Austin Design and Construction Conference Makes Clear Case for Airtightness in Buildings

Last month, sev­er­al Bau­tex team mem­bers had the oppor­tu­ni­ty to attend the 2019 ATX Build­ing Per­for­mance Con­fer­ence in Austin, Texas. This has become a seri­ous region­al con­fer­ence that is held every oth­er year, oppo­site the larg­er Humid Cli­mate Con­fer­ence (Image Source). The ATX Build­ing Per­for­mance Con­fer­ence is joint­ly host­ed by Pas­sive House Austin, AIA Austin Build­ing Enclo­sure Coun­cil and the 2019 AIA Austin Com­mit­tee on The Envi­ron­ment (COTE).

The cen­tral top­ic of this year’s con­fer­ence was air­tight­ness of build­ings and how imper­a­tive it is for archi­tects, engi­neers, con­trac­tors and even build­ing own­ers to under­stand why we, as an indus­try, must keep push­ing for bet­ter-per­form­ing build­ings. Through­out the day, we heard from a num­ber of speak­ers rep­re­sent­ing a broad cross-sec­tion of con­struc­tion project teams, each with their own per­spec­tives on build­ing air­tight­ness. Yet, all of the speak­ers rein­forced the theme of the con­fer­ence that air­tight­ness is a crit­i­cal goal to achieve in all build­ings.

For those of you who could not attend, here are five of the most impor­tant take­aways from this year’s ATX Build­ing Per­for­mance Con­fer­ence.

1. Our buildings cost us trillions extra, and we don’t even know it.

Researchers esti­mate that improv­ing the indoor envi­ron­ment of build­ings could have an annu­al pos­i­tive impact of $700 per per­son. Extrap­o­lat­ing that to the 320 mil­lion or so cit­i­zens in the Unit­ed States, it would yield tril­lions of dol­lars in work­er pro­duc­tiv­i­ty and reduced health­care costs annu­al­ly. In fact, oth­er than improv­ing our diet, indoor envi­ron­men­tal qual­i­ty may have the most sig­nif­i­cant impact on reduc­ing health­care costs in this coun­try.

We spend over 85% of our lives indoors, near­ly 70% of our lives in our homes, and around 30% of our lives just in our bed­rooms sleep­ing. Build­ings are micro­cli­mates, and we are bio­log­i­cal machines that con­stant­ly inter­act with the cli­mate around us. It’s no sur­prise, then, that the qual­i­ty of our indoor envi­ron­ments has a sig­nif­i­cant impact on our phys­i­cal and men­tal health. Unfor­tu­nate­ly, the envi­ron­men­tal qual­i­ty of the build­ings we work and live in today is not good. In fact, it can be quite bad.

The prob­lem is that most peo­ple aren’t aware of the impact their build­ings have on their phys­i­cal and men­tal health. They can’t see or hear the mold, bac­te­ria, pro­to­zoa, irri­tants and chem­i­cals that are float­ing around in the air or lay­ing on the sur­faces of our build­ings. They don’t real­ize that mois­ture and humid­i­ty in their build­ings are not only uncom­fort­able, they are dan­ger­ous because they dri­ve the growth and dis­tri­b­u­tion of all those things that cause us harm.

How con­fi­dent are you that the build­ings you are design­ing or con­struct­ing are pro­vid­ing indoor envi­ron­ments where peo­ple can live healthy, safe and com­fort­able lives? How many tril­lions of dol­lars are we cost­ing our­selves when we don’t get the build­ing enve­lope and indoor envi­ron­men­tal con­trol sys­tems right? As an indus­try, we need to address this prob­lem head-on and soon, espe­cial­ly before we build the next few mil­lion square feet of build­ings that will be in ser­vice for the bet­ter part of this cen­tu­ry.

2. “Build Tight, Ventilate Right” is here to stay.

Lead­ers in build­ing per­for­mance cir­cles have been talk­ing about and pro­mot­ing tight build­ing con­struc­tion for over 40 years; yet in 2019, many in the con­struc­tion indus­try are still skep­ti­cal of (and some­times down­right hos­tile to) the idea of build­ing air­tight build­ings.

For one, these antag­o­nists assume that all build­ings will get wet so they need to be con­struct­ed in a way that they can dry out quick­ly. Sec­ond­ly, they believe that if the build­ing is too tight, peo­ple will get sick due to improp­er ven­ti­la­tion. And last­ly, they argue that it costs sig­nif­i­cant­ly more to build an air­tight build­ing which is a non-starter in a cost-con­scious world. All of these argu­ments fall way short.

We could use the same log­ic in the first state­ment to say that we should build large holes in the bot­tom of our walls so that when snakes get in, they have a way to get out. Air migra­tion through the build­ing enve­lope is the largest source of mois­ture in build­ings and must be con­trolled. Besides, with­out a tight build­ing enve­lope, we will sig­nif­i­cant­ly over­spend to try and con­trol the indoor envi­ron­ment with our mechan­i­cal sys­tems.

The answer to the sec­ond objec­tion is prop­er­ly designed and bal­anced ven­ti­la­tion sys­tems. The answer is not to let air come into a build­ing any­where it can, but to build tight and ven­ti­late right.” Ven­ti­la­tion should be designed into a build­ing from the begin­ning, tak­ing into account the build­ing design, enve­lope per­for­mance and all sources of ven­ti­la­tion, includ­ing make-up air ven­ti­la­tion, bath and kitchen vents, and dry­ers. Ide­al­ly, the active ven­ti­la­tion sys­tems would be designed to bal­ance out­flow and inflow so that the build­ing is not pos­i­tive­ly or neg­a­tive­ly pres­sur­ized.

The cost argu­ment is always the tough­est one to address, at least in the begin­ning. This argu­ment assumes there are no economies of scale or tech­no­log­i­cal effi­cien­cies that make costs decrease as improved tech­nolo­gies come to mar­ket and we learn how to build bet­ter. This argu­ment also fails to address the huge long-term, con­se­quen­tial cost of low-per­form­ing build­ings dis­cussed above. Besides, get­ting to a mod­er­ate lev­el of air­tight­ness isn’t as hard as peo­ple make it out to be.

To put things in per­spec­tive, the nation­al aver­age of exist­ing com­mer­cial build­ings is 1.55 cubic feet per minute per square foot of build­ing enve­lope at 75 pas­cals of pres­sure (CFM75). Here are the infil­tra­tion rates of sev­er­al oth­er cur­rent stan­dards in use today:

0.40 CFM752015 Inter­na­tion­al Ener­gy Con­ser­va­tion Code (IECC)

0.25 CFM75 Unit­ed States Army Corps of Engi­neers (USACE)

0.15 CFM75 Cana­di­an Build­ing Code

0.08 CFM75 Pas­sive House US (PHIUS)

At the con­fer­ence, we heard about an archi­tect in Austin who is build­ing his own home to the Pas­sive House stan­dard and who achieved a 0.02 CFM75 air infil­tra­tion rate! That is 20 times less air infil­tra­tion than the cur­rent ener­gy code in Texas and 77.5 times less than the aver­age exist­ing build­ing in this coun­try. Meet­ing cur­rent build­ing code is not dif­fi­cult. Going 50% bet­ter is also quite achiev­able. Here’s how Joe Lstibu­rek put it to the audi­ence:

To get to 0.4 CFM, just get rid of all the big holes in the enve­lope.

To get to 0.25 CFM, get rid of all the small holes.

To get to 0.6 CFM, get Ger­man (Pas­sive House).

This argu­ment that it is too expen­sive to build air­tight build­ings might have held a bit of truth in the 1980s, but it is cer­tain­ly not true today. Besides, build­ing codes now require more air­tight con­struc­tion. These build­ing code require­ments will soon become the new nor­mal,” at least until they change the codes again.

The con­struc­tion of the Iron­sight Office Build­ing in San Mar­cos was a great exam­ple of air­tight con­struc­tion that achieved a 0.25 CFM blow­er door score sim­ply using Bau­tex Blocks and Bau­tex Air and Mois­ture Bar­ri­er.

Are you mea­sur­ing the air­tight­ness of your build­ings? Are you test­ing new tech­nolo­gies and meth­ods to see what it will take to con­tin­ue to dri­ve down air infil­tra­tion in all of the build­ings you design and build?

3. Air barriers aren’t about energy efficiency (at least not in the beginning).

Joe Lstibu­rek has been in build­ing sci­ence for sev­er­al decades and par­tic­i­pat­ed direct­ly in the spec­i­fi­ca­tion and adop­tion of ener­gy effi­cien­cy and air qual­i­ty build­ing codes and stan­dards in the U.S. and Cana­da. One inter­est­ing sto­ry he shared was the his­to­ry of air­tight­ness stan­dards.

Com­mon per­cep­tion is that air­tight­ness came about as an ener­gy effi­cien­cy mea­sure; how­ev­er, the ini­tial dri­ve to require more air­tight­ness was the pre­ven­tion of mois­ture infil­tra­tion into build­ings.

Framed wall assem­blies are frag­ile and sus­cep­ti­ble to rot­ting and mold growth when humid­i­ty is high. As stat­ed ear­li­er, the biggest source of mois­ture in a build­ing is air infil­tra­tion through the build­ing enve­lope. As ener­gy code stan­dards increased the amount of insu­la­tion required in build­ing assem­blies, the dry­ing poten­tial of the assem­blies were reduced. To coun­ter­act this, build­ing codes need­ed to reduce the wet­ting poten­tial by reduc­ing the flow of mois­ture-laden air into a build­ing. Hence, low­er air infil­tra­tion stan­dards.

While vapor bar­ri­ers are often a top­ic of con­ver­sa­tion in build­ing cir­cles, it did not get much atten­tion here except as a way to com­pare the degree of the prob­lem rep­re­sent­ed by air infil­tra­tion ver­sus vapor dif­fu­sion. This is large­ly because water vapor dif­fu­sion through mate­ri­als is a weak and slow force. As a result, the amount of mois­ture that comes into a build­ing through air infil­tra­tion can be 30 – 50 times larg­er than what can come into or exit a build­ing through vapor dif­fu­sion.

As we learned, there are many argu­ments for air­tight con­struc­tion. Air bar­ri­ers are more about build­ing resilien­cy and occu­pant health and only sec­on­dar­i­ly about ener­gy effi­cien­cy. Regard­less of your posi­tion on these goals, air­tight­ness in build­ings is crit­i­cal.

4. Building envelope details continue to be complex and challenging.

Based on what we heard at the con­fer­ence, there is no ques­tion that build­ing enve­lope designs are get­ting more com­plex and more expen­sive over time. Increased build­ing code and own­er per­for­mance require­ments have caused sig­nif­i­cant changes in build­ing designs which have increased costs and con­struc­tion chal­lenges in the field.

One fac­tor dri­ving this increased lev­el of com­plex­i­ty in build­ing enve­lope design is the addi­tion of new mate­ri­als and lay­ers to tra­di­tion­al wall assem­blies. The instal­la­tion of these mate­ri­als is more tech­ni­cal, and often the sequenc­ing and scope over­lap between trades aren’t imme­di­ate­ly clear or explic­it. In addi­tion, many of the con­di­tions in a project are not detailed in the plans or spec­i­fi­ca­tions, which caus­es more back-and-forth between the con­struc­tion and design teams.

A sec­ond fac­tor is the chal­lenge of hir­ing, train­ing and retain­ing com­pe­tent and skilled trades. The increased com­plex­i­ty of build­ing designs is a chal­lenge for much of the labor force who don’t have a lot of train­ing or expe­ri­ence. Prob­lems are going to hap­pen in the field and the per­for­mance of the build­ing enve­lope will suf­fer.

Roof-to-wall tran­si­tions tend to be the tough­est to detail in designs and to work out in the field. This is the area where mul­ti­ple lay­ers of mate­ri­als in the wall assem­bly meet mul­ti­ple lay­ers of mate­ri­als in the roof assem­bly. With all of these lay­ers, main­tain­ing a con­tin­u­ous air bar­ri­er in this tran­si­tion area is a real chal­lenge.

Anoth­er area that is a real chal­lenge to design and con­struct are par­ty walls in mul­ti-fam­i­ly con­struc­tion. Most of the atten­tion on air infil­tra­tion is focused on the exte­ri­or walls of the struc­ture, but less time is spent study­ing the walls between units as well as adja­cent inte­ri­or uncon­di­tioned spaces such as trash chutes and plenum spaces.

While spe­cif­ic solu­tions to these chal­lenges were not dis­cussed at the con­fer­ence, it was clear that sim­pli­fy­ing the build­ing enve­lope design and reduc­ing the num­ber of mate­ri­als used in the assem­bly was the most effec­tive way to improve per­for­mance and con­trol con­struc­tion costs for future build­ing projects.

5. Just “nibbling” on innovation doesn’t solve anything.

Dur­ing the after­noon Light­ning Round” where atten­dees were giv­en a throw­able padded micro­phone to pass around and a chance to make a brief state­ment or ask a ques­tion, the theme of inno­va­tion came up sev­er­al times.

It is clear that how we are build­ing today is all new, despite the fact that the basic build­ing sys­tems we are using may be over a cen­tu­ry old and may feel quite famil­iar. The mate­ri­als are dif­fer­ent, the lay­ers are dif­fer­ent, the sequenc­ing is dif­fer­ent and the tran­si­tions between assem­blies are dif­fer­ent. The way we are build­ing today is NEW!

There was gen­er­al agree­ment that we need to be more strate­gic and sys­tem focused in how we approach build­ing designs today. This approach means look­ing at inte­grat­ed and test­ed build­ing sys­tems rather than rely­ing on dis­in­te­grat­ed assem­blies of stand-alone build­ing mate­ri­als that are often sup­plied by mul­ti­ple man­u­fac­tur­ers. But whose job is it to do the inte­gra­tion of these sys­tems?

Ide­al­ly, it would be build­ing mate­ri­als man­u­fac­tur­ers. And when inno­v­a­tive build­ing sys­tems like these come to mar­ket, the design and con­struc­tion com­mu­ni­ty must do their part to test, deploy and help make the most suc­cess­ful tech­nolo­gies part of the main­stream way of build­ing.

There is a cost to doing new things, but we are doing new things today and every day. How­ev­er, the return on invest­ment of dif­fer­ent solu­tions varies sig­nif­i­cant­ly. Iron­i­cal­ly, the new things that appear to offer the least amount of change are, in many cas­es, more cost­ly to imple­ment and pro­vide few­er ben­e­fits. Many times, the seem­ing­ly big­ger change is sim­pler to imple­ment and, in the end, pro­vides sig­nif­i­cant­ly greater per­for­mance gains.

As one audi­ence mem­ber who shared their per­spec­tive in the Light­ning Round, the real risk is not in adopt­ing new tech­nolo­gies, but in going part of the way and only nib­bling on inno­va­tion” but nev­er expe­ri­enc­ing any real ben­e­fit. We couldn’t agree more.

For the Bau­tex team that attend­ed the 2019 ATX Build­ing Per­for­mance Con­fer­ence, all of these points spoke to the heart of what we do and why we do it. The theme of the con­fer­ence fit per­fect­ly with our com­pa­ny mis­sion to devel­op build­ing sys­tems that sim­pli­fy, and, as a result, simul­ta­ne­ous­ly reduce con­struc­tion costs and improve build­ing per­for­mance.

Our com­pa­ny mot­to is Con­struc­tion. Sim­pli­fied.” The Bau­tex Wall Sys­tem is both struc­ture and com­plete build­ing enve­lope in one inte­grat­ed solu­tion that is quick­ly and effi­cient­ly installed by a sin­gle trade. Bau­tex makes design­ing and con­struct­ing resilient, healthy, com­fort­able, safe and ener­gy-effi­cient build­ings eas­i­er.

If you are want­i­ng more infor­ma­tion or need some help get­ting start­ed with The Bau­tex Wall Sys­tem, let us know what you are work­ing on.


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