Look for a low u factor.
Exterior metal door u factor.
The solar heat gain coefficient tells you how much heat from the sun is able to pass through the glass of the door or window.
A u value also known as u factor measures how much heat or cold passes through the window or the door.
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.
U value has an inverse relationship to r value.
U factor the total or overall transmission of heat through a combination of materials assembly measured in btu s per hour per square foot of area for a difference in temperature of 1 f between the air on one side to the air on the other side.
The fire door rating measures how long a door can prevent the passage of flame from one side of the door assembly to the other.
Select doors with a very low u value the lower the best that is a u value close to 0 10 metric.
U factor is the rate at which a window door or skylight conducts non solar heat flow.
It basically tells you how well a door or window insulates the home.
In new homes especially in cold climates in very energy efficient buildings look for the best performance doors possible.
For windows skylights and glass doors a u factor may refer to just the glass or glazing alone.
A few german manufacturers have such doors.
All u factors for exterior doors in the table are for doors with no glazing except for the storm doors which are in addition to the main exterior door.
Fire doors are usually rated for 20 or 90 minutes.
It s usually expressed in units of btu hr ft2 of.
Interpolation and moderate extrapolation are.
Any glazing area in exterior doors should be included with the appropriate glass type and analyzed as a window.
Factor the more effective the insulation of the material.
The range is from 0 00 2 00.
Therma tru offers a wide selection of fiberglass 20 minute fire rated doors for protection with a sense of style.
For example a building with material with an r value of r 11 converts to an u value of 0 09 1 r or 1 11 0 09.
The trio e door is steel stiffened for strength but has achieved an operable u factor of 0 36 which is better than most other steel stiffened doors currently available on the market today.
The lower the u factor the better the door keeps in heat.