Building owners and operators are attempting to determine what they can do to reduce the spread of disease in the built environment. Many facility managers already implement guidelines from the Centers for Disease Control and Prevention and government authorities and have strengthened administrative controls, such as occupancy planning and social distancing. They also use masks, hand washing, and adequate cleaning.

These steps will lead to an improvement in HVAC controls. The guidelines of the Epidemic Task Force of ASHRAE, the American Society of Heating, Refrigerating and Air-Conditioning Engineers, can help facility managers ensure that the safety of their occupants and staff is always put first.

They can also be sure that these recommendations will increase energy consumption. Prioritizing the health of a building does not require owners to sacrifice their ability optimize energy usage and minimize costs.

Take Control of the Pandemic

Many HVAC systems have data collection, reporting, trending, and alarming features, which enable managers to track in real-time the cost and impact of any changes made to improve IAQ. The age and diversity of the equipment used present a challenge. This suggests that there is no one solution to minimize energy consumption, while still meeting ASHRAE guidelines. Facility managers should consider different options to achieve this goal.

Optimizing Outdoor Air Ventilation

To create a healthier indoor climate, it is important to optimize the HVAC system’s ventilation of outdoor air. ASHRAE urges facility managers increase outdoor air ventilation to the maximum extent possible to reduce recirculation of air. Facility engineers will need to consider the climate, unit capacity, and space requirements in order to achieve this. Increasing OA will increase the load placed on HVAC systems and lead to a significant energy penalty.

There are ways to maximize the outside air ventilation and minimize the penalty. You should ensure that the system fans and dampers work properly, that the cooling coils are cleaned, and that there are no obstructions at outside air intake or exhaust. The demand control ventilation system should be adjusted so that the minimum ventilation rate is equal or higher than ASHRAE standard. Updated control logic can also be added to the economizer in order to provide outside air as fast as possible.

Additional humidification controls and equipment may be needed to deal with the increased outside air. Building operators will also need to consider improving freeze protection or heating to cope with it. Some other steps, such as putting continuously unoccupied parts of the building in setback mode, adjusting the space temperature setpoints to conditions outside normal comfort, and using supply air temperature reset, may also be helpful. Facility managers should also maximize their building automation system’s energy-saving features.

More Control Option

Other control systems can help create a healthier environment in the building:

• Air Flush. Before and after scheduled occupancy, ASHRAE suggests that facility managers initiate a purge process “sufficient to reduce concentrations of infectious airborne particle by 95%.” (See “Coronavirus (COVID-19), Response Resources from ASHRAE & Others”). For a well maintained space, this would take three changes in building volume, using outside air or a four-hour flush.
• Free Cooling at Night. Pre-cooling an area with outside air can replace or supplement a purge cycle.
• Zone occupancy strategies. When a building is partially occupied, HVAC can be set up to create a continuous but temporary unoccupied mode. This can allow for more outside air in the occupied areas while maintaining optimal indoor air quality and reducing energy usage.
• Filtration. Building operators and owners should upgrade to higher MERV rated filters in accordance with ASHRAE guidelines and their systems’ capabilities. Upgrades can require adjustments to airflow setpoints, fan speeds and differential pressure switches. They may also require more frequent filter changes and the addition of a status switch, if not already present.
• Humidity. ASHRAE research suggests that relative humidity levels between 40% and 60% are beneficial. However, the results of this research remain inconclusive. (See ‘Coronavirus Response Resources (COVID-19), from ASHRAE, and Others’.) Indoor humidity levels should always be monitored in order to prevent condensation and mold. Facility managers should also stay informed about new recommendations.
• Remote Commissioning. In order to commission an older HVAC system or one that has been idle for some time, an on-site inspection is required. However, remote commissioning can be an affordable and effective option when the equipment is relatively new, has only been inactive a short period of time, and has advanced control features.
• Airside Remote Management. Airside Remote Management uses the building’s automation to create a comfortable and safe environment, with minimal input from local engineers. A team of engineers, data scientists and analysts can assess the operational health of the control system, IAQ, filters and equipment. The team can schedule services for exhaust and ventilator equipment by using planned assessments, remote diagnosis and remote resolution.
• IAQ sensor alarms. The sensors can monitor temperature, relative humidities, volatile compounds, filters status, and occupancy. They can also alert building operators when corrective actions are needed.