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Application examples

The following examples show how typical tasks are modelled in EPOS-Plan: which modules you need, which inputs are decisive, what to watch out for when sizing and which result figures carry the actual message. The figures quoted are orders of magnitude for orientation and do not replace an object-specific calculation.

Single-family house with a heat pump

Situation. An existing house built in 1985 with around 160 m² of living space is to be converted from an oil boiler to an air-to-water heat pump. The bill shows 2,400 litres of heating oil per year, the radiators are designed for 55 °C flow temperature, and a partial replacement with underfloor heating is under discussion.

Approach. Create the project with the building blocks building, hot water and heat pump and select the climate region. Filter the building catalogue for residential buildings and the construction period 1984–1994. Instead of the floor area, enter the oil consumption as the reference quantity; EPOS-Plan converts it into useful heat using the annual utilisation ratio of the old boiler and scales the building model accordingly. Add hot water demand with a typical 12 to 15 kWh per square metre and year, or roughly 500 kWh per person and year.

Sizing. Filter the catalogue for air/water, modulating control and a flow temperature range that includes 55 °C. What matters is using the performance map for the correct flow temperature: between 35 and 55 °C the same machine easily differs by 30 % in coefficient of performance. Enable the back-up heater and set parallel or partially parallel operation. Calculate both variants – 55 °C as built and 40 °C after replacing the radiators – and compare.

What to look at. The share of the back-up heater in annual heat, the bivalence point and the full-load hours. A back-up share above roughly five per cent indicates an undersized machine or too high a flow temperature. The chart of output over ambient temperature shows immediately from which temperature the heat pump can no longer cover demand on its own. If utility lock-out periods apply, enter them – they shift the bivalence point noticeably.

Apartment building

Situation. A building with 18 flats and about 1,400 m² of living space, high year-round hot water demand, a circulation line and roughly 300 m² of roof available for photovoltaics.

Approach. In addition to building and hot water, activate heat pump, buffer tank, photovoltaics, battery storage and the electricity consumers for common areas. Hot water can account for a third of the annual heat and completely determines summer operation, so set it carefully and include the circulation losses – experience shows they are of the same order as the useful hot water itself.

Sizing. Assign a buffer tank to the heat pump and define the switching thresholds. In summer the simulation then shows the intended behaviour: the machine runs in cycles, charges the tank and stays off until the switch-on threshold is undercut again. With two heat pumps, give them different priorities – a smaller machine for hot water with the heat sink “hot water” and a larger one for space heating is a proven split.

What to look at. Calculate the battery in several sizes and watch in the self-sufficiency analysis when the gain in self-consumption flattens – usually well below the capacity a rule of thumb based on daily consumption would suggest. Check whether the PV-optimised operating mode of the heat pump raises self-consumption further by running the machine at midday and using the tank as thermal storage.

Office building

Situation. An office building with 4,500 m² of usable area, operation on weekdays from 7 a.m. to 6 p.m., low hot water demand and high electricity demand from lighting, IT and ventilation.

Approach. Choose a non-residential building; for this class EPOS-Plan uses daily distribution curves by season and cloud cover that reflect weekday operation. The decisive inputs are the usage conditions: night setback, weekend setback and holiday or shutdown periods. Electricity demand is recorded through consumer types; if a quarter-hourly load profile from the grid operator is available, import it – for office buildings this is by far the most reliable basis.

Sizing. The typical combination is heat pump plus photovoltaics. The advantage lies in simultaneity: unlike in residential buildings, electricity demand occurs exactly when the sun shines, so high self-consumption is achieved without a large battery. Calculate the variant without storage first and add it only if the self-sufficiency analysis shows a worthwhile gain.

What to look at. Heat load is strongly shaped by internal gains and weekend setback; watch the Monday morning peaks that determine the required generator output. The load duration curve is worth a look: a few hundred hours a year define the peak load – the classic argument for a small base-load generator plus a peak-load boiler.

Swimming pool

Situation. An indoor pool with a 25-metre pool and a teaching pool. Heat demand consists of pool water heating, evaporation losses, ventilation heat, shower hot water and space heating – and is almost constant throughout the year.

Approach. The characteristic feature is the high, steady base load. Model it through the process heat module: enter monthly values for pool heating and evaporation and a weekly profile reflecting opening hours and night covers. Record shower hot water separately with pronounced daily peaks, and space heating through the building module with the elevated set temperatures of the pool hall.

Sizing. Precisely this flat demand curve makes the swimming pool the classic case for a heat-led CHP unit: high full-load hours are the prerequisite for economic operation, and a pool reaches them easily. Add a peak-load boiler and assign a buffer tank to both generators so that the CHP does not cycle. Alternatively or additionally, a heat pump using the ventilation exhaust as its source can be calculated – enter a source profile or a constant source temperature instead of ambient air.

What to look at. Check the operating hours of the CHP and the heat surplus. If heat has to be rejected, the module is too large or the buffer too small. Compare heat-led with electricity-led operation; in a pool with high in-house electricity demand for pumps and ventilation the latter can be economically favourable.

Industrial plant with process heat

Situation. A manufacturing company on two shifts needs process heat at two temperature levels, plus hall heating and a high, steady electricity demand. The question is which share can be electrified and whether a CHP unit remains economical.

Approach. Record process heat through dedicated process types with monthly values and a weekly profile that reflects shift operation – two shifts from Monday to Friday produce a completely different profile than a continuous process and lead to different generator sizes. Create a separate entry for each temperature level. Hall heating comes from the building module, electricity demand ideally from the measured quarter-hourly load profile.

Sizing. Configure the generators as a cascade: first the base-load generator – CHP or high-temperature heat pump –, then the boiler for the peaks. For the heat pump the available heat source determines economics; where process waste heat is available, enter it as a constant source temperature or source profile and use the regeneration rate to model its limited availability.

What to look at. Watch the residual heat demand at the end of the cascade – it shows whether the design carries the peaks. The CSV export is particularly useful here because process and space heating can be evaluated separately and compared with operating data. For electrified processes, check the effect on the grid connection capacity: the annual peak of electricity demand rises considerably with heat pumps and electric boilers.

District with a heat network

Situation. Several buildings of different age and use are to be supplied through a local heat network from a common energy centre.

Approach. Create every building as its own entry – with its own construction period, area or consumption. EPOS-Plan adds the hourly profiles, so simultaneity is modelled realistically instead of being estimated with a blanket diversity factor. Enter network losses as a percentage or as an annual figure; they are distributed evenly over the year and directly affect generator sizing.

Sizing. In the energy centre you define the order of the generators, usually heat pump or CHP for base load, solar thermal as a supplement and a boiler for the peaks. The central buffer tank is assigned to the base-load generators and managed through the switching thresholds.

What to look at. Compare the aggregated annual profile with the sum of the individual peaks – the difference is the real benefit of the network and justifies a smaller generator. Also watch how strongly network losses raise the summer load; they determine whether summer operation of the base-load generator is still worthwhile.

Commercial site with photovoltaics and storage

Situation. A trade or manufacturing business with workshop and offices, high daytime electricity demand, a hall with heating demand and a large, well-oriented roof.

Approach. The measured load profile is the most important input here; a single year of quarter-hourly values from the grid operator improves the result considerably compared with a standard profile. Model the PV system with the real number of modules, tilt and azimuth, if necessary in several sub-arrays for east and west roofs, which spreads generation over the day and raises self-consumption.

Sizing. Calculate the pure PV system first and read off self-consumption and surplus. Then add battery storage and heat pump step by step. The PV-optimised operating mode of the heat pump shifts heat generation into the midday hours and uses buffer and building mass as storage – often cheaper than additional battery capacity.

What to look at. Self-consumption ratio and self-sufficiency matter, not the annual yield of the system. A look at a single summer day in the electricity chart shows clearly how generation, direct use, battery charging and feed-in interact.

Hotel and care home

Situation. Accommodation or care with high year-round hot water demand, circulation, elevated hygiene requirements for storage temperature and steady electricity demand for kitchen, laundry and ventilation.

Approach. The focus is on domestic hot water. Choose a type with a suitable daily profile – in a hotel with a pronounced morning peak, in a care home more evenly spread – and set the annual consumption including circulation losses. Add space heating through the building module.

Sizing. The high temperature requirement calls for a combination: a heat pump covers space heating and hot water preheating, a second generator handles the final heating. In EPOS-Plan this is modelled through the heat sinks – one machine with the sink “space heating”, a second with “hot water”, each with its own flow temperature and priority. The steady demand also makes the building a good case for a CHP unit.

What to look at. Watch summer operation: when only hot water is required, storage management decides whether the generators run sensibly or cycle. The separate display of space heating and hot water in the demand chart shows the situation immediately.

School and sports hall

Situation. A school building with an attached sports hall, lessons on weekdays, pronounced holiday periods and hall use by clubs in the evening and at weekends.

Approach. This is where the holiday management of the building module pays off: four freely definable holiday periods with their own setback temperature reflect real operation. Create school building and sports hall as separate buildings because usage times and set temperatures differ. Record the hall showers with a separate hot water type with evening peaks.

Sizing. The strongly fluctuating load with pronounced reheating peaks after weekends and holidays is the real challenge. A buffer tank smooths the peaks and allows a smaller base-load machine; calculate several storage sizes and watch the effect on the required peak boiler output.

What to look at. The key figure “minimum peak boiler output” in the heat pump result area shows the reserve actually needed. Also check whether the reheating peaks can be reduced by raising the set temperature earlier – in the model this can be traced directly through the setback times.

Recommended procedure for your own projects

Regardless of the application, the same sequence has proven itself. Start with demand and check it against known consumption data before adding technology – a demand that is twenty per cent wrong renders every subsequent design worthless. Then calculate a simple reference variant, for instance boiler only, to have a basis for comparison. Add the components one by one and observe which key figure changes how; this keeps the contribution of each building block traceable. Only once the technical design is settled should you enter investment, operating and energy costs, because then the quantities they refer to are fixed.