Photo 207582400 © Carolyn Franks |
Some schools have upgraded the HVAC systems to combat Covid-19, but most report they have opted for lower-cost ventilation improvement strategies.

To retrofit or not to retrofit?

July 4, 2022
Factors to consider when deciding whether to upgrade or replace a school’s HVAC system.

Having an HVAC unit that runs at optimal levels has become increasingly important because of the heightened concern about airborne pathogens over the past few years. Cold and flu viruses already were discussed frequently, but the Covid-19 pandemic has pushed indoor air quality (IAQ) to the forefront of the news cycle. K-12 schools were put under a microscope as ensuring health and safety within these facilities became a greater priority.

With the wide availability of vaccines, many people have become less worried about Covid-19, but as schools look at the ways they can improve the healthfulness of their facilities, the efficiency of HVAC units continues to be a prime topic. Should schools consider replacing their HVAC units completely, or will a few upgrades do the trick of providing better heating and cooling solutions? In addition, would replacing the entire unit improve indoor air quality within the building? These are questions that K-12 schools should consider when thinking about their HVAC units.

One of the responsibilities of a school is to ensure its occupants, students and staff alike, are comfortable and have fresh air to breathe. Schools need to determine whether retrofitting HVAC units is the best route to achieve that goal.

Whether a school is retrofitting an HVAC unit or replacing it, it is always important for a system to be operating efficiently. The age of the unit factors heavily into its efficiency. If a system has a motor that is older or worn out, it will have added amp load, which increases the utility bill. Older filters and dirtier coils will add extra static and put more force on the motor as well. When it comes to IAQ, an older system may not be bringing in the fresh air that’s required by ASHRAE Standard 62.1 if the dampers or economizers aren’t working properly. With less efficiency comes less fresh air and potentially a higher energy bill. Efficiency is critical for HVAC units.

Upgrade or Replace?

Several small signs could indicate a need to replace or upgrade an HVAC unit, but the most common is continual breakdowns. Think of an HVAC system like a car. If a car keeps breaking down, it will have to be fixed repeatedly; eventually it will have to be replaced. The same applies to an HVAC unit. In addition, carrying out repairs can be costly. Repeated repairs can quickly eat up the limited budget that schools have for such work.

Complaints from a building’s occupants are another telltale sign it’s time for an upgrade. When the heating or cooling systems keep failing or the air is uncomfortable to breathe, complaints from occupants will increase.

Schools should consider several factors when determining whether to retrofit an HVAC unit. The age of the unit plays a major role in the decision. The air conditioning industry has seen R-12 and R-22 refrigerants be phased out in recent years. If schools have systems that use those refrigerants, they may want to consider replacing them with systems that use more modern refrigerants like R-410, R-407C or even refrigerants that will be coming once R-410 is phased out.

From an IAQ viewpoint, the idea of upgrading an HVAC system with needlepoint bipolar ionization, higher-rated MERV filters or UV lights is a great move if the unit’s motors can handle the added stress. When speaking with facility managers, many of them attempt to add these components without upgrading their motors at the same time. Many motors in older equipment are not sized to handle the added static. Some motors have failed because facility managers did not accommodate for the increased static pressure and less airflow brought about by added filters. If a school decides to retrofit an HVAC unit, it needs to make all the necessary upgrades so it can avoid added repair expenses down the line.

Older Units and Upgrades

Retrofitting more modern units have several benefits. The overall cost to retrofit can be considerably lower than a full replacement. The time involved to do a retrofit would be less than a full replacement, and schools would experience less downtime during the retrofitting process.

When it comes to older units, deciding whether to retrofit becomes more difficult. It all goes back to the age of the equipment. Would it be worthwhile to upgrade an HVAC unit that is 20 years old? After replacing the motor and filters and adding needlepoint bipolar or UV lights, schools could still have their unit go out of service five years later. So, there are always more things to look at than just a simple upgrade.

Indoor Air Quality and Retrofitting

UV lights, needlepoint bipolar ionization and higher-rated MERV filters may enhance an HVAC unit’s IAQ capabilities. But do these upgrades offer the same level of IAQ as a full replacement? The short answer is possibly. Remember, the age of the HVAC units is paramount. When it comes to older units, one could change the filters and still not be meeting the fresh air requirements stated by ASHRAE. The ability for a retrofitted unit to meet the same standards as a new unit change from unit to unit.

There is no simple yes or no answer on whether a school should retrofit its HVAC unit or replace it. For more modern units, retrofitting could provide multiple benefits and enable the unit to bring in fresh clean air. By offering a solution that increases efficiency at a cheaper cost than a replacement, retrofitting is a great solution for these systems.

On the opposite side of the spectrum, older units may not be able to handle upgrades. The motors in these units may malfunction as a result of added static pressure. Although replacing motors on these units is possible, the unit could easily go out of service soon after the upgrades are made. In that scenario, replacing the entire unit may provide optimal results. It is important to take all things into account when deciding to retrofit or replace.

Jason Gillis is a regional sales manager and former application engineer at Modine Manufacturing Company ( Modine specializes in thermal management systems and components.


Schools opt for lower-cost ventilation strategies

A national survey indicates that only 38.5% of U.S. public schools say they have replaced or upgraded their HVAC systems to improve ventilation and combat the spread of Covid-19.

The U.S. Centers for Disease Control and Prevention (CDC), in a Morbidity and Mortality report from June, said that instead of pursuing HVAC system replacement or upgrades, most schools opted for lower-cost strategies for improving ventilation: 73.6% of respondents said they moved activities outdoors; 70.5% said they inspected and validated their existing HVAC) systems; 67.3% said they opened doors, and 67.2% said they opened windows.

“The most frequently reported ventilation improvement strategies were lower-cost strategies,” the CDC says. “Focusing support on schools least likely to have implemented resource-intensive ventilation strategies might facilitate equitable implementation.”

Inadequate ventilation in schools can lead to poor indoor air quality and increase the risk of contracting Covid-19. Even before the pandemic focused greater attention on air quality in schools, the problem of deferred maintenance and inefficient HVAC systems in school buildings was known to be a widespread problem.

The U.S. Government Accounting Office (GAO) issued a report in 2020 that said 41% of the nation’s school districts needed to update or replace the HVAC systems in at least half of their schools. That equates to about 36,000 schools, the GAO said.

The June 2022 CDC report said that HVAC upgrade or replacement—which the report categorized as higher-cost, resource-intensive ventilation improvement strategies—were employed less frequently by schools than lower-cost steps; 38.5% of schools said they replaced or upgraded HVAC systems; 29.8% deployed high-efficiency particulate (HEPA) filtration systems in eating areas; and 28.2% used HEPA filtration systems in classrooms.

City schools were less likely to report opening windows for ventilation (53.9%) than were suburban (69.5%), town (75.3%), and rural (73.5%) schools; city schools also were less likely to use fans to increase effectiveness of opening windows (26.1%) than were town (43.0%) and rural (43.3%) schools.

Rural schools were less likely to use HEPA filtration systems in areas where students eat (19.1%) or to use portable HEPA filtration systems in classrooms (15.6%) than were city (33.4% and 37.7%, respectively) and suburban schools (33.2% and 32.9%, respectively). Rural schools were less likely than were city schools to use portable HEPA filtration systems for high-risk areas (22.0% versus 44.7%), the survey found.

“Differences by locale and school poverty level in implementing more resource-intensive strategies might be due to supply chain challenges, differences in school or community resources, or accessibility of technical assistance and support for applying to available sources of funding,” the report said.

Schools categorized as mid-poverty used higher-cost strategies less frequently than either higher-poverty or lower-poverty schools.

“Mid-poverty schools might have been least likely to implement these strategies because higher poverty schools might have had more experience in accessing and using federal funds, and lower poverty schools might have been able to implement some of these strategies without additional government support,” the CDC says.

The agency says the findings indicate that mid-poverty schools and schools in rural areas should be made more aware that they may have access to Covid relief funds that could help pay to replace or upgrade their HVAC systems.

“Despite availability of substantial federal resources to improve ventilation in schools, findings suggest that additional efforts might be needed to ensure that all schools successfully access and use resources for ventilation improvements,” the CDC says, “particularly schools least likely to report using resource-intensive ventilation strategies (i.e., rural and mid-poverty schools).”

The CDC said that public health professionals and funding agencies could assist state and local education agencies and school districts by raising awareness about funding sources and ensuring their equitable distribution.

“Supplemental training and technical assistance can help schools identify and access applicable funding and understand what types of strategies can improve ventilation,” the agency said.

The CDC notes that improving ventilation in schools would have long-range health benefits beyond the Covid-19 pandemic.

“In addition to preventing spread of Covid-19 and other infections, such as influenza, ventilation improvements implemented now might lead to broader and lasting improvements in the health of students and staff members,” the agency says. “For example, improved ventilation has been linked to better measures of respiratory health (e.g., allergy symptoms), higher student performance, and decreased student absenteeism.”

The CDC’s findings were based on a web survey in February and March of a nationally representative sample of administrators from 420 K-12 public schools.

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