▁which ▁can ▁be ▁indicated ▁by ▁the ▁Energy ▁Star ▁label ▁or ▁the ▁Pass ive ▁House ▁standards . ▁Prem ium ▁composite ▁( including ▁steel ▁doors ▁with ▁a ▁thick ▁core ▁of ▁poly ure th ane ▁or ▁other ▁fo am ), ▁fi berg lass ▁and ▁vin yl ▁doors ▁benefit ▁from ▁the ▁materials ▁they ▁are ▁made ▁from , ▁from ▁a ▁thermal ▁perspective . ▁ ▁Ins ulation ▁and ▁weather st ri ps ▁▁ ▁But ▁there ▁are ▁very ▁few ▁door ▁models ▁with ▁an ▁R - value ▁close ▁to ▁ 1 0 ▁( which ▁is ▁far ▁less ▁than ▁the ▁R - 4 0 ▁walls ▁or ▁the ▁R - 5 0 ▁ce il ings ▁of ▁super - ins ulated ▁buildings ▁– ▁Pass ive ▁Sol ar ▁and ▁Zero ▁Energy ▁Build ings ). ▁Typ ical ▁doors ▁are ▁not ▁thick ▁enough ▁to ▁provide ▁very ▁high ▁levels ▁of ▁energy ▁efficiency . ▁ ▁Many ▁doors ▁may ▁have ▁good ▁R - values ▁at ▁their ▁center , ▁but ▁their ▁overall ▁energy ▁efficiency ▁is ▁reduced ▁because ▁of ▁the ▁presence ▁of ▁glass ▁and ▁rein for cing ▁elements , ▁or ▁because ▁of ▁poor ▁weather st ri pping ▁and ▁the ▁way ▁the ▁door ▁is ▁manufact ured . ▁ ▁Do or ▁weather st ri pping ▁is ▁particularly ▁important ▁for ▁energy ▁efficiency . ▁German - made ▁Pass ive ▁House ▁doors ▁use ▁multiple ▁weather st ri ps , ▁including ▁magnetic ▁stri ps , ▁to ▁meet ▁higher ▁standards . ▁These ▁weather st ri ps ▁are ▁critical ▁to ▁reduce ▁to ▁a ▁minimum ▁energy ▁losses ▁due ▁to ▁air ▁leak age . ▁ ▁Dim ensions ▁ ▁United ▁States ▁ ▁The