In truth, a concrete wall house is substantially warmer than stick-built construction. Advanced technology ICF (Insulated Concrete Form) homes are actually much warmer than traditional stud wall construction, as well as being far more energy efficient. Here are the facts. Thermographic tests done by the National Association of Home Builders Research Center showed that a solid ICF wall (a wall without windows or other penetrations) has fewer cold spots than a wood framed wall. This is because the thermal envelope – the shield between outside and inside temperatures – is much more difficult to seal in conventional stud wall construction, so that cold easily travels through thermal bridging to create uncomfortable cold spots inside the house concrete walls. ICF walls, by contrast, are tightly sealed so that thermal bridging is reduced, which makes for even temperatures and fewer cold spots and drafts. Moreover, houses with ICF wall construction result in a 50% decrease in the capacity of HVAC equipment as compared to wood framed wall construction (which of course implies greatly reduced heating and cooling costs).
How does ICF construction accomplish this? Concrete form insulation is constructed of blocks of parallel slabs of expanded polystyrene foam. These blocks are stacked up and snap together like children’s Lego toys. Steel rebar is placed inside them and then concrete is poured into the hollow. When the concrete sets the foam slabs which had been forms now become layers of insulation – one outside the concrete wall and one inside it – which are chemically bound to the concrete and form a tight seal. The blocks are standard in size, not manufactured to the building’s particular specifications and size, so they can be cut to fit any design and to allow apertures for doors, windows, and ducts. All joints are tightly sealed with injected polystyrene foam, which reduces or eliminates air leaks, so the home is more comfortable and loses far less heat than stick built construction (which lacks this solid air barrier).
Besides resulting in a much warmer house which is much cheaper to heat and cool than conventional stud wall construction, an ICF concrete wall home is much safer than stick framing since it is very strong and vastly exceeds local code requirements in areas which are prone to hurricanes and tornados. ICF construction is also four times more fire resistant than stick construction (ICF walls easily sustain four hours of extreme fire temperatures, whereas wood frame walls don’t exceed a one hour rating). Moreover, ICF walls have much higher sound absorption than stick framed walls, which makes these homes much quieter and more peaceful to live in.