recoverable energy to the water [kwh/timstep] Recoverable energy to the surrounding air [kwh/timstep] 26

27 A.1.2 Calculation method For deined values o correction actors ( = 10) the hydraulic energy demand can be expressed as a S S unction o heating hours per time step and the mean part load o distribution: = β (43) 1000 hydr W d hydr th NET HB G M NET is only necessary to distinguish between one-pipe and two- The correction actor or hydraulic networks pipe heating systems. An approximation or the dierential pressure at the design point can be made with a ixed pressure loss per length o heating circuit (100 a/m) and an additional pressure loss ratio or components o 03. Variables or determining the dierential pressure at the design point are thus only the maximum length o the heating circuit in the zone and the pressure losses o the heat emission system and the heat generation system: where: Δp = Δp FH + Δp G 0 max (ka) (44) max Maximum length o the heating circuit [m] Δ p FH additional pressure loss or loor heating systems [ka] Δ p G pressure loss o heat generators [ka] This approximation is applicable or the primary heating circuit as well as or the secondary heating circuit. I the manuacturer's data or p ΔpFH and/or G Δ is not available the ollowing deault values can be applied: Δ p FH = 25 ka including valves and distributor Δ p G see Table A1 Table A.A.1 A.ressure loss o heat generators Type o heat generator p Δ [ka] Generator with water content > 03 l/kw 1 Generator with water content <= 03 l/kw h max < 35kW h 35kW 80 & 2 max G 20 V & where: & hmax maximum heat load [kw] V & design low [m³/h] 27

28 The maximum length o the heating circuit in a zone can be calculated approximately rom the outer dimensions o the zone: where: B B = ng hg + lc 2 max (m) (45) ength o the zone (part o building) [m] Width o the zone (part o building) building [m] n G Number o heated levels in the zone (part o building) [-] h G Mean height o the levels in the zone (part o building) [-] l c = 10 m or two-pipe heating systems = + B or one-pipe heating systems A.1.3 Correction actors A Correction actor or hydraulic networks NET = 1 or two-pipe heating systems; NET NET = 8 6 m + 07 or one-pipe heating systems where m is the ratio o low over the heat emitter to low in the ring [-] A Correction actor or hydraulic balance HB HB = 1 or hydraulic balanced systems = 115 or hydraulic non-balanced systems HB A Correction actor or generators with integrated pump management G M or outdoor temperature controlled standard generator (OTC) G G M = 1 or outdoor temperature controlled wall hanging generator (OTC) G M = 075 M = 045 or room temperature controlled wall hanging generator (RTC) A Recoverable auxiliary energy rec or not insulated pump rec = 075 rec = 090 or insulated pump 28

29 A.1.4 Expenditure energy actor For the simpliied calculation method the expenditure energy actor is calculated similarly as or the detailed calculation method re. equation (7) in with the ollowing additional assumptions: Correction actor or control umpmax C is determined rom igure 4 with = 1 11 ump Correction actor or design point selection = 1 5 (see igure 2) Eiciency actor e = η Approximation o the eiciency curve o the pump Thus the expenditure energy actor is simpliied to: where: 1 2 S S 1 = e 1 2 e ( C + C β ) (46) d e C C Constants according to Table A2 [-] e Eiciency actor given by: ump e = (47) hydr or or pumps where ump is not available e = b 1 5 hydr (48) where b = 1 or new buildings and b = 2 or existing buildings and Table A.A.2 Constants C C 1 2 or calculation o the expenditure energy actor (simpliied method) ump control C 1 C 2 Not controlled Δ p const Δ p var iabel hydr given in W. For existing installations it is approximately correct to use the power rating given on the label at the pump or ump. (In case o non-controlled pumps with more than one speed level ump shall be taken rom the speed level at which the pump is operated). 29

30 A.1.5 Intermittent operation For the simpliied calculation method the boost mode time actor is assumed to be 3 % and the electrical energy demand is given by W = W e 6 ( α + 0 α + α ) d e d hydr d e r setb b (49) The expression in the brackets represents the energy saving by intermittent operation. The time actors should be calculated as shown in o the standard. A.2 Tabulated calculation method o annual electrical auxiliary energy demand The input data or the tabulated calculation method are listed below. These are all part o the detailed project data. A Heated loor area in the zone [m²] Type o heat generator One-pipe/two-pipe heating system Type o pump control The output data are: W Total electrical energy demand [kwh/year] d e W d e M d r w d r a Monthly total electrical energy demand [kwh/month] Recovered energy to the water [kwh/timstep] Recoverable energy to the surrounding air [kwh/timstep] The tabulated calculation method combines all the assumptions o the simpliied method and provides with additional assumptions or speciic types o heating systems values or annual electrical energy demand. National Annexes providing tabulated values or this method may be elaborated. The simpliied calculation method shall orm the basis or determination o tabulated values at a national level and the tables should ollow the same structure as in A.2.1. The necessary boundary conditions which can be changed on national requirements are given in A.2.1. also. A.2.1 Tabulated calculation o annual electrical auxiliary energy demand Annual electrical auxiliary energy demand is given in Table A.3. The values have been calculated rom the simpliied method (see A.1) with some additional assumptions: mean part load o distribution = 04 heating hours = 5000 per year design heat load per m² = 40 W/m² (new buildings) hight o a level = 3 m length o the zone depending on the heated loor area: = A B = 2 A + width o the zone depending at the heated loor area: 72 ln( )

31 = A /( B number o levels in the zone: ) n G A = m² o the zone (one pump or a maximum o 1000 m² per zone) Table A.3 Annual electrical auxiliary energy demand Annual electrical auxiliary energy demand [kwh/year] (5000 heating hours) Generators with standard water volume Generators with small water volume Two-pipe-system with A [m²] radiators not controlled dpconst dpvariabel not controlled dpconst dpvariabel Two-pipe-system with A [m²] loor-heating not controlled dpconst dpvariabel not controlled dpconst dpvariabel One-pipe-system with A [m²] radiators not controlled not controlled

32 Annual electrical auxiliary energy demand [kwh/year] (5000 heating hours) Generators with standard water volume Generators with small water volume For a dierent number o heating hours than 5000 per year the tabulated values can be corrected by heating _ hours multiplication with a actor = 5000 For intermittent heating the tabulated values can be corrected by multiplication with the actor int : Regular mode 06:00 22:00 h every day and set back mode or the remaining time: int = 0 87 ; I the pump is turned o during the set back mode: int = 0 69 Regular mode 06:00 22:00 h on Monday Friday and set back mode or the remaining time: int = 0 87 ; I the pump is turned o during the set back mode: int = 0 60 Recovered energy to the water: d r w = 0 75 Wd e Recoverable energy to the surrounding air: d r a = 0 25 Wd e (Note: similar table can be created or existing buildings) A.3 Simpliied Calculation Method o heat emission For the simpliied calculation method some assumptions are made or the most relevant cases reducing the required input data (e.g. the length o pipes are calculated by approximations depending on the outer dimensions o the building). This method may be applied i only ew data are available (in general at an early stage o design). The assumptions in A.3.2 and A.3.3 can be changed on national requirements but the calculation method must be used as described in 6.2 o the standard. A.3.1 Input- / Output data The input data or the simpliied calculation method are listed below. These are all part o the detailed project data: length o the zone B width o the zone h G height o the storey in the zone n G number o storeys in the zone U tabulated U-Values per length in W/mK or each part o the distribution system in the zone ϑ mean medium temperature in the zone in C m 32

33 ϑ a surrounding temperature in the zone (unheated and heated space) in C t H heating hours in the time step in h/(time step) Number o valves and hangers taken into account The output data are: d r Total heat emission o the distribution system in the zone [kwh/year] Recoverable energy in the zone [kwh/timstep] Unrecoverable energy in the zone [kwh/timstep] d u A.3.2 Approximation o the length o pipes per zone in distribution systems For the simpliied calculation method approximations o the length o the pipes in a building or a zone (see Figure 6) are made based on the length () and width (B) o the building or zone the storey height (h G ) and the number o storeys (n G ) see Table A.4 and Table A.5. V ipe length between generator and vertical shats. These (horizontal) pipes could be in unheated space (basement attic) or in heated space. S ipe length in shats ( e.g. vertical). These pipes are either in heated space in outside-walls or in the inside o the building. The heating medium is always circulating. A Connection pipes. These pipes are low controlled by the emission system in heated spaces. Figure A.1 Type o A.A.pipes in a distribution system Table A.A.4 A.Approximation o pipe lengths (two-pipe heating systems) Values result unit part V distribution to the shats part S Vertical shats part A connection pipes Mean surrounding temperature ipe length in case o shats in outside walls C 13 respectively i m B B. h G. n G B. n G ipe length in case o shats inside the building i m B B. h G. n G B. n G 33

34 ipe length in case o shats inside o the building Table A.A.5 A.A.Approximation o pipe length (one-pipe heating systems) m B B. h G. n G + 2. ( + B). n G 01.. B. n G A.3.3 Approximation o U-Values For the simpliied calculation method approximations o the U-Values are made or the dierent types o pipes (see Table A.6). These should be constant values. Table A.A.6 A.Typical Values o linear thermal transmittance [W/mK] or new and existing buildings Age class o building istribution V S S From 1995 assumed that insulation thickness approximately equals to pipe external diameter 1980 to assumed that insulation thickness approximately equals to hal o pipe external diameter Up to Non-insulated pipes A <=200 m² m² < A <=500 m² A > 500 m² aid in external walls total / usable * External wall non-insulated 135 / 080 External wall external insulated 100 / 090 External wall without insulation 075 / 055 but low thermal transmittance (U=04 W/m²K) * (total = total heat emission o the pipe usable = recoverable heat emission) A.3.4 Equivalent length o valves Table A.7 gives the equivalent length o valves including langes depending on the kind o insulation: Valves incl. langes Table A.A.7 A.A.Equivalent length o valves equivalent length in m equivalent length in m d <= 100 mm d > 100 mm not insulated insulated

35 A.4 Tabulated Calculation Method o annual heat emission The input data or the tabulated calculation method are listed below. These are all part o the detailed project data: A Heated loor area in the zone [m²] ϑ m mean medium temperature in the zone in C (supply/return temperature) t heating hours in the time step in h/(time step) H The output data are: d r Total heat emission o the distribution system in the zone [kwh/year] Recoverable energy in the zone [kwh/timstep] Unrecoverable energy in the zone [kwh/timstep] d u The tabulated calculation method combines all the assumptions o the simpliied method and provides with additional assumptions regarding the design system temperature values or annual heat emission. National Annexes providing tabulated values or this method may be elaborated. The simpliied calculation method shall orm the basis or determination o tabulated values at a national level and the tables should ollow the same structure as in A.5. A.5 Tabulated calculation o annual heat emission Annual heat emission is given in Table A.8 or two-pipe heating systems. The values have been calculated rom the simpliied method (see 4.6) with some additional assumptions: mean part load o distribution = 04 heating hours = 5000 per year length o the zone depending on the heated loor area: = A width o the zone depending on the heated loor area : B = 2 72 ln( A ) number o levels in the zone: = A /( B) n G A = m² o the zone U-value or pipes o part V o the distribution system in unheated spaces U = 02 W/mK U-value or shats and connecting pipes o the distribution system in heated spaces U = 0255 W/mK shats inside the zone loor height = 30 m Table A.8 Annual heat emission in kwh/year at design temperature 35