There are two main strategies to prevent the spread of COVID-19 in building interiors. Direct transmission between persons can be minimized by following the guidance from health authorities: wearing face coverings, practicing social distancing, frequent handwashing, etc. However, there is also evidence that coronavirus can stay in the air for several hours, which has two consequences:
- It can travel more than six feet before settling on a surface.
- People can be exposed even when an infected individual has already left the building.
ASHRAE has provided extensive guidance on how to minimize the spread of COVID-19 indoors. The recommendations change depending on the type of building, but three main guidelines are given: increasing ventilation with outdoor air as much as possible, upgrading the air filters to capture viral particles more effectively, and deploying ultraviolet germicidal irradiation to inactivate the virus.
Improve your indoor air quality and reduce the risk of COVID-19 transmission.
These measures from ASHRAE are an excellent complement for personal protective equipment, social distancing and frequent handwashing. However, they all increase the energy consumption of a building - more ventilation and finer filters require more fan power, while UV lights require electricity. For additional prevention, building owners can also follow the guidance provided by the US Green Building Council (USGBC) and the International Well Building Institute (IWBI):
- Buildings can now earn LEED credits for COVID-19 prevention measures.
- The IWBI launched the WELL Health-Safety Rating, which can be achieved more easily than a complete WELL Certification.
Improving Ventilation Efficiency
Increased ventilation with outdoor air and improved filters are both recommended by ASHRAE. However, both measures increase energy consumption. Consider that the electricity consumption of a fan depends on both airflow and the resistance to that airflow.
- When more outdoor air is supplied to the building, the ventilation system must handle a higher airflow.
- On the other hand, a higher filter rating represents more resistance to airflow.
In other words, the fans must supply more air, while overcoming a greater pressure drop caused by the improved filters. These factors increase electricity consumption.
An effective measure to reduce ventilation costs is by installing NEMA Premium Efficiency motors on fans. The exact savings depend on the specific horsepower, design features and operating schedule of each motor. However, a motor upgrade can often reduce heat losses by 10-25%. When multiple motors are upgraded to NEMA Premium, a facility can save thousands of dollars each year.
An increased outdoor air supply also leads to a higher workload for air conditioning and space heating systems. Outdoor air must be cooled or heated depending on the time of the year, and more outdoor air leads to higher HVAC workload overall. However, there are two effective measures that can improve HVAC efficiency:
- Using an energy recovery ventilation (ERV) to exchange heat and humidity between the outdoor air supply and the air exhaust. An ERV can pre-cool air during summer or it can pre-heat air during winter.
- Using an airside economizer, which takes advantage of “free cooling” with outdoor air when the weather is adequate.
The combination of NEMA Premium fan motors, ERV and an airside economizer can help compensate for the extra ventilation costs brought by the COVID-19 pandemic.
Reducing Lighting Costs When Using UV Disinfection
Ultraviolet germicidal irradiation systems normally use mercury vapor lamps. While there are LED versions available, the technology is still being developed and traditional UV lamps offer better performance. Consider that LED lamps save electricity by providing equivalent lighting with a reduced energy output. However, UV disinfection is based on using high-energy lighting to eliminate germs.
Reducing the operating cost of UVGI systems directly is impractical. However, building owners can reduce lighting costs overall, by upgrading their normal lighting systems to LED.
- An LED lighting upgrade typically saves between 30% and 90% of lighting costs, depending on the lamp types being replaced.
- These sayings can then help cover the additional operating cost brought by UV disinfection systems.
Ideally, buildings should use LED products with certification labels such as ENERGY STAR or DesignLights Consortium (DLC). Lamps and luminaires with these labels have been subject to rigorous testing by laboratories that are independent from manufacturers.
LED lighting also saves many lamp replacements over time, thanks to its long service life. While a fluorescent tube lasts around 20,000 h and a metal halide lamp lasts around 10,000 h, there are LED versions of these lamps rated for 50,000 h or more.
COVID-19 prevention measures bring additional costs for building owners, and this includes energy costs for functions like air filtering or UV disinfection. However, energy efficiency measures can help compensate for these additional expenses.
A qualified MEP engineering firm can help you improve indoor air quality and energy efficiency at the same time. This makes your building a safer place during the COVID-19 emergency, while reducing your electricity and gas bills.