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Temperature and Humidity Control for Laboratories, Medical Imaging Rooms, Libraries & Archives

By Mike Lawler, Data Aire

Whether your emphasis is on pioneering technology, developing life-saving drugs or managing the integrity of sensitive documents or artifacts, maintaining the perfect environmental envelope is vital to your success.

  • Require tight control over temperature and humidity
  • Have large swings in cooling requirement daily & annually
  • Must dehumidify when little or no cooling is required

What Type of HVAC Provides Precision Air Control for Low Load Applications?

Applications that require both temperature and humidity control must use equipment that is capable of cooling, heating, humidifying and dehumidifying modes. The most effective way to address this need is to provide one piece of equipment that provides all those modes of operation. If the load in the space is large, over 40 or 50 tons, a custom package unit can provide this function.

It can be challenging, however to find equipment in smaller tonnages that can do the job. In response to this, engineers often attempt to use Computer Room Air Conditioners (CRAC) equipment in laboratories, libraries, archives, and medical imaging rooms that have lower cooling requirements. CRAC units provide all the modes of operation needed and they are available in sizes as small at 2 tons. A deeper look into these applications, however, will show that standard CRAC units are not suited to these applications.

Standard Computer Room Air Conditioning         

  • Cooling runs more than half the time to cool the room
    Minimal moisture removal (80-90% SHR adequate) needed
    Dehumidifies <10% of running time.

Highly Variable Cooling Load Rooms

  • Zero cooling load at times
  • 60-70% SHR needed
  • May have to dehumidify half of the run hours

Design Day Reasonable Tolerances

Standard CRAC units do a good job of controlling temperature and humidity when they are required to produce cooling that is at or near their maximum capacity. Maximum cooling capacity is called for on days when the outdoor ambient temperature nears its annual maximum and, at the same time, internal heat generation from lights people, and equipment are at their maximum. This condition is known as a design day with a concurrent design load in the space. Unfortunately, these conditions only occur a few hours a year. The farther the conditions fall below the above described maximums, the more difficult it becomes to control humidity in the space to within a reasonable tolerance. When the cooling requirements fall much below 50% of maximum, the space is often subject to wide swings in temperature & humidity that are totally unacceptable to the occupants of the space.

The reason is that the standard CRAC units are not designed to remove a significant amount of humidity per hour. The dehumidification in a CRAC unit is done by the cooling coil. As long as there is a call from the thermostat to deliver cooling to the space, dehumidification happens as a byproduct of cooling down the room. When the thermostat requires that cooling be delivered for 70% or 80% of the time, the CRAC unit can keep up with the dehumidification requirements in the space. But think about how few hours per year this requirement exists in rooms that are not data rooms. Essentially, those conditions only exist in the daytime, during the hottest part of the summer.

Understanding Dehumdification and Cost Controls

Dehumidification mode, by definition, means removing humidity from the air without sending any cool air into the space. Since the cooling coil removes the moisture this means that the CRAC unit must run the cooling and the heating in the unit at the same time.

There are two problems with this. First there is only ½ as much heat capacity in a standard CRAC unit as there is cooling capacity. That means the already minimal amount of dehumidification available at full load is cut in ½. You cannot increase the cooling capacity to get more dehumidification. If you do, there is not enough heat in the unit to offset the increased cooling capacity. Cold air would be delivered to the space and the space temperature will begin to drop too low. Unless it is hot outside and there is a significant requirement for cooling from the space a standard CRAC units simply cannot reach the desired humidity setpoint.

The second problem is that heat in CRAC units is provided by electric resistance heating elements. From a power cost standpoint, this is absolutely the most expensive source of heat anyone can use. In a data room the electric heat runs only a handful of hours a year so this is not an issue. In other applications though, the electric heat runs hundreds or even thousands of hours per year while in the dehumidification mode.

These problems are particularly acute in laboratories, archives, libraries, clean rooms, dry storage and other applications that require that humidity be controlled in the absence of a need for cooling.

Small clean rooms are usually rooms surrounded by a space that already has temperature, but not humidity control. Like an archive, there is very little need to cool the space and the primary mode of operation is dehumidification. Laboratories, libraries, museums, MRI suites, CT scan rooms, art vaults and many other applications face the same challenge, dehumidification is needed more than cooling is needed.

Interpret the Temperature and Humidity Needs of Your Space with an All-In-One HVAC

Data Aire has solved these challenges by introducing InterpretAireTM, a packaged cooling, heating, humidifying, and dehumidifying unit that has all of the advantages of a standard CRAC unit and none of the drawbacks. The thing that sets InterpretAireTM apart from the competition is its ability to dehumidify when there is no need for cooling. Humidifying is relatively straightforward and easy for a standard CRAC to accomplish. Precise temperature control is not that difficult in most applications either. There are multiple strategies that standard CRAC units can use to deliver good temperature control. None of those strategies allow the CRAC unit to deliver better dehumidification control.

The Data Aire InterpretAire climate management system can be programmed to maintain constant temperature and humidity within a laboratory, clean room, museum, library or archive to ensure a desired outcome. Consistency and precision were key drivers in the development of the InterpretAire solution. InterpretAire quite literally interprets the needs of the space, and maintains the unique temperature and humidity perimeters mandated for high-accuracy standards.

Your application needs are specific; your environmental control equipment should be, too.

 

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Q&A:  New Generation of Alternative Refrigerants

What concerns are there about HFCs?

With growing concerns about the impact on the environment and climate change, pressure has been mounting for years to reduce the use of high-GWP refrigerants across many applications and industries.

One of the reasons HFCs are under pressure is because they have longer atmospheric lives. For example, R-134a survives 14 years compared to R-1233zd(E), one of the new alternative refrigerants, at only 29 days. All chemicals have a finite life, but some are more stable than others. In general, the shorter the atmospheric life, the lower the environmental impact because the chemical does not endure long in the atmosphere and have an impact.

Today, the next-generation refrigerants are more expensive than the current refrigerants in the marketplace.  If we look at the history of past refrigerant transitions, we can expect the current generation HFCs to begin to become more expensive in the coming years, and the new HFO refrigerants to come down in price as more factories are built and use spreads to more industries.  This pricing shift in refrigerants could push the transition to next generation solutions ahead of current mandated phase out dates.

What actions have been taken to phase down HFCs? (i.e., SNAP, Kigali Agreement) What is the timeline?

On October 15, 2016, the Kigali Amendment to the Montreal Protocol was signed, paving the way for the global phase-down of HFCs. All 197 member countries, including the United States and Canada, agreed last year to amend the Montreal Protocol (an international treaty originally designed to reduce the production and consumption of ozone-depleting substances) to phase down HFCs.

Ahead of the Kigali Amendment, the U.S. Environmental Protection Agency (EPA) issued two rules regarding the change of listing status of certain HFCs in the United States. The first rule established phase-out dates for HFCs in retail food refrigeration, aerosol propellants and motor vehicles. The EPA used its regulatory authority through the Significant New Alternatives Policy (SNAP) by designating particular HFC refrigerants as “unacceptable” and disallowing their use in aerosol propellants starting in 2016, new retail food refrigeration starting in 2017, and motor vehicles with model year 2021. The second EPA rule established the phase-out date for certain HFCs in chillers. Specifically, R-134a, R-410A and R-407C are banned from use in new chillers (air-cooled and water-cooled, scroll, screw and centrifugal) beginning January 1, 2024.

In a separate rule, the EPA also made several other changes to management requirements for refrigerants in Section 608 of the Clean Air Act, entirely in effect by January 1, 2019, to include the following:

  • Extending the requirements previously in place for only ozone depleting substances, such as chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) to include all replacement substances, including HFCs and the new hydrofluoroolefin (HFO) options. Hydrocarbons in small, self-contained systems are given an exception for venting.
  • Reduced trigger leak rates for a 12-month period (for example, from 15% to 10% for comfort cooling equipment), which require owners or operators to take corrective action. This may push or incentivize the industry to move to technologies that are more hermetic with fewer joints and seals, for better long-term refrigerant containment.
  • New requirements for mandatory leak inspections on equipment and increased record keeping requirements.

Are alternative refrigerants available?

New refrigerant technology is developing rapidly and alternative refrigerants are starting to emerge as potential next-generation solutions. These choices are nonflammable solutions. The two low pressure options feature ultra-low GWPs, one of which has operating pressures similar to R-123, that are ideal for chiller applications with larger refrigerant charge sizes. There is also a nonflammable alternative to R-134a, which has a significantly reduced GWP.

These alternative refrigerants are characterized by very short atmospheric lives (measured in months or even days, which results in refrigerants with “effectively zero” ODP and low GWPs.  This new class of refrigerants is collectively referred to as hydrofluoroolefins (HFOs) and includes new options such as R-1233zd(E), R-1234yf, R-1234ze(E), R-1336mzz(Z), R-513A, R-514A, R-452B and R-454B).

What are the main ones for commercial and institutional HVAC equipment?

The low–global warming potential refrigerants that are primarily being used for commercial and institutional HVAC equipment are: R-514A and R-1233zd(E) — both featuring an ultra-low GWP of less than 2, and R-513A, a next-generation, low-GWP refrigerant. R-513A provides an excellent performance to R-134a, with a 56 percent reduction in GWP.

Is equipment that uses the alternatives available now?

Yes, there are equipment options already available on the market that can use these alternative refrigerants. Trane® is already offering customers options to reduce greenhouse gas emissions in their facilities through the use of next generation refrigerants in HVAC products. Trane plans to transition their current portfolio of HVAC products that use refrigerants to be compatible with next generation refrigerants well before phase-out dates to offer customers choices without compromising safety, reliability and efficiency.

We have expanded our chiller portfolio significantly in the last 18 months to address the increasing customer demand for climate-friendly systems. Our promise to customers has always been to deliver right product with the right refrigerant at the right time, ensuring that products meet all regulatory requirements.

The EcoWise™ portfolio was created by Ingersoll Rand® as part of our company’s Climate Commitment to reduce greenhouse gas emissions from its products and operations by 2030. Trane products within the EcoWise portfolio meet the following requirements:

      • Are available with next-generation, lower-GWP refrigerants
      • Reduce greenhouse gas (GHG) emissions
      • Maintain safety and energy efficiency through innovative design
      • Meet or exceed emissions regulations

The following products have earned the EcoWise endorsement:

Trane® CenTraVac™ centrifugal chillers for large buildings and industrial applications can operate with either R-123 or next-generation refrigerants R-514A or R-1233zd(E) — both featuring an ultra-low GWP of less than 2.  

Trane Series S™ CenTraVac chillers deliver the highest full and part-load efficiencies on the market today, offering customers a choice of either R-123 or the next generation refrigerant R-514A that has an ultra-low GWP of less than two.

Trane Series R® RTWD water-cooled chiller and Trane Sintesis™ air-cooled chillers can operate with a choice of R-134a or Opteon™ XP10 (R-513A), a next-generation, low-GWP refrigerant.

Is the industry expecting any disruptions?

As standards and codes continue to change, there are many factors to consider as the industry works to find the best balance between minimizing environmental impacts, maintaining safety, and managing product costs.

The HVACR industry will likely have to adjust product refrigerant charge sizes in most direct expansion applications to meet the standards. The establishment of the new 2L sub-classification for refrigerant flammability addresses new next-generation refrigerants that have lower flammability characteristics. The HVACR industry is actively investigating the safety of flammable refrigerants for indoor and outdoor use, and determining the risks of flammable refrigerants by understanding the probability of potential occurrences and severity of events in various application situations including servicing and handling. Some direct refrigerant expansion applications where refrigerant charge sizes are quite large, such as large splits, VRF systems, and large distributed commercial refrigeration systems, may not be available in their current form in the future because of flammability requirements.

The HVAC industry has worked very closely with the US EPA to ensure that the phase down timelines allow an appropriate amount of time for manufacturers to develop product with next generation solutions.  Ingersoll Rand® intends to have products available in all market segments with next generation solutions ahead of the required transition dates.

Are there tradeoffs with the new refrigerants?

Refrigerant selection is a balancing act. While the HVACR industry evaluates next-generation refrigerant alternatives, the challenge is to balance environmental benefits with safety, sustainability and design requirements. It’s likely that tradeoffs between GWP, flammability and efficiency will be needed to be made in selecting refrigerants.

When considering refrigerant alternatives for the future, policy makers, the public and manufacturers must select refrigerants with the best balance of the following:

  • Environmental performance (direct environmental impact such as reduced GWP)
  • Safety for consumers (flammability and toxicity)
  • Energy efficiency (indirect environmental impacts such as reduced CO2 emissions)
  • Intellectual property considerations
  • Transition costs (impact on industry and consumers)
  • Product sustainability (long operational life, reliability, maximizing recyclable content and repurposing components)

One of the most important environmental impacts to consider when transitioning to new refrigerants is energy efficiency.  We believe that there will be a great opportunity for the industry to improve energy efficiency with next-generation solutions.  R-410A replacements are currently being developed which could see significant efficiency improvements. For large tonnage centrifugal chillers, we are seeing the industry looking toward more efficient low pressure solutions (like R-514A and R-1233zd(E)) that are better in efficiency than medium pressure R-134a.

U.S. Environmental Protection Agency, 2015, Federal Register, Vol.80, No.138, p.42870-42959.

U.S. Environmental Protection Agency, 2016, Federal Register, Vol.81, No.231, p.86778-86895.

U.S. Environmental Protection Agency, 2016, Federal Register, Vol.81, No.223, p.82272-82395.

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Improving Indoor Air Quality

By: United Cool Air

Most air conditioners recirculate indoor air. While this saves energy, there is a very serious health cost to pay when people breathe indoor air instead of outdoor air! According to the United States Environmental Protection Agency (EPA), indoor air is two to five times MORE TOXIC on average than outside air. This is true even in the most heavily polluted United States metropolitan areas! In fact, some inside air has been found to be as much as one hundred times more toxic than the outside air in metropolitan areas!

Why Is the Inside Air So Toxic?

It’s a combination of a great many factors, some of which we’ll discuss below. For now, just know that the toxins found in inside air are mostly all human made and are more heavily concentrated during seasons when we don’t open windows, such as the warmer seasons when we run air conditioning. Furthermore, newer buildings that are “better insulated” tend to have inside air that is more toxic than older “drafty” buildings.

Toxins that Diffuse Out of Common Indoor Items

Many buildings have carpet and furniture. The foam on the back of the carpet and in the stuffing of the furniture provides a constant source of volatile organic chemicals (VOCs), which are known carcinogens and irritants. These VOCs are found in many other indoor items too such as drapes and shower curtains. You know that funky “new odor” you smell when you hang the new shower curtain? That’s VOCs leaching out. They continue to leach out into the air even when you don’t smell them any more so your nose is not the best guide when it comes to toxins in inside air.

We Bring Other Nasty Chemicals Indoors That Contaminate Our Air

We use pesticides that emit toxins into the air we breathe. Popular industrial cleaners contain toxic chemicals like phthalates, erchloroethylene or “PERC), triclosan, ammonia, chlorine, and 2-Butoxyethanol. There’s paradicholorbenzene in mothballs. Flame-retardants found in mattresses, clothes, electronics, and are composed of polybrominated diphenyl and ethers–PBDEs, both highly toxic! These same nasty chemicals plus PCBs (phthalates) are found in many plastic products, including toys, plastic plant pots, food containers, lamps, picture frames, eyeglass frames, and plastic organizers. Particleboard furniture emits formaldehyde for as long as you have it in your space!

Does your carpet, furniture, clothes, or other products state they are “stain resistant?” Does your cookware say “non stick?” If so, these items contain perfluorinated acids (PFAs), which cause birth defects! Then there are all the nasty chemicals in our building supplies such as the methylene diphenyl diisocyanate found in spray foam insulation and the resins found in paint, varnishes, and tiles! There’s also radon gas from your flooring and toxins released from mold!

What Are Health Costs?

We’ve already mentioned cancer and birth defects but there are other health hazards that are also caused by toxic indoor air as well. For example, scientists now believe that toxic indoor air may be partially responsible for the soaring rates of autism and Asperger’s in children! It can also cause nervous conditions like ADD and general anxiety. Heart diseases has been linked to the many of the nasty chemicals found in toxic indoor air too. Asthma and allergies that have been on the rise are thought to be linked to toxic indoor air. In fact, many chronic illnesses are linked to or exacerbated by toxic indoor air. These include sinus issues, skin rashes, dizziness, runny nose, persistent cough, achy joints, digestive issues, irritated eyes, nausea, poor concentration, memory loss, weakened immune system, and general fatigue.

OmegaAir and Alpha Aire — DOAS That Pull 100% OUTDOOR Air

When it’s hot and or humid outside, it can be just miserable if you don’t run your air conditioner! However, since most air conditioners recirculate toxic inside air, it can be a difficult choice on what to do. Do you open your windows and just try to bear the hot sticky feel? Or do you close your windows and feel comfortable while knowing you’re breathing in all that toxic air?

The Alpha Aire and Omega Air 100% outdoor air systems like all UCA air conditioning equipment are designed for indoor installation! Air handlers and condensers require no exterior mounting space, which is critical in multi-floor, urban applications. Indoor unit mounting preserves the architectural integrity of the building by keeping the roof and perimeter free of obstructions. In addition to eliminating the roof loads, the installation and maintenance costs are lower, the equipment is protected from the elements and security is enhanced because of limited outdoor access.

 

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