Emissions

The emission balance is part of the evaluation and rests on the same quantities as the cost calculation: on the fuel consumption and the grid supply from the annual simulation. They are valued with the emission factors of the energy carriers involved; reported are carbon dioxide (CO₂), sulphur dioxide (SO₂), nitrogen oxides (NOx), carbon monoxide (CO) and particulates. There is no separate input for this – the balance arises from the simulation result and the master data and changes with every change to the design.

Emission factors in the master data

The factors belong to the energy carrier and are maintained under Administration › Energy carriers and cost parameters – together with working, standing and demand price, net and gross calorific value and the unit conversion. Every status carries a validity date, so that it remains traceable which factors a statement is based on. Factory data sets are write-protected; own factors are created alongside them.

With the factor you also determine the system boundary: it can cover the direct emissions on site alone or include the upstream chain of supply. More important than this choice is to make it uniformly for all energy carriers – otherwise a boiler with an upstream chain competes against a heat pump without one. The electricity mix carries particular weight: the factor of the energy carrier electricity determines the entire electricity side of the balance.

Valuation per generator

Boiler. The fuel consumption is reported separately by energy carrier and valued with the respective factor. Because standby and storage losses have to be covered as well, heat production is higher than heat demand – the emissions follow the consumption, not the demand.

CHP. Here too the fuel consumption is reported by energy carrier and valued. The contribution has two sides: the module burns fuel and at the same time replaces grid supply with its own electricity. How large this replacement turns out to be depends on the operating mode – heat-led, electricity-led or without feed-in – which can be changed in the result area.

Heat pump, back-up heater and electric boiler. At the place of installation they emit nothing; their emissions arise solely through the electricity drawn. What matters is the reported electricity consumption including the back-up heater share and the factor of the energy carrier electricity; flow temperature and operating mode therefore also act on the emission balance. An electric boiler is modelled by selecting electricity as the energy carrier; its consumption then appears in the electricity balance.

Solar thermal. The collector yield is free of emissions in operation and acts indirectly by displacing fuel of the downstream generators. Surpluses that cannot be used contribute nothing to this.

Photovoltaics and battery storage. Both act through the grid supply avoided. What matters is the order of precedence in the electricity balance of direct use, storage charging and feed-in: only the first two routes reduce the grid supply and thus the emissions in the balance; the store increases this share by shifting generation into periods without sun. Electricity fed into the grid leaves the system boundary of the object – whether a credit is applied for it has to be settled for the individual project.

Buffer tank and heat delivery. Neither emits anything itself, but both change the quantity valued: standby losses of the tank and the losses of a heating network increase the fuel input per kilowatt hour delivered.

Savings against the reference variant

An emission figure only becomes meaningful in comparison. On the electricity side the self-sufficiency analysis reports the CO₂ savings alongside self-sufficiency, solar thermal coverage and thermal utilisation ratio and compares month by month which share of the electricity demand is covered directly, from the store or from the grid.

For whole concepts, set a simple reference variant against the planned solution, for instance boiler-only supply. Because all variants are based on the same demand data and the same climate data set, the difference is genuinely the effect of the measure. The simulation result can be saved for every project; change only one quantity at a time and make sure that both variants use the same status of the factors.

Presentation and export

The emission figures appear in the result areas of the individual generators and among the key figures of the evaluation, alongside coverage shares, full-load hours, annual utilisation ratios and fuel consumption. The underlying time series can be exported as a CSV file with time stamp and ambient temperature, so that the grid supply can be assessed in time resolution outside the program.

Notes for practice

Keep the factors up to date; the validity date documents their status. Over an assessment period of 15 to 20 years a constant electricity mix is an assumption, not a forecast. Do not apply the natural gas factor to biomethane or biogas, but create a separate energy carrier for them. Check every saving against the reference it comes from – a credit for CHP electricity is only as reliable as the assumption about which generation it displaces. Subsidy and regulatory evidence may call for their own factors and balancing rules; these have to be checked for the individual project.

The preceding working sequence is described by the Program workflow overview, the valuation of the same quantities in money by the subpages Revenue calculation and Economic analysis, the output by the subpage Creating the report. The engineering background is given under Fundamentals in the Energy balance comparison and in the Cost calculation; worked cases are collected under Examples.