District Personnel with the addition of contracted services for the server room units.

Located on the roof, except that the 15 Linden warehouse unit has a sidewall air intake.

15 Linden Park has 3 roof top units that serve the conference rooms and offices supported by a hot water boiler for heating and one self-contained floor mounted unit in the warehouse.  11 Linden Park has 6 self-contained roof top units that serve its offices and conference rooms and 2 self-contained roof top units that serve the Server Room.

In HVAC jargon an economizer is a term that can describe a number of strategies that use outside air to provide temperature correction. In all cases, the outside air passes through a filter whether being brought in at 100% or 20%. Some units add to this by using heat recover where the temperature of the exhausted air to lower or raise the temperature of the incoming make-up air.  The exhausted air is contained, separated from the incoming air and the heat transfer is accomplished indirectly through metal panels or coils.  The Linden Park roof top units also have enthalpy controls which evaluate the outside air temperature and humidity relative to the desired indoor set points and directly use the outside air to temper the indoor air, also requiring all outside air to pass through a filter before its distribution.

Yes.  20% outside air is now the minimum level of outside air brought in whether heating or cooling.  As an energy efficiency measure, the programming pulls in additional outside air if the difference between the outdoor air temperature and the indoor set point (72 degrees cooling, 68 degrees heating) allows for it.

We have installed high grade commercial filters based on the manufacturer’s operation manual recommendation.  Currently this is at least MERV 8.  While it is true that ASHRAE is recommending MERV13 for new building designs, they are NOT recommending installation higher rated filters to be installed without careful study of each system.   Their latest update: “Select filtration levels (MERV ratings) that are maximized for equipment capabilities, use MERV 13 if equipment allows, while assuring the pressure drop is less than the fans capability. See Filtration Upgrades.” (ASHRAE, 2020, Re-Opening Schools and Universities, Retrieved from https://www.ashrae.org/technical-resources/reopening-of-schools-and-universities, 2020 Aug 17.)  Please note that there are caveats throughout the ASHRAE guidance, they state the optimum, then the limit. Those of us in O&M are very concerned with this issue.  We continue to evaluate the performance of our units.  They work the hardest in the summer and so we are evaluating the winter performance as a separate issue from the summer performance. We do not want to reduce airflow, cause the units to suck in unfiltered air through gaps in the unit of duct work, nor overwork the units to failure.  A comparison might be that a MERV13 filter is like a N95 mask v. surgical mask which is more of MERV8.  The N95 is superior to a surgical mask and the surgical mask out performs most reusable cloth face coverings.  But, over and over again it has been proven that the cloth face covering works.

We are increasing the HVAC runtime.  We program them to operate as if occupied for at least 2 hours after their scheduled use is completed and at least 2 hours before staff arrive.  It is our objective to have not less than 4 room air turn overs before reducing to the unoccupied schedule and to have at least 2 room air turnovers before opening in the morning.  The average schedule will be 5 AM – 6 PM.  The units may run longer depending upon the outside weather.  It is not that the units are shut off but rather that the desired set point is changed to maintain 80 degrees in the cooling season and 60 degrees in the heating season.  We can override the schedule at any time.  If a nurse or director alerts O&M of a suspected COVID-19 case, we can place the area of concern into a high outside air intake to purge the area, and extend the run time.  Similarly, we can re-schedule for special events.

We do not have high occupant loads, and occupant loads have been further reduced by the new schedules, and we have good ventilation in occupied areas.  Our class sizes are relatively small.

UVGI devices are specifically not approved by SED because they feel their safety is not proven. Regardless, we do not have high occupant loads.

We do not have this type, our energy recover systems separately “pipe” the exhaust air from the incoming air. 

We do maintain these temperature and humidity targets without issue except in the winter where we have noted humidity drops below 40% when it is very cold outside and when school is out of session. A few of newer units allow specific programming to regulate humidity but the older ones do not.