WHATELY — The town can reduce its annual energy expenditure by 62 percent or more if it takes measures recommended by a group of University of Massachusetts students trained in building science and energy analysis.
Whately invited the UMass Clean Energy Corps, working under the direction of professor Ben Weil, to investigate the Whately Elementary School — the largest energy user of all municipal buildings in town — for potential energy savings, improved comfort and functionality, and a possible transition toward renewable energy.
Ventilation results in the largest single source of heat loss, accounting for nearly 50 percent of it. According to the site assessment the students produced, recommendations include installing air barriers at the ceiling level for $7,400; adding a new modulating condensing boiler to heat the building (while maintaining the existing boiler for code-required redundancy) for as little as $14,000; adding heat recovery to existing ventilation systems for $24,000; and incorporating variable frequency drives on the hydronic pumps and ventilation fans.
Uncontrolled air leakage can be greatly reduced with a complete air barrier, saving $1,430 a year, and installing in-line heat recovery ventilators in the duct system would provide an additional 42 percent, or $8,700, in heating energy savings each year and improve indoor air quality, the assessment states.
The addition of variable frequency drives, which varies the frequency and voltage supplied to an electric motor, could save almost $8,000 a year in electrical charges, and adding smaller modulating condensing gas boilers could result in a savings of 20 percent, or about $3,780, according to the site assessment.
A complete air barrier can be created by adding a gypsum board ceiling attached with screws directly through the existing ceiling tiles. The students estimate installation would likely pay for itself in less than five years.
There are cracks and unsealed openings in the ceilings, according to the assessment. The blown-in cellulose insulation that has been installed on top of the gym area is loose fill. Some walkable, floored areas of the attic have batt insulation and unsealed foam boards in the cavity spaces.
This configuration, coupled with the significant connections and level changes between the conditioned and unconditioned spaces, results in a high degree of air leakage through the ceiling to the attic, and through the roof vent openings. The lack of an air barrier also results in airflow through the fibrous insulation.
Condensed heat loss through ceilings leads to 13 percent of the heat loss at Whately Elementary, and amounts to $3,300 in annual fuel costs. The estimated cost of installed in-line heat recovery ventilators is about $4,000 per unit. With six units, that equals about $24,000 — with a payback period of less than three years.
The boiler has an estimated 75 percent efficiency. Newer modulating condensing boilers have efficiencies of between 95 and 98 percent, according to the site assessment. The existing boiler is also oversized.
According to the assessment, the sprinkler system is almost entirely in the unconditioned attic space. This has resulted in multiple problems over the years due to the temperature differentials above the ceiling plane.
The assessment states condensation is problematic with dry sprinkler systems, and the school has invested in measures to alleviate the water that gathers in the piping, including installing a hallway drain. This, according to the students’ assessment, has been relatively successful as a short-term fix but does not address the problem of condensation within the piping.
Installing a new wet fire sprinkler system just below the new ceiling is the preferable option, according to the assessment, as that would allow for the simplest installation with the least requirement for detailed work in the attic. The reports states wet systems are less expensive, more reliable and incur much less maintenance cost.
However, the cost of installing a new sprinkler system could be about $10,000. It is also possible to adapt the existing system for roughly $2,000.
Reach Domenic Poli at: firstname.lastname@example.org or 413-772-0261, ext. 262.