Rigid polyurethane foams obtainable by reaction of a foam-forming reaction mixture comprising a component A) containing hydrogen atoms which are reactive toward isocyanate groups and comprising a polyol component A1), water A2) and optionally stabilizers A3), catalysts A4) and other auxiliaries and additives A5) and at least one physical blowing agent T) and a polyisocyanate component B), characterized in that the polyol component A1) comprises the following components (i)-(iii) (based on the total weight of the component A1) (i) 60-75% by weight of polyether polyol A1a) having a hydroxyl number of from 300 mg KOH/g to 600 mg KOH/g and a functionality of from 3.0 to 6.0, which is obtainable by addition of an epoxide onto one or more starter compound(s) selected from the group consisting of carbohydrates and bifunctional or higher-functional alcohols; (ii) 20-35% by weight of polyether polyol A1b) having a hydroxyl number of from 100 mg KOH/g to 550 mg KOH/g and a functionality of from 1.5 to 5.0, which is obtainable by addition of an epoxide or epoxide mixture onto an aromatic amine; and (iii) 3-10% by weight of polyether polyol A1c) having a hydroxyl number of from 15 mg KOH/g to < 300 mg KOH/g and having a functionality of from 1.5 to 4.0, which is obtainable by addition of an epoxide or epoxide mixture onto one or more starter compound(s) selected from the group consisting of carbohydrates and bifunctional or higher-functional alcohols, and in that the polyisocyanate component B) contains at least 85% by weight (based on the total weight of B) of polymeric MDI which has an NCO content of from ≥ 29.0% by weight to ≤ 32.0% by weight and a viscosity at 25°C (EN ISO 3219, October 1994) of from ≥ 300 mPas to ≤ 750 mPa·s and comprises, based on its total weight, from ≥ 25% by weight to ≤ 40% by weight of monomeric MDI. a component A) containing hydrogen atoms which are reactive toward isocyanate groups and comprising a polyol component A1), water A2) and optionally stabilizers A3), catalysts A4) and other auxiliaries and additives A5) and at least one physical blowing agent T) and a polyisocyanate component B), characterized in that the polyol component A1) comprises the following components (i)-(iii) (based on the total weight of the component A1) (i) 60-75% by weight of polyether polyol A1a) having a hydroxyl number of from 300 mg KOH/g to 600 mg KOH/g and a functionality of from 3.0 to 6.0, which is obtainable by addition of an epoxide onto one or more starter compound(s) selected from the group consisting of carbohydrates and bifunctional or higher-functional alcohols; (ii) 20-35% by weight of polyether polyol A1b) having a hydroxyl number of from 100 mg KOH/g to 550 mg KOH/g and a functionality of from 1.5 to 5.0, which is obtainable by addition of an epoxide or epoxide mixture onto an aromatic amine; and (iii) 3-10% by weight of polyether polyol A1c) having a hydroxyl number of from 15 mg KOH/g to < 300 mg KOH/g and having a functionality of from 1.5 to 4.0, which is obtainable by addition of an epoxide or epoxide mixture onto one or more starter compound(s) selected from the group consisting of carbohydrates and bifunctional or higher-functional alcohols, (i) 60-75% by weight of polyether polyol A1a) having a hydroxyl number of from 300 mg KOH/g to 600 mg KOH/g and a functionality of from 3.0 to 6.0, which is obtainable by addition of an epoxide onto one or more starter compound(s) selected from the group consisting of carbohydrates and bifunctional or higher-functional alcohols; (ii) 20-35% by weight of polyether polyol A1b) having a hydroxyl number of from 100 mg KOH/g to 550 mg KOH/g and a functionality of from 1.5 to 5.0, which is obtainable by addition of an epoxide or epoxide mixture onto an aromatic amine; and (iii) 3-10% by weight of polyether polyol A1c) having a hydroxyl number of from 15 mg KOH/g to < 300 mg KOH/g and having a functionality of from 1.5 to 4.0, which is obtainable by addition of an epoxide or epoxide mixture onto one or more starter compound(s) selected from the group consisting of carbohydrates and bifunctional or higher-functional alcohols, and in that the polyisocyanate component B) contains at least 85% by weight (based on the total weight of B) of polymeric MDI which has an NCO content of from ≥ 29.0% by weight to ≤ 32.0% by weight and a viscosity at 25°C (EN ISO 3219, October 1994) of from ≥ 300 mPas to ≤ 750 mPa·s and comprises, based on its total weight, from ≥ 25% by weight to ≤ 40% by weight of monomeric MDI.