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Cost calculation
The technical simulation provides the quantities – heat and electricity, fuel consumption, operating hours, self-consumption and grid supply. The cost calculation evaluates these quantities. Only together do they form a sound basis for decisions, because a technically elegant solution may fail on investment and an inexpensive plant on operating costs.
Cost categories
The usual structure distinguishes four groups. Capital-related costs arise from the investments and are spread over the service life of the respective component – generators, storage, hydraulics, electrical installation, planning and commissioning have very different lifetimes. Consumption-related costs are fuel and electricity purchase costs and follow directly from the simulation. Operation-related costs cover maintenance, repair, chimney sweep, metering and operation; for engine-based plants they are often set as an amount per kilowatt hour generated. In addition there are other costs such as insurance, lease or administration.
Recording in EPOS-Plan
The cost module is divided into investment, operating and energy costs. For every component in the project – heat pump, boiler, CHP, solar thermal, photovoltaics, buffer and battery storage – any number of positions can be recorded, each with amount, unit, service life in years and a range between a favourable and an unfavourable case. The plant costs stored in the technical module can be adopted as planning values at the touch of a button so that design and calculation do not diverge. Totals are shown continuously per component and for the whole project.
Ranges instead of false precision
Cost data are uncertain in early project phases. Recording a favourable and an unfavourable value per position is therefore not a detour but the more honest approach: it shows how robust a decision is. If the ranking of two variants already flips within the range, the decision cannot be made by the calculation but has to rest on other criteria.
Energy prices
For every energy carrier the working price, standing charge and – where applicable – demand price are maintained, together with calorific values, unit conversion and emission factors. Prices can be stored with a validity date so that a traceable history is built up. For electricity, a distinction has to be made between purchase price, avoided purchase through self-consumption and feed-in tariff – these three quantities carry completely different weight in the assessment.
Service lives
The service life determines how strongly an investment burdens the annual costs. Common assumptions are 15 to 20 years for boilers and heat pumps, considerably less for CHP engines and more for hydraulics, storage and distribution networks. Because components with a short life have to be replaced within the observation period, replacement investments belong in the assessment.