Ventilation

Status of School HVAC Analyses:

* Information updated October 14, 2020

In preparation of the opening of the school year, the district asked the highly qualified HVAC experts employed by the Town of Andover Facilities Department to evaluate the ventilation systems in each schoolhouse.[1] They produced information that was posted to the Return to School webpage. In summary, their analysis concluded that HVAC systems within Andover schools follow current ASHRAE 62 standards or local ventilation standards for minimum outside air requirements.

Additionally, the district engaged an outside HVAC contractor, NV5, to conduct an independent inspection of the ventilation systems in each school building. NV5 has prepared a comprehensive report, which states the Town of Andover's Department of Facilities meets, and in many cases exceeds, the guidelines outlined in the ASHRAE guidance for the reopening of schools. 

In their report, NV5 provided a list of “high priority” and “low priority” items (page 7, table 2) for the district. These items have been addressed by the Town of Andover’s Facilities Department. The information also includes description of each issue, the possible and/or completed remedies, and status of resolution.

It is important to clarify that the NV5 report classified issues as "high priority" or "low priority" based on the amount of outside air that would be required when space is occupied at full capacity.

Andover schools are only at about 50% capacity in the current hybrid learning model, which began on September 17, 2020, and were occupied at even far lower capacity with only staff present from August 31 to September 16, 2020. With that in mind, there were no issues identified by either town facilities or the independent report that suggests there were any problematic or unaddressed issues when staff and students returned for the school year.


Additional Information Regarding HVAC and Ventilation Protocols for School Reopening: 

  • HVAC systems are designed to meet the ASHRAE (American Society of Heating, Refrigerating, Air Conditioning Engineers) Standards. Classrooms have individual unit ventilators, which bring outdoor air into the space. The quantity of outdoor air is controlled by the measure of CO2 in the space and is monitored by the Town of Andover Building Management System (BMS). Common areas, offices, and the classrooms in new buildings have centralized systems which provide HVAC to a group of spaces. These units are also controlled by our BMS.
  • As an additional precaution, Andover custodial staff will conduct a daily air flush a minimum of 2 hours prior to occupancy and run 2 hours post occupancy. For more information on ventilation see the description of existing conditions and procedures developed by the engineer for the Town of Andover.
  • Each nurse’s office has a direct air supply designed to provide fresh air and most nurses’ offices have a direct exhaust to the outside. Nursing isolation rooms designated to provide an isolated environment for students who become ill with coronavirus-like symptoms have exhaust systems that create a negative pressure environment in which the exhaust exits to the outside and is not recirculated. 
  • The district will program its HVAC systems to maintain carbon dioxide levels in school buildings at less than 800 ppm during the school day.
  • The district will set HVAC systems fans to “On” or “Circulate” at the thermostat if the HVAC system does not provide a constant airflow at all times during the school day and during the flushing sequence.
  • Fresh air is provided to all bathrooms, is exhausted to the outside, and is not recirculated. 
  • The district will keep all supply and return grilles and registers open to the maximum extent possible so fresh air flows through them when the HVAC system’s fan is on.
  • The district will set outdoor air intakes or controls to the maximum level of fresh outdoor air the system is capable of handling or providing.
  • The district will set outdoor air intakes or controls to the maximum level of fresh outdoor air the system is capable of handling or providing.
  • The district will use filters rated at the highest efficiency the system is capable of handling. Filters will be changed every three months. At present, each school building’s system is able to handle filters with a minimum rating of MERV-8; the systems in some buildings are able to handle filters with ratings of MERV-13 or MERV-14.
  • The DESE Guidance states to “open windows or doors (when appropriate and safe).” This guidance is meant for facilities or spaces that are not equipped with an HVAC system that is functioning as designed. Opening windows is not meant to be a first course of action and can be a detriment to the proper function of the HVAC system due to pressurization issues. Currently, Minimum Efficiency Reporting Value 8 filters (MERV 8) and MERV 13 in some locations, are used in all HVAC equipment and are replaced every three (3) months as part of the regular preventative maintenance program during the school year.
  • For Variable Air Volume (VAV) systems, the district will set the minimum airflow to the highest possible setting.
  • The HVAC system in each school building is compliant with and will be maintained to remain in compliance with local and state laws, regulations, and codes.

Information from the Andover Department of Facilities

* Information updated on September 10, 2020

The Department of Facilities has both a work order system and a preventative maintenance system and on-site full-time staff so that any system complaints can be addressed immediately. Below is a listing of work completed in support of the return to schools and in response to reopening schools during this unprecedented time:

  • Building Management Systems (BMS) controls for building occupancy have been rescheduled to provide for a 2-hour flush of building air for pre- and post- occupancy of staff.
  • All central air handling units and rooftop units (AHU’s and RTU’s) that can accommodate MERV13 filters have been checked and changed to MERV13.  This represents better than 95% of all AHU’s. For those few that could not accommodate a MERV13, the filters were checked and replaced if needed.
  • At Andover High School, all classroom unit ventilators have been checked for proper operation, repaired if needed, and all filters have been changed to new MERV8 filters.
  • At West Elementary School, all classroom unit ventilators have been checked for proper operation, repaired if needed, and all filters have been changed to new MERV8 filters.
  • By the end of this week, at South School, all classroom unit ventilators will have been checked for proper operation, repaired if needed, and all filters will have been changed to new MERV8 filters.
  • Exhaust vents at Andover High School, West Elementary and South Elementary have been cleaned.
  • Isolation rooms at each school have been identified through analysis of plans and the physical locations.  All approved rooms can achieve negative pressure and alterations are underway where needed.  Negative pressure sensors will be outside each room to display the negative pressure reading.  All isolation rooms will be completed and running negative by the start of school.

The above lists only Heating, Ventilation and Air Conditioning (HVAC) work.  Much more work has been performed by the Department of Facilities to support school opening.  We will continue to support the Andover School Department as always.

[1] The Town of Andover employs a complete full-time staff dedicated to HVAC improvements and maintenance in all town and school buildings. Among these experts is a mechanical engineer with over eight years of prior experience as a private HVAC designer in healthcare, with expertise in the design of negative pressure isolation rooms for infectious patients. Her experience has been particularly relevant to COVID-19 school HVAC evaluations.