If you chose the previous over the latter in the questions above, then you may want to skip this article and move on to a safer one describing the method of selecting the proper color of a fan or something equally benign. If, on the other hand, you fancy yourself a risk taker, then this feature and its subject market may be worthy of your daring.
Fasten your chinstrap ... are you ready? ... are you bold enough to tackle ... a school?
You may be thinking, "All that hype over schools? Everyone does schools. What's the big deal?" Well, you wouldn't know it by the size of the typical fee (two-thirds of 6% of nothing) but schools are some of the most professionally precarious project types out there.
In the last five years, a number of landmark studies and reports have put the design community on notice: Either design a healthy and safe building, or go ahead and forward your address to the local magistrate so your summons doesn't get lost in the mail later.
Theoretical Sticky Wicket
Beyond simple comfort, proper school HVAC design, like all design, has always been an ethical issue. Like doctors, P.E.'s pledge to do no harm. But for years, the individual practitioner carried the day as "common practice" and "industry standard," filtered through the prism of personal preference, defined acceptable protection.In the '70s, the energy crisis lead us to button up buildings, which in turn led to IAQ problems in the '80s. Subsequently, ASHRAE Standard 90.1, regarding energy efficiency, and Standard 62, pertaining to ventilation, both evolved and school design changed as well. The issue of acceptable design was now more structured and, most would argue, more complicated and controversial. To this day, basic questions such as the appropriateness of operable windows (once a given in most school settings) are hotly debated in many corners.
However, in the last decade a new phenomenon, the politicization of design - or more to the point, the politicization of failed design - entered the arena of ideas. This new factor has upped the ante in the high stakes poker game that is HVAC design in our litigious society.
This conclusion regarding politics was reached during the course of researching a previous column for ES on schools and sustainable design1. While searching the Internet with terms like schools, IAQ, sick building, etc., I came across the minutes from a Senate hearing on green school initiatives2.
During this hearing, the EPA testified, "About 40% of schools report at least one unsatisfactory environmental condition such as poor ventilation, heating or lighting ... these unsatisfactory environmental conditions are most often reported in urban schools, schools with high minority student enrollment, and schools with a high percentage of low income students." Note that this statement framed a healthy indoor environment as not merely an engineering concern, but a matter of civil rights.
Take a look at the facility study sponsored by the DOE3 referenced in this same hearing. You will see that the built environment clearly bears on both the students' and teachers' ability to perform. Its conclusion that "what is needed [is] clean air, good light, and a quiet, comfortable, and safe learning environment ..." makes our practice an education issue.
Ethics, public health, civil rights, and education: All matters of great import. Now throw in the tenacity of organized labor (the National Education Association [NEA] and the American Federation of Teachers [AFT]), helpless children, and the notoriously troublesome nature of building renovations, and you have a toxic mix (eat your heart out, black mold) that makes a school project a theoretical sticky wicket to be approached ever so carefully.
Still think schools are a cinch to design?
A Real-World Sticky Wicket
In the last year, the progressive and ever-growing Plano Independent School District (PISD) outside Dallas approached my company, Jacobs Facilities, Inc., regarding a renovation project. A property had become available, and the objective was to convert this existing building into a school. No big whoop, right? In a unique case of integration of church and state, the structure to be transformed was, in fact, a former Methodist church.Built in stages from 1967 through 1983, the 46,000-sq-ft group of interconnected buildings included a sanctuary, classroom, and family center incorporating a gymnasium. The architectural program called for a second floor to be built within the vaulted ceiling cavities of the sanctuary and gym, which in turn would increase overall area to nearly 62,000 sq ft. The mechanical systems were in various degrees of disrepair and obsolescence, and even if they had been in working order, they were not appropriate for the new use and occupancy.
Just to make things a bit more interesting, the renovated facility would house the PISD Special Programs Center (SPC) offering curriculums for at-risk students. These special programs address the needs of expectant parents, tackle behavior management, provide transitional assistance, and work to recover dropouts. Remember the reference above to civil rights? This facility was being created for the most vulnerable in our midst. If they were merely warehoused, it would have been a clear case of what they describe in DC-speak as "environmental injustice."
One more twist: Plano is one of many enlightened municipalities that now require all designers to meet and demonstrate compliance with the energy requirements of the International Energy Conservation Code, which is based on ASHRAE 90.1. Clearly, the expectations were high across the board. And the challenge, while laudable, was no less daunting.
Rules and Tools
Okay, enough fear mongering. The beauty of HVAC is that while the stakes are high and the potential for lawsuits and health risks is real, what we do is not brain surgery. On top of that, there is a plethora of reference materials and design guidelines available to us. And finally, it has all been done before, both correctly and incorrectly, so there are lessons learned and lessons to be learned. Bottom line: this is doable.My mentor was always fond of saying, "If you understand the problem, the solution is obvious." Easy for him to say. For a designer right out of school, (who was not particularly brilliant, I might add) understanding the problem was almost always easier said than done. But a decade or so later with a few trials and tribulations under my belt, the problems are significantly more obvious.
So what are the problems to avoid? Well the biggest, a lawsuit or ill health, are best addressed by an appropriate design, conveyed clearly and executed properly. Due to the need for brevity, this article will not elaborate on construction or focus on communicating design (drawings, specifications, etc.) but it cannot be overstated that in the end, most problems boil down to a breakdown in communication vis-à-vis the documents or a bidder/builder's mistaken interpretation of same. A nice primer on design deliverables is Howard McKew's column in the May 2003 issue of ES4.
Another reality is that the devil is in the details. This article will pluck the more obvious low hanging "problem" fruit, but all kinds of little stuff can create troubles. Recognize that something as unimposing as a condensate trap, if improperly designed or installed, can create moisture, molds, and a mess in no time. While many details are standard, no detail is trivial, so revisit your own collection of details to make sure they are up to speed.
There is an excellent best practices resource published by the DOE's Rebuild America EnergySmart Schools program5. In the mechanical chapter, with an organization emphasizing the interrelationship between systems, there is an excellent overview and discussion on HVAC matters, plus 28 design guidelines on systems for mechanical ventilation, natural ventilation, heating, and cooling systems.
In the end, all roads lead to thermal comfort and IAQ. Therefore, maintaining both is the golden rule of HVAC.
SPC Solution
Albert Einstein said, "Everything should be made as simple as possible, but not simpler." So in that vein, it should come as no surprise that the solutions employed at the SPC were both uncomplicated and proven.Because of the existing parameters, including security, slab-to-slab limitations, and weather, strategies described in the DOE best practices manual could not be employed. Some of these include natural ventilation, displacement ventilation, hydronic ceiling panels, evaporative cooling systems, radiant slabs, and water loop heat pumps.
A four-pipe fancoil system with DOAS was employed. Linda Newman, the HVAC designer said, "Due to the deep arch beams and sloped roof, clearance was down to zero in some areas. Clearance problems also occurred where the additions connected to the original building. As a result, routing ductwork and piping and locating units with adequate service access was tedious."
Brent Byers, Jacobs' design architect saw the yin and the yang of the design challenge, "All classrooms have completely evenly distributed ducted air, which was more complicated due to the addition of the second floor. But ultimately, it was better for the classroom floor plan as opposed to floor mounted or upright closet ventilators."
While difficult to accommodate in the shell, this simple design approach is significant if only for the way the ventilation air was treated. Just five years ago, the concept of decoupling the ventilation (IAQ) component from the thermal comfort component was introduced6. The SPC design was a variation on that theme.
All ventilation air is introduced via dedicated outdoor units with integrated total energy wheels. This air is then heated using duct-mounted coils for unconditioned (heat only) spaces, or for conditioned spaces, ducted to an inlet plenum at a four-pipe fancoil unit (FCU), where it mixes with return air from the space (Figure 1).
Regarding the use of a four-pipe instead of a cooling-only FCU, Newman said, "The facilities manager was not enthusiastic about using a DOAS. The few ERV units that existed in the school district did not function well due to the fact the downstream FCU's could not handle the outside air load at extreme winter conditions. He was the one who has to hear the complaints from teachers when classrooms were too cold." He was clearly in no mood to hear these complaints arise in a new facility.
With the DOAS, the exact quantity of ventilation air is known at every room and set based on ASHRAE 62 requirements. All thermal comfort, both sensible and latent, is then handled by the FCU. Exhaust is drawn through the DOAS, but not before energy is reclaimed at the wheel.
What is interesting about this design is that conventional wisdom said the cost would be prohibitive. In fact, that is quite often the first excuse given for not even considering a DOAS. But in this case as in others, the bids came in under the original estimates based on more traditional, but less effective systems.
In this author's humble opinion, the concept of a dual-path system is one of the simplest yet under utilized opportunities available to the HVAC designer. By separating the ventilation issue from the thermal comfort question (and possibly even the sensible component from the latent component7), the designer is liberated to handle each appropriately without compromise.
Summary
The K-12 market can be one of the most difficult sectors to practice within because of heightened sensibilities and real obstacles. Because of an evolving sense of what is a right vs. what is a convenience or privilege, those in our profession need to be forewarned and aware.That said, schools do not have to be such a conundrum from a technical perspective. The consequences of bad design may be heightened because of the target users, but avoiding these penalties is, as always, a matter of simply providing reasoned design based on established principles and procedures.
In the case of the SPC, rocket science was not employed, but instead a functional, proven, and affordable dual path concept was successfully engaged.
The reader is encouraged to dig deeper into the topics touched on by exploring the referenced documents, especially the statements from the Senate hearing and all of its attachments at www.senate.gov/~ epw/stm1_107.htm#10-01-02 and the DOE design guide at www.energysmart schools.gov/energysmartschool/pdfs/31545.pdf.
And in spite of the hyperbole at the beginning of this feature, you really don't have to be a daredevil. In fact, while I normally don't wait 30 minutes before heading back to the pool, I have yet to jump off a high dive ... nachos or not. ES
