LAND TRANSFORMATION GAME

The digital game was initiated by the Chair of Landscape and Urban Systems Planning (PLUS) at ETH Zurich and created in collaboration with incolab and Grafik & Kontrabass: Ralph Sonderegger. It is based on many different scientifically determined factors that are used to calculate CO₂ storage and food production. The factors are described in more detail below.

SPECIAL ACKNOWLEDGEMENT

We would like to express our sincere thanks to the following persons, research groups and companies for their concept, design, scientific advice and implementation:

• Prof. Dr. Adrienne Grêt-Regamey and Ralph Sonderegger from the Chair of Planning of Landscape and Urban Systems at the Department of Civil, Environmental and Geomatic Engineering, ETH Zurich;
• Dr. Enrico Celio from incolab

DESCRIPTION OF FACTORS IN THE GAME

CO₂ storage

• Permanent grassland: 67 t C/ha
  The value for permanent grassland was taken from the Swiss National Inventory Document (FOEN, 2024) and corresponds to the sum of the average annual biomass (6 t C/ha) and the average annual mineral soil carbon content (61 t C/ha) for areas up to 1200 m above sea level.

• Agricultural land: 65 t C/ha
  The value for permanent grassland was taken from the Swiss National Inventory Document (FOEN, 2024) and corresponds to the sum of the average annual biomass (6 t C/ha) and the average annual mineral soil carbon content (59 t C/ha) for areas up to 1200 m above sea level.

• Agroforestry systems: 133 t C/ha
  The value describes the carbon sequestration in the trees of an agroforestry system at a fertile location after 60 years for a field with 113 trees per hectare. It is based on model calculations for 42 randomly selected landscapes in the Netherlands, France and Spain (Kaeser et al., 2011).

• Settlement: Wood: 0 t C/ha and concrete: – 500 t C/ha
  The values for timber and concrete construction were calculated on the basis of two studies. The first study (proHolz, 2024) is based on a six-storey building with a floor area of 3,800 m² and a gross floor area of 22,800 m². For comparability, the values were converted to 7,380 m² GFA/ha, based on the calculated Zurich average (BFS, 2024): 10 buildings/ha × 184.5 m² × 4 floors = 7,380 m² GFA/ha

Net C-storage wood construction: – 30.75 t CO₂/ha
Net C storage concrete construction: – 443.45 t CO₂/ha
The values in the second study (Liang et al., 2020) are taken from a comprehensive life cycle analysis of a twelve-storey building, including construction, operation, material use and disposal. The data was standardised on a per-hectare basis.

Net C-storage wood construction: 14.76 t CO₂ / ha
Net C-storage concrete construction: – 1742.42 t CO₂ / ha

Both studies suggest that emissions from timber construction are largely offset by carbon storage in wood over the life cycle. In contrast, concrete construction involves virtually no sequestration. Net CO₂ emissions depend heavily on factors such as building height, service life, demolition practices and cascading use.

• Productive forest: 198 t C/ha
  The value for permanent grassland was taken from the Swiss National Inventory Document (FOEN, 2024) and corresponds to the sum of the average annual biomass (141 t C/ha) and the average annual mineral soil carbon content (57 t C/ha) for areas up to 1,200 metres above sea level in the Central Plateau.

• Unproductive forest: 87 t C/ha
  The value for permanent grassland was taken from the Swiss National Inventory Document (FOEN, 2024) and corresponds to the sum of the average annual biomass (28 t C/ha) and the average annual mineral soil carbon content (59 t C/ha) for areas up to 1,200 metres above sea level in the Central Plateau.

• Natural moorland: 510 t C/ha
  The baseline value for the storage capacity of moors in Switzerland (0.056 t C/m³) was taken from the report Climate Protection through Raised Bog Conservation (WSL, 2020) and rounded. It corresponds to the average organic carbon content in drained peatlands in Switzerland and Northern Europe.

Food production

• Permanent grassland: 467 kg/person/year, 1278381 kJ/person/year
  The value describes the total domestic production of cow’s milk and meat [kg/person/year] (Baur & Flückiger, 2018). The energy content of milk (2450 kJ/litre of milk) and beef (5650 kJ/kg of meat) was used for conversion to kJ (Swiss Nutrient Database, 2022).

• Agricultural land: 170 kg/person/year, 1,487,500 kJ/person/year
  The value describes the domestic production of plant-based foods [kg/person/year] (Baur & Flückiger, 2018). The energy content of cereals (14,300 kJ/kg wholemeal flour) and potatoes (3,200 kJ/kg potatoes) was used for conversion to kJ (Swiss food composition database, 2022).

• Agroforestry systems: 221 kg/person/year, 1933750 kJ/person/year
  No specific production values could be determined for agroforestry systems. However, production is approx. 30% higher than in traditional agriculture (Kaeser et al., 2011). Therefore, the base value of agricultural land was multiplied by a factor of 1.3 to determine the approximate value.

• Settlement: 17 kg/person/year, 148,750 kJ/person/year
  No specific production values could be determined for the settlement. However, approx. 10% of the yield of agricultural land can be achieved in the settlement area (Saha & Eckelman, 2017). Therefore, the base value of the agricultural land was multiplied by a factor of 0.1 to determine the approximate value.

• Productive forest: 0 kg/person/year, 0 kJ/person/year
  No food production function was assumed for productive forest.

• Unproductive forest: 0 kg/person/year, 0 kJ/person/year
  No food production function was assumed for unproductive forest.

• Natural peatlands: 0 kg/ person/year, 0 kJ/person/year
  No food production function was assumed for peatlands.