There is an effective R-value for a north facing 10-in wall of R0=10 hr ft2 °F/Btu, which corresponds to thermal conductivity k=10 in x 1 ft/12 in /R0=0.33 Btu/(hr
ðɛɹ ɪz ɐn ɪfˈɛktɪv ˈɑːɹvˈæljuː fɚɹə nˈɔːɹθ fˈeɪsɪŋ tˈɛnɪn wˈɔːl ʌv ˈɑːɹ zˈiəɹoʊ ˈiːkwəlz tˈɛn ˌeɪtʃˈɑːɹ ˌɛftˈiː tˈuː dᵻɡɹˈiːz ˈɛf slˈæʃ bˌiːtˌiːjˈuː, wˌɪtʃ kˌɔːɹɪspˈɑːndz tə θˈɜːməl kɑːndəktˈɪvᵻɾi kˈeɪ ˈiːkwəlz tˈɛn ɪn ˈɛks wˈʌn ˌɛftˈiː slˈæʃ twˈɛlv ɪn slˈæʃ ˈɑːɹ zˈiəɹoʊ ˈiːkwəlz zˈiəɹoʊ.θˈɜːɾi θɹˈiː bˌiːtˌiːjˈuː slˈæʃ ˌeɪtʃˈɑːɹ