ANNEX IISupplementary provisions
ANNEX II MEASUREMENTS AND CALCULATIONS 1. Definitions for the purposes of Annex II (1) ‘Inlet stagnation volume flow rate’ (q) is the volume of gas that passes through the fan per unit of time (in m 3 /s) and is calculated on the basis of the mass of gas moved by the fan (in kg/s) divided by the density of this gas at the fan inlet (in kg/m 3 ). (2) ‘Compressibility factor’ is a dimensionless number that describes the amount of compressibility that the gas stream experiences during the test and is calculated as the ratio of the mechanical work done by the fan on the gas to the work that would be done on an incompressible fluid with the same mass flow, inlet density and pressure ratio, taking into account the fan pressure as ‘total pressure’ (k p ) or ‘static pressure’ (k ps ). (3) k ps means compressibility coefficient for the calculation of fan static gas power. (4) k p means compressibility coefficient for the calculation of fan total gas power. (5) ‘Final assembly’ means a finished or assembled on-site assembly of a fan that contains all the elements to convert electric energy into fan gas power without the need to add more parts or components. (6) ‘Not final assembly’ means an assembly of fan parts, consisting of at least the impeller, which needs one or more externally supplied components in order to be able to convert electric energy into fan gas power. (7) ‘Direct drive’ means a driving arrangement for a fan where the impeller is fixed to the motor shaft, either directly or with a co-axial coupling, and where the impeller speed is identical to the motor’s rotational speed. (8) ‘Transmission’ means a driving arrangement for a fan which is not ‘direct drive’ as defined above. Such driving arrangements may include transmissions using a belt-drive, gearbox or slipping coupling. (9) ‘Low-efficiency drive’ means a transmission using a belt whose width is less than three times the height of the belt or using some other form of transmission apart from a ‘high-efficiency drive’. (10) ‘High-efficiency drive’ means a transmission using a belt whose width is at least three times the height of the belt, a toothed belt or using toothed gears. 2. Measurement method For the purposes of compliance and verification of compliance with the requirements of this Regulation, measurements and calculations must be made using a reliable, accurate and reproducible method, which takes into account the generally recognised state-of-the-art measurement methods, and whose results are deemed to be of low uncertainty, including methods set out in documents the reference numbers of which have been published for that purpose in the Official Journal of the European Union . 3. Calculation method The methodology for calculating the energy efficiency of a specific fan is based on the ratio of gas power to electrical input power to the motor, where fan gas power is the product of gas volume flow rate and pressure difference across the fan. The pressure is either the static pressure or the total pressure, which is the sum of static and dynamic pressure depending upon the measurement and efficiency category. 3.1. Where the fan is supplied as a ‘final assembly’, measure the gas power and the electric input power of the fan at its optimum energy efficiency point: (a) where the fan does not include a variable speed drive, calculate the overall efficiency using the following equation: η e = P u(s) / P e where: η e is the overall efficiency; P u(s) is the fan gas power, determined according to point 3.3, of the fan when it is operating at its optimal energy efficiency point; P e is the power measured at the mains input terminals to the motor of the fan when the fan is operating at its optimal energy efficiency point; (b) where the fan includes a variable speed drive, calculate the overall efficiency using the following equation: η e = (P u(s) / P ed ) · C c where: η e is the overall efficiency; P u(s) is the fan gas power, determined according to point 3.3, of the fan when it is operating at its optimal energy efficiency point; P ed is the power measured at the mains input terminals to the variable speed drive of the fan when the fan is operating at its optimal energy efficiency point; C c is a part load compensation factor as follows: — for a motor with a variable speed drive and P ed ≥ 5 kW, then C c = 1,04, — for a motor with a variable speed drive and P ed < 5 kW, then C c = – 0,03 ln(P ed ) + 1,088. 3.2. Where the fan is supplied as ‘not final assembly’, the fan overall efficiency is calculated at the impeller’s optimum energy efficiency point, using the following equation: η e = η r · η m · η T · C m · C c where: η e is the overall efficiency; η r is the fan impeller efficiency according to P u(s) / P a where: P u(s) is fan gas power determined at the point of optimal energy efficiency for the impeller and according to point 3.3 below; P a is the fan shaft power at the point of optimal energy efficiency of the impeller; η m is the nominal rated motor efficiency in accordance with Regulation (EC) No 640/2009 whenever applicable. If the motor is not covered by Regulation (EC) No 640/2009 or in case no motor is supplied a default η m is calculated for the motor using the following values: — if the recommended electric input power ‘Pe’ is ≥ 0,75 kW, η m = 0,000278*(x 3 ) – 0,019247*(x 2 ) + 0,104395*x + 0,809761, where x = Lg (P e ), and P e is as defined in 3.1(a), — if the recommended motor input power ‘Pe’ is < 0,75 kW, η m = 0,1462*ln(P e ) + 0,8381, and P e is as defined in 3.1(a), where the electric input power Pe recommended by the manufacturer of the fan should be enough for the fan to reach its optimum energy efficiency point, taking into account losses from transmission systems if applicable. η T is the efficiency of the driving arrangement for which the following default values must be used: — for direct drive η T = 1,0; — if the transmission is a low-efficiency drive as defined in 1(9) and — P a ≥ 5 kW, η T = 0,96, or — 1 kW < P a < 5 kW, η T = 0,0175 * Pa + 0,8725, or — P a ≤ 1 kW, η T = 0,89, — if the transmission is a high-efficiency drive as defined in 1(10) and — P a ≥ 5 kW, η T = 0,98, — or 1 kW < P a < 5 kW, η T = 0,01 * Pa + 0,93, or — P a ≤ 1 kW, η T = 0,94. C m is the compensation factor to account for matching of components = 0,9; C c is the part load compensation factor: — for a motor without a variable speed drive C c = 1,0, — for a motor with a variable speed drive and P ed ≥ 5 kW, then C c = 1,04, — for a motor with a variable speed drive and P ed < 5 kW, then C c = – 0,03 ln(P ed ) + 1,088. 3.3. The fan gas power, P u(s) (kW), is calculated according to the measurement category test method chosen by the fan supplier: (a) where the fan has been measured according to measurement category A, fan static gas power P us is used from the equation P us = q · p sf · k ps ; (b) where the fan has been measured according to measurement category B, fan gas power P u is used from the equation P u = q · p f · k p ; (c) where the fan has been measured according to measurement category C, fan static gas power P us is used from the equation P us = q · p sf · k ps ; (d) where the fan has been measured according to measurement category D, fan gas power P u is used from the equation P u = q · p f · k p . 4. Methodology for calculating the target energy efficiency The target energy efficiency is the energy efficiency a fan from a given fan type must achieve in order to comply with the requirements set out in this Regulation (expressed in full percentage points). The target energy efficiency is calculated by efficiency formulas that include the electrical input power P e(d) and the minimum efficiency grade as defined in Annex I. The complete power range is covered by two formulas: one for fans with an electric input power from 0,125 kW up to and including 10 kW and the other for fans above 10 kW up to and including 500 kW. There are three series of fan types for which energy efficiency formulas are developed to reflect the different characteristics of various fan types: 4.1. The target energy efficiency for axial fans, centrifugal forward curved fans and centrifugal radial bladed fans (axial fan within) is calculated using the following equations: Power range P from 0,125 kW to 10 kW Power range P from 10 kW to 500 kW η target = 2,74 · ln(P) – 6,33 + N η target = 0,78 · ln(P) – 1,88 + N where the input power P is the electrical input power P e(d) and N is the integer of the energy efficiency grade required. 4.2. The target energy efficiency for centrifugal backward curved fans without housing, centrifugal backward curved fans with housing and mixed flow fans is calculated using the following equations: Power range P from 0,125 kW to 10 kW Power range P from 10 kW to 500 kW η target = 4,56 · ln(P) – 10,5 + N η target = 1,1 · ln(P) – 2,6 + N where the input power P is the electrical input power P e(d) and N is the integer of the energy efficiency grade required. 4.3. The target energy efficiency for cross flow fans is calculated using the following equations: Power range P from 0,125 kW to 10 kW Power range P from 10 kW to 500 kW η target = 1,14 · ln(P) – 2,6 + N η target = N where the input power P is the electrical input power P e(d) and N is the integer of the energy efficiency grade required. 5. Applying the target energy efficiency The fan overall efficiency η e calculated according to the appropriate method in Section 3 of Annex II must be equal to or greater than the target value η target set by the efficiency grade to meet the minimum energy efficiency requirements.