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EPOS-Plan at a glance

EPOS-Plan is planning software for the integrated design of heating and power supply systems. It addresses engineering offices, energy consultants, municipal utilities, planning departments in industry and housing associations as well as universities. The program models a complete energy system in a single model: the heat demand of buildings, hot water and processes, the electricity demand, the generation technology from heat pumps through boilers, CHP units and solar thermal to photovoltaics, and the thermal and electrical storage. On this basis EPOS-Plan simulates a full year in hourly steps and shows how the planned configuration actually behaves.

The decisive difference from a simplified design method lies in this time resolution. Only when demand and generation are compared hour by hour does it become visible how large the share of the back-up heater really is in February, how many operating hours a heat pump achieves at its design point, how much solar power remains unused in summer and from which storage size self-consumption can no longer be increased appreciably. These are the questions that decide about investment, eligibility for funding and operating costs.

What the software does

Determining energy demand. Heat demand can be calculated from building characteristics, derived from existing consumption data or imported as a measured load profile. Hot water and process heat are added through monthly values and type-specific weekly profiles, electricity demand through consumer profiles or an imported quarter-hourly load profile.

Sizing the plant. Heat pumps, boilers, CHP modules, solar collectors, photovoltaic modules, buffer tanks and battery storage are selected from supplied manufacturer catalogues or created as own data sets. Sizing uses the real performance maps of the devices, not blanket efficiencies.

Simulating operation. An annual simulation with 8,760 hourly values on the heat side and 35,040 quarter-hourly values on the electricity side maps the generator cascade in the order you define, including storage management, lock-out periods and operating strategies.

Assessing results. Coverage, bivalence point, full-load hours, annual utilisation ratios, fuel consumption, self-consumption, self-sufficiency and CO₂ savings are available as key figures, charts and tables and can be exported as CSV files.

Recording costs. Investment, operating and energy costs are stored per component with service life and price history and thus provide the input for the economic assessment.

Easy to use

EPOS-Plan guides new projects through a wizard. At the beginning you select which components your project contains at all; all steps that are not needed are skipped. The start page then shows a tile for every building block, highlighted as soon as data are available. This makes it clear at any time what is still missing, and you can switch between the areas in any order.

Extensive master data catalogues take away most of the input work: building types with construction periods, hot water and process heat profiles, electricity consumer profiles, heat pumps with complete performance maps, boilers, CHP modules, collectors, PV modules and storage. What you change in the project never affects the catalogue, because a project-specific copy is always created. Climate data are fetched by the program on request: you enter a place name, EPOS-Plan determines the coordinates and downloads a complete climate data set.

Help is available wherever it is needed. Moving the mouse over an input field shows a short hint with a reference to the matching chapter of this online documentation. In addition a help assistant can be opened that knows the area you are working in and answers questions on operation and on the calculation logic.

Using the assistant is optional. Searching the built-in help is free of charge, runs without an internet connection and transmits nothing. For freely worded answers you store your own access key for the language model service; billing runs directly with its provider, and 50 requests per workstation and day are possible. Only your question, the name of the program area and extracts from the help texts are transmitted – project and customer data, simulation results and file paths stay on your computer. Before the first request the program presents a legal notice, and the function can be switched off completely.

What you can control. The switches are in the chat window: Search only restricts the assistant to the built-in help without any transmission. Allow actions is what releases steps in the program in the first place – underneath it you can always see what leaves your computer in the current state. Via Tools… you carry out an action yourself, without the language model being involved: pick it from the list, enter the details, start it. What is being sent? shows the exact text that would be transmitted before you send it, and Show log lists every action with time and result, including the rejected ones. Under Settings… you store the access key, view the fixed daily limit and have the language model re-detected if needed; for models without tool support there is a fallback in which the assistant proposes actions in the answer text instead of calling them itself. The assistant can be switched off completely under Administration › Settings.

On request the assistant also carries out individual steps in the program, from listing the variants to creating a variant or setting a cost amount. These actions have to be enabled separately; anything that changes data is carried out only after your explicit confirmation, supplied catalogues stay locked, nothing is deleted, and a backup copy of the database is made before the first change of a session. Bear in mind that answers from a language model can be incomplete or wrong: check every preview before confirming it, and leave the actions switched off if you use the assistant only to look things up.

Program workflow

A project passes through seven stages in EPOS-Plan. The order is not mandatory, but it has proven itself in practice because every stage builds on the results of the previous one. A more detailed description is given under Program workflow.

Step 1: Create a project

The wizard starts via Projects › New or the tile New project. On the first page you define by ticking which building blocks the project comprises – building, external heat demand, process heat, electricity consumers, electricity load profile, heat pump, boiler, CHP, solar thermal, photovoltaics and battery storage. On the following page you enter project name, person in charge, client and description and select the climate region. Project name and climate region are mandatory, everything else can be added later.

Step 2: Define the climate region

Every project is assigned to exactly one climate region. A climate data set contains the ambient temperature, the global, direct and diffuse irradiance and the derived solar positions for all 8,760 hours of the year. In the climate data management you either enter coordinates directly or select a place; the program determines the geo-coordinates and then downloads a typical meteorological year (TMY) from the European PVGIS database – separately for the orientations south, east, west and north, so that window gains as well as collector and PV yields can later be calculated depending on orientation.

Step 3: Record the heat demand

Heat demand consists of up to four components that are recorded separately and then added hour by hour: building space heating, hot water, process heat and, if available, an externally imported load profile. In addition, network losses can be added either as a percentage or as an absolute annual figure.

For building space heating you select a building from the catalogue, filtered by residential or non-residential use, building type and construction period. If consumption data are available instead of areas, you enter them directly: oil in litres per year, gas in cubic metres or megawatt hours, general fuel in megawatt hours. EPOS-Plan converts the consumption into useful heat taking the annual utilisation ratio of the previous plant into account and scales the building model so that it reproduces exactly this demand.

From the building characteristics the program calculates, for each of the 365 days, the solar gains through the window areas, the specific transmission and ventilation losses and, taking the thermal mass and the configured setbacks into account, the daily heat load. Each daily value is then distributed to hourly values via a type-dependent 24-hour distribution curve.

Step 4: Record the electricity demand

Electricity demand is built in the same way from consumer types with monthly values and 168-hour weekly profiles. Because hourly resolution is too coarse for self-consumption considerations, EPOS-Plan converts the profile to quarter hours and works internally with 35,040 values per year. Measured load profiles can be imported and are fitted automatically depending on their time raster.

Step 5: Select generators and storage

In this step you equip the project with technology. For every device category a catalogue with manufacturer data is available from which you select using filters and search; the design data of the selected device are then completed for the project.

Step 6: Configure and start the simulation

In the Simulation configuration dialogue you define which generators take part in covering demand and in which order they are called upon. Four selection fields are available for the heat generators – heat pump, boiler, CHP and solar thermal – plus one field each for photovoltaics and battery storage. The order of the fields is the priority.

A separate section is dedicated to the buffer tank. Here you assign storage to the selected generators and define flow and return temperature as well as the switch-on and switch-off thresholds of the storage management. An overview table on the right continuously shows all selected generators with the corresponding plants of the project. For heat pumps, priority, heat source, heat sink and operating mode can be set there by double-clicking.

Step 7: Evaluate results and record costs

After starting the simulation the results are available in a multi-level evaluation – first as an overview of the coverage, then separated by generator with annual profiles, key figures and module tables. All time series can be exported as CSV files. In parallel you record investment, operating and energy costs in the cost module so that the technical and economic assessment rest on the same data.

Variants and report

A project and the variants derived from it form a comparison group. Variants are created from the open base project through the menu entry Save as variant… and carry their own data records, so that changes do not act back on the base. From such a group EPOS-Plan produces a Word comparison report with cover sheet, table of contents, project description, component matrix including the deviations per variant, results per variant, comparison of variants with difference tables and an appendix with simulation states and methodology, plus an Excel workbook with key figure, comparison and detail sheets. Embedded are pie and bar charts as well as annual heat profile, load duration curve, monthly electricity balance and storage level. Every report run simulates all selected projects afresh beforehand and then calculates their economics; for three projects around 35 seconds are to be expected. The sections are configurable per report, the output is in German or English, and the Word template can be adapted to your own corporate design. An Office installation is required for neither of the two files.

Economic analysis

The economic analysis assesses the entire comparison group by the net present value method in accordance with DIN EN 17463 and reports net present value, annuity and present values, including replacement investment and a residual value determined on a linear basis. The base project is the reference; the key figures of the variants are differences against it – net present value difference, dynamic payback period and internal rate of return. The calculation is carried out in three scenarios – expected, best and worst case – complemented by sensitivities for the discount rate and the energy price escalation (one percentage point each) as well as investment and energy costs (ten per cent each). Taken into account are the bonus rules of the German CHP Act (KWKG) 2025, the CO₂ levy under the German Fuel Emissions Trading Act for fossil fuels and an electricity matrix of high and low tariff for winter and summer. The emission balance compares combined and separate generation and reports the amount of CO₂ avoided. The net present value over time is shown by a line chart with a freely selectable period from 2 to 60 years. All results appear on screen, in the Word report and in the Excel report.

Industry and commerce

EPOS-Plan is not limited to residential buildings. In industry and commerce in particular, the time resolution decides whether a design holds up: production runs in shifts, process heat occurs at several temperature levels, and electricity demand determines both the grid connection capacity and the benefit of a photovoltaic system. Buildings, processes and the electricity side are therefore recorded separately and then balanced together.

Commercial and industrial buildings

Production halls, workshops, office wings and warehouses are recorded as non-residential buildings. For this class EPOS-Plan uses daily distribution curves by season and cloud cover that reflect weekday operation. Besides geometry and U-values, the decisive inputs are the usage conditions: operating hours, night and weekend setback, shutdown periods and the set room temperature, which in a production hall is often considerably lower than in an office. The increased air change caused by hall doors, extraction systems and process ventilation is modelled through the air change rate; internal gains from machinery and lighting noticeably reduce the heating demand and have to be taken into account. Mixed-use objects – heated hall, tempered storage area and office wing – are created as separate buildings because usage times and set temperatures differ.

Process heat

Process heat is recorded independently of the building. For every temperature level and every process you create a separate entry with annual consumption, monthly distribution and a weekly profile of 168 hourly values – this profile is effectively the shift schedule. Two shifts from Monday to Friday produce a completely different picture than a continuous process and lead to different generator sizes. Separating temperature levels is decisive because it determines which technology is feasible at all: baths, cleaning and preheating processes up to about 60 °C are accessible to heat pumps, drying and steam generation above that generally are not.

Where waste heat from refrigeration plants, air compressors, injection moulding machines or exhaust air is available, it can be defined as the heat source of the heat pump – as a constant source temperature, as a source profile from monthly and weekly values or as an imported temperature profile. The adjustable regeneration rate models the fact that waste heat is available only to a limited extent and only during production hours.

Electricity demand and load profile

In industry and commerce the measured quarter-hourly load profile is the most reliable input; one year of metering data from the grid operator improves the result considerably compared with any standard profile. EPOS-Plan works internally in 35,040 quarter-hourly values anyway. This answers three questions that arise regularly in commercial projects: which share of a photovoltaic system is actually consumed on site because production and sunshine coincide? How much does the annual peak load rise when processes are electrified – and is the existing grid connection still sufficient? And is a CHP unit in electricity-led operation worthwhile because on-site electricity demand is high all year round?

Typical applications

Bakery and food trade. Ovens and refrigeration run in the early morning hours when there is no sunshine – the waste heat from ovens and refrigeration, however, is available all year. It is defined as a heat source and covers hot water and space heating through a heat pump; electricity demand is taken from the measured load profile because the pattern deviates strongly from any standard curve.

Laundry. Washing at 60 to 90 °C and drying create a high, steady heat demand throughout the year – the classic case for a CHP unit with high full-load hours or for a high-temperature heat pump using waste water heat recovery as its source. Record washing and drying as separate process entries because they operate at different temperature levels.

Metalworking and electroplating. Heated baths at 50 to 70 °C form a constant base load that can be covered well by a heat pump; hardening and drying lie above that and remain with the boiler. Separate process entries per temperature level make visible which share can be electrified.

Plastics processing. Injection moulding machines release waste heat at a low level of 35 to 45 °C. As the source of a heat pump this yields high coefficients of performance and covers hall heating and hot water; in the simulation the availability is limited to production hours through the regeneration setting.

Painting and drying. Heat demand arises mainly from heating large volumes of supply air and therefore follows ambient temperature and operating hours directly. The weekly profile represents shift operation, the ventilation heat is recorded as a separate process entry.

Warehousing and logistics. Low heat demand with large roof areas: here photovoltaics take centre stage. With the measured load profile of conveyors, refrigeration and charging infrastructure, self-consumption can be determined reliably and a sensible storage size narrowed down.

A fully worked case with two temperature levels, hall heating and shift operation is available under Examples, where further commercial applications are described as well.