The Impact Of COVID 19 On Residential MEP Design

The COVID-19 pandemic heavily affected the building sector and made healthy building interior one of the most important safety factors. In residential buildings, indoor air quality has gained the utmost importance for stopping the transmission of coronavirus. To create safe indoor spaces, the MEP design plays a critical role.

The requirements of every building might be the same as each building is unique. However, the most common requirements that must be met for preventing the transmission of COVID-19 and other viruses are:

• High ventilation rates for preventing accumulation of harmful viral particles in the air.
• Smart ventilation layout for ensuring that the air pollutants are eliminated at the source and not distributed to nearby building areas.
• Efficient filtering for eliminating viruses up to 0.3 microns.
• Reliable disinfection methods for destroying germs that aren’t removed with ventilation and filtering.

One of the common concerns with building system upgrades is the higher associated costs due to increased energy consumption. The above mentioned measures can be compensated with effective energy efficiency measures.

COVID Prevention with Effective Ventilation Design

For an optimal ventilation system design, ASHRAE has 2 main recommendations:

• Increased outdoor air ventilation for displacing any contaminated indoor air.
• Minimum to none recirculation of indoor air for stopping transmission of viruses and germs.

Even in absence of viral particles, an effective ventilation design can greatly improve the indoor air quality and promote comfort.

Keep in mind that patients with mild COVID-19 symptoms are often instructed to recover at home until medical attention is needed. This is where ventilation systems come to the picture for ensuring removal of harmful airborne particles.

During emergency situations like coronavirus pandemic, the additional ventilation can increase the energy consumption. However, there are ways how the excess requirement can be compensated:

• In favourable weather condition, residential ventilation systems can use airside economizer for achieving free cooling as the outdoor air is cool enough for replacing the need of air conditioning.
• HVAC systems coupled with Energy Recovery Ventilator (ERV) can further reduce the heating and cooling costs without sacrificing indoor air quality and comfort.

Role of Filter Ratings in COVID Prevention

Air filters have the ability of trapping harmful air particles. This can be done by a series of filters that trap the viral particles before the filtered air is circulated. The filter rating refers to the ability of air filters in trapping the tinniest of harmful air particles.

ASHRAE recommends upgrading air filters to a minimum rating of MERV 14. These filters have the ability of providing 85% to 90% efficiency for capturing harmful air particles between 1 to 3 microns in size. An important thing to keep in mind that the fan capacities must be checked before upgrading air filters, or the new air filters might hinder or restrict airflow.

High Efficiency Particulate Air (HEPA) filters are more effective than MERV 16 filters, the highest MERV rating, with the ability of capturing 99.97% of particles with 0.3 to 0.1 microns in size. For comparison, 1 mm is equal to 1000 microns. Even though they are better than the recommended MERV 14 air filters, not all ventilation systems can handle them. Thus, they are often used as portable air cleaners.

Which is the Best Air Purification Method Against COVID?

Ventilation can remove viral air particles and air filters can capture them. However, there is a way to destroy the airborne viruses and germs. This can be done by Ultraviolet Germicidal Irradiation (UVGI). HVAC systems couples with UVGI can provide optimal protection against COVID 19 and other harmful viruses and germs. Health authorities like CDC and engineering organizations like ASHRAE highly recommend UVGI.

UV rays have the ability to kill viruses by destroying their DNA. The best results can be achieved with UV-C radiation, which has a wavelength of 200 to 280 nm. The highest germicidal effect is achieved at 254.7 nm, thus UVGI systems.

UVGI systems are versatile. Some UVGI systems are designed to be installed in air handlers and air ducts for eliminating viruses when the air passes through them, while other UVGI systems are portable and designed to clean objects or specific surfaces.