The installed system is the cost
Budgeting must cover the heat pump, heat exchangers, pipework, pumps, buffer storage, electrical works, controls, foundations, acoustic treatment, process modifications, design, commissioning and production downtime. Grid reinforcement can dominate a project where spare electrical capacity is limited.
Operating cost depends on the duty
The central calculation compares the cost of delivered heat, not electricity with gas on a simple per-kWh basis. Seasonal COP, auxiliary loads, electricity tariff, fuel price, boiler efficiency, maintenance, taxes and the value of any simultaneous cooling all belong in the model.
A single brochure COP should not be applied across a year. Model performance at representative source and sink conditions and weight the results by expected hours.
Calculate the cost of useful heat
For each operating interval, divide the electricity price by system COP and add auxiliaries, capacity charges and maintenance. Compare that with fuel price divided by measured or defensible boiler efficiency. When cooling is supplied at the same time, show its avoided cost on a separate line so it cannot be counted twice.
A worked model should show where taxes, network charges and carbon costs enter. Spanish tariff data from the actual site is more useful than an annual national average.
Capital boundaries that often disappear
Electrical reinforcement, heat-source capture, process-side exchangers, storage, civils, noise control, water treatment, controls, design, commissioning and production downtime may sit outside an equipment quotation. State estimate class and exclusions. Do not present a vendor budget as total installed cost.
Treat savings as a range
Capital and energy prices are site-specific and change over time. A useful decision model tests high and low energy-price cases, reduced operating hours, lower source temperature, outages and delayed grid work. CAE revenue or grant support should be shown separately so the project remains understandable without it.
A transparent operating-cost example
For a simple screening comparison, assume electricity costs €100/MWh and the heat pump achieves a system COP of 3.5. Compressor and included auxiliary electricity then costs about €28.60 for each MWh of useful heat before fixed charges and maintenance. If gas costs €40/MWh and the displaced boiler is 85% efficient, fuel alone costs about €47.10 per MWh of useful heat.
Those figures are arithmetic examples, not Spanish market benchmarks. The site model must use its contracted electricity structure, actual fuel invoices, measured boiler efficiency and the selected heat pump's performance. Capacity charges, taxes and the value of simultaneous cooling can materially alter the comparison.
Payback is sensitive to annual heat
Installed cost is often quoted in euros per kilowatt while savings arise from megawatt-hours delivered. A well-used 1 MW system can produce several times the annual heat of a machine serving a short batch process. Comparing equipment prices without operating hours says little about payback.
The annual model should apply the expected load profile and planned outages. It should also show the cost of retained boiler capacity, because a hybrid plant can continue paying fixed fuel-system costs even when annual gas consumption falls.
Separate the estimate classes
An early screening allowance may be suitable for comparing concepts. It is not a construction budget. Concept design should replace allowances with defined pipe routes, exchanger duties, electrical scope, civils, controls and shutdown requirements. Supplier quotations should be normalised to one scope before they are compared.
Contingency should reflect unresolved work rather than compensate for missing boundaries. If the grid study, hazardous-area classification or production shutdown has not been completed, list it as an open risk with an owner and decision date.
Sources
Primary and authoritative sources used for the material claims on this page.