Building Science

Mass Walls and Energy Efficiency

There’s a reason man has built with mass walls for centuries

From mud huts to stone cas­tles, build­ings con­struct­ed with thick and dense walls have always been val­ued for their ther­mal prop­er­ties. In parts of the south­west Unit­ed States adobe build­ings have been the hous­ing of choice for as long as peo­ple have resided in that area.

Adobe build­ings pro­vide excep­tion­al ther­mal ben­e­fits, keep­ing res­i­dents inside cool on even the hottest sum­mer days, and warm at night in spite of win­ter tem­per­a­tures that can drop below freez­ing. This ther­mal mass, or ther­mal iner­tia, effect is well under­stood in the archi­tec­tur­al world and is also fea­tured promi­nent­ly in recent build­ing codes. While insu­lat­ing mate­ri­als in the build­ing enve­lope help to slow down the rate of trans­fer of ener­gy through a wall sys­tem, ther­mal mass ampli­fies the ener­gy effi­cien­cy of the sys­tem by absorb­ing a sig­nif­i­cant amount of heat ener­gy that reach­es the insu­la­tion. This boost in ener­gy per­for­mance is strongest in cli­mates and sea­sons where there are large swings in tem­per­a­tures through­out the day.

In the 2015 Inter­na­tion­al Ener­gy Con­ser­va­tion Code (IECC), for exam­ple, the amount of added insu­la­tion required for a com­mer­cial build­ing in Dal­las, Texas (IECC Zone 3, Pre­scrip­tive R‑value Method) con­struct­ed of light gauge fram­ing is R‑13 in the wall cav­i­ties – plus an addi­tion­al R‑7.5 con­tin­u­ous insu­la­tion on the out­side of the wall. For the same build­ing con­struct­ed of a mass wall sys­tem, the code only requires the addi­tion of R‑7.6 of con­tin­u­ous insu­la­tion to achieve the same lev­el of per­for­mance.

While wood and light-gauge steel fram­ing are still very pop­u­lar, they have become more com­plex and cost­ly to con­struct. New build­ing codes with stricter ener­gy-effi­cien­cy require­ments are forc­ing builders to add more and more lay­ers of expen­sive insu­la­tion, as well as pay for the addi­tion­al labor and costs of adding these mate­ri­als. In the end, the new build­ing might pass code, but it will fail to pro­vide near­ly as much ener­gy effi­cien­cy as a mass wall sys­tem. Just as impor­tant, cav­i­ty wall build­ings fail to pro­vide the lev­el of fire and storm safe­ty that has been demon­strat­ed by many mass wall sys­tems.

In con­trast to light-frame cav­i­ty-wall sys­tems, Bau­tex Block is a light­weight, insu­lat­ed con­crete block that, when used to con­struct a build­ing, pro­vides struc­ture, enve­lope, fire and storm resis­tance, an air and mois­ture bar­ri­er, and con­tin­u­ous insu­la­tion – all in a sin­gle inte­grat­ed assem­bly. It’s a mod­u­lar, mor­tar­less wall sys­tem where blocks are stacked and then filled with rein­forced con­crete to cre­ate an insu­lat­ed struc­tur­al wall. The wall sys­tem is con­struct­ed using the same labor, tools and tech­niques as those used in tra­di­tion­al con­crete mason­ry con­struc­tion.

The result is a sim­ple, sin­gle, inte­grat­ed wall assem­bly that cre­ates an air­tight, R‑14 con­tin­u­ous­ly insu­lat­ed mass wall for the build­ing enve­lope with high­er ener­gy effi­cien­cy per­for­mance than most cav­i­ty-wall or tra­di­tion­al mass wall sys­tems – all with­out any addi­tion­al insu­la­tion – while pro­vid­ing sub­stan­tial­ly improved lev­els of per­for­mance and safe­ty.

Down­load Under­stand­ing R‑value, Mass Walls, Con­tin­u­ous Insu­la­tion and Air Tight­ness