Age alone may not be reason enough to scrap school HVAC

Age alone may not be reason enough to scrap school HVAC A dehumidification air-handling unit is hoisted to the roof of Burlington High School, above the school's swim complex. Installation is part of $9 million in ESSER-funded HVAC improvements at the school in Burlington, Iowa. (CANCO photo)

3 weeks, 6 days ago

Going the extra mile to determine whether existing HVAC systems still have life left in them can result in big savings on school renovation projects.

By Craig T. Neises
Carl A. Nelson & Company

BURLINGTON, Iowa — Over a span of 56 years, from the time its foundations were laid in 1966 until the spring of 2022, Burlington High School sat essentially untouched.

Several additions expanded the southeast Iowa school to nearly 300,000 square feet. But beyond that? Upkeep was kept up, and that was about all.

So, when the Burlington Community School District (BCSD) moved in 2021 to leverage an extension of Iowa’s school infrastructure sales tax fund, plus several million dollars from the federal government for COVID-related air-quality improvements, most of what the construction management team from Carl A. Nelson & Company (CANCO), architects and engineers found waiting for them was original to the day the school opened in 1969. As design began for Phase I, which is focused on HVAC upgrades and relies on $9 million in ESSER program funds, the solution to so many outdated mechanical and electrical systems seemed obvious:

“The conventional wisdom was, everything needed to be replaced,” said CANCO President Tim Seibert, P.E., who is leading the overall two-phase, $42 million Construction Management Agency (CMa) project.

In this case, however, convention was only partially wise. True to expectations, the school’s pneumatic HVAC controls will be updated to digital in Phase I. Also as expected, the domestic plumbing and electrical systems throughout the building were beyond their useful life, although those systems will be replaced in Phase II. But, as it turned out, half-a-century of careful upkeep by generations of BCSD maintenance employees meant plenty of useful life remained in the extensive network of hydronic pipes used in the heating and cooling system for the building.

Initially, Seibert said, he suspected the pipe would have to be replaced. On that, he was in agreement with engineering partners at IMEG, and also with a 2018 master plan assessment completed by another firm. But with an estimated replacement cost of $2.2 million, Seibert said, “I thought it was worth the time and effort” to find out for sure.

Ultrasonic thickness testing of the carbon steel pipe, carried out at a cost of less than $6,000, showed the existing pipe systems met new-pipe specifications for thickness. Seibert credited BHS staff for maintaining the system properly to prevent corrosion over more than 50 years.

“They obviously had done a good job of keeping their chemicals up-to-date,” he said, referring to anti-corrosion additives circulating with the water in the closed-loop hot- and chilled-water systems. To help preserve it well into the future, the system was set to be flushed, and a pair of pot-feeders were added that will allow maintenance workers to more precisely and easily add new chemicals when needed.

A similar testing approach was taken to expected replacement of return and outdoor air dampers in the academic wing — 18 of them in a variety of sizes up to the largest at 228 x 60 inches, each dating to before 1969. Replacement was anticipated to cost $197,000, but testing — done at a cost of less than $12,000, including erection of temporary scaffolds to reach the dampers inside elevated air shafts — showed the equipment was in good shape and suitable to retain. Permanent access was added to make the dampers easier to maintain going forward. Between the hydronic pipe and the dampers, less than $18,000 in testing cost saved the district $2.4 million in unnecessary replacements. The savings allowed for scope in Phase II to increase by the amount saved in Phase I. The time saved by not having to replace the entire hydronic piping system meant Phase I also can be more easily completed before the July 2024 deadline associated with the ESSER funding.

New terminal air boxes for classrooms in the academic wing at Burlington High School in Burlington, Iowa, are installed in an air-supply tunnel as part of the Burlington Community School District’s $9 million ESSER-funded HVAC upgrades. (CANCO photo)

Existing hydronic pumps being removed for replacement, left; strainers for hydronic coils await installation. (CANCO photos)

Additional work in Phase I includes expanding cooling to areas that were on separate systems or not cooled at all by taking advantage of idle capacity in new chillers installed in 2017, replacing all of the 1966-vintage air-handling units and terminal boxes and phased replacement of the pneumatic controls with digital, Seibert said. New systems will provide significant improvements to dehumidification and air filtration in the building, as well as better temperature control.

Structurally and architecturally, the building is sound, but it lacks any of the kinds of modern, 21st Century Learning spaces found in newer schools across Iowa. In a 2021 master plan update, modernization and expansion goals, combined with mechanical and electrical necessities, added up to about $95 million. With less than half of that amount available to spend, the School Board issued marching orders to the project team to prioritize extending the building’s life by fixing and replacing things that had surpassed their useful life, and to save any changes related to student and faculty spaces for whatever money was leftover. Making the cut for Phase II, which kicks off in 2023 and goes into 2025, were replacement of exterior windows and curtain walls, and updates to the school environment that include relocating offices and creating a secure entrance off the student parking lot; remodeling the office wing to provide updated classroom space and better building access for special needs students; gutted and reconfigured academic areas that will introduce collaborative and small-group learning spaces; improved building security; new fire alarm system; an enclosed and climate-controlled passageway leading to the Industrial Arts Building, and new HVAC in that building. Additions for a second gym and a performing arts building, among other desired improvements, were cut out entirely.

A question is asked in December 2021 at a master planning session to review design concepts and priorities for improvements at Burlington High School. Areas in red are proposed additions, in blue existing spaces with renovation options. With just $42 million available, and $95 million in identified wants and needs, the Burlington Community School District opted to repair and replace building systems before turning toward updates to the school environment. (CANCO photo)

Portions of what will be done to improve the quality of the learning environment at BHS will be possible because of the extra effort expended to avoid the costly and ultimately unnecessary replacement of the hydronic piping and the dampers. CANCO has had similar experiences in other schools, including a high school remodeling project at Shenandoah High School in southwest Iowa, where testing of the HVAC resulted in design changes that saved $500,000 and allowed increased scope elsewhere. Seibert said the lesson of that and of BHS to school districts with older buildings to remodel is to “challenge conventional wisdom and find the root cause of any operating issues.”

If the parts are old, and someone says they need to be replaced, Seibert said, find out whether that’s correct. And if a system isn’t working properly, test it then, if possible, fix it.

“We might have found out it was broken,” Seibert said, referring to the systems at BHS and at Shenandoah. “Testing revealed that it wasn’t.”

Heating water hydronic piping with the asbestos abated is seen in the air-supply tunnel of Burlington High School. Testing showed the 56-year-old pipe still met new-pipe specifications due to careful maintenance and did not require replacement. (CANCO photo)

An in-use pneumatic HVAC control panel from the year construction of Burlington High School began in 1966, is seen at the school. (CANCO photo)

Carl A. Nelson & Company President Tim Seibert, P.E., shows a new electronic power panel installed as part of the school’s ESSER-funded HVAC upgrade. (CANCO photo)