A Blog

A Blog

How to Clean Your Home After a Flood

By Haniya Rae

Last year, tens of millions of Americans experienced just how devastating floods can be. From January to October 2019, the estimated overall losses for damage caused by severe thunderstorms and flooding in the U.S. was more than $180 billion, according to the National Oceanic and Atmospheric Administration.

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BSI-001: The Perfect Wall

By: Joseph Lstiburek

Source

 

The perfect wall is an environmental separator—it has to keep the outside out and the inside in.  In order to do this the wall assembly has to control rain, air, vapor and heat. In the old days we had one material to do this: rocks. We would pile a bunch or rocks up and have the rocks do it all. But over time rocks lost their appeal. They were heavy and fell down a lot. Heavy means expensive and falling down is annoying. So construction evolved. Today walls need four principal control layers—especially if we don’t build out of rocks. They are presented in order of importance:

  • a rain control layer
  • an air control layer
  • a vapor control layer
  • a thermal control layer

A point to this importance thing here, if you can’t keep the rain out don’t waste your time on the air. If you can’t keep the air out don’t waste your time on the vapor.

The best place for the control layers is to locate them on the outside of the structure in order to protect the structure (Figure 1). When we built out of rocks the rocks didn’t need much protection.  When we build out of steel and wood we need to protect the steel and wood. And since most of the bad stuff comes from outside the best place to control the bad stuff is on the outside of the structure before it gets to the structure.

Also, after generations of building out of rocks folks somehow got the idea that they wanted to be comfortable—and they figured out that rocks were not the best insulation. I mean rocks are not that bad compared to windows—memo to architects: you can’t build an energy efficient green building out of glass, but you can get design awards and we all know which is more important. Back to rocks, they are heavy and you need a lot of them to make the wall have any decent thermal resistance so we invented thermal insulation.

But where to put the insulation?  If we put the insulation on the inside of the structure the insulation does not protect the structure from heat and cold. Remember we really do want to protect that darn structure—especially for the sake of making the structural engineers life more happy. Expansion, contraction, corrosion, decay, ultra violet radiation, and almost all bad things all are functions of temperature. So all the control layers go on the outside. Keep the structure from going through temperature extremes and protect it from water in its various forms and ultra violet radiation and life is good.


Figure 1: “The Perfect Wall”—In concept the perfect wall has the rainwater control layer, the air control layer, the vapor control layer and the thermal control layer on the exterior of the structure. The claddings function is principally to act a an ultra-violet screen. Oh, and architects might consider the aesthetics of the cladding to be important.

What about this air control thing?  Well air can carry a lot of water and water is bad for the structure. So we have to keep air out of the structure as well because of the air-water thing—or if we let it get into the structure we have to make sure it does not get cold enough to drop its water. Now, just one other thing, tends to be important if you intend on living in the building or working in the building or keeping things safe in the building, we might want to control the interior environment. We especially ought to be concerned about what is in the interior air because when we are in the interior we tend to breathe it. Well, it turns out that we can’t control air until we enclose air. So we need an honest to god airtight enclosure in order to provide conditioning such as filtration and air change and temperature and humidity control. And once again the best place to control this air thing is on the outside of the structure—but under the insulation layer so the air does not change temperature. Presto: the perfect wall. A water control layer, air control layer and vapor control layer directly on the structure and a thermal control layer over the top of the other control layers (see Figure 1 again).

This was figured out long before I was born—I think the Canadians figured it out first [1], but the Norwegians have some claims to this plus the Russians. I am going to go with the Canadians on this one because I am biased and proud of it. Also, I met Professor Hutcheon, and that is a story for the grandkids when I get some—memo to Christy and Andrew: so what’s the delay here?  For a more detailed discussion of the physics of all of this go to the old masters: Hutcheon and Handegord [2] and the new kids on the block Burnett and Straube [3].

In a beautiful bit of elegance and symmetry if you lie the perfect wall down you get the perfect roof (Figure 2) and then when you flip it the other way you get the perfect slab (Figure 3). The physics of walls, roofs and slabs are pretty much the same—no surprise (Figure 4). This insight was shone into a whole generation of practioners by Max Baker [4] when I was first getting started.

  
Figure 2: "The Perfect Roof"—The perfect roof is sometime referred to as an “inverted roof” since the rainwater control layer is under the insulation and ballast (i.e. roof cladding). Personally I don’t view it as inverted. Those other folks got it wrong by locating the membrane exposed on the top of the insulation—it is they that are inverted.

  
Figure 3: "The Perfect Slab"—The perfect slab has a stone layer that separates it from the earth that acts as a capillary break and a ground water control layer. This stone layer should be drained and vented to the atmosphere— just as you would drain and vent a wall cladding.

 
Figure 4: A Wall is a Roof is a Slab—The physics of walls, roofs and slabs are conceptually the same.

Notice in the perfect roof assembly the critical control layer or membrane for rainwater control and air control and vapor control is located under the thermal insulation layer and the stone ballast (i.e. “roof cladding”) so that it is protected from the principle damage functions of water, heat and ultra violet radiation.  Arrhenius* would be proud. Why we put the most critical control layers on roofs on the very, very top where they can be trashed by these damage functions never fails to amaze me. Yes, I know, they are easier to replace when they are located there. Standard answer for our disposable, unlimited resource available society.

Most problems in building enclosures occur where roofs meet walls. The classic roof-wall intersection is presented in Figure 5 (will both credit and apologies to Max Baker). Notice that the control layer for rain on the roof is connected to the control layer for rain on the wall, the control layer for air on the roof is connected to the control layer for air on the wall . . . and so it goes. Beautiful. And when it is not so…ugly.

  
Figure 5: "The Roof-Wall Connection"—Notice that the control layer for rain on the roof is connected to the control layer for rain on the wall, the control layer for air on the roof is connected to the control layer for air on the wall…and so it goes.

Time to put some meat on the bones of Figure 1. How should this perfect “conceptual” wall actually be built?  Three ways. The best of the best of the best can be found in Figure 6. This is a very special wall. I refer to it as the 500-year wall for two important reasons:

  • it represents 500 years of evolution; and
  • it will last 500 years

 
Figure 6: "The Institutional Wall"—The best wall that we know how to construct. Works everywhere in all climate zones.

It is the type of wall that you use for special buildings. Buildings that are passed down from one generation to the next. Museums, art galleries, courthouses, libraries. I call this wall the “institutional wall.” It is sweet in that it can be constructed in any climate zone. The only thing that may be changed is the level of thermal insulation. My advice here is very simple: what ever you think the right amount of thermal insulation should be double it and shut up. If you love your kids don’t argue with me.

A clever version of this first wall is where spray-applied closed-cell high-density foam is used to combine the four principal control layers in one material (Figure 7).


Figure 7: Clever Wall—One material combines four principal control layers

The second wall should be the “meat and potatoes” wall for commercial buildings. The wall every commercial building should use. The base wall that our infrastructure should depend on. So, no surprise I call it, yes you guessed it: the “commercial wall” (Figure 8). It has a conductive structure—metal studs. All of the insulation should—and must be located on the outside. It is a thermodynamic obscenity to insulate within a conductive structural frame. Again, you can build it anywhere in any climate location. Just consider the insulation levels (see above—particularly the part about loving your kids).

The third wall is the “residential wall” (Figure 9). Notice the structural cavity is insulated. That is because we are using a relatively non-conductive structural frame—the structure is wood and wood material based. Wood is not particularly conductive— that is why we do not have wood frying pans.

For this third wall to work almost everywhere (except Alaska and north of Flyn Flon** where we would not insulate even within a relatively non-conductive wood structural frame) we would split the thermal resistance of the insulation on the exterior of the structural frame with this insulation within the structural frame at least 50:50. So in an R-20 wall—at least R-10 or more on the outside of the non-conductive structural frame. And no vapor barrier on the inside of the assembly. Repeat after me, no vapor barrier on the inside of the assembly. We want the assembly to dry inwards from the control layers—and to dry outwards from the control layers. Always. Everywhere.

  
Figure 8: "The Commercial Wall"—The almost best wall we know how to construct. Affordable. Works everywhere in all climate zones.

 
Figure 9: "The Residential Wall"—The best residential wall we know how to construct. Not cheap. Works almost everywhere – except in extreme cold climates where we would not insulate within the wood structural frame.

National & International Standards to Establish How Infrared Febrile Scans Are Performed & Minimal Equipment Requirements

There are other national and international standards that are in place to establish how these Infrared Febrile Scans are performed and minimal equipment requirements. These recommendations have not been waived; however, these standards are considered voluntary with 510K requirements temporarily waived. These standards, ISO/TR 13154 and IEC – 80601-2-59 have recommendations that require 320 x 240 IR detector array for accuracy, equipment temperature tolerances, face size on the scan area, black body implementation to improve scanning accuracy and integrated software and a repeatable process to verify validity of the scan.

There are long back orders on most camera systems, so your startup options are limited in the short term. Infrared-A Closer Look Inc. is trying to balance the needs of our clients, their budget for Infrared equipment that already has compliance with ISO/TR 13154 and IEC-80601-2-59…. or will have equipment before the 510K certification is reinstated. Our priorities for helping you to keep your workplace safe with an effective Fever Screening process in place. Those priorities are as follows.

  • 320 x240 (or larger) Infrared detector using Long Wave IR Camera
  • Equipment accuracy of 0.5° C or better
  • Integrated software with semi autonomous function or Artificial Intelligence (AI) for face recognition capability to minimize inaccurate readings not from face area.
  • Black body integration or plans for a Black Body integration in the hardware / software package.
  • Manufacturer and Equipment reliability

Infrared Thermal Scanning for Elevated Febrile (Fever) Temperature

It has been said that within crisis there is opportunity. Given the current crisis created by the COVID-19 pandemic, this is especially true for thermographers and many of those involved with the manufacture of non-contact temperature measuring devices. Opportunity, however, should not be confused with opportunism.

 

One of the symptoms of COVID-19 is an elevated body temperature. In light of this, many companies have turned to body temperature measurement as a means of screening employees and visitors prior to granting them entry into their properties. Infrared devices are particularly well suited for body temperature measurements since they can provide temperature values quickly and without contact.

  

In mid-April of this year, the United States Food and Drug Administration issued guidance allowing industrial grade thermal imagers to be used as a screening tool for detecting elevated body temperatures provided that they met certain recommendations and that elevated temperatures detected were confirmed with a clinical grade thermometer.

 

It was the FDA's belief that the policy set forth in their guidance would help address public health concerns raised by shortages of temperature measurement systems during the current public health emergency. This policy has created a tremendous opportunity for trained thermographers to put their equipment and talents to good use either as professional body temperature screening technicians or as consultants to those initiating a body temperature screening program.

 

Unfortunately, the current pandemic has also seen its share of opportunists. Over the past several weeks there has been a marked increase in the number of companies that are now offering 'infrared technology' for body temperature screening. Many of the products do not conform to best practices nor are they suitable for human body temperature measurement.  

 

Bayou State Inspections fully supports thermal imaging for body temperature screening provided that the proper equipment is selected and is operated by trained technicians in accordance with industry best practice.  If you or your company are seeking to acquire infrared equipment for body temperature screening, we would invite you to call our office to schedule a net meeting or a meeting at your facility that will help you to understand the technology and how to select the proper equipment without marketing hype.

 

Properly applied, thermal imaging can help to ensure the health and safety of the public. It is an opportunity we cannot afford to miss. 

Reopening America Again Guidelines

On April 13th 2020, the President of the United States issued the Reopening American Again Guidelines to help guide the State Governors and community leaders in a path to reopen businesses in this post COVID-19 environment. As each state, region or metropolitan area moved past their peak outbreaks and into a more manageable situation, the guidelines established three distinct phases where businesses and operations could return to a more normal state of operations. The guidelines presented responsibilities for the States, Individuals and Employers.

The States are responsible for testing, contact tracing, screening of the most vulnerable, health care capacity and planning to limit and mitigate further outbreaks. Individuals are responsible for personnel hygiene, using face mask and staying home if they are sick.

Employers are responsible for developing and implementing appropriate policies in accordance with Federal, State and local regulations and guidelines bases on industry best practices to protect their workforce. Those include:

  • Workplace social distancing and protective equipment,
  • Temperature checks,
  • Testing, Isolating and contact tracing of employees.
  • Sanitation
  • Use of disinfection of common and high traffic areas
  • Business travel
  • Develop and implement policies and procedures for workforce contact tracing following COVID-19 + test.

The Guidelines want you to monitor your workforce for indicative symptoms and not allow symptomatic employees to physically return to work until cleared by a medical provider. IACL’s focus is different from many companies because we want to help advise on a broad range of these recommendations instead of just temperature checks. We can definitely help with the Temperature Check, but there is much more in these recommendations that just temperature checks. Everything basically starts with your company’s Policies and Procedures. The Reopening America Again Guidelines has these recommendations spread between the three phases of reopening.

Phase One for Employers encourages telework whenever possible and then allow for a return to work in phases. Close common areas where people gather, congregate and interact to enforce social distancing protocols. Strongly consider special accommodations for personnel who may be especially vulnerable to COVID-19. There are other restriction related to specific types of business and employers.

Phase Two still encourages telework whenever possible and feasible with your business operations. They still want common areas closed where employees are likely to congregate to enforce moderate social distancing. It does allow non-essential travel to resume but still strongly considers special accommodations for especially vulnerable personnel. There are other relaxed restrictions related to specific types of business and employers.

Phase Three basically allows unrestricted staffing activities on worksites with some mild restrictions on some specific employers.

People think of the transition from Phase One to Phase Two to Phase Three as a linear progression in one direction. If there are further outbreaks of infection in a region, state or locality, our society could move from Phase One or Two directly to Phase Three and then back to Phase One. We will be dealing with COVID-19 for years to come and with the high mortality rate, it will affect your business’s ability to be productive and profitable for a long time. That is why planning and preparation is so important.

What is Fever Screening and what does it have to do with thermal infrared (IR) imaging?

For the purpose of this discussion, normal core body temperature in the human body varies, but the average is 37°C or 98.6°F. Among other reasons, infections cause the body's temperature to rise. When a human's body temperature rises, it's called a fever. A fever is considered anything above 38°C or 100.4°F.

 

In its purist form, Fever Screening is the act of checking the internal temperature of a human being by placing an analog or digital thermometer in the mouth, armpit or rectum. This is accomplished by a qualified person with a thermometer at a check point -for instance, at an airport, factory or office building, before entry is granted. Tympanic thermometers (infrared ear thermometers) have gained popularity because they are fairly accurate, more non-contact and faster than other types. But this process takes a considerable amount of time.

 

Since there is a closely locked relationship between the internal and external body temperatures of humans, it has been determined that; a) to reduce screening times, and b) to reduce the risk of cross-infection between the incoming person and the screener, that thermal infrared imaging does have an acceptable level of accuracy and repeatability to be used confidently as a primary screening method.

 

In the primary screening process, when people with a skin surface temperature higher than that of a given set point are found, this apparent elevated body temperature warrants that person should be directed to secondary fever screening, using thermometers.

 

So, it can be said that thermal infrared imaging is a valid method of detecting Elevated Body Temperature in humans by using Skin Temperature Measurement -which speeds the process of entry screening for Human Febrile Temperature Screening.

Home Maintenance Tips for Spring

  • Loose or leaky gutters can lead to drainage issues that can allow water into your basement or crawl space.  Downspouts should be clear of debris and drain away from the foundation.
  • The grade around your home should be sloped away from the foundation to prevent water from pooling up and entering the home.  Use compact soil to increase the grade so that water flows away from the foundation. 
  • Check any wood trim surrounding windows, doors, railings, or decks for rot.  This can easily be done by using a screwdriver to probe the material.  You'll want to repair any trouble areas before the spring rains begin.
  • Examine the roof's shingles and flashing around skylights, vents, and chimney's from the ground.  Missing or damaged shingles should be replaced.
  • The exterior of the chimney should be examined for signs of damage. Have the flue cleaned of debris from any winter fires you may have had in your fireplace.
  • Concrete slabs should be inspected for signs of movement or cracks. All exterior concrete should drain away from the home's foundation. Fill cracks with a concrete crack filler. When weather permits, power-wash and then seal the concrete to increase longevity.
  • Check outside hose faucets for freeze damage. Turn the water on and place your thumb or finger over the opening. If you can stop the flow of water, it is likely the pipe inside the home is damaged and will need to be replaced. While you're at it, check the garden hose for dry rot.
  • Have a qualified heating and cooling contractor clean and service the outside unit of the air conditioning system. Clean coils operate more efficiently, and an annual service call will keep the system working at peak performance levels. Change interior filters on a regular basis. 

Using Tmax Corrected to Prioritize Electrical Exceptions

Thermographers have long used temperature differentials or Delta T measurements as a means of prioritizing electrical and mechanical exceptions. Typically, Delta T values are calculated by comparing the temperature of an exception to similar components under similar load or to ambient air temperature. Although they work well in many circumstances, Delta T readings are not applicable for components that do not qualitatively manifest themselves as an exception.

 

An alternative to Delta T calculations is a formula known as Tmax Corrected. This formula is based upon an IEEE formula and calculates pass/fail criteria based upon several factors including equipment type, ambient air temperature, and circuit load.

 

Although requiring a little more time to apply than Delta T calculations, Tmax Corrected allows one to determine if a component of interest is running within specification for any load or ambient temperature. Tmax Corrected is especially useful for equipment that is not manifesting itself as an exception. Tmax Corrected can be an invaluable tool for those who perform infrared inspections as part of commissioning studies or use thermography for acceptance testing of new installations, repairs, or retrofits.

COVID-19 Air Testing

We have received a number of inquiries in regards to air testing for the virus that causes COVID-19. As far as we are aware there is no test for the virus in the air. The current test kits in use now only test for the presence of the disease in a person.

 

The testing kits for COVID-19 are in short supply and are being strategically distributed to areas in need. Due to the shortage of test kits for health care facilities themselves.

 

We will inform you of any changes to air quality testing options as soon as anything is available. Be safe, use common infectious disease control procedures, and stay up to date.

Do Infrared Thermometers Detect Accurate Temperatures on Humans?

It has been said that desperate times call for drastic measures. However, when faced with a crisis, it is imperative to ensure that measures taken are appropriate and effective for the challenge at hand.

 

In an effort to help stem the spread of coronavirus, many people have been using non-contact infrared thermometers to determine human body temperature.  Often, the chosen instruments are industrial grade devices which are unreliable for human body temperature measurement.

 

Unlike infrared thermometers that are designed for medical use, industrial grade instruments can vary as much as 7.2 Fahrenheit (4 Celsius) degrees from a target's actual temperature.  In other words, using an industrial grade instrument on a person with a normal body temperature could yield temperature values ranging from 91.4°F (33°C) to 105.8°F (41°C).  Inaccuracy aside, the greatest risk in using industrial grade instruments is missing feverish persons who could infect others.

 

When using infrared thermometers on humans, one should only use medical grade instruments that have been certified for such use.  These instruments are far more accurate and will provide temperature values that are acceptably close to body core temperature.  For those electing to use infrared thermometers, we strongly encourage them to be trained in the proper use of their chosen equipment.

 

Thank you to all involved in treating the sick and helping to control the spread of COVID-19.  For those who are ill, we wish you a full and speedy recovery.