The rate at which the glass transfers loses heat.
													
																	R values for windows and doors. 
									
	
		
	
																	Know exactly how much you need with our project calculators. 
																	Ultimately when talking about windows the u and r values are both a representation of the same thing. 
																	Truly windows can be energy holes. 
																	In the chart above you will notice that there are two vastly different r values provided for insulated metal doors with polyurethane insulation. 
															
													
									
	
		
	
																	The r value of a 1 3 4 inch wood door is 3 03. 
																	Rustica s french style sliding barn doors entry doors and rustica s replacement windows have the most efficient r value on the market listed at 3 94 for interior doors and replacement windows and 5 31 for a 2 1 4 exterior door. 
																	This includes the use of caulking and insulation around the window where it meets the walls of the building. 
																	A single layer of uncovered glass window has an r value of 1 75. 
															
													
									
	
		
	
																	When determining how much insulation you need don t guesstimate calculate. 
																	The r value as it is known to most consumers is really an inverse representation of the u value. 
																	Here is a simple chart to help understand how r value is calculated for windows and doors. 
																	Based on astm c518 calculation method the door has an r value of up to 11 but using astm c1363 tested operable the same door only have an r value of up to 3 5. 
															
													
									
	
		
	
																	The higher the r value the greater the insulation performance. 
																	High r value windows offer lots of other benefits for your home including. 
																	R value measures how well certain building insulation materials can resist heat. 
																	The higher the r value of any material the greater the insulating value. 
															
													
									
	
		
	
																	R value and your home a replacement window with a high r value will definitely help reduce heat loss and gain in your home making it easier to keep warm or cool. 
																	A replacement window with an r value of 5 is 50 more efficient than one with an r value of only 3 3. 
																	Single pane glass that is one fourth inch thick has an r value around 90 while a double paned window of similar thickness would be nearly double at roughly 1 7. 
																	R value also known as r factor is relevant in terms of insulation used around the window during installation. 
															
													
									
	
		
	
																	For instance a window s frame would have a specific r value while the glass or glazing would have a different value. 
																	Foot than the rest of the exterior. 
																	R values climb as thickness of the material increases. 
																	A 2 1 4 inch solid core wooden door for example has an r value of 3 70.