Killing a Virus - How Do The Guideline Processes Work?

Over the last 14 weeks or so we have been encouraged to do all sorts of things to avoid contracting the Covid-19 virus.  Much of that information is bogus as people share misinformation and conspiracies around the Internet. But...there are guidelines from the CDC and other professionals in the medical and science fields. Although those guidelines are based in fact I don't remember seeing the reasons why those actions will work to limit your chances of becoming ill. That has sent me on a search to gain a basic knowledge of why we should do those things. 

One of the first things I learned was that the Coronavirus is actually a pretty fragile virus. Unlike viruses such as the Norovirus which has a hard protective protein shell, the Coronavirus is protected by a lipid coating...much like a layer of fat around the cell. 

Because this protective coating is relatively weak the virus can be defeated using some fairly routine procedures. Of course, one of the most frequently mentioned techniques is "social distancing". This is because the virus is primarily transmitted in an airborne fashion when people cough or sneeze. We all know about that but the other side of this is that the droplets created by a cough or sneeze add a second layer of protective mucus to the virus that can keep it viable on surfaces where the particles land. The length of time that the virus can live on a surface outside of the human body is still being researched but the fact that it can be deposited on surfaces is why the use of disinfecants is one of the guidelines. But why does that work? 

The answer is pretty simple. The chemicals in the disinfectants break down the lipid barrier exposing the virus to the chemicals that can then render the virus "dead". The problem is that not all disinfectants are the same and some are not effective enough at breaking down the lipid barrier. The information about what disinfectants are most effective is available from the EPA and various company websites but the average consumer simply buys what is on the shelf when they can find it. There are some consumer grade disinfectants that have been tested against the virus, and could carry a label stating that fact, but until more research is complete the companies are only allowed to put the statement on their websites...not something the average consumer refers to...but something that your purchasing people should be aware of. 

Alcohol and bleach are both very effective at breaking down the lipid barrier so disinfectants that contain strong enough blends of those items will accomplish the mission....if they are allowed sufficient time to work. Studies indicate that the average consumer will do a quick wipe and dry of surfaces but that does not allow time for the disinfectants to work. Wiping or spraying the disinfectant on the surface but then leaving it to dry on its own should provide adequate time and any of your HVAC maintenance technicians who use disinfectants should make sure that they allow adequate time for the process to work. 

The other common guideline is to wash your hands with soap for at least 20 seconds. In this case two things are happening to the virus. First is that the soap can break down the lipid barrier if you wash for the appropriate length of time. The second thing that is happening is good old friction. As you scrub your hands you are scrubbing the surfaces of the virus and using friction to strip some of the lipid barrier away. You are also simply separating the virus from the skin and sending it down the drain. 

So far these guidelines work at the individual level...what you can do for yourself. The use of disinfectants in a commercial setting will work the same way on the virus but there are obviously many more surfaces to deal with. That leads to the discussion of UV light as a means to "kill" the virus in large areas or as an option in an air handler.

UV light works in a different manner than disinfectants or soap. Viruses have a DNA/RNA that works to infect cells that it comes in contact with. UV light breaks the DNA/RNA pattern of the virus cell so that it does not recognize and attach to the host cell. This sounds like a simple and effective way to treat large spaces...just blast it with UV. However, much like disinfectants, not all UV is created equal. 

Anyone who spends much time at the beach has probably heard of UVA and UVB. UVA is the most abundant version of UV light that the sun emits and is of a fairly long wavelength. UVB is a somewhat shorter wavelength light. But there is also UVC which is a very short wavelength light that can penetrate past the layer of human skin and cause some serious intermal problems. The good news is that our ozone layer filters out virtually all UVC (something to think about related to refrigerants but that is for another time). Because of the different wavelengths it is estimated that it would take roughly seven days of continuous exposure to the sun to modify the virus DNA/RNA. This is obviously too long to be useful in controlling the virus in almost all cases. UVC, on the other hand, is very effective in a short time (seconds) in rendering the virus inert. The challenge is that UVC in its shortest wavelengths is approaching x-ray wavelengths and continuous exposure by humans is dangerous. So in order to "clean" a space with UVC it must be unoccupied...a problem in a crowded hospital ward or many commercial buildings. The other issue with UVC is that due to its short wavelength it also has difficulty penetrating cracks, folds, or crevices in a space. That means that even after a blast of UVC a space will require a second dose of liquid or spray disinfectant in order to eliminate the virus threat. 

So...for those involved in cleaning and sanitizing HVAC equipment or the spaces that equipment serves adequate employee training and a basic understanding of how the recommended methods work will help companies implement the best strategies for their situations.

HVAC's Unseen Protectors

As the world deals with the Novel Coronavirus I was reminded of research that I was involved in some 35 years ago.  At that time I was directly engaged in modeling airflow and temperature profiles using Computational Fluid Dynamic (CFD) software for a major air distribution products company.

While we used CFD modeling for a wide variety of complex air distribution problems the case that came to my mind this week was modeling an infectious disease isolation room for the CDC.  The challenge was to design a negative pressure isolation room that also minimized exposure of a health care worker positioned directly adjacent to the patient bed. 

The specific type of infection to be studied at that time was tuberculosis (TB).  Much like the current coronavirus, TB is often spread by droplets when a patient coughs.  A healthcare worker standing next to the patient bed was almost certain to risk exposure if the room used conventional air distribution layouts and patterns.  The correlation with today's problem is obvious.

My current company, Mestex, has been using CFD analysis for 20 years.  Although our modeling efforts have not included the case mentioned above we can apply the same techniques to create accurate temperature and airflow models of data centers, pharmaceutical storage warehouses, chocolate or wine warehouses, eCommerce fulfillment centers, or virtually any temperature sensitive application.  Much like the goal of the CDC study of 35 years ago our objective is to use modeling to optimize our product applications without the expense of full scale mockups or, worse yet, finding out about a problem after the building is complete.

The HVAC industry is continuing to refine the modeling techniques that I used those many years ago in order to create even better solutions to healthcare worker protection.  In general, when we do our jobs correctly, the end user is not aware of what is involved.  After all, you cannot "see" temperature or air so our work is "invisible".  However, the HVAC industry has a vital role in helping protect people and critical products from many types of threats.

Hot Air Balloons and eCommerce

I live in an area that is almost ideal for hot air ballooning.  On almost any morning it is not uncommon to see at least 6 hot air balloons dotting the horizon.  Watching some the other day as they prepared for launch and then ascended it struck me that there is a basic lesson in the process that is useful to remember when designing HVAC solutions for eCommerce buildings and warehouses in general.

The obvious lesson is that hot air is buoyant and the hotter it is the more buoyant it becomes.  When prepping for launch the crews use their direct fired burners to blast hot air into the balloon causing it to fill and lift.  Once the balloon is vertical the crew fires the burners at full heat to get the balloon off the ground and on its way upward.  While in the air you can hear the burners firing whenever the balloon starts to drop below the altitude the pilot is looking for.  Short blasts produce little heat and balloon either stays stable or starts to slowly descend.  Long blasts produce more heat and the balloon rises.

So...what does this have to do with eCommerce and warehouses?  While the HVAC equipment cannot produce air that is hot enough to lift the building off the ground it can produce air that is hot enough to rise rapidly and stay near the top of the space. In an eCommerce fulfillment building with dozens of humans occupying the bottom 6 feet of the building that hot air can be a problem.

There are some HVAC companies that propose using very high temperature air to heat the entire space.  This becomes a real challenge as the hotter the air the more it wants to stay up near the ceiling.  There are a couple of ways to deal with this but both ways impact electrical operating costs.

One method is to install several large fans that are intended to pull air from the ceiling space and force it down to the floor level.  In addition to the electric power required to spin the fans this solution can also make it difficult to achieve the rack heights that are desired in the building.  There may also be structural cost implications depending upon the weight of the fan/motor assemblies.

The other method is to use the HVAC equipment fans themselves to force the hot air to the floor area.  This also requires electrical energy to overcome the buoyancy of the air. A secondary characteristic of this method is that the velocity of the air from the HVAC unit must be pretty high in order to force the air downward.  The result is a column of air moving at pretty high speed that reaches the floor in a relatively small area that can cause worker discomfort or stir up paperwork or products that are in the airstream.

Mestex has been producing a product concept for decades that overcomes these problems.  The concept is called "air turnover" and many companies have since copied the idea under different names.  The idea is simple....push warm (not hot) air into the space just above the worker level and pull it back across the floor where the workers benefit from the relatively slow moving warm air flow.  Not only does this method produce even temperatures where it is needed it also avoids wasting heat energy that collects near the ceiling with the hot air methods.

Deciding how to design an air turnover system can be challenging since the system sends air into the occupied space that also includes equipment, bottoms of racks, conveyor systems and such.  Another Mestex first is the use of Computational Fluid Dynamic ("CFD") modeling of the space to refine and optimize these designs.  CFD modeling originated in the defense industry to model aircraft performance and later was adopted by the process industry to evaluate things such as the impact of ocean currents on offshore oil rigs.  Since air is a fluid Mestex started using CFD modeling 20 years ago to assure owners that temperature critical products would be kept at the proper condition.  Mestex' use of CFD has expanded over the years to optimizing more mundane warehouse applications as well as more sophisticated applications such as data centers.  This expertise is available exclusively for Mestex customers.

So the next time you see a hot air balloon rising into the air you can appreciate the challenges of heating a warehouse or eCommerce building.

Cybersecurity

You have probably heard or read about "Internet of Things", or "IoT" as it is called.  The numbers of devices being connected to the Internet are staggering with some projections of over 26 billion devices connected by the end of this year.  Many of those devices are going to be HVAC products either via a connected Building Management System or as a "stand alone" device with remote monitoring and diagnostic capabilities.

AHRI recently sponsored a meeting to discuss the security implications of connected HVAC products. It has already been acknowledged that one of the major "hacks" in the last few years (Target stores) was made through the HVAC equipment.  One of the messages of the AHRI meeting was that HVAC equipment is becoming a key target for hackers (either domestic or foreign) due to the lack of rigorous "cybersecurity" protection.  In one study a building system was tested using four attack models and 54 "threat vectors" were discovered.

The need to increase HVAC cybersecurity mechanisms is obvious in the Target case but there are other scenarios that cause concern to the government and utilities.  Many products are now being connected to the electric grid for purposes of load management or to implement real time pricing strategies.  The fear is that lax security at the HVAC equipment level could allow a hacker to penetrate and disable parts, or all, of the electric grid through the same ports used for communication with the grid.  Hacking into a building system that is not isolated from the occupants' business network would obviously open the door to financial information, proprietary product information, and personnel information that could be extremely damaging to a business.  During the meeting it was noted that small businesses that have been hacked have a high probability of going through bankruptcy due to the cost of recovery.

But suppose the HVAC equipment is not connected to the Internet but only to the building management system or even as a stand alone piece of equipment?  Could such a system be hacked also?  I would suggest that, although more difficult, it is entirely possible.  Most modern HVAC equipment operates with a digital control system.  That controller will have a port used for diagnostics or software updates.  A "bad actor" with a laptop and a cable could gain total control of the unit and disrupt a business operation through temperature or ventilation control settings.  Interestingly, in the AHRI meeting, it was noted that the three most common attack pathways were WiFi, Bluetooth, and finally an Ethernet cable....so a physical connection as mentioned above is not even necessary.

The financial, legal, and reputational impact on an HVAC manufacturer whose equipment is used as the pathway for a hack can be substantial.  Unfortunately there are no current cybersecurity standards for HVAC equipment as there are for medical devices, vehicles, military applications, or financial institutions.  A key goal of the AHRI meeting was to identify which current standards might be adapted to the HVAC industry and what role AHRI would play in establishing an industry standard.  There was also discussion of whether or not this should lead to an industry certification process so that manufacturers certify their equipment and processes to serve as an affirmative defense in a case where their equipment was the doorway into a hack.

In the meantime, before an industry standard might be created, manufacturers are warned to establish their own cybersecurity policy...updated frequently...as a means to establish that they are following "best practices" with regard to cybersecurity.  There are a number of cybersecurity policies from NIST, ASHRAE, UL and others that could be modified or adapted by an individual company to create such a policy.  NIST-SP800-171 is one such document that includes a comprehensive check list of security steps that could be used as a model.

The bottom line is that no matter how an HVAC manufacturer chooses to respond to this growing concern some response is better than no response at all.

Going Vertical with Ecommerce

Vertical Ecommerce Mechanical Infrastructure Thoughts

I was emailed a copy of an article that was published in Building Design + Construction magazine that stimulated some thought.  The article spoke about the trend in Ecommerce buildings to go vertical in order to fit their large square foot requirements into a smaller footprint.  This allows the Ecommerce company to put distribution and order fulfillment closer to their customers and meet the expectations of same day and next day deliveries.

This approach is obviously appealing to developers and the Ecommerce companies themselves.  However I would suggest that it can create some difficult challenges for the mechanical and electrical infrastructure.  By reducing the footprint of the building the available square footage for mechanical and electrical equipment on the roof is also reduced significantly.  Given that most of these buildings would be built in urban locations and will require large parking areas there will also be very little room on the ground for the infrastructure.

Another characteristic of Ecommerce buildings is the clear height requirements for racking and conveyor systems.  Although the building might be as tall as a normal 8 story building it might only have 3 levels inside.  This complicates the approach to the heating and cooling of the space and creates large volume spaces that must be conditioned for worker comfort and efficiency.

A traditional approach to an Ecommerce space is to install multiple packaged HVAC units on the roof with simple overhead air distribution systems.  The challenge that I see with the vertical ecommerce buildings is the lack of roof space for the packaged HVAC solution.  Even if the square footage could be allocated for large packaged units they will need to be located closer to the center of the roof and require huge ducts to move the air toward the exterior walls (so as not to interfere with racking systems) and then down through each floor.  Branch ductwork from these large main ducts would then be needed to serve the area of each floor.  The construction costs for such systems could be quite high...if it were even possible to use the large packaged HVAC units on the roof.

Mestex has been manufacturing a solution called Air Turnover for over 20 years and it seems this might be a better fit for these vertical buildings.  The Air Turnover concept places the HVAC distribution systems on the floor close to where they are needed...a similar concept to why ecommerce is going vertical...in order to put the source closer to where it is needed.

Since Air Turnover equipment can be built with cooling coils and electric heat internally the only equipment needed on the roof would be a single air cooled chiller.  The piping system from floor to floor would consume much less space (and require much smaller floor penetrations) than the duct system and would actually perform more efficiently due to the thermal characteristics of water.  Air Turnover units would typically be mounted along an outside wall and could even take advantage of fresh air cooling by installing wall louvers adjacent to the units.  The floor space required for the Air Turnover units would not be much greater than that required for the large duct systems and Air Turnover would also not require the branch duct systems.

There are other major advantages to the Air Turnover system in the areas of performance, efficiency, ease of maintenance, ease of installation, etc...but this article is long enough now.  If you are interested in those details please contact us at www.mestex.com and we can explain the advantages in more detail.

Helping to Solve Future Demands for Food

Well...it has been a long, long time since I have posted anything on the blog.  Time flies by at times and it is easy to lose track of the months since the last posting.  However, I am back :-) and will become more diligent in sharing my thoughts with you.

In the last couple of months I have participated in two unique meetings organized by "the Vertical Exchange" folks.  One of the meetings focused on the food industry and the other focused on design/build contractors.  Mestex is  such a diverse division of Mestek that we have solutions for projects in both of those segments...among many others.  There was an overlap between those two markets that might not, at first, seem obvious.

Increasing population densities in many parts of the world combined with changing climates is beginning to impact the ability of food companies to grow quality produce in the volumes needed.  There is also the specialized "boutique" grower who supports the "farm to table" concept in urban environments.  A solution to these scenarios that is emerging is the world of "indoor agriculture".  This goes well beyond traditional greenhouse facilities.  Indoor farms use sophisticated lighting, watering, and nutrient systems to grow produce 24/7/365 in controlled environments.  These facilities can be single story purpose built buildings, multi-story repurposed commercial buildings, or even "modular" buildings similar to modular data centers.  With the exception of the modular solutions all of these projects require the talents of design/build contractors for proper execution.  Even the modular solutions that are "factory built" still require qualified on-site contracting for completion of the project.

From a mechanical design point of view these facilities can be quite challenging.  In order to create an artificial environment for growing plants the power demands of the lights used to create an "artificial sun" will create very high thermal loads.  The watering and transpiration of the plants creates high latent loads on the HVAC equipment.  Providing the necessary CO2 without creating a hazard for employees is also important and, finally, preventing the introduction of pests and unwanted biological hazards requires very high levels of filtration.

In short....the HVAC systems must be able to handle very high sensible loads, very high latent loads, very high filter densities, and include controls that can flush a grow space quickly and efficiently...preferably all in one package!  No small task.

Mestex has had decades of experience providing equipment to the food industry and to design/build contractors.  We are leveraging that experience to develop solutions to the problem of indoor agriculture.  One of the first areas where we are working is in the world of cannabis growing.  This market is unique in that the revenue stream and profits are large enough to justify development of an advanced HVAC solution that accomplishes all of the needed functions in a single package.  The lessons learned in that market will transfer to more cost sensitive indoor agriculture products that can help meet the demands of those markets as well.

For more information about some of the work being done by Mestex you can refer to a couple of articles that were published by Business News Publishing for the 2016 Mechanical Exchange.  This link (http://eblast.bnpmedia.com/News/MXC_0916/MXC.html) will take you to the eblast site where you can open the entire Air Conditioning News supplement.

The "Open Access Project"

In the data center and technology world there is an on-going "discussion" about "openness".  Facebook really kicked this into high gear with their "Open Compute Project" where they share design specifics for their data center product designs in order to encourage energy savings across the data center design community.  This bold move allows virtually anyone to take a peek into how Facebook manages the hardware side of their business and how their equipment operates in the real world environment.

Here at Mestex we have taken our own steps in the same direction.  Anyone, anywhere in the world, who has Internet access can see some of our HVAC product designs operating in the real world environment of heating and cooling our facilities in  Dallas, Texas.  Think about how many other HVAC product manufacturers provide such "open access" to their equipment in real time in the real world? 

By logging in as a guest user (adaptaire.appliedair.com and use "guest" for both username and password) anyone can see how our DOAS unit is operating to serve our engineering department, or how a direct fired unit is operating to heat one of our production buildings, or how an air turnover unit is performing to cool a large uninsulated warehouse building, or how an indirect/direct evaporative cooling unit is functioning to control temperatures in a research server room pod located outside our buildings.

No filters, no marketing BS, no "wordsmithing" of performance...just raw unadulterated data and graphics showing what the equipment is doing in real time and how it is performing against the setpoints and goals set for the equipment.   Does this take guts?  Of course it does, but if you have been in the HVAC business for as long as Mestex has, and you have the proven track record that we have, then why not share how equipment really functions and give people a chance to evaluate concepts in the real world?

Our control software continues to be refined and developed based upon user feedback and our own research projects so the information on the display changes from time to time.  It now includes electrical energy data...kw demand information and kwh consumption information for each piece of equipment on the display.  Again, to give viewers an idea of the true cost of operation for various types of equipment.

So, for real world information about data center equipment you can go to Facebook's "Open Compute Project" and for real world information about HVAC equipment you can go to Mestex's "Open Access Project".

Kit Car or Ferrari?

Sticking with my motorsports analogies for a while...do you want to buy a "kit car" or a Ferrari even if the Ferrari costs more?

I am a big fan of Top Gear and watch most every episode at least once.  From time to time they will air an episode that features some sort of "kit" or one-off vehicle from a small manufacturer or garage.  Often times these vehicles have breathtaking performance and attractive costs when compared to a Ferrari.  But they usually end the broadcast with the conclusion that, great as the "kit" car might be, they would not buy one.

Time after time these "one-off" vehicles break during Top Gear's testing.  When that happens the crew has to wait for unique parts to be delivered or sort out the problem without the benefit of an owner's manual or factory service department to call.  Even in cases where the vehicle performs well they find that it cannot be licensed for the street or has no DMV certifications.  So they conclude that a buyer would be better off to spend a bit more and purchase a vehicle that is tested, certified, and supported by a company that is large enough to stand behind their products for the long haul.  Both solutions can provide exhilarating transportation but only one can be counted on to provide that transportation for as long as the owner keeps it.

The same question should be asked regarding HVAC equipment.  There are many small businesses that can purchase components, sub-contract the sheet metal, and hire temporary help to assemble units.  But the end user is basically getting the HVAC version of a "kit car".  The first cost might be attractive but certifications, IOMs, application and testing expertise, technical support, and supplier financial strength will all typically be important missing ingredients.

For some speculative buildings the "kit car" solution might be chosen because the developer knows he will soon pass the potential problems off to the new owner.  But for larger corporate owners and developer/owners is the "kit car" solution really the right answer?  Those end-users are investing in a building that will last years...they deserve an HVAC solution that matches that time frame from a company that will also be around to provide support for the duration.

So You Think Your Critical Cooling System Is Reliable?

An HVAC system with 3 components in series

System Reliability Versus System Complexity

 

I just read an article in Engineered Systems magazine that reminded me of one of my own blog postings from a few months ago.  The difference is that the author in the ES magazine article went all mathematical on us and showed the formulas for calculating HVAC system reliability given the reliability of the individual components in the system.  Although it was a long time ago I remember going through the mathematical exercise in one of my engineering courses back at the University of Texas...so we have all known about this procedure for a very long time.

During this same week I have been asked to do a competitive analysis on a "new" system concept compared to one of our systems.  While I could name names that is not necessarily the important point of this posting.  What struck me about the competitor's "new" system concept was just how many parts were required to accomplish the task of providing "free cooling".  Many of those component parts had dependencies that meant that the proper reliability analysis was the "series" analysis.  You can refer to the latest issue of Engineered Systems if you don't remember what that means but in keeping with my simple approach to my postings the bottom line is that the reliability of a "series" of components is the compounded product of each item's reliability multiplied together.  In other words if the "new" system concept required 4 compressors that are staged in series, a direct drive exhaust fan array, a direct drive supply fan array, a sensible heat wheel motor, sensible heat wheel belt, sensible heat wheel bearings, digital control module, etc...and we gave each of those items a reliability of 98% (which sounds pretty good and is generous for some of the items in the chain)...then the "system" reliability would be:

 

.98 x .98 x .98 x .98 (compressor section) x .98 (exhaust fan) x .98 (supply fan) x .98 (sensible heat wheel motor) x .98 (sensible heat wheel belt) x .98 (sensible heat wheel bearings) x .98 (digital control module) = .817

So, the "new" system concept under this scenario would actually have a reliability of only 81.7%...not quite so good I think you would agree. 

The information from this example is actually directly from the competitor's product literature...and I left out some components for simplicity sake.  The reliability of the components at .98 was an estimate and you can plug in whatever numbers you think are accurate.  The important thing is to recognize that the more complex the system is the lower the reliability will be.

In a previous blog posting I quoted Albert Einstein who said ..."make everything as simple as possible, but not simpler.".  I still think Albert was a pretty smart guy and when I look at some of the design solutions being proposed today for data centers, pharmaceutical warehouses, or cooling in general I just have to wonder why we sometimes design such complex solutions. 

Remember..."it is not sustainable if it is not maintainable"...and, as a corollary to that statement, "it is not maintainable if it is too complex and has too many parts".

Shading and Make-Up for Building Designers

I just returned from a meeting in Florida and I was reminded of a couple of basic concepts that apply to virtually all building designs.

Our meeting room faced an outside wall with a couple of French doors to a nice patio area.  The weather was unusually cool for Florida and everyone sitting on that side of the table was able to experience that coolness first hand...even though the doors were closed.  During breaks the smokers in the group would gather on the patio and, again, in spite of closed doors the meeting room started to smell of cigarette smoke.

The problem, of course, was a lower pressure in the meeting room compared to the outdoors.  Somewhere in the conference center there was an exhaust system churning away without a counterbalancing make-up air system.  The only way that the exhaust system could satisfy its demand for air was to pull that air from outside the building, through the conference room, to its final point of exit.  Cold, smoke-laden air was drawn into the meeting room and occupant comfort was compromised.  Simply adding a make-up air system similar to the Applied Air DFL-series would have improved the indoor environment and cost very little extra to operate.  Remember that all of that cold air that was being sucked into the building caused the occupants to raise the thermostat set-point in order to compensate for being cold and forced the large main air handlers to operate for more hours than necessary.  Maintaining a positive pressure in buildings controls infiltration of smoke, dust, and un-tempered air and it is relatively simple to achieve.

The other basic concept that popped into my head is how important the building envelope is to controlling operating costs.  This particular resort was built many years ago but employed some pretty effective passive shading for the guest rooms.  My room had a wall of windows for natural light and a view but had a deep setback that prevented direct solar radiation.  This deep setback meant that the air conditioning system would see far fewer operating hours than an unprotected glass exposure would allow.  Since solar radiation is also a significant portion of the building cooling load the setbacks allowed a reduction in HVAC equipment size as well.

Building design has changed since the days when this hotel was built and deep setbacks are much less common.  But effective solar shading is still feasible through the use of external shades and louvers.  External shade technology has advanced to the point where it is possible for the shades to track the location of the sun and automatically provide continuous reduction in solar radiation.  Some external shading systems such as those developed by Colt Group actually contain photovoltaic cells that can reduce the building electrical demand by more than providing shading alone.

So two basic concepts for sustainable building design:  maintaining a positive indoor pressure to eliminate unwanted and untreated outside air from entering the occupied areas; and using modern external shading technology to reduce the solar load in the occupied areas which, in turn, reduces operating and capital costs.

Equilibrium

Equilibrium…we all try to achieve it in our lives.  An argument can go on forever if both sides maintain a high energy level and refuse to cool things down.  An argument can end when both sides take it down a notch and each reaches a happy place that they can both accept…a state of emotional equilibrium.

Odd as it may seem your air conditioning system is trying to do the same thing…reach a happy state of equilibrium…a balance between the high energy state and the low energy state.  Fortunately the system won’t get there under most circumstances because when the high and low energy states are equal then the unit stops providing cooling.

To simplify our thinking about this, substitute the word “temperature” for the word “energy”.  Now remember back to your days in physics class and remember that energy flows from a high state to a low state until the two states match and then the flow stops.  An air conditioning system takes advantage of that basic law of physics by absorbing the warm energy in a room and sending it to a lower energy place where the warmth is released and the cycle can start all over again.

One problem in this description of an air conditioning unit is that we usually don’t want the high energy released back into our rooms so we have to send that energy outside the room, or building, to get rid of it.  We do that by using refrigerants or water to transport the heat energy.  We also have to be sure that when we send it outside that it is at a higher energy level than the outdoors.  That is why we have compressors (and chillers which are just really big compressors) in our systems.  The compressors act as both a pump and as a device to actually add energy to the fluid that is pumped through the cooling coil in the room.  If you grab the side of a pipe entering a cooling coil it will feel relatively cold.  If you grab the pipe between the coil and the compressor it will feel a bit warmer.  If you grab the pipe on the leaving side of the compressor you might burn your hand.  The system has added enough energy to make sure that when the refrigerant or water reaches the outdoors it is at a higher energy state than the air outside the building.  That can be quite a challenge in a place like Phoenix or Dubai.

Most manufacturers realize that their equipment might be installed in those climates so they pick components in their systems that can operate under those circumstances.  But there are limits to what can be done.

The most widely available commercial cooling systems on the market are DX packaged units.  In order to satisfy the largest market (and sell the most equipment) these units are intended to be used for comfort cooling of people.  Since most people are “comfortable” when their office is around 75 degrees these units are designed around that operating point.  That is their happy point and that is the temperature of the air that is being returned to the cooling coil where heat energy can be absorbed into refrigerant or water and then sent outside to be removed.  The units will continue to operate at higher temperatures but remember that we need to be sure we send the heat outside at a higher level than the air outside. 

If you read the technical manuals for virtually every rooftop unit on the market you will see that, for a lot of really esoteric reasons, that rooftop unit is designed to operate at no more than 90 degrees returning to the cooling coil.  At that point the combination of components in the rooftop unit will be “maxed out” if the outside air temperature is in the 120 to 130 degree range. When the outside air temperature is 135 degrees on a roof in Phoenix then the high energy state and low energy state are so close together that almost no work is done and the temperature of the air coming out of the air conditioning unit starts to go up because the system is no longer rejecting much heat.  The system has quit working as intended and the situation usually spirals out of control as more heat builds up in the refrigerant or water.  Eventually so much heat has built up, and is compounded by the compressor, that the system shuts itself down to protect itself.

So, what does all this rambling have to do with anything?  Most of my blogs lately have been about mission critical/data center energy issues.  It is a big deal, and lots of folks are working on solutions, but economics sometimes trumps clear thinking or limits what can be achieved.

We are seeing more and more data centers specified with DX rooftop packaged units.  While these are normally high quality products they were originally designed to be at a happy place with, at most, 90 degree air being returned to the coil.  In a data center that is being designed to the latest ASHRAE standards the cold aisle can be anywhere between 80.6 and 113 degrees F.  When you allow a 20 degree F temperature rise across the servers before you return the air to the unit then I think you can see the problem.  The rooftop unit is being asked to operate well above its built in safety circuit limits.  Thus you end up with a self-limiting factor on how effective you can be in reducing the operating expense in the data center.  Even if you believe that your servers will be fine at 80.6 degrees F your HVAC unit probably will not be so fine.  And, to be honest, this same logic applies to CRAC units as they are nothing more than split DX systems.  So you have self-limited your options to cold aisle temperatures of no more than about 70 degrees F and your data center costs more to run than it could.

There is a class of rooftop unit that is better equipped to handle these situations and that class of equipment is commonly known as a DOAS, or Dedicated Outdoor Air System.  These systems, like our Applied Air FAP product, have been designed to expect Phoenix type temperatures across the cooling coil.  Returning hot aisle air at 105 or 110 degrees F is well within their “normal” operating ranges.  These systems are more expensive than a conventional rooftop packaged unit because of the components that are selected but they also provide the operating range that will allow the designer and operator to take advantage of the elevated temperatures that ASHRAE and the IT equipment people recommend for reducing data center operating expenses.

The MEP World Collides

Well, this weekend the MEP world (Mechanical, Electrical, and Plumbing) will converge on Dallas for the AHRI/ASHRAE annual meeting and trade show.  This is the one place where many engineers and contractors can view the vast assortment of products and services that are used in making the buildings we work and live in functional. 

The exhibit company says there are 3,500 booths set up in the Dallas Convention Center.  That is a lot of different companies that are invested in the construction industry...and many companies in the industry are not even showing!

Of course, our parent company Mestek will be on the show floor with a wide variety of products ranging from residential baseboard to machinery for producing ductwork for commercial buildings.  Look for the most diverse company in the HVAC industry in booths 2632 and 2845.

As for Mestex itself since we are based in Dallas we have a unique opportunity.  On Sunday, the 27th, we have over 100 sales representatives visiting our factory to learn more about what Mestex has planned for 2013 and to tour the facilities and see some of the hardware.  Then Monday through Wednesday we will be hosting several engineer and contractor tours of our operations. 

This is an exciting way to kick off the new year for Mestex and for the entire industry.  It also shows just how diverse our industry is and just how important to building occupants our industry can be.

How I Spent My Summer Vacation

It has been a while since I have posted anything to this blog...no, I was not on sabbatical on some desert island...I have been traveling around North America talking to consulting engineers, contractors, and data center owners and operators.  This posting just provides a few insights that I garnered over the last 2 months on the road.

First, the data center/mission critical market continues to occupy the minds and the design resources of many, many companies in the design community.  It is clear that this is a market segment that is vibrant and all indications are that it will continue to be for quite some time to come.  The latest issue of Datacenter Dynamics FOCUS indicated that the world is now consuming over 300 Tkwh annually to drive data centers, with the US consuming over 25 Tkwh alone.  The consumption in the US is projected to grow over 9% in 2013.  While this information points to a growing market it also points to the urgent need for improved operating efficiency in data centers.

Second, and related to the first item, is the lack of knowledge about new "best practices" in data center design.  I have talked to dozens of engineers, contractors, and data center people who are not aware of the latest design guidelines from ASHRAE.  In fairness, those guidelines were only officially announced a few weeks ago...but they have been rumored and discussed for about a year now.  I mentioned in one of my earlier posts that education of the design community is an important, and ongoing, task.  This has been reinforced to me over the last 2 months.

Third, for those engineers and contractors who understand and embrace the new standards, is the challenge of convincing the data center people to adopt those standards.  This is less of a problem at the top levels of the data center company than it is on the floor of the data center.  The IT equipment operators who live in "the white space" seem not to understand the allowable operating temperatures of the equipment that they manage every day.  I have heard many different reasons for their reluctance to adopt the new best practices but I think it comes down to fear.  Because of stringent SLAs the operators worry about losing any equipment for any period of time...even though there is mounting research that this fear is unfounded.

Fourth, I have heard of several cases where the local electric utility has started to put limits on the available service capacity for planned centers.  In the US we are so comfortable with the idea that our electric grid can provide unlimited power that we forget that is not true.  We have a fixed number of powerplants with only so much generating capacity.  With the tremendous growth of data centers, and data centers with 300 to 500 watt per square foot electrical demands, there is a limit to what a utility can do.  And timing is another element of the equation.  A data center can be built in a matter of months...a powerplant takes years.  So even when a utility sees the demand coming they cannot add capacity as quickly as the demand can be added.

So, these are a few observations from the last couple of months.  Of course there is more to the story and feel free to comment on this post with any questions you might have.  I will try to respond as quickly as possible.

Too Hot to Handle? A Simple Reminder

Well, this is embarrasing.  I have been in the HVAC industry for over 40 years now and have helped design and manufacture some of the more sophisticated products that have been introduced.  But, in spite of that I have to admit that I messed up.  And the lesson that I was reminded of can help you too if your residential, commercial, or mission critical system is struggling to keep up with the heat.

Over the past couple of weeks the temperature here in Texas has been over 100 degrees F every day...sometimes up around 105 to 110.  That is nothing unusual for Texas in the summer and not as bad as last year.  But I started to notice that my residential HVAC unit was no longer able to maintain my thermostat setpoint of 77 to 79 degrees F.  The system was consistently running 3 degrees behind and running non-stop...and was only installed a year ago.

Refrigerant leak?  Undersized?  Dog left the door open?

No...it was one of the most common problems in any HVAC system that is not running correctly...the condenser coil was coated with a fine film of dirt.  Let me repeat that...a FINE film of dirt.  Not clogged...not even very obvious at a quick glance...a FINE film.  In my case it was actually a fine film of dryer lint since the clothes dryer outlet was located behind the condensing unit...but the point is that had a service tech not looked at the coil with a flashlight I never would have noticed the dirt.  Running water over the coil from a garden house to wash off the film dropped the system head pressure and restored the system's ability to maintain the thermostat setpoint without running non-stop.

Many years ago Louisiana State University conducted some tests on residential HVAC systems to determine the impact of dirty condensing coils.  The results were eye-opening.  A fine film of dirt, similar to what I had on my system, would reduce system capacity by up to 20%.  If your home, business, or server room is too hot then imagine what giving it an extra 20% of capacity could do...and it would only cost you a bit of water and time to wash off the coils...with no service tech assistance required.

Preaching to the Choir

Electrical Power Meters Keep Spinning

I have had a busy few weeks traveling to meetings and visiting with owners, operators, engineers, and researchers.  This has given me an interesting perspective and awareness of an issue that our industry needs to address.  My awareness of this issue was increased by an editorial in Mission Critical Magazine that bemoaned the lack of progress in data center design due to secrecy regarding "best practices".

I came away from all of those meetings with the sense that there are many very smart people who know how to design more efficient solutions to energy use in mission critical applications.  "Best practices" can be described by experts from the largest server manufacturers, global data center developers/operators, and from academia.  The issue is that we are all sitting around a large table in a closed meeting room and sharing that knowledge with others who already have a pretty good idea what to do.  We are "preaching to the choir".

The result is that the vast majority of data centers, server rooms, and telecom facilities are operating in very inefficient ways.  While a Microsoft might be able to design a data center with a 1.2 PUE the rest of the world is struggling to reach a 2.0. 

This came out in a technical committee meeting at ASHRAE's mid-year meeting a few days ago.  A comment was made by a server cooling system manufacturer that he finds it very difficult to convince smaller users to adopt the latest operating standards that could save the user tens of thousand of dollars a year in energy costs.  This sentiment was echoed by several around the room and pointed to how difficult it has been to educate the broader public on the reliability of modern equipment in warmer rooms.

And when I say "broader public" I mean just that.  The mechanical design director for a global retail data center operator told me that he knows his equipment will run just fine at 78 or 80 degree F inlet temperatures but his customers have not gotten the message and demand a "cold" room.  It seems that until corporate IT managers and executives understand all of this we will continue to see skyrocketing energy use by data centers.  Even small server rooms could benefit from elevated temperatures if key elements of "best practices" were implemented.  So called "legacy" data centers might be difficult to retrofit but they can certainly be upgraded with the basic elements of "best practices"...if only the occupants understood what is possible.

The industry has a massive educational challenge if it is to stem the rising cost and consumption of energy.  And the education cannot come soon enough because the projections are that server power densities will continue to climb and data storage power densities will climb even faster.  Today we talk about 300 watt per square foot densities but systems are being designed already that push almost 10 times that density.  It may seem that we have an endless supply of power from the grid but there are only so many power plants around the world and building a new one takes a decade or longer...data power consumption grows at a much faster rate and will stress grids around the world eventually if we cannot educate the "broader public" more effectively.

Direct Evaporative Cooling Analysis for Two Diverse Climates

One of the common concerns expressed about the use of evaporative cooling for data centers, server rooms, telecom facilities, or other facilities housing heat producing electronics is the ability of evaporative cooling to achieve the target inlet conditions for the electronics.

These two psychrometric charts show the results of an actual analysis in two distinctly different climates.  The target server inlet temperatures were between 65 and 85 degrees F and between 20% and 80% RH.  The mechanical system criteria mandated that direct evaporative cooling be used.

The proposed mechanical system consisted of a direct evaporative cooling system with 12" cellulose media, a steam humidifier, DDC controls, and a hot aisle/outside air mixing section.  The controls would be configured to modulate the outside air dampers, hot aisle dampers, evap media water flow, and the humidifier to maintain the target conditions.

Server Inlet Temperatures from Evaporative Cooling System in Pacific Northwest US

Server Inlet Temperatures from Evaporative Cooling System in Southeastern US

As you can see from the charts the proposed system would easily achieve the desired results.  In fact, it was found that outside air cooling could achieve the targets during roughly 15% of the year, direct evaporative cooling could achieve the results during roughly 60% of the year, and remaining hours of the year when the air was too cold to properly operate the evaporative cooling without fear of freezing a combination of hot aisle and outside air supplemented with the humidifier would hit the target.  The only excursions of temperature over the maximum target of 85 degrees would occur for no more than 5 hours a year based on the NOAA TMY2 weather history.

While not every location would achieve these results the diversity of climate for these two studies imply that direct evaporative cooling, with creative use of mixing and controls, will work in many more climates than most people expect.  To further expand the capabilities of evaporative cooling an indirect evaporative cooling element could be provided to produce even broader temperature control.  Although it was not analyzed for this case we would expect that adding an indirect evaporative cooling element to these systems would have eliminated the few hours of excursion above the maximum dry bulb temperature.

As a means to dramatically reduce energy consumption for these data modules the evaporative cooling solutions such as those manufactured by the Aztec division of Mestek would prove to be extremely effective.  Since evaporative cooling systems are also relatively simple mechanical systems with no refrigerants maintenance of the systems does not require licensed refrigeration technicians and there are very few elements that could fail...increasing uptime and providing much faster recovery time should a repair be necessary.

"Make everything as simple as possible, but not simpler."

I have addressed this topic before but it bears discussing again.  I was reading an article in a high tech blog the other day and they repeated the oft quoted "rule" of good design from Albert Einstein..."make everything as simple as possible, but not simpler."...  A few months ago I also quoted an engineer who reminded me that a system is not "sustainable" if it is not "maintainable".

It seems that in spite of these two pieces of advice, and numerous studies that highlight efficiency degradation when equipment is not properly maintained, we continue to see elaborate custom cooling solutions when a simple "off the shelf" product will accomplish the same thing...and has a better chance of staying that way.

As an industry we bemoan the lack of qualified service technicians and then we turn around and send them to jobsites populated with unique, one of a kind, complicated HVAC solutions.  What are we thinking?

I will admit that there are some cases that are so difficult to solve that something special is truly needed.  Critical human medical care might apply.  Some very high tech product production might apply.  Production of pharmaceuticals might apply.  But most server rooms and data centers no longer seem to apply.  ASHRAE and the server manufacturers themselves have said that the old ways no longer apply.  IT equipment can stand much higher temperatures and humidities than previously thought and much broader swings of those measures than ever before.  So why design around complex custom equipment?

As a manufacturer we know, and can pretty accurately predict, how a standard piece of equipment will perform in any given situation.  As soon as we are asked to "change it just a little"...which normally actually means throwing out the original design and starting over...then all bets are off.  We can use the same standard of components that we would normally use with an expectation of similar performance but, in reality, we no longer know exactly what to expect.

And then there is the issue of compliance with the myriad of agency and code safety tests that all manufacturers must apply to their equipment.  Standard equipment is designed, tested, and certified to meet those standards...custom equipment is designed to the standards but is probably not tested and certified to the standards.

And finally we have the issue of maintainability.  Service technicians are trained to work on specific types of equipment.  Many types of standard equipment require licensed technicians for service.  Given the broad range of equipment types in the market today it would be extremely rare to find a service technician who could be proficient on all standard equipment....much less something he or she has never seen before.

The topic of "total cost of ownership" is starting to pop again in some publications.  It is reassuring to see that some people are starting to go back to considering something beyond the initial capital expense...but operating expenses consist of more than just energy costs...remember the cost of maintaining the mechanical system in the long run so that the money spent up front for an efficient solution does not go out the window a couple of years down the road.

Green Grid Updates Free Cooling Maps for Data Centers

The Green Grid has released White Paper #46 as an update to their "free cooling" maps for data center design and operation.  The research was edited by Emerson Network Power, Intel, and Schneider Electric. 

The reason for this update to the "free cooling" maps was the latest changes to the ASHRAE TC 9.9 operating/design guidelines for data centers.  For those who have not yet seen those new guidelines they allow a much larger operating range for data centers and server rooms that use some of the latest equipment from companies like Dell and HP.

For those of us who are "metric challenged" 40 degrees C = 104 degrees F and 35 degrees C = 95 degrees F.

When you consider that many data center operators still seem to want their rooms at 70 degrees or lower it is clear that these new criteria are a massive change in operation and design concepts.  It is also clear that adopting the newest guidelines can result in enormous energy savings.

The Green Grid paper includes a couple of maps to quickly illustrate how extensive the potential for "free cooling" has become under the latest operating/design guidelines. In these maps the darker the blue color the more hours that "free cooling" could be employed.  The darkest color blue indicates that all 8760 hours are suitable for "free cooling".  The maps also consider the coincident dewpoint temperatures as that metric is important also.

This first map is for ASHRAE Class A3 environments and shows that virtually all of North America could have their data centers cooled without using chillers or compressors.  The second map is for ASHRAE Class A2 environments and shows that roughly 80% of North America could still be cooled most of the year with no chillers or compressors.

The question for data center operators and designers who want to implement these new temperatures is what to do about those 500 or 1,000 hours when the outside air conditions are not quite right.

It is still quite possible to operate the center with no compressors or chillers if the designer will incorporate an evaporative cooling system such as the Aztec indirect evaporative cooling system or even the Alton direct evaporative cooling system.

Since evaporative cooling systems operate using 100% outside air all the time they make an excellent "hybrid" approach.  During the many hours of the year when "free cooling" will satisfy the conditions either type of evaporative cooling system will provide cool, filtered, outside air.  The Aztec indirect evaporative cooling system has the added advantage of allowing recirculation of hot aisle air during the very coldest months when "free cooling" could actually over-cool the data center.

During those few hours of the year, however, when it is simply too warm for "free cooling" to work, the Aztec or Alton systems can automatically initiate their evaporative cooling cycles and trim the outside air temperatures down to levels that fall well within the new ASHRAE guidelines...again, with no compressor or chiller energy required.  The air leaving the evaporative cooling system will usually be about 3 degrees F higher than the wet bulb temperature.  This chart should give you an idea of the potential air temperature that an evaporative cooling system can provide.

The Green Grid whitepaper is just the latest in a growing number of research papers and documents that point operators and designers in a direction that can save tens of thousands of dollars and kwh if they are willing to make the investment in the latest technologies from both the IT equipment manufacturers and the HVAC equipment manufacturers.

Ten Reasons to Tone Down on Climate Control

Sometimes the best thing to do is to acknowledge when someone else does something right.  In this case Nicholas Greene posted an article on TechAxcess that sums up the ten reasons why data center designers and operators should adopt modern cooling design criteria for their centers.  Nicholas clearly articulates the reasons and I cannot improve on what he says.

I can only reinforce the message that there are alternative cooling methods that can provide cool...not cold...filtered, clean, air for data centers.  Aztec Indirect Evaporative Cooling Systems from the Mestex division of Mestek can send 65 to 80 degree air to the cold aisle and allow the designer to exhaust 100% of the heat from the hot aisle without using any refrigerants or compressors.  The result is cold aisle conditions that meet the latest ASHRAE TC 9.9 criteria and that address the issues that Nicholas covered in his article.

As Nicholas says...it is time for operators and designers outside of the "big names" to get on board and start implementing these energy saving technologies.

Air Pollution and HVAC

Over the Christmas/New Years holiday break I was able to spend some time on the road crossing Texas, New Mexico, and parts of Arizona.  While I saw plenty of interesting sights it is not the goal of this blog to create a travel channel.  The goal is to highlight technologies and subjects of interest in the HVAC arena.

The subject that came to mind as I drove across these states was that of indoor air quality.  Two areas, in particular, raised my attention to this topic.  Phoenix, Arizona and El Paso, Texas were both covered with a thick layer of smog as I passed through those towns.  The climatic reasons are not all that relevant to this discussion but the "temperature inversions" that are common in those areas at certain times of the year mean that smog will develop and stay trapped for hours, if not days.  But those two cities are not alone.  Los Angeles, California has been well known for poor air quality for years.  New York City leaders have become concerned enough about outside air quality to include provisions in their new "Green Codes" that are intended to address the issue.  Finally, attention has been brought by the folks at NOAA to the fact that pollution in China eventually makes it way to the US on the jet stream.

HVAC products can either help mitigate this problem or simply move it from the outdoors to the indoors.  All buildings with occupants are required by building codes to have some amount of "ventilation air".  It has been common practice to introduce that ventilation air through conventional air handlers or packaged rooftop equipment.  In the vast majority of cases that equipment was designed, and is applied, with only the minimum level of air filtration included.  The primary goal of the filtration has been to protect the components of the equipment from dust fouling and to provide a nominal level of indoor air quality improvement.  New requirements and guidelines that specify MERV 11 and higher filtration are intended to let the equipment begin to mitigate the outdoor air quality before it enters the space.  But how effective is this?

In a conventional HVAC system design there will be dozens of these filters, if not hundreds, scattered all over the building in numerous air handlers or packaged units.  Maintaining all of these filters properly becomes an ongoing task.  In addition, if even better filtration is required, or desired, the average piece of HVAC equipment simply lacks the space to provide more filtration.

Dedicated Outdoor Air Systems, or "DOAS", equipment helps address this.  By isolating all of the ventilation air requirements into a single point, maintenance of the filtration system becomes much easier.  In addition, some "DOAS" equipment, such as the Applied Air FAP, is designed to allow multiple stages of filtration.  When combined with low airflow systems such as chilled beams the result can be very clean ventilation air even in areas such as those I drove through over the holidays.

As a final consideration for indoor air quality I would suggest that the old, ancient actually, technology of adiabatic or evaporative cooling might be considered.  Although adiabatic or evaporative cooling can provide effective temperature control in vast parts of the United States it can also provide an extremely effective filtering system as well.  Air is literally "washed" as it passes through the unit.  As part of an overall system where the adiabatic or evaporative cooling system, such as the Alton or Aztec products, only provides the ventilation air and other equipment handles sensible and latent cooling the improvement in indoor air quality could be dramatic.