Bsi bs en 15316 3 2 2007 (2008)

BRITISH STANDARD Heating systems in buildings — Method for calculation of system energy requirements and system efficiencies — Part 3-2: Domestic hot water systems, distribution ICS 91.140.10 12&23 500 m² 3,0 3,0 3,0 Non-insulated pipes exposed Non-insulated pipes installed in external walls total/usable External wall non-insulated 1,35 / 0,80 External wall with external insulation 1,00 / 0,90 External wall without insulation but characterized by a low thermal transmittance (U = 0,4 W/m²K) 0,75 / 0,55 a a (total = total thermal losses of the pipe, usable = recoverable thermal losses) D.2.4 Tabulated method for calculation of linear thermal transmittance An alternative simplified method for calculation of the linear thermal transmittance may be applied The simplified equation for the linear thermal transmittance is: U W ,dis = AW ,dis ,U * d R + BW ,dis ,U (W/m⋅K) (D.2) where AW ,dis ,U and BW ,dis ,U are coefficients depending on the pipe insulation class and dR is given in metres 33 BS EN 15316-3-2:2007 EN 15316-3-2:2007 (E) The coefficients AW ,dis ,U and BW ,dis ,U may be given in a national annex If a national annex is not provided or does not include these values, default values given in Table D.4 may be applied Table D.4 — Parameters for calculation of the linear thermal transmittance of pipes Type of pipe insulation dR dR max AW,dis,U BW,dis,U (m) (m) (W/m K) (W/mK) Class 0,010 0,300 2,60 0,200 Class 0,010 0,300 2,00 0,180 Class 0,010 0,300 1,50 0,160 Class 0,010 0,300 1,10 0,140 Class 0,010 0,300 0,80 0,120 D.2.5 Determination of average ambient temperature The average ambient temperature is solely dependent on the location of the pipe θ amb = θ int − bW ,dis * (θ int − θ e ) o ( C) (D.3) where θ int is the internal temperature ( C); θe mean outside temperature ( C); bW ,dis location factor (-) o o Values for the location factor are given in Table D.5 Table D.5 — Location factor corresponding to the location of the pipes Location of the circulation loop bW ,dis Outside the building Outside the heated space, horizontal circulation 0.8 Within the heated space Other (e.g embedded pipe) to be calculated and substantiated D.2.6 Determination of average hot water temperature of pipe section The average domestic hot water temperature within a pipe section may be given in a national annex If a national annex is not provided or does not include this value, the default average temperature of the water is: o  32 C in an individual spur;  60 C in a circulation loop 34 o BS EN 15316-3-2:2007 EN 15316-3-2:2007 (E) Annex E (informative) Calculation of thermal losses from user outlets If thermal losses associated with the thermal capacity of the user outlets are to be taken into account, the effect of different outlet types may be calculated from the following procedure The thermal losses due to the user outlets are: QW ,em ,ls = β W ,em * nem * ntap (MJ/day) (E.1) where β W ,em is the heat loss of the specific type of user outlet (MJ/tapping cycle); nem is the number of user outlets of the specific type in the building; ntap is the number of tapping cycles per day If this calculation is considered necessary, values for β W ,em depends β W ,em and ntap are provided in a national annex on the domestic hot water temperature, the cold water inlet temperature and the water flow rate, and should be determined based on the values in Table E.1 Table E.1 — Basic conditions for determination of Domestic hot water temperature 60 °C Cold water inlet temperature 10 °C Water flow rate The number of tapping cycles during the day, β W ,em 12 l/min ntap , depends on the type of activity 35 BS EN 15316-3-2:2007 EN 15316-3-2:2007 (E) Annex F (informative) Calculation of auxiliary energy requirement of a circulation pump F.1 Simplified method for calculation of auxiliary energy requirement of a circulation pump For the simplified calculation method for estimating the auxiliary pump energy, the default value tpmp = 24 h/day may be applied (this is the worst case situation, assuming the pump operates continuously through the day) F.2 Detailed method for calculation of auxiliary energy requirement of a circulation pump F.2.1 Hydraulic energy requirement The hydraulic energy depends on the hydraulic resistance of the system and the pump running time: WW , dis , hydr = 3,6 * Phydr * tW (MJ/day) (F.1) where Phydr is the hydraulic power required by the pump (kW); tW is the duration of the provision of domestic hot water (h/day) F.2.2 Hydraulic power required by the pump The hydraulic power required by the circulation pump to overcome the hydraulic resistance of the system is: Phydr = • * ∆p * V 3600 (kW) (F.2) where • V is the volume flow rate (m³/h); ∆p is the differential pressure across the pump (kPa) The volume flow rate depends on the thermal output of the heat generator, temperature difference, • V= 36 QW , gen,out 1,15 * ∆θ W , gen QW , gen,out (kW), and the maximum ∆θ W , gen (oC), across the heat generator: (m³/h) (F.3) BS EN 15316-3-2:2007 EN 15316-3-2:2007 (E) The differential pressure across the circulation pump depends on the resistance of the pipes and fittings in the circulation system as follows: ∆p = 0,1 * LW , dis ,col + ∑ ∆pW , fittings + ∆pW , gen (kPa) (F.4) where LW ,dis ,col is the maximum pipe length (m); ∆pW , fittings is the differential pressure across fittings, such as back-flow preventer and thermostatic valve (kPa); ∆pW , gen differential pressure across heat generator (kPa) If no product data are available, the following default values may be applied:  for storage tanks kPa;  for continuous-flow systems 15 kPa The maximum pipe length for the circulation loop can for a rectangular building approximately be determined from the external dimensions of the building/zone: LW , dis ,col = * (L B + 2,5 + n f * h f ) (m) (F.5) where LB is the largest extended length of the building (m); nf is the number of heated storeys; hf is the average height of a storey (m) F.2.3 Duration of the provision of domestic hot water The running time of the circulation loop tW = 10 + and tW is determined for apartment blocks by: 50 0,07 + 0,32 * LB * BB * nf * hf (h/day) (F.6) tW is limited to 24 h/day where LB is the largest extended length of the building (m), BB is the largest extended width of the building (m); nf is the number of heated storeys; 37 BS EN 15316-3-2:2007 EN 15316-3-2:2007 (E) hf is the average height of a storey (m) For non-residential buildings, tW is to be set equal to the daily utilisation time period (h/day) F.2.4 Pump performance coefficient The performance coefficient e pmp ,eff = f eff * C pmp * β D e pmp ,eff for operation of the circulation pump is: −0 , 94 (-) (F.7) where f eff is the efficiency factor; C pmp is the pump control factor according to Table F.1; βD is the load factor If power rating of the circulation pump is given, the efficiency factor f eff = Ppmp f eff is calculated by: (-) Phydr (F.8) where Ppmp is the power rating of the circulation pump (kW) If power rating of the circulation pump is not available, the efficiency factor, f eff = 1,5 * b 0,015 * Phydr , 74 f eff , is given by: (-) + 0,04 (F.9) where b = for new buildings and b = for existing buildings Table F.1 — Pump control factor Cpmp Pump control Fixed speed ∆pconst ∆p var Cpmp 0,97 0,66 0,52 β D , is the ratio of the actual circulated flow to the maximum circulated flow If there is no flow controller applied, β D = The load factor, In an existing building, power rating of the circulation pump may be available from the pump data plate The specific power rating should be used for the calculations, if available If details of the piping and/or pump specification are not available, representative values or a simplified calculation method may be applied 38 BS EN 15316-3-2:2007 EN 15316-3-2:2007 (E) F.2.5 Intermittent pump operation If domestic hot water is not required for a full 24-hour period per day, the circulation pump may be operated at an intermittent basis For convenience, this may be considered as continuous normal operation during daytime and continuous operation at minimum load during the night The auxiliary energy required for the circulation pump in this case is: WW , dis , pmp = WW , dis , hydr * e pmp ,eff * (α day + 0,6 * α night ) (MJ/day) (F.10) where α day is the ratio of circulation pump running hours at normal operation to total running hours; α night is the ratio of circulation pump running hours at minimum load to total running hours; α day + α night = 1,0 If the circulation pump is shut off during the night, circulation pump is taken into account by α night = and α day = 1,0 (The total running hours of the tW in Equation (F.1).) F.2.6 Expenditure value coefficient For evaluation of the operating characteristics of the circulation pump, an expenditure value coefficient eW,d,aux is: eW,d,aux = f eff * (C p1 + C p2 ) (-) (F.11) where CP1 , CP are constants given in Table F.2; f eff is the efficiency factor according to the following definition: f eff 0,   200     = 1,25 +  *b P   hydr     f eff = Ppmp Phydr for an un-identified pump for an identified pump where b is the over-dimensioning factor, which is determined as follows:  for pumps, which are designed for the demand, b = 1;  for pumps, which are not designed for the demand, b = 39 BS EN 15316-3-2:2007 EN 15316-3-2:2007 (E) For existing pumps, the relevant performance data on the type plate of the pump can be taken as an approximation for Ppmp Table F.2 — Constants CP1 , CP for calculation of the expenditure value coefficient of circulation pumps Pump control C P1 CP No control 0,25 0,94 Control 0,50 0,63 F.3 Auxiliary energy recoverable factor A proportion of the auxiliary energy supplied to the pump may be recovered as heat transferred to the circulating water If no value is provided, a default value of 80 % of WW ,dis, pmp may be applied This recovered auxiliary energy should be subtracted from the total thermal losses of the circulation loop 40 BS EN 15316-3-2:2007 EN 15316-3-2:2007 (E) Bibliography [1] EN 15316-1, Heating systems in buildings — Method for calculation of system energy requirements and system efficiencies — Part 1: General [2] EN 15316-3-1, Heating systems in buildings — Method for calculation of system energy requirements and system efficiencies — Part 3-1 Domestic hot water systems, characterisation of needs (tapping requirements) [3] prEN 15603, Energy performance of buildings — Overall energy use and definitions of energy ratings [4] prCEN/TR 156151 , Explanation of the general relationship between various European standards and the Energy Performance of Buildings Directive (EPBD) ("Umbrella document") [5] EN ISO 9488, Solar energy — Vocabulary (ISO 9488:1999) [6] EN ISO 13790, Thermal performance of buildings — Calculation of energy use for space heating (ISO 13790:2004) [7] EN 13203-2, Gas-fired domestic appliances producing hot water — Appliances not exceeding 70 kW heat input and 300 l water storage capacity — Part 2: Assessment of energy consumption ) 1) To be published 41 BS EN 15316-3-2:2007 British Standards Institution (BSI) BSI is the independent national body responsible for preparing British Standards It presents the UK view on standards in Europe and at the international level It is incorporated by Royal Charter Revisions British Standards are updated by amendment or revision Users of British Standards should make sure that they possess the latest amendments or editions It is the constant aim of BSI to improve the quality of our products and services We would be grateful if anyone finding an inaccuracy or ambiguity while using this British Standard would 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