A guidance document for operation of HVAC (heating,
ventilation and air conditioning) systems in the residences, commercial
buildings and hospitals was issued by Indian Society of Heating, Refrigerating and Air
Conditioning Engineers (ISHRAE). The Guidance covers standalone
and central air-conditioning systems. The Concerns related to temperature
humidity, ventilation and filtration are clearly addressed in the ISHRAE
COVID-19 guidance document.
ISHRAE’s COVID-19 guidance document refers to studies
conducted at various RH levels showing that using viral culture methods, low
temperatures (7-8 Deg C) were optimal for airborne influenza survival with
virus survival decreasing progressively at moderate temperature (20.5-24 Deg C)
and further decreases at higher (greater than 30 Deg C) temperatures.
ISHRAE recommends safe operation of air conditioning
& cooling systems with indoor air temperature and humidity set between 24
Deg C - 30 Deg C and 40%-70% respectively. Dry climates can set temperature
closer to 30 Deg C and operate fans to improve air movement for comfort.
Commercial buildings have multiple occupants and
transient visitors and thus the need for additional precautions, especially in
the operation of their air conditioning systems. Hence, it would be prudent for
all commercial buildings to limit risk by ventilating the indoor environment
with outdoor air as much as possible. As per this document Mechanical
ventilation and filtration provided by a Central Air conditioning system, can
perform this function most effectively compared to simply opening the windows,
because they correctly ventilate the space and improve the indoor air quality
with prescribed outdoor air filtration.
In the healthcare sector, ISHRAE recommends
converting general patient rooms and ICUs into COVID-19 patient areas with
specific considerations pertaining to the HVAC systems in use. According to the
guideline, the conversion of the rooms would first require changing the room
into a non-recirculatory system. This can be achieved by blanking-off the
return air vents in the COVID-19 patient rooms. It is important to make sure
that the air handling unit has the provision to receive adequate outdoor air
supply and the exhaust air from the room is treated as per the methodology recommended.
The Indian Society of Heating, Refrigerating and Air
Conditioning Engineers (ISHRAE), was founded in 1981 at New Delhi by a group of eminent HVAC&R
professionals. ISHRAE today has more than 28,000 HVAC&R professionals and
Student-members. ISHRAE operates from 43 Chapters and sub Chapters spread all
over India , with HQ in Delhi . It is led by a
team of elected officers, who are members of the Society, working on a
voluntary basis, and collectively called the Board of Governors.
At this time of Lockdown, the Wheels of ISHRAE keep
turning through online Meetings and Webinars. ISHRAE’s key Technical deliveries
are Research, Standards, Education and Publications. Visit www. ishrae.in to
be updated.