ISO 50046:2019 pdf free.General methods for predicting energy savings.
4 Objectives, context and principles of calculation of PrES
4.1 Clarifying the objectives
The choice of a calculation method depends substantially on the context and objectives of the calculation of PrES. Before calculating PrES, objectives should be specified as described in SA. Examples of some objectives are:
— arriving at preliminary stage investment decisions (rough estimate to identify EPIA opportunities);
— ranking EPIAs while developing an action plan;
— taking final investment decisions (a detailed or comprehensive estimate is required);
— performance monitoring of an energy management system or an energy performance contract (for further comparison between predicted and actual energy savings).
Benefits, risks, costs or other factors that influence the accuracy, timeliness or cost in calculating the PrES should he considered in making a decision.
Specifying the objectives is important in determining the applicable clauses of this document:
— objective = to determine PrES at the level of an EPIA —‘ Clause 7 does not apply;
— objective = to determine aggregated PrES —‘ all clauses apply.
Annex A provides more details about the main criteria to take into account while using this document.
4.2 Analysing the context
When calculating PrES, two general situations can be considered:
a) in which data are based on a specific context (context-specific data);
b) in which data are based on a general context and independent of a specific context (reference data). Both situations can co-exist, as they are not mutually exclusive. As far as possible, the use of contextspecific data is recommended as it results in higher accuracy. Reference data may he considered when:
— the specific context is not known in advance; or
— many EPIAs are being assessed, which makes it very difficult or costly to collect context-specific data for each EPIA.
The choice between context-specific data and reference data also depends on the calculation objectives (as shown in Figure 2. see also the examples in Table A.1).
The following examples describe situations in which context-specific data, reference data or a combination of both are required:
— context-specific data:
— contract or agreement between a service provider and a customer;
— recommendations of an energy audit;
— assessment of PrES while preparing a project;
— reference data:
— accounting or cre(liting of energy savings for an energy efficiency obligation scheme or energy efficiency port folio standardsll4l;
— impact assessment of a future energy efficiency olicy or programme;
— COrnbiflC(I situations:
— the energy savings of the same EPIA considered by a company can Lw calculated with context- specific data through an energy audit to ascertain the particular energy performance improvement it can bring to the company, and with reference data to ascertain the energy savings that could he credited if the EPIA were reported for an energy efficiency obligation scheme having its OWfl rules for calculation of PrES. In some cases, the PrES can be determined while comparing alternative potential EPIAs. For example, in determining which change(s) or new installation of lighting to designate as the EPIA, an organization might predict the energy savings of several candidate EPIAs. The PrES of the selected EPIA will have already been determined.ISO 50046 pdf download.