Who among us doesn’t take indoor air quality for granted? That is, we take it for granted until it’s bad. I once had the opportunity to be in a building that was replacing 3,000 s.f. of carpet. The glue they used had a high VOC content. Within hours, the smell of glue had permeated the building, across several floors and several hundred thousand square feet of space. It took three days to flush the building. Believe me, after three days of headaches, me and the other eleven hundred occupants in the building understood how important indoor air quantity is!

One of the main factors in Indoor Air Quality (IAQ) is source control. There are many pollutants out there, be it odor, spores, pollen, dust, or other allergens and irritants. Once these pollutants are in an HVAC system, it is much harder to get them out. So, what’s one of the most effective ways to reduce these pollutants? It’s simple really; you don’t let them in to begin with.

So, how does this impact construction? Well, let’s take a common scenario. Construction has just completed, after several months of agonizing work. The schedule is very tight, and it’s been a rush to get everything closed in and conditioned, so that finishes can go down. It’s time to start testing and balancing the HVAC system. Turn those units on full blast, and watch that big cloud of gyp dust come out of every grill. Ever wonder what else is still in the system? Ever checked the filters?

The LEED-NC system has two credits that are specifically tuned to the above scenario. EQcr3 allocates one point for practices during construction, and one point for practices after construction but prior to occupancy. At the Hensley Field Operations Center, we went for both these credits – but let me tell you, while not difficult, there are some issues you should be aware of up front.

Hensley Field was contracted under a design/build contract. One of the advantages to this method of contracting was that we had the entire design team, along with the contractor, present from the very start of design. We were already going after the four points available under EQcr4 low-emitting materials credits, so it made sense to go after EQcr3. It was quickly determined that the first half of the EQcr3 was easily achievable. SMACNA guidelines governing clean installation practices would have to be incorporated on the job site. This was not difficult, as this also tied in nicely with our construction waste management plan. Additionally, we would have to protect all ductwork throughout construction. Again, this didn’t seem to be a major construction issue.

The second half of EQcr3 was going to be a little more difficult. At the time of design, the testing procedures referenced in the reference guide were a little vague. It seemed that a two-week building flush-out would be relatively simple, as long as the schedule permitted. Our initial prices on air testing were a little high, so we decided to plan on the flush-out, and if the schedule didn’t permit, then to do the indoor air testing.

Overall, construction went very smoothly. We had one small hiccup with the mechanical sub- contractor. The very first batch of ductwork was not covered during install. Coincidently enough, we had high winds that day, resulting in lots of dirt blowing around on site. This was quite evident as you ran your finger along the inside of the duct already installed but not covered. We ended up rejecting that entire batch of ductwork, and making the sub take down and reinstall all the installed duct. It’s funny, as we had discussed this very issue during the weekly sub meetings for the previous five weeks; it took the rejection of the first load of duct work to emphasize how serious we were. After that, we never had an issue.

So, you might ask, what where the real issues? It might surprise you, but they were more on the design side. EQcr3.2 calls for a two week building flush-out with 100% outside air. Unfortunately, this doesn’t factor in the humidity that is generally found in our climate. In order to compensate, most mechanical engineers design around this parameter by reducing the amount of outside air that is brought in, and mixing it with return air.

We were no different. Our HVAC design for normal building usage was based upon 30% outside air. This is a far cry from the 100% required by the credit. When we realized this (during construction no less), we first went and reviewed the Credit Interpretation Requests (CIR’s) available on-line. Many others had run into this same problem, for which USGBC had supplied a new calculation that took into account the amount of outside air brought in compared to the square footage. Of course, this is easier said than done – this calculation made IRS tax forms simple by comparison.

We ran the calculation, and were not happy with the results. The calculations changed our projected two week flush-out into a six week flush-out. And, this was running the system at max speed (which we didn’t design the equipment for, and would probably void every warranty we had). If we ran it at normal speeds (for which it was designed), the flush-out could take up to ten weeks! Well, this is pure insanity! No construction schedule can absorb that.

If that wasn’t bad enough, with the systems running at that speed, we wouldn’t be able to control humidity during the flush-out. This means that we would have to wait until after the flush-out to install ceiling tile. Since ceiling tile is over 95% cellulose (paper) material, there is a pretty decent chance of growing mold with that much moisture in the air. Growing mold is exactly what we were trying to avoid with this credit! Further complicating this is that, in order to test and balance the systems, ceiling tile would have to be installed – which means we would have to wait until after the flush-put to commission the entire system. And, to top it all off, our systems were not designed to accommodate the larger filters required during flush-out. This would be the only time in their lifetime that our systems would ever require a filter this large, and this small detail was left out of the design drawings. This zero cost item, if implemented during design, quickly magnified into a $3700 field modification per air handler.

This is where you have to stop, take a deep breath, and reassess the situation. The beauty of the LEED system is that it is ever evolving and becoming easier to use, exactly because of issues like this. We knew that we had a pristine HVAC system, due to the SMACNA measures that had been implemented. We also knew that we had relatively little off-gassing, due to all the low VOC materials used during construction. We decided to reassess the air quality testing.

During design, we had obtained a price was $18,000 for testing which covered our 20,000 s.f. of conditioned space. We didn’t have a really good feeling about this; the initial proposal was quite vague on exactly what was included. We decided to go another route, and consult an environmental testing firm. After review, they were able to provide us a specific proposal detailing the different air tests that would occur, for a much more reasonable price of $2,200. We went ahead and tested, and the results confirmed our initial hopes – the containments in the air found were so low, they were barely detectable, and in some cases, within the error range of the equipment.

So, when choosing LEED credits, it is important that you take advantage of complimentary credits. For example, EQcr3 ties in nicely with MRcr2, EQprereq1, and EQcr4, and if you are pursuing one set, you should look at the others. This methodology gets you out of the mindset of buying credits. There are many items that can be implemented at no cost during design, but can cause issues (and increased cost) during construction if not addressed properly and early enough. And, if you run into a situation that spins out of control (like we did on the flush- out), review the additional information on-line and talk to other individuals who may have run into the same issues. LEED is simply a method of rating sustainable buildings; it’s not meant to be unattainable, impossible, or unreasonable.