Commission Delegated Regulation (EU) 2019/331Show full title

7.2. Methodologies for determining net amounts of measurable heat U.K.

For the purpose of selecting data sources for quantification of energy flows in accordance with section 4.5, following methodologies for determining net amounts of measurable heat shall be considered:

Method 1: Using measurements U.K.

Under this method, the operator measures all relevant parameters, in particular temperature, pressure, state of the transmitted as well as the returned heat medium. The state of the medium in case of steam shall refer to its saturation or degree of superheating. The operator furthermore measures the (volumetric) flow rate of the heat transfer medium. Based on the measured values, the operator determines the enthalpy and the specific volume of the heat transfer medium using suitable steam tables or engineering software.

The mass flow rate of the medium is calculated as

(Equation 3)

Where ṁ is the mass flow rate in kg/s, V is the volumetric flow rate in m³/s and υ is the specific volume in m³/kg.

As the mass flow rate is considered the same for transmitted and returned medium, the heat flow rate is calculated using the difference in enthalpy between the transmitted flow and the return, as follows:

= (hflow – hreturn ) · ṁ

(Equation 4)

Where Q is the heat flow rate in kJ/s, h_flow is the enthalpy of the transmitted flow in kJ/kg, h_return is the enthalpy of the return flow in kJ/kg, and ṁ is the mass flow rate in kg/s.

In case of steam or hot water used as heat transfer medium, where the condensate is not returned, or where it is not feasible to estimate the enthalpy of the returned condensate, the operator shall determine h_return based on a temperate of 90 °C.

If the mass flow rates are known to be not identical, the following shall apply:

• Where the operator provides evidence to the satisfaction of the competent authority that condensate remains in the product (e.g. in ‘life steam injection’ processes), the respective amount of condensate enthalpy is not deducted;

• Where heat transfer medium is known to be lost (e.g. due to leakages or sewering), an estimate for the respective mass flow shall be deducted from the mass flow of the transmitted heat transfer medium.

For determining the annual net heat flow from the above data, the operator shall – subject to the measurement equipment and data processing available, use one of the following methods:

• Determine annual average values for the parameters determining the annual average enthalpy of the transmitted and returned heat medium, and multiply with the total annual mass flow, using equation 4;

• Determine hourly values of the heat flow and sum up those values over the annual total operating time of the heat system. Subject to the data processing system, hourly values may be substituted by other time intervals as appropriate.

Method 2: Using documentation U.K.

The operator determines net amounts of measurable heat based on documents in accordance with section 4.6 of this Annex, provided that heat quantities provided in such documents are based on metering, or on reasonable estimation methods in accordance with section 3.4 of this Annex.

Method 3: Calculation of a proxy based on measured efficiency U.K.

The operator determines amounts of net measurable heat based on the fuel input and the measured efficiency related to the heat production:

Q = ηH · EIN	(Equation 5)
EIN = Σ ADi · NCVi	(Equation 6)

Where Q is the amount of heat expressed in TJ, η_H is the measured efficiency of heat production, E_IN is the energy input from fuels, AD_i are the annual activity data (i.e. quantities consumed) of fuels i, and NCV_i the net calorific values of fuels i.

The value of η_H is either measured by the operator over a reasonably long period, which sufficiently takes into account different load states of the installation or taken from the manufacturer's documentation. In that regard the specific part load curve is to be taken into account by using an annual load factor:

LF = EIN /EMax

(Equation 7)

Where L_F is the load factor, E_IN the energy input as determined using Equation 6 over the calendar year, and E_Max  the maximum fuel input if the heat producing unit had been running at 100 % nominal load for the full calendar year.

The efficiency should be based on a situation in which all condensate is returned. A temperature of 90 °C should be assumed for the returned condensate.

Method 4: Calculating a proxy based on the reference efficiency U.K.

This method is identical to method 3, but using a reference efficiency of 70 % (η_Ref,H = 0,7) in Equation 5.