U value requirement roof 0 13 w m k.
Roof u value table.
U value has an inverse relationship to r value.
While the values do vary for each particular material and method of construction the following table gives general figures for some common modes of construction.
Equipment not listed in tables above shall be limited to 10 of total building system capacity reduced lighting power per c406 3 or whole building lpd determined using 90 of values in table c405 4 2 1 x floor area for the building types or using 90 by the space by space method in section c405 4 2.
Notes to the table above.
Rosato asbestos insulation is the most authoritative source on asbestos properties and gives data for the thermal conductivity of asbestos in different forms and with varying temperatures for magnesia asbestos insulation at mean temperatures ranging from 100 f to 400 f the k value thermal.
Tables of building material r values.
The r values for specific assemblies like doors and glazing in the table below are generalizations because they can vary significantly based on special materials that the manufacturer uses.
U value requirement semi glazed doors 1 2 w m k.
U value requirement windows whole window u value 1 4 w m k.
U value requirement opaque doors 1 0 w m k.
The required u value will depend on the location of the project england scotland or wales type of building domestic or non domestic and the application floor wall or roof.
R value of building materials material r inch r thick ness fiberglass inch 3 00 1 inch 4 00 inch 6 00 extruded polystyrene inch 3 75 1 inch 5 00 1 inch 7 50 foil faced polyisocyanurate inch 5 40 1 inch 7 20 1 inch 10 80 siding materials hardboard inch 0 34.
There are a few good u value calculators online that if you are short on time are worth checking out.
These r values were taken from manufacturer technical data sheets and are the reported r values per inch of actual products.
The tables below show the suggested u values in england wales and scotland.
To learn more about r value see roof online s r value page.
Reference table for u values u value is the coefficient of transmission i e the transmission of heat through the materials which compose the building s envelope or outer shell.
In a few cases the r values we give were taken from a non manufacturer source.
For instance using argon gas in a double pane insulating glass unit will dramatically improve the r value.
U values of typical building methods u values overall coefficient of heat transmission indicate the heat flow through materials the higher the figure the higher the heat loss.
These are expressed as a u value which needs to be achieved.
Conservation of fuel and power approved document l1 24 l1 tables of u values table a2 indicative u values w m2 k for windows with metal frames 4mm thermal break gap between panes 6mm 12mm 16mm or more single glazing 5 7 double glazing air filled 3 7 3 4 3 3.
