Division 4 Methodology for calculating the target energy efficiency
United Kingdom
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 Pe(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 ηtarget = 2,74 · ln(P) – 6,33 + N ηtarget = 0,78 · ln(P) – 1,88 + N where the input power P is the electrical input power Pe(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 ηtarget = 4,56 · ln(P) – 10,5 + N ηtarget = 1,1 · ln(P) – 2,6 + N where the input power P is the electrical input power Pe(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 ηtarget = 1,14 · ln(P) – 2,6 + N ηtarget = N where the input power P is the electrical input power Pe(d) and N is the integer of the energy efficiency grade required.