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Making Steel Framing as Thermally Efficient as Wood
Abstract
In many world regions like North
America and Scandinavia wood framing
is dominant technology for residential
buildings. During last two decades
several companies around the world
started to promote a low-gage steel
framing for residential and commercial
buildings. Steel framing has many
advantages over wood framing; strength,
low weight, dimensional stability,
resistance to termite damage, almost
100% recycleability, etc .. However
because of several reasons an application
of steel as a framing material in US
residential building market is relatively
low. Steel industry has noticed much
more success on commercial building
market which is not as rigorous
regarding thermal efficiency and energy
conservation.
Steel framing has one significant
disadvantage over wood; Steel members
conduct heat extremely well. This effect
is known as thermal bridging, and it can
sharply reduce a wall's effective Rvalue.
The simplest and most common
way to overcome this problem is to
block the path of heat flow with rigid
foam insulation. Adding rigid foam
insulation not only increases the whole
wall's R-value, but it also reduces the
temperature difference between the
center of the cavity and the stud area,
which cuts down on the possibility of
black stains forming from dirt getting
asymmetrically attracted to cold spots on
a wall's surface. However, rigid foam
insulation is an expensive solution.
Several material configurations were
developed in the past to increase thermal
effectiveness of steel-framed structures.
This paper is focused on most common
options of thermal improvements of
steels framed walls. They were as
follow: 1) diminishing the contact area between
the studs and exterior sheathing
materials, 2) reducing the steel stud web area, 3) replacing the steel web with a less
conductive material, and 4) placing foam insulation in locations
where the thermal shorts are most
critical.
Researchers at Oak Ridge National
Laboratory (ORNL) have utilized both
hot box testing and computer
simulations in aim to optimize thermal
design of steel stud walls.. While
examining several material options,
ORNL's BTC was also striving to
develop energy-efficient steel stud wall
technologies that would enable steel-stud
walls to beat the performance of
traditional 2 x 6 wood stud walls.
Several, most current, ORNL
developments in steel framing are
presented below.
Citation
Kosny, J.; Childs, P. (2002). Making Steel Framing as Thermally Efficient as Wood. Energy Systems Laboratory (http://esl.tamu.edu); Texas A&M University (http://www.tamu.edu). Available electronically from https : / /hdl .handle .net /1969 .1 /4591.