We have to clean air which we are recirculating in the system

We need to be very careful particularly for space factor, while designing the air handling rooms.

In today’s post Covid scenario, the designs have been drastically changed. This is more to understand for other people who are doing the installation, design, civil construction. So, when we start speaking about Indian contracts, you know, its ISHRAE doing a lot on making standards. And, when we start overdoing in any condition, be your commercial application, be it a residential, be it industrial application, we tend to lose a lot on energy, which is a counter effect of making indoor air quality better. We are doing more projects with either recirculation or mixed ventilation and by doing that, we have to do either a filtration when we are bringing the air from outside. Secondly, we have to clean the air which we are re-circulating in the system.

Before Covid, was worried about filters. Now, MERV13 or MERV14 or H14 or H17 are getting more prominence, but somehow with Covid awareness of people, everybody has started looking at a better filtration, but our existing projects, existing designs or anything is not suitable to take care of those additional filtration systems. So, what is happening is we are trying to incorporate H13 filter into it which is hyper class, and you are increasing the pressure on fan as well as on cutting your motors and the result of that is we are bringing down the overall capacity. The overall CFM of the system is coming down and we start having more problems in the ventilation or indoor air quality.

What will happen if we don’t put a proper filtration over there, we are going to start losing again the PM 2.5 levels or another kind of gases, and other pollutants will start coming into our indoor environment. So, we really need to be very sure what kind of systems we are implementing and trying to bring the fresh air in. And, based on the location, we can decide whether it’s a gaseous, chemical or just PM 2.5 or other kinds of filters can be installed and that additional fresher can be introduced into the air handling units. So, now as we are designing the new project, we are trying to put all the available technologies into our specifications, which is not recommended. Like we have seen in past couple of months there are a lot of tenders which have been coming out from government and private authorities where they are using ESP filters in recirculation system, they are using UVGI, they are using EPA on the same which is not recommended.

If we use too many in these items like ESP and new UVGI into return systems, that is going to increase the ozone conditions inside very high, which is not recommended because the ozone does not affect us on system. Let’s say, if you have an exposure to ozone for a short time, it is not going to affect us, but if we are sitting into an environment for a much longer time, that is going to affect our body and it can also lead up to cancer situations in future. So, we need to be very a careful when we are deciding when we are choosing. What will happen if you don’t have a thermal break, we are going to have a condensation. And as indicated earlier, if we have moisture, if we have condensation, it is equally bad for indoor air quality. Wherever we get condensation, low temperatures and no light, it will lead to a generation of microbes and bacteria which generally happens on our coil.

So, when we are designing, when we are looking at the construction, apparently units, or the rooms or the air handling units, we really need to provide enough of space, which is required for breathing of an air handling unit. I have been studying a lot of our customers also, where they want to upgrade their air handling unit in size with the latest technology but somehow, they don’t have enough space available in their air handling unit room. So, we need to be very careful while designing the air handling rooms. Why I’m pointing this out because this is more challenging thing for us and for others when talking about kind of technology and the design.

So, I was trying to point out all these construction issues, because this is something which has never been addressed in any kind of forum so far, when we speak about HVAC. And, I find here is an opportunity to share my experiences, which we are facing day to day on the new and old projects.