By Jocelyn Sarrantonio, PE | Technical Director, MeyerFire
 
Think State of the Union, but today I’m going to talk about the State of ESS in Fire Protection. So without further ado, members of the community, today I have the privilege and honor of discussing battery energy storage systems. Please clap. [Applause Please]

Just kidding, but today I wanted to talk about where we are as a fire protection community with regards to the response to the widescale adoption of battery energy storage systems (BESS) practically everywhere.
 
THERMAL RUNAWAY
If you didn’t take my Introduction to ESS course (shameless plug for our recent course, Introduction to Energy Storage Systems), the primary risk that comes with BESS, particularly lithium-ion batteries, is their susceptibility to thermal runaway.

Thermal runaway is a process resulting from a battery failure, where cells inside a battery undergo a rapid temperature increase and vent flammable gases, creating an explosion risk.
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The risk is proportional to the quantity of batteries in an installation, so you can imagine if we’re not even allowed to have lithium-ion batteries in our checked bags on airplanes, then enormous utility installations pose a substantially higher risk. 

The risk has been a part of our lives for years, so what are we learning about ESS?
 
#1 THE FIRE RISK CAN BE LONG-LASTING.
It can take large volumes of water to sufficiently extinguish and cool fires involving ESS, and due to the stranded energy in battery cells, re-ignition is a risk.

Even battery cells that are not plugged into anything can still undergo thermal runaway, if they are abused.

Emergency responders typically use thermal detectors to find any hot spots after a fire is extinguished, but it is critical to continue monitoring for longer than you’d think after a battery fire. Re-ignition can happen months after the fire! That’s long after the emergency responders have left, so there's a need to develop a protocol to monitor and prevent re-ignition.
 
#2 REGULATION OF E-SCOOTERS, E-BIKES & OTHER MICROMOBILITY DEVICES
In large cities where space is hard to come by and small lithium-ion batteries are everywhere, tighter regulation of micromobility devices is coming.

In New York City, for example, the market has been flooded with low-cost and unsafe products, partially due to the rise of food delivery apps.

The delivery workforce generally earns low wages, and there is no accountability from the app companies on the micromobility devices used. So the workforce is not motivated to purchase quality products, and the result is low-quality batteries being charged inside densely populated buildings.  
 
#3 SHIFTING PUBLIC PERCEPTION
Public perception may start to shift.

We’ve seen the videos of battery fires that include large plumes of smoke, and it’s hard not to imagine how local residents are faring.

Public pushback about BESS projects has increased following recent fire incidents, and the path forward likely includes educating the public to ease their concerns.

Even though the public directly benefits from lower electricity costs or stability of the utility grid, people are not willing to sacrifice safety and negatively impact their community. I’m not sure what that looks like, but it does seem like with any large project, developers have a responsibility to educate the people who are negatively impacted when there is an emergency situation.

If you want to build in someone’s backyard, you’ve got to convince them that what you’re doing is safe, and is a benefit to them.

Maybe that means highlighting training of your staff, the safety of the equipment you’re buying, or investing in local emergency responder equipment.

CONSUMER SAFETY
On the face of it, BESS safety is not just an area of concern for us as fire protection engineers, but as consumers as well.

Lithium-ion batteries are in our cellphones, laptops, electric vehicles, solar panels, and e-bikes. It’s important to note that when we talk about energy storage systems, the IFC and NFPA 855 have a threshold of 20 kWh where these requirements kick in.

For reference and speaking in rough orders of magnitude, a laptop battery might be 0.1 kWh, a phone might be 0.015 kWh, an electric scooter may be 1.5 kWh, EV’s may be up to 100 kWh, but a large Tesla Megapack that would be used in a utility grid installation is up to 4000 kWh, or 4 MWh. 

The risk of thermal runaway exists in all of these products, but the impact is greater as the capacities increase. 

As a consumer, if it is an option you should always buy products that have a mark from a nationally recognized testing laboratory (NRTL). What does that mean? Without getting too far into the weeds, there are several organizations, the most prominent one being UL, that test consumer electronics including TV’s, computers, and even Christmas tree lights.

When a product “bears the UL mark” it means it went through rigorous testing and complies with UL’s safety standards.

​That’s not saying there is no risk, but when we’re talking about a product which carries some inherent risk already, having a genuine product that complies with some standard of safety is even more important. 

It may be tempting to buy the cheapest version of a product, but using non-certified products, or even worse, fake products, can increase the potential risk for fire. This is because those products haven’t been tested to safety standards and they do not necessarily meet those higher quality and safety thresholds. 

You should also follow all manufacturers’ guidance when it comes to temperature control, clearances, ventilation, and where and how to charge devices.

We never want to charge these devices where they will block access to an exit.

Thinking about where people who drive e-scooters might live, it’s probably in a densely occupied apartment structure, and where they may charge their scooter, it’s probably by a door. Many apartments and condos only have one common path of travel, so if there’s a problem it may block the only exit and now a bad situation is worse. 

TRENDS IN INDUSTRY RESPONSE
Some of the trends the industry is seeing come in the form of alternate electrolyte recipes, methods of early detection, and more large-scale fire testing for extinguishing agents. 

First, if lithium-ion batteries are the problem, why don’t we just use different batteries? 

The reason this is even a challenge is that the industry quickly adopted lithium-ion batteries because they are lighter than their historical predecessor, lead-acid batteries. They also have a higher power density, so they can either take up a smaller footprint for the same capacity or get a higher capacity with the same footprint. 

It’s not a perfect analogy, but I think this is akin to the fire protection industry’s history halon as a fire extinguishing agent. 

Halon is a gaseous fire suppression agent that is quite effective, but then we learned how bad it was for the environment, so the industry shifted to other solutions. These other solutions may not be as effective as halon, but they sure outweigh halon’s major disadvantage. 

Similarly, the strategy here is to find other battery chemistries that may not be as inexpensive or energy-dense as lithium-ion, but that outweigh lithium-ion’s major disadvantage. 

Another strategy for the industry is smarter products, which can detect thermal runaway earlier, leaving more time for response. 

I’m keeping a discerning eye out for new products that include more sensitive gas detection, thermal imaging, or other sensors that will help us design more robust systems that mitigate explosion risk. 

Lastly is more large-scale fire test data for extinguishing agents. The code opens the door for alternative extinguishing agents, but I have yet to see good large-scale fire test data for these non-water based agents. There may be a reason for that, if they are ineffective, but so much of our design criteria is based on testing, so I’m looking forward to more data to help us validate design criteria. 

CODE DEVELOPMENT
As you probably are aware, the codes are doing their best to keep pace with the risks, in a reasonable timeline. 
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The IFC has been revised extensively since 2018 to integrate ESS requirements, and the latest 2024 Edition brings it largely in agreement with the 2023 version of NFPA 855. That standard is currently undergoing its normal revision cycle, with a new edition set to be published in 2026.

It is expected that the 2026 Edition will include additional large-scale fire testing requirements beyond the current UL9540A testing and further development of the Hazard Mitigation Analysis (HMA) procedures.  

With each jurisdiction’s unique adoption of its building and fire codes, there is an opportunity for further amendment of these standards.

It is critical to verify if a jurisdiction has any amendments to the generic code language for ESS and to verify if there are any special permitting procedures for ESS. My next course, coming this quarter, will be a review of the major code requirements for ESS.
 
PROBLEMS THAT REMAIN
It seems that the world is not going to soon give up on the use of lithium-ion batteries in BESS installations, so the toughest challenge that remains is how to deal with the explosion risk.

The tools we have at our disposal, NFPA 68 & 69, were not developed with BESS in mind, but can be part of a layered approach to addressing the explosion risk.

Since we are a prescriptive code-driven industry (in North America at least), we look for guidance on how to design these systems or how to perform these evaluations from the codes & standards themselves. I’m really looking forward to any new guidance in these documents to help give us consensus on how to approach the risk.
 
BEST PRACTICES: SO WHAT DO I DO?
If you are a fire protection engineer (or anyone) involved in an ESS installation, the basic process is as follows:

• EDUCATE: Educate yourself on how you may see ESS in your work.
  
  
• PRODUCT DATA: Gather the data. You will need product data for the ESS and the associated UL9540A test report.
  
  This is the fundamental information you will need to design the system spacing, ventilation, and associated fire protection systems.
  
  
• DEFLAGRATION OR EXPLOSION CONTROL: Evaluate the need for deflagration or explosion control. 
  
  This can have major impact on a design, depending on where the ESS is intended to be installed. Identifying where pressure-relief vents or exhaust ductwork can be routed is key.
  
  
• ENGINEERED SYSTEM INTERFACES: What systems are available that can interface with the BESS?
  
  Understanding the battery monitoring system to determine if information can be used for emergency control functions.
  
  
• COUNSEL OWNERS ON THEIR RESPONSIBILITIES: Many jurisdictions are focusing on the commissioning plans, yes, but also decommissioning plans.
  
  What is the life cycle of these batteries, and how will they be disposed of safely once they have reached their useful life?
  
  Because of the unique hazard BESS can have with stranded energy, you can’t just stack old equipment in a storage room and deal with it later. IFC 2024 also has a new requirement for a fire safety and evacuation plan to be included with the BESS construction documents.
  
  As fire protection engineers, we need to do our best to make owners aware of their increased responsibilities.
  
  

WHAT’S NEXT?
There’s quite a bit to keep up with. Many of us in this space are watching the development unfold. Deployments will only increase as utility grids move toward lower reliance on fossil fuels. Monitoring changes in codes, battery chemistries, and expectations of the public, owners, and AHJs will be needed to build trust and achieve reasonably safe outcomes.  Staying current and educated is our challenge today. Rigorous testing and proactive stakeholder engagement will be important as we all move forward to safer energy storage systems.

So in conclusion, the State of our Union is strong!

​Thanks for reading, until next time, stay safe, and always check your local jurisdiction’s amendments!

This week we're featuring a free preview of one of our instructor-led videos on the MeyerFire University platform. Chris Campbell, a Fire Protection Engineer & Writer at the BuildingCode.Blog joins us to discuss what is a "Mixed-Use", or more appropriately, a "Mixed-Occupancy" building under the International Building Code. 

Click here, or the video above, to check out what exactly is a Mixed-Use Building.

​Hope you have a great week!

In my regular code calls I used to include a specific question on the use of clean agent systems in server rooms.

Building Owners & Sprinklers 
Many building owners provide clean agent systems to extinguish fires in high-value content areas, such as server rooms, data centers, archival storage, and many other applications.

When the owners voluntarily pony-up for extra protection in these areas, they often ask whether sprinklers have to be installed in those spaces at all.

My Code Call Question
On my code calls, my question would go something like: “does your jurisdiction require sprinklers to be installed in rooms which are protected by a clean agent system?”

I would get a mixed response. Some jurisdictions considered clean agent systems to be an equivalent for sprinkler protection, others would not.

A couple years after asking this question on every applicable project I had a fire marshal shoot me straight.

“If you don’t have sprinklers in the room, you don’t have a fully-sprinklered building. Check the IBC.”

This was news to me. I was under the impression that use of clean agent systems could be used as a substitute for fire sprinklers and still be effectively “fully-sprinklered”.

Back to the Book
There is a path for this approach – the International Building Code (2018) Section 904.2 states that:

“Automatic fire-extinguishing systems (ie: clean agent) installed as an alternative to the required automatic sprinkler systems of Section 903 shall be approved by the fire code official.”

This was the foundation on which I had been asking the question.

The big kicker was the code section just a paragraph later:

“904.2.1 Restriction on using automatic sprinkler system exceptions or reductions. Automatic fire-extinguishing systems shall not be considered alternatives for the purposes of exceptions or reductions allowed for automatic sprinkler systems or by other requirements of this code.”

Outside of the lawyer-phrasing, this section simply states “no sprinklers in the room – no sprinkler reductions or exceptions for your building.”

The commentary by the International Code Council goes further, stating that while the authority has the ability to approve alternative systems in lieu of sprinklers, doing so invalidates the “fully-sprinklered” status of a building.

Why Does this Matter?
Why is this important? There is a long list of code kickbacks that sprinklers offer a building.

A couple months ago I diagramed a cheatsheet for all of the major code benefits a “fully-sprinklered” NFPA 13 fire sprinkler system offers. You can download it free here.
 
Code benefits include allowable building heights, building areas, number of stories, egress benefits, passive rating reductions, Draftstopping reductions, fire alarm reductions, and a handful of other benefits.

I realized after that code call that the question affected well more than just my isolated “fire sprinkler” silo. Omitting sprinklers in just one server room would have code implications throughout the complex.

Now, should building owners ask about omitting in these rooms we often look at other strategies – such as concealed sidewall sprinklers, use of dry sprinklers, drip pans, use of pre-action systems, or piping without joints and heavy-duty cages. Some of these solutions can be painless, without great cost and satisfy code as well.

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For the contractor clients I work with I regularly look over jobs pre-bid. I’ll review drawings, read specifications, and compile all my notes looking for red flags that could impact the job from a design standpoint. (The cheatsheets that I use to breakdown a job is now all in the Toolkit)

Last month I reviewed an apartment complex job for a bid where the code summary had conflicts. The IBC Chapter 5 summary indicated and NFPA 13 system while the IBC Chapter 9 indicated an NFPA 13R system. There were no other references to a fire sprinkler system in the rest of the documents or specifications.

These are the projects that I blame my hair loss on. It's another bad example of project documentation. Regardless, the question of NFPA 13 versus NFPA 13R is something that comes up regularly and is the topic of this and next week's article.

Why Does it Matter?

NFPA 13R is not built with the same intent as an NFPA 13 system.

NFPA 13R systems are designed to “prevent flashover (total involvement) in the room of fire origin”. By doing so, they intend to improve the ability for occupants to survive a fire by evacuation. 13R design is primarily concerned with protecting areas of residential buildings where fires cause loss of life. It is not as concerned with fires in areas where fatal fires in residential occupancies do not originate. (Reference IBC 903.3.1.2 Annex)

NFPA 13 systems, however, intend to provide a “reasonable degree of protection for life and property”. In a general sense, NFPA 13 systems are concerned with both life safety and property protection. The goal is to suppress a fire near its' point of origin, regardless of the level of risk to life safety.

Cost Impact

Aside from having different purposes, NFPA 13 vs. 13R decisions can have major implications on system cost.

NPFA 13R systems allow sprinkler omission in a handful of areas which 13 does not. These include small closets, exterior balcony closets, concealed spaces, elevator machine rooms, garages, carports, attached porches, and attic spaces. I've summarized these with a cheatsheet here.

For wood-construction (a mainstay in residential design), attic sprinkler systems under NFPA 13 can command a major cost premium. These attic systems need dry valves, air compressors, use of steel in lieu of CPVC, special application sprinklers, and design requirements that can require large diameter pipe.

Testing and maintenance is also a long-term ownership concern. Not only do dry attic systems require regular low-point drainage, but they often corrode faster than wet systems . 

Attic systems are one area of a building that can be a huge difference between NFPA 13 and 13R.

That said, I’ve also worked on projects where 13R has little to no impact on the project price. A flat-roof building built with non-combustible structure, for instance, offers no major difference. The only impact was the lower density permitted for residential-style sprinklers. Using the 0.05 gpm/sqft in lieu of 0.10 gpm/sqft of NFPA 13 resulted in smaller pipe diameters for an NFPA 13R system.
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​
When Can I Use NFPA 13R?

There are four global limitations where an NFPA 13R system can be used. These include:

1. The building must be a residential occupancy.
   NFPA 13R Section 1.1 expresses this limitation, as does the IBC 903.3.1.2.
   If the building is mixed-occupancy, the IBC does provide guidance. If any of the non-residential occupancies require an NFPA 13 system, then 13R is not allowed. If non-residential occupancies do not require an NFPA 13 system, then 13R could be used in the residential portions of the building. Non-residential areas would still require protection per NFPA 13. [IBC 903.3.1.2 Annex and Commentary Material]
   
   
2. The number of stories above grade plane must be four or less.
   One exception to this is for pedestal-type construction, where the limitation is four stories above a horizontal assembly instead of grade plane. IBC 510.2 and 510.4 have more information on this.
   
   
3. The height of the building cannot exceed 60 feet (18 meters).
   
   
4. If any code exceptions for an NFPA 13 fully-sprinklered building are used in the building design, then an NFPA 13R system cannot be used.
   
   

Can’t this be determined by the Contractor?

"My project is design/build with deferred submittals. Can’t the contractor determine this?"

No - and I can’t stress this enough – please do not leave this determination to a contractor.

It doesn’t matter if you’re an architect, mechanical engineer, or the expert code consultant. There are a number of code exceptions that can only practically be determined by the design team. The sprinkler contractor is an expert on suppression – not on architectural design decisions and the code paths for those decisions.

What are the building code exemptions that require an NFPA 13 system?

The code exceptions show up for building height increases, building area increases, egress widths, travel distance limitations, occupancy separations, corridor wall ratings, hazardous material increases, inclusion of atriums, unlimited area buildings, allowable area of openings, vertical separation of openings, draftstopping, interior finishes, floor finishes, manual fire alarm systems, and several others.

Sounds like a lot? It is. Fortunately I’ve got a cheatsheet coming next week where I’ll explore these differences in more detail. If you’re interested in getting a copy, subscribe here and it’ll be emailed directly to you.

Other Thoughts

A couple weeks I posted a link on this month’s sponsor Engineered Corrosion Solution’s whitepapers. Many of you have already checked it out, but if you haven't there's a MeyerFire welcome page here: https://www.ecscorrosion.com/meyerfire-welcome

I had a couple people ask about the whitepapers, so here’s a direct link to them. Specifically, be sure to check out "Industry Myths Regarding Corrosion in Fire Sprinkler Systems"  and "Six Reasons Why Galvanized Steel Piping Should NOT be used in Dry and Preaction Fire Sprinkler Systems."

PE Prep Guide 2019 Selling Out

There's been a ton of interest this year in the PE Prep Guide. I genuinely appreciate every single person who's checked out the book for this year's exam  - there has been more interest than ever before and I suspect the exam turnout could be the most ever for the Fire Protection P.E. Exam.

Next year's exam in 2020 will go computer-based and have major changes, so the PE Prep Guide will undergo big changes as well. This year's shipment of the 2019 Edition is just about out, and because of the big changes next year I won't be ordering extra copies. We currently have 16 copies available, so the 2019 edition will likely sell out by October's PE Exam. If you'd like to get a copy of the 2019 PE Prep Guide, please consider doing so now.

After the 2019 Edition sells out we'll still have 2018 PE Prep Guides available, and I'll ship an errata list with it. Any questions, please reach out to me at [email protected]. 

Last week I discussed across a common misconception with porte-cochere sprinkler requirements and how code addresses sprinkler protection for these structures.

This week I’m diving a little deeper with some estimates of how a porte-cochere fire would actually affect a main building, based on distance from the building.

It’s important to note that this exercise is largely academic: with the calculations below I’m making some gross assumptions that overly simplify the situation. This has not been vetted with Ph.D. experts nor gone through full scale fire testing. I’m just running some basic numbers with big assumptions to illustrate a point.

Heat Transfer

From what science gives us - heat is transferred by three methods. Conduction, convection, and radiation.
Conduction is the transfer of heat by objects touching each other. The direction of transfer is dictated by hot-to-cooler materials in direct contact.

Convection is the transfer of heat caused by the movement of gas (or a fluid). The direction of transfer is largely dictated by overall movement of the fluid, and for smoke tends to be vertical.

Radiation is the transfer of heat from the emission of electromagnetic waves. The direction of transfer is in all directions, but can reflect and re-emit from other surfaces.

Heat Transfer for a Flame

For a flame, depending on the fuel, most of the heat will be transferred away from the flame source primarily by convection. The chemical reaction (oxidation) of a flame will cause gases to heat. The heated gas’ molecules will become more active and less dense. With less-dense gas than surrounding cooler air, the warm gas will rise up and away from the flame source and carry solid particles forming hot smoke.

Radiation will typically comprise 20-35% of the overall heat release rate for a fire. Radiation transfers heat from the source in all available directions until it contacts another surface. Once in contact with other surfaces, radiation can be absorbed or re-emitted from the surface, depending on the surface material.

Conduction is the least important mode of heat transfer in an open fire. Radiation near a flame’s origin, for example, often emits and heats up adjacent surfaces with more impact than conduction. For wall assemblies, conduction of heat through penetrations becomes important, but for flames in open environments conduction plays only a small role.

Three Porte Cochere Scenarios

100-foot Separation
Now imagine a porte-cochere that is 100 feet (30 m) from the face of a larger main building to the center of the porte-cochere. If the porte-cochere is completely inflamed, how would it transfer heat to the main building?

It would transfer heat only by radiation; and in very small amounts. Assumptions include a 5 megawatt (MW) fire from a wood-built porte-cochere, a 100-foot (30 m) center distance from the main building, an atmospheric transmissivity of 0.95, and a 30% of the overall heat loss as radiation.

Using the Lawson and Quintiere Point-Source Method, the incident radiant flux (a measure of the heat energy per area) is 0.13 kW/sqm.

 
This radiant flux is about 10% of the flux for a 1st degree burn on unprotected skin.

30-foot Separation
Now move the porte-cochere to be 30 feet from the face of the building. Radiation will again transfer heat to the face of the building, but in a much larger amount. Because radiant flux is related to the inverse square of the distance between the targets, this 30-foot distance will actually have a radiant heat flux 10 times greater than a porte-cochere fire 100 feet away. For the same size fire as before but at 30-feet, this could be about enough heat for a 1st degree burn.
​

At the 30-foot distance, however, heat transfer to the main building is still primarily by radiation. The hot, buoyant smoke is still primarily driven upward from the porte-cochere and would likely not reach the main building unless strong winds directed the hot gases.
​
​10-foot Separation
Now imagine this same porte-cochere, but this time centered only 10 feet (3 m) from the main building. Radiation heat transfer is now 10 times greater than the 30-foot distance, and 100 times greater than the 100-foot distance.

At only 10 feet from a 5 MW fire, the heat flux is enough easily cause 2nd degree burns for unprotected skin.

Additionally, this heat flux is now approaching the critical heat flux for ignition of some building materials. The critical heat flux is the minimum amount of heat, per area, required to cause ignition. There's several factors that contribute to ignition including exposure time, material thermal properties, surface temperatures, and the actual heat flux versus critical heat flux - but for our purposes I'm only showing this critical heat flux for a couple siding materials.

Wood, for instance, has been tested to have a critical heat flux of approximately 10 kW/sqm. Vinyl siding has a critical heat flux of approximately 15 kW/sqm (both values from SFPE Handbook of Fire Protection Engineering, Table A.35, 5th Volume).

When we look at the heat flux already produced by a fire of this size at 10 feet we can see that we're already approaching the critical heat flux for both wood and vinyl.

Actual Separation

Now let's speak in practicality. Porte-cocheres are built to allow visitors to enter and leave cars without exposure to rain or sun. Is a 30-foot or 100-foot separated porte-cochere provide any value to a building? No, of course not. This exercise just shows that with reasonable assumptions, a 10-foot physical separation assuming a 5 MW fire begins to approach the critical flux needed to ignite a nearby building.

Fire Size

Would the actual fire be 5 MW? It's difficult to predict and will vary widely by the materials used and the shape it conforms. A point-source approximation is a large oversimplification given that a wooden canopy would burn in a very different configuration than a condensed pile of wood pallets, for instance.

Convection

What about convection? Up to now we've still only discussed heat transfer by radiation. If a porte-cochere is close enough to a building, convective heat transfer from the hot smoke will begin to contact the main building and heat surfaces along the face of the main building. This could also be aided by wind conditions as well.

As I explored a little last week, a porte-cochere that is only separated inches or a couple feet from a building is hardly any different than a porte-cochere that's attached to the building. That's largely because of convective and radiative heat transfer. The further away the porte-cochere is, the less convective heat transfer plays a role and the lower amount of radiative heat will be transferred.

Fire-Resistive Construction

What if we create a firewall or fire barrier? Both would slow the spread of fire and help prevent the main building from burning. The International Building Code​ relaxes the physical separation with fire-resistive construction, and for good reason. Heat flux becomes much less important when the exterior is of non-combustible construction.

Summary

It can be easy to get lost in code minutiae and live by the black and white lines of what code reads. I find that it's important to remind myself about context about each building and where good engineering judgement plays a role in protecting buildings from fire.

This overly-simplified series of calculations just shows the tiers of radiative heat transfer and how much it is affected by the separation distance. The further away a building is from another, the less convective heat transfer plays a role (if any) and the less radiative heat transfer occurs. 
 
If you found this interesting, let me know by leaving a comment here. Always happy to hear other opinions. If you don't already follow the weekly blog, consider subscribing here. Thanks for reading!