The Elementary School Building Committee at its Tuesday meeting approved rooftop unit upgrades corresponding with accommodations for future expansions to the Charleswood School.

Factored in the project’s design is space for 18 additional classrooms, which would be added on to the ends of each wing. The upgrade increases the capacity of air movement from 24,000 cubic feet per minute (CFM) to 32,000 CFM.

Jeff D’Amico, vice president and project director at Vertex, said upgrading the mechanical equipment for $275,000 now would be less costly than paying an estimated $360,000 plus escalation if the work is done at the time of expansion.

He said the larger unit operates at a lower speed, potentially increasing its life expectancy compared to adding stand-alone 3,000 CFM outside air units in the future.

Elementary School Building Committee (ESBC) member Mike Shepard said he was concerned that 10 years from now, the town could end up paying twice if some new technology has evolved by then.

But Dan Colli, project manager at architect Perkins Eastman, said outside air unit technology had not significantly changed over the past 30-40 years.

D’Amico noted the district already had made a commitment to geo thermal energy and “this (alternate) capitalizes on that investment.”

ESBC member Bill Flannery asked about enrollment projections and when the district expects it could exceed the 1,200 students for which Charleswood School is being built.

Assistant Superintendent Susan Rothermich said the student population has been growing more than 100 students year after year, and the town continues to have development and families with kids moving in.

Rothermich said she and Superintendent Carol Cavanaugh “got comfort” from the fact that separate enrollment projections by the Massachusetts School Building Authority (MSBA) and Arthur Wagman are very similar.

Cavanaugh said it is unlikely the district will gain 212 students just in Grades 2-4 over the next few years, but eventually it could happen.

D’Amico noted MSBA enrollment projections are at 1,223 students in 2029 and 1,300-plus by 2032.

He clarified that this unit is for “fresh air,” and the plans already have capacity for additions with their heat and cooling components.

D’Amico said there is funding available within the construction budget, which is running $1.2 million under budget at around $123.7 million.

The committee voted unanimously to include the rooftop unit upgrades in the construction plans.

Large building mock-up suggested

The board, however, did not agree to a second “alternate” presented — a six-sided, 10-foot-by-10-foot building mock-up used for performance testing. D’Amico said a larger mock-up would be comprised of all the same features and materials of the new school — including roof, masonry, windows, etc., and could be kept after testing for storage or as a wellhead. The cost would be $85,000 to $103,000.

Shepard said it would be “just crazy” to locate that size mock-up structure where it could be prominently seen as people enter the school site.

He said it would be “God awful, ugly and awkward.”

D’Amico said designers would at least like to have a two-sided, L-shaped mock-up structure, and certain performance tests could be done on the school building itself.

D’Amico said he would write to the commissioning agent, who is the person advocating for the larger mock-up. Ultimately, the decision rests with the EBSC, he added.

Board members spoke in favor of adding more oversight and spot-checking during construction instead so that pressure and other tests on the main building are successful.

In other business, the ESBC gave the go-ahead for the 60% construction documents to be submitted to the MSBA.

Tweaks made to design

The board heard a presentation by Robert Bell, education programmer at Perkins Eastman, highlighting slight changes that were made since the last design review.

These tweaks included a slight field location shift, revised crosswalks with added flash signals, reduction of light poles to 15 feet, reconfiguration of small mechanical rooms, removal of one of 15 staff toilets, and minor furnishing revisions.

Bell said his team would be using long and narrow bricks of different colors for the building exterior that “don’t look thick and clunky” and are “more tactile and accommodating for students at the ground level.”

The next ESBC meeting will be Tuesday, Oct. 8, at 6 p.m.