Rinnai UK to bring industry together to develop common whole-system SPF method at elementalLONDON
Rinnai UK is calling on the heating industry to work together on a common approach to predicting a whole-system Seasonal Performance Factor (SPF).
The industry already has recognised SPF frameworks, including SEPEMO, but there is currently no single, consistently applied method for predicting and comparing whole-system performance across commercial projects.
The company is convening a roundtable of experts from across the sector at elementalLONDON on 25 November with a brief to examine where current approaches differ and to agree the first steps towards a transparent method that can be applied consistently before a system is installed. This is expected to be followed by creation of an SPF Coalition to continue the work.
With current frameworks, different system boundaries can be used, while variables including weather data, load profiles, flow temperatures, storage losses, controls, backup energy and auxiliary loads can materially affect the result. Without common rules for boundaries, inputs, assumptions and reporting, two models can produce different answers for the same proposed system, the company notes.
Chris Goggin, Operations Director at Rinnai UK, said:
The industry does not need another proprietary calculation that simply gives people another number to compare. An SPF figure is only useful if everyone understands what sits behind it and can have confidence in the way it has been calculated.
Rinnai believes the industry now needs to build on existing work and to agree a method that produces repeatable and comparable results when competent designers are working from the same project data and assumptions.
The company said:
The methodology would need to define areas including the system boundary, calculation period, useful heat output, weather data and treatment of auxiliary and backup energy. Its development should involve consultants, engineers, manufacturers, industry bodies, building operators and independent technical specialists.”
The elementalLONDON discussion is intended to start that process rather than present the industry with a finished answer. Attendees will examine the technical barriers to reliable predicted SPF, discuss what a common method should define and consider how it could be independently validated. Rinnai will also propose the formation of an SPF Coalition to continue the work in 2027, with the outcomes of the roundtable forming the basis of a public report planned for January. The roundtable will focus specifically on the prediction of SPF at design stage and should not be confused with in-use performance verification following installation, the firm added.
Rinnai said:
SPF is an important metric because it can provide a measure of the performance of the complete installed system, rather than the heat pump alone. While COP measures heat pump performance at a defined operating point and SCOP estimates seasonal heat pump performance under standardised assumptions, a clearly defined whole-system SPF can account for pumps, controls, heat exchangers, storage losses, backup heaters and other auxiliary loads. Predicted SPF can therefore give clients and consultants a more complete basis for comparing system designs, energy consumption, operating costs and carbon performance.
Chris added:
We are not asking the industry to accept a Rinnai number or methodology. We are asking the industry to help create a transparent method that any competent consultant can apply, explain and defend. elementalLONDON gives us the opportunity to get the right people around the table and start agreeing how we get there.”
- elementalLONDON takes place on 25 and 26 November at Excel London. For more details and to register, see the button below
