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When and how to use codes and standards for HVAC in laboratories, part 2

Apr 7, 2023 | Public | 0 comments

Insights on Laboratories

  • Codes and standards are an important part of ensuring a laboratory is safe.
  • Properly handling exhaust streams is imperative to ventilation.

HVAC can look different, depending on the setting that it is in. Brandon Fortier, IMEG’s National Science and Technology leader, and Jeremy Barrette, principal at Affiliated Engineers Inc., walk us through different codes and standards for laboratories, as well as air changes in this partial transcript from the Aug. 11, 2022, webcast “HVAC: Labs and research facilities.” This has been edited for clarity.

Brandon Fortier: When we talk about codes and standards and things that may apply to laboratories, the first lesson to take away is that there is not a one stop location that governs everything in a laboratory. There are certainly codes that you’ll need to follow. There are general purpose standards that will apply to many types of laboratories, and then there are very specialty guidelines and standards that are going to apply to a very small subset of laboratories.

ANSI Z9.5 and ASHRAE standards for fume hoods are very generalized standards that fall into what I would consider the 80/20 rule; probably apply to 80% of laboratories, maybe not some of the specialty spaces. The next couple of standards in terms of ASHRAE have applications in a lot of different environments, laboratories included. There are certain sections of those standards that are very relevant and good to familiarize yourself with.

The rest of those codes and standards are unique and apply to certain specific types of spaces. If you have hydrogen, for example, in your laboratory, NFPA 2 is a good resource. If you don’t, it’s probably not something you’re going to want to spend a lot of time with.

Your first step, especially as an engineer working in laboratories, is to get with your architectural partners, make sure you’re reviewing what codes are required by your local jurisdiction, and beyond that, engage very closely with the owner and the users of the space. Oftentimes, they’re great resources, especially industrial hygienists that that owners may have on staff, to make sure you’re not only following all the required codes, but you’re also referencing the correct standards for the projects you’re engaged in.

ANSI Z9.5 standard covers laboratory ventilation in very generalized terms. If you’re getting into animal holding spaces, BSL 3 labs, it isn’t applicable. For most general-purpose chemistry or biological laboratories that don’t have significant chemical or life safety risks, this standard is a great source for starting your design. It starts and covers everything from general lab ventilation, covers fume hood requirements and other types of containment devices.

gets into ventilation system requirements, everything from differential pressures and air balances, how you set up supply and exhaust air systems. It’s a very good resource for people that are just getting into laboratory design and even experienced engineers that maybe have some specific questions on systems that they haven’t run into before. ANSI just came out with an updated version of this standard in 2022, so for those of you who are familiar with the older version, there is new material out there just recently here.

NFPA 45, which is a standard for fire protection, deals with laboratories that have chemicals in them. It goes into detail on how to design these sprinkler systems in those type of laboratories that have chemicals. There is additional information in there, things on ventilation design, things on electrical systems design. It’s another good standard to really familiarize yourself with.

Once you’ve gotten the labs that you’re going to be working in, you understand the types of facilities, you’ve gotten into the types of codes and standards that may be driving your design. There are a very large number of considerations. Jeremy and I are going to take some time, go through things you may run into. Like any engineered system, there are multiple ways to address specifics, but here’s some ideas, some thoughts, some approaches that have been used in other systems.

Jeremy Barrette: The way to approach this is to work with the project team and specifically the researchers, because they’re generally the best ones for the job. They generally know what their research requires or what their testing or teaching requires. Start by asking the simple questions; what temperature range are you looking for? Is it kind of just standard 70° to 75°F, or is there a special high temperature or low temperature requirement?

You also want to identify the tolerance they’re looking for. For a lot of laboratories, plus or minus a degree or two is perfectly fine, but then again there’s spaces such as optical laboratories or maybe even those animal spaces, where that’s not good enough and you’re down in that plus or minus half degree, quarter degree, etc.

The same thing applies to humidity. Sometimes, we’ll humidify a lab building to a base level, just to deal with static dissipation and then dehumidifying on the top end so that in our wet rainy months, we’re not being too humid inside. In some lab buildings, a general range is fine, and in some cases, specific labs have different needs even within that building. Sometimes they want a specific humidity and a tighter tolerance on that. You may have to deal with that space separately or the whole building may be that way.

Another thing to consider is what your pressurization and airflow direction for your labs in adjoining spaces are. Most of the time, in your general laboratories, the negative pressurization is generally where you want to start, but there are certainly many laboratory types that also want to be positive with respect to the surrounding spaces.

Sometimes your cell culture rooms, or your imaging rooms want to be positive so that you’re not allowing outside contamination and dust into those spaces to contaminate what they’re doing. Most lab spaces you’re looking at, you want to be negative to keep in any nuisance odors or things like that.

Some spaces as you’re looking about biocontainment or again clean rooms, you may have anti rooms that get designed too, and staging that pressurization to go from the dirtiest space to the cleanest space, and that’s a good way to think about that.

A lot of labs have specific vibration and acoustical concerns. There are certainly mechanical considerations to consider with that. Not all of that is mechanical can be a structural design as well, but certainly good questions to ask to see if there’s anything special required. With filtration, ask is the air in that space is just your base level of filtration at your main air handler, is that good enough for the cleanliness of the air or are we looking at needing something cleaner? In an optical lab you may be doing HEPA filters.

Then, what’s really driving our air change rates? Generally, we’re talking about how there’s a base industry accepted standard for air change rates in a laboratory. In six to eight air changes per hour is a good starting point, but there may be certain requirements that drive that above that. Do we have a lot of equipment that’s driving that higher or if we’ve got a lot of fume hoods in a space and the exhaust needs a lot of makeup air, so that can drive how much airflow we need to provide in the space.

In some cases, we’re looking at even lower air changes. If it’s a dry data driven laboratory or looking at an unoccupied set point, we may be going lower, but make sure you’re also always covering the ventilation needs of the space for the people, based on ASHRAE 62.1.

Looking at the equipment loads, a lot of times when we’re designing a laboratory, they may or may not have all the researchers identified and they may not know all the equipment that’s going in the space. Knowing how the space is going to be used, you can generally apply a flat cooling rate to those spaces for design. If they are material handling spaces, they’d be on the low end, and then as you get up kind of in your optical laser labs, you may be in that higher 12 or 15 watts of square foot, 18 watts of square foot and maybe for a freezer farm where you just have a high density of sensible cooling needs.

You’re going to provide that cooling, especially as we get into the sensible needs, whether you’re doing it through an all-air system or if you’re coupling that with a hydraulic means of cooling. We know that water is a much more efficient removal of heat source, it’s higher density of heat removal and it’s a lot more efficient to use water than it is for air; pipes are smaller, pumping energies lower. It’s something to consider if you’re in those high density of sensible cooling spaces.

Another big item to look at, especially right at the beginning of a project, is how you’re going to handle your exhaust streams. The first thing to do is define what exhaust streams you’re going to have. Do you have specialty exhaust like your exhausted bio safety cabinets, any special hoods like perchloric acid hoods or your radiology hoods? Do you have animal holding spaces? Identify those because those generally need to have independent exhaust systems. Some of those may have filtration requirements. You want to identify those upfront, make sure you’ve got room for your equipment and for your duct work.

Then from there, look at what’s left, and most of the time your general labs, your biology labs, your chemistry labs, engineering labs, a lot of those, including your fume hoods, can all be combined on a central lab exhaust system. This has a lot of benefits for routing of equipment, locating equipment and providing energy recovery, back to the makeup air.

Historically, energy recovery was only required if we were over a certain percentage of outdoor air. Sometimes if we’re doing a combined supply system where offices and classrooms may be on the same air handlers as the labs, we may not have hit that threshold. As ASHRAE the energy standard 90.1 has been getting more stringent, most of the time now we’re looking at having to do energy recovery in our lab exhaust. There are various types, and they’re not always applicable to all exhaust streams.

Then as we’re trying to also not only design the laboratories to be safe and meet the user’s requirement, we also want them to be as efficient as they can, because laboratories use a lot of energy and it’s mainly in heating and cooling, especially when we’re a 100% exhausting most of the spaces.

There are a few strategies that you can look at. Using hydronic means for cooling, different sources of energy recovery, whether it be wheels or enhanced runaround loops. Heat recovery chillers are a great one when you’ve got simultaneous heating and cooling needs within the building, and then various types of fume hood technologies where the exhaust needs may be lower. Systems to where we can vary the air change rates in the space if the air is clean.

We can vary the discharge, the stack velocity out of our fans, again, depending on how clean the air is. Then certainly working with the laboratory planners and the researchers to have them specify high efficiency lab equipment so that that sensible heat rejection can be lower for a lot of these spaces.

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The post "When and how to use codes and standards for HVAC in laboratories, part 2" appeared first on Consulting-Specifying Engineer

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