CO₂ and local pollutant emissions
TESSA calculates emissions at two levels: from the district heating/cooling network it designs, and from the existing building stock being replaced. The comparison between these two figures is a key output for decarbonisation studies.
DHC network emissions
Emissions from the network are calculated per heat source, based on the fuel or energy carrier it uses and the amount consumed.
CO₂ equivalent
For fossil fuels (gas, oil, wood), TESSA multiplies final energy consumption by the fuel's CO₂ intensity (kg CO₂/kWh):
CO₂eq [kg] = energy_final [kWh] × fuel_co2_intensity [kg/kWh]
For electricity, there are no direct emissions at the point of use, but TESSA applies a country-specific grid carbon intensity factor (kg CO₂eq/kWh) that reflects the average CO₂ embedded in the electricity supply. This factor is configurable per energy source.
Local air pollutants
For combustion sources (gas, oil, wood/biomass), TESSA also calculates local pollution from five pollutants:
| Pollutant | Most significant for |
|---|---|
| NOₓ (nitrogen oxides) | Gas and oil combustion |
| CO (carbon monoxide) | Incomplete combustion |
| SOₓ (sulphur oxides) | Oil combustion |
| PM10 (particulate matter) | Wood/biomass combustion |
| PM2.5 (fine particulate matter) | Wood/biomass combustion |
Emission factors per kWh of final energy are taken from standard databases and are configured per energy source type.
Existing building emissions
TESSA calculates CO₂ emissions from the existing building stock when the current heating system type and fuel are provided in the building data. This enables direct comparison of:
- Current annual CO₂ from decentralised heating (gas boilers, oil boilers, etc.)
- Projected annual CO₂ from the new DHC network
If the current heating system is not provided in the input data, existing building emissions are not calculated and the comparison is not shown in the report.
Where emissions appear in the report
The scenario report shows:
- Annual CO₂ per energy source (network side)
- Total annual CO₂ for the network vs the baseline (if available)
- CO₂ per kWh delivered
Where to go next
- Energy sources — CO₂ intensity factors and emission factors per fuel type.
- Financial model — fuel cost calculation that uses the same energy consumption figures.
- Heat loss and simulation — how annual energy consumption per source is computed.