Abstract
Ice formation occurs on unventilated roofs when snow melts due to heat leakage from the building while the outside temperature remains below freezing, posing safety risks to pedestrians and causing structural damage to buildings. This study introduces a conceptual model to quantify ice formation in nine Norwegian cities for historical (1985–2005), near future (2040–2060), and far future (2080–2100) periods using climate simulations from a regional climate model with 3 km grid resolution. The model also evaluates the role of green roofs in mitigating ice formation. Results show significant geographical differences: northern cities remain most affected, while coastal cities show minimal risk. Thin-layer green roofs provide negligible benefits, but retrofitting poorly insulated buildings with 400 mm green roofs with light weight extruded clay reduces ice formation to levels comparable with new buildings meeting current insulation standards while enhancing stormwater management. Climate change scenarios (RCP4.5 and RCP8.5) predict a substantial decrease in ice formation across all cities in the future. The reductions were higher under RCP8.5, particularly in the far future period, where ice formation may disappear in some coastal cities. The developed model provides a tool for assessing the risk of ice formation and guiding decisions on roof design and drainage strategies under changing climate conditions.