NOVELTY - In the production of rigid polyurethane foam with low thermal conductivity by reacting (a) (modified) organic polyisocyanates with (b) compound(s) containing not less than 2 reactive hydrogen atoms and having a mol. wt. of over 400 and optionally (c) H-functional low-molecular chain extenders and/or crosslinking agents of mol. wt. less than 400 in the presence of (d) blowing agents, (e) catalysts and optionally (f) additives, component (b) contains (cyclo)alkyl-, aralkyl-, benzyl- and/or aryl-(alkoxy)alkanol(s) (I).    USE - The PUR foam is used as intermediate layer for composites and for in-situ foaming in refrigeration unit housings or heating elements (all claimed), especially refrigerators, freezers and hot water tanks. It is also useful for insulating heated materials, as engine cover and as pipe insulation.    ADVANTAGE - The use of alcohols (I) reduces the thermal conductivity to less than 18 mW/mK. Toxic and/or environmentally harmful blowing agents can be avoided. The polyol and polyisocyanate components are stable, whilst the reaction mixture has very good flow, cures without shrinking and give a strong bond to the covering layer when foamed in situ.    DETAILED DESCRIPTION - In the production of rigid polyurethane (PUR) foam with low thermal conductivity by reacting:    (a) organic and/or modified organic polyisocyanates with    (b) compound(s) containing not less than 2 reactive hydrogen (H) atoms and having a molecular weight of over 400 g/mole and optionally    (c) H-functional low-molecular chain extenders and/or crosslinking agents of molecular weight less than 400 g/mole in the presence of    (d) blowing agents,    (e) catalysts and optionally    (f) additives    component (b) contains (cyclo)alkyl-, aralkyl-, benzyl- and/or aryl-(alkoxy)alkanol(s) of formula (I).    R, R' = (m)ethyl, 3-6 carbon (C) alkyl or hydrogen (H);    R' may also = benzyl;    n = 0-4;    m, o = 1-3;    X = n-, iso-, neo- or cycloalkyl, aralkyl, benzyl or aryl; and    m + o = 4.    An INDEPENDENT CLAIM is also included for the use of compounds (I) in the production of rigid PUR foam with reduced thermal conductivity.