A method for preparing a rigid polyurethane foam by the reaction of a polyurethane reaction system comprising the following components: component A, comprising a polyisocyanate; component B, comprising B1) a polyether polyol having a functionality of 3.0 to 8.0, preferably 3.0 to 6.0, a weight average molecular weight of 350 to 900 g/mol, preferably 400 to 900 g/mol, measured according to ISO 14900-2017, in an amount of 50 to 80 pbw, preferably 55 to 75 pbw, based on 100 pbw of component B; B2) a hydroxyl-terminated polyether polyol started with a polyamine having a functionality of 4.0, a weight average molecular weight of 550 to 750 g/mol, preferably 550 to 700 g/mol, measured according to ISO 14900-2017, in an amount of 6 to 15 pbw, preferably 6 to 12 pbw, based on 100 pbw of component B; B3) an aromatic polyester polyol having a functionality of 2.0 to 2.4, a weight average molecular weight of 300 to 650 g/mol, preferably 300 to 600 g/mol, measured according to ISO14900-2017, in an amount of 3.0 to 10.0 pbw, preferably 3.0 to 9.0 pbw, based on 100 pbw of component B; B4) a polyether amine having a functionality of 2 to 3, a weight average molecular weight of 1200 to 2000 g/mol, preferably 1300 to 2000 g/mol, measured according to ISO14900-2017. component A, comprising a polyisocyanate; component B, comprising B1) a polyether polyol having a functionality of 3.0 to 8.0, preferably 3.0 to 6.0, a weight average molecular weight of 350 to 900 g/mol, preferably 400 to 900 g/mol, measured according to ISO 14900-2017, in an amount of 50 to 80 pbw, preferably 55 to 75 pbw, based on 100 pbw of component B; B2) a hydroxyl-terminated polyether polyol started with a polyamine having a functionality of 4.0, a weight average molecular weight of 550 to 750 g/mol, preferably 550 to 700 g/mol, measured according to ISO 14900-2017, in an amount of 6 to 15 pbw, preferably 6 to 12 pbw, based on 100 pbw of component B; B3) an aromatic polyester polyol having a functionality of 2.0 to 2.4, a weight average molecular weight of 300 to 650 g/mol, preferably 300 to 600 g/mol, measured according to ISO14900-2017, in an amount of 3.0 to 10.0 pbw, preferably 3.0 to 9.0 pbw, based on 100 pbw of component B; B4) a polyether amine having a functionality of 2 to 3, a weight average molecular weight of 1200 to 2000 g/mol, preferably 1300 to 2000 g/mol, measured according to ISO14900-2017. B1) a polyether polyol having a functionality of 3.0 to 8.0, preferably 3.0 to 6.0, a weight average molecular weight of 350 to 900 g/mol, preferably 400 to 900 g/mol, measured according to ISO 14900-2017, in an amount of 50 to 80 pbw, preferably 55 to 75 pbw, based on 100 pbw of component B; B2) a hydroxyl-terminated polyether polyol started with a polyamine having a functionality of 4.0, a weight average molecular weight of 550 to 750 g/mol, preferably 550 to 700 g/mol, measured according to ISO 14900-2017, in an amount of 6 to 15 pbw, preferably 6 to 12 pbw, based on 100 pbw of component B; B3) an aromatic polyester polyol having a functionality of 2.0 to 2.4, a weight average molecular weight of 300 to 650 g/mol, preferably 300 to 600 g/mol, measured according to ISO14900-2017, in an amount of 3.0 to 10.0 pbw, preferably 3.0 to 9.0 pbw, based on 100 pbw of component B; B4) a polyether amine having a functionality of 2 to 3, a weight average molecular weight of 1200 to 2000 g/mol, preferably 1300 to 2000 g/mol, measured according to ISO14900-2017.