Be Careful What you Say...Your Walls Could be Listening!

Princeton researchers develop a way to
 embed ultra-thin radios  to plastic sheets. 

Eavesdropping just took on new heights with the creation of walls that can listen and even speak. 

Researchers at Princeton University have developed a way to embed ultra-thin radios to plastic sheets, which can be placed on a variety of structures.  These listening walls have the potential to be the foundation for invisible communication systems inside buildings or to function as sophisticated structural monitors for bridges and roads. 

Originally the intent of this technology was for the application of smart building energy management. Through the use of distributed radio arrays that are patterned on wallpaper, temperature sensors and occupancy sensors are able to communicate with a central management system. 

These thin plastic sheets have the potential for several applications. The sheets can be painted without diminishing their function and can be applied to irregular surfaces such as bridge decks or supporting columns because of their flexibility. 

Patterning Circuits on Plastic 

One of the major difficulties with this technology was patterning circuits on the plastic sheets, as the high temperatures needed to create circuitry will melt the plastic. New methods for patterning circuits on plastics have helped researchers surpass this problem. However, these new methods compromise the performance of electronic components such as transistors, which are vital in the operation of complex devices such as radio transmitters. 

Transistors, the building block of modern electronics, are devices that control or switch the flow of electrons in circuits. The silicon crystal that forms the base of transistors allows for electrons to move quickly.  

Because plastic is susceptible to melting at high temperatures, researchers turned to amorphous silicon transistors in place of crystalline silicone, as amorphous silicon does not require high temperatures like the crystal form.  However, amorphous silicon lacks the highly ordered inner structure of the crystal form. This inhibits the electrons ability to move efficiently, as it is like changing from a smooth superhighway to a gravel road. 

Researchers were poised with the challenge of speeding up the movement of electrons through the transistor (faster movement means higher frequency), despite the lower-performing amorphous silicon transistors. 

The Super-Regenerative Circuit 

To overcome this problem, the Princeton researchers found inspiration from the father of FM Radio, Edwin Armstrong. In 1922, Armstrong developed the super-regenerative circuit, which uses other components to increase the radio's frequency and bypass the poor performance of the amorphous silicon transistors. 

In 1922, Edwin Armstrong
developed the super-regenerative circuit.

By bouncing electrons between a capacitor and an inductor, the super-regenerative circuit, is able to store and discharge energy.  The energy change caused by the bouncing electrons depends on the super regenerated circuit's capacitor and inductor--not the transistor.  This allows the radio to operate at a high frequency despite the poor quality of the transistors. 

The key was to prevent the electrons from being lost as they bounced back and forth between the capacitor and the inductor, as lost electrons would than be compensated through the faulty transistors. This meant high quality capacitors and inductors.  

This was good news to researchers as large inductors are easier to build. And due to the fact that the radios were designed to fit on walls, there was plenty of space. In the end, despite the poor quality transistors, the circuit worked perfectly with the new system.  

The Future of Structural Monitoring Systems? 

Researchers are developing ways to use this technology to create flexible structural health monitoring systems for bridges, buildings, pipelines and other structures.  

Plastic sheets embedded with radios
could better detect structural problems. 

Currently, engineers are able to use single-point sensors or fiber optic strips to detect structural problems. Unfortunately these devices are limited and can only collect data from relatively small spaces. This makes detection of early problems difficult, as most problems occur on larger spaces. 

Plastic sheet technology could make monitoring these structures more efficient.  The linked sensors could potentially detect imminent structural problems over larger areas. 

While the research of this project still remains in early development the results are encouraging. A prototype is in the works, but it will take many years of research and development before this technology is utilized in such a manner. 

This article was originally published, "The Walls have Ears: Princeton researchers develop walls that can listen, and talk" from Phys.org on August 21, 2013.  

Sick? Your Air Conditioning Could be the Cause

Is your air conditioning making you and your family sick? 

For many, air conditioning is the embodiment of comfort living, particularly in the summer months when the heat index can be unbearable.  But could your air conditioning be causing more harm than good? 

According to the Director of the Common Cold Centre at Cardiff University in Wales, Professor Rob Eccles, exposing the body to extreme temperatures could actually make you sick. 

 Here's Why: 

As warm blooded animals, the human body's optimal temperature is around 98 degrees Fahrenheit. In extreme cold environments the body will fight to maintain this body temperature.

Cold temperatures cause blood vessels
 to  constrict and diminish number 
of white blood cells.

One of the body's defense mechanisms against the cold is the thermal regulator in the brain. As soon as it receives a message from the temperature sensors in the skin, the blood vessels are alerted to constrict. This immediately causes a person's skin to become ashen or mottle, which is quickly followed by shivering in order to generate heat to raise the body temperature. 

As a result, the blood vessels in the nose and throat, both of which are favorite locations for bacteria and viruses to hide, will constrict therefore limiting blood flow. 

As the blood flow diminishes, the white blood cells that typically fight bacteria and viruses do too. This allows these dormant risks to develop in to colds. Low blood flow to the throat means that there isn't enough white blood cells to ward off infection. 

Sweating exacerbates the problem because it keeps the body colder. This makes it more of a challenge for the body to maintain its optimal temperature. 

Going from hot to cold environments could put
you at risk for a cold. 

Professor Eccles emphasizes that a cold will only develop if the bacteria or virus is already present in the body.  

This phenomenon occurs when going from a hot environment to a cold atmosphere not the other way around. Though, Professor Eccles recommends limiting the number of times you go from a cold environment to the hot outside as when your body acclimates to the heat and steps back inside the chilling cycle will begin again. 

This article was derived from the headline "Does Going from Hot to Cold Cause Colds?" which appeared on August 20, 2013, in the U.S. edition of The Wall Street Journal. 

Benefits of Green Building

The green building phenomenon is sweeping across the world, but many doubt the benefits of this movement.

Instead, they believe it is simply a political agenda or a means for more costly construction projects.

The reality is, a green building project can have environmental, economic and social benefits as described below: 

Environmental Benefits 

• Emission Reductions--Green building techniques such as solar powering and daylighting can increase energy efficiency and reduce harmful emissions.
• Water Conservation-Implementing water recycle programs for urinal flow and irrigation can significantly lower water consumption and increase savings.
• Temperature Moderation-Conscientious building designs and site selection can reduce the urban heat island effect caused the heat retention properties of tall buildings and urban materials.

Economic Benefits

• Energy & Water Saving- Green design and technology can drastically reduce operation costs. This can offset any additional project costs, while offering long-term savings. 
• Increased Property Advantages-Low operating costs that come with green facilities can lead to lower vacancy rates and higher property values.
• Increase Employee Productivity & Health-There is a positive correlation between indoor environmental conditions and improved employee health and productivity. 
• Sales Improvements-Studies show stores with more natural light have more sales. 

Social Benefit 

• Improved Health-Poor indoor environment quality can contribute to respiratory problems, allergies, and nausea headaches. Implementing green building features can provide for a healthier and more comfortable living and working environment.  
•  Improved schools-About 40% of the schools in the United States are subject to poor environmental conditions that can affect the health and learning of students.  Studies show that schools utilizing green building techniques often experience a reduction in student absentees and see an improvement in test scores. 
• Healthier Lifestyles & Recreation- Sustainable designs preserve natural environments and provide for more recreation and exercise opportunities. They also promote alternatives to driving such as bicycling and public transport. 

What’s so special about Clubhouses?

Ballen Isle Country Club
West Palm Beach, Florida

The Complexities of Designing HVAC Systems for Clubhouses  

Clubhouses are unique among buildings. They house restaurants, community centers, banquet halls, entertainment complexes, retail spaces, fitness and spa centers and even offices all wrapped up into one facility! 

Dripping Diffusers

The clubhouses' unique nature is one of the major reasons why faulty HVAC systems are common; especially in humid climates such as Florida.

Perhaps, one of the most frequent issues that engineers uncover during a due diligence survey is a facility operating under a severely negative air pressure condition.

Common Symptoms of Negative Air Pressurization  

•  A lack of fresh or clean air, instead a musty smell or other bad odors lingering in the air
• Condensation on the Diffusers
• Visible Mold or Mildew Growth along with Moisture on the Walls 
• Sticky or Damp Furnishings
• Varying Temperatures Throughout the Facility 
• Stagnant, Stale or Heavy Air that causes Humidity or Condensation 
• A Rush of Air or Draft when Opening an Exterior Door 

According to Bob Davenport, RGD Consulting Engineers' Principal Engineer, who has over 35 years of experience designing HVAC systems, "Operating a clubhouse with severely negative pressure can result in serious indoor air quality problems over time." 

Solutions

 If not caught before the start of microbial growth, negatively pressurized facility can be a costly issue to rectify. This is why having the proper HVAC equipment and a good maintenance program is important to preventing issues such as negative air pressure from occurring. 

Ensuring that the clubhouse building is equipped with 100% outside air pre-conditioner, runs continuously and supplies a constant and equal volume of dehumidified outside air to the building is key to maintaining the air pressure. 

There are a variety of methods for achieving this goal, and the most effective HVAC design system can be determined by a professional engineer after completing a thorough survey of the facility's systems. However, even the best designed HVAC systems can fail when they are not maintained. 

Just as important as working closely with an engineer for the design of your facility's HVAC system, is the creation of an aggressive maintenance program.   With these two factors planned well, your facility's HVAC system will stay balanced and healthy for years to come. 

This article is adapted from "Is Your Clubhouse Stuffy" written by Robert Davenport, PE, LEED AP + BC. 

Self-Healing Concrete...the Future of Structures?

Bonita Bay Country Club Construction 2013
Bonita Springs, FL 

Self-healing concrete? It's closer to being possible than you think.

Concrete is a remarkable material. It can be molded into a number of forms, it sets like stone and it is extremely strong when combined with a metal such as steel.  It's no wonder it is the basic structural foundation for buildings, roadways and bridges.

Despite all these notable qualities, concrete has a major weakness--water.  Water poses a serious threat to the stability of a concrete structure, as all it takes is one small crack for water to get inside to turn a concrete structure into a pile of rubber.

Corrosion of the rebar in concrete. 

In colder climates, water can freeze and expand, compromising stability.  Water can also bring carbon
dioxides, sulfates and sulfate reducing bacteria that can cause even more damage to a structure. Perhaps the worst consequence of water in concrete is if it reaches the metal rebar. Overtime, the metal will rust, expand and slowly destroy the structure.

The key to preventing water from entering concrete is preventing the cracks from occurring. This is easier said than done. As even the most carefully prepared concrete is susceptible to cracking, especially when in a moisture prone area.

Researchers at the University of Bath in collaboration with Cardiff University and the University of Cambridge may have discovered another way to prevent concrete from cracking--a concrete mix with bacteria within microcapsules. The hope is that when water enters a crack, the bacteria will germinate and produce limestone, which will then plug the crack before water can do damage to the rebar.  The bacteria would actually use the oxygen present to repair the structure.

While this study is still in its early stages, researchers are optimistic that self-healing concrete will be able to increase the life of concrete structures vastly and would remove the need for repairs, reducing the lifetime cost of a structure by up to 50 percent. It would also reduce man-made carbon dioxide revisions.

Currently, researchers are assessing how the varying strand of bacteria survive in concrete over a period of time.

Thermostat Wars: HVAC vs. Home Security Industries

The HVAC industry is battling with homeowners, home security and home automation companies to determine who has the authority to install thermostats as a part of "smart home systems." 

The issues has taken on new heights with several HVAC industry organizations pushing for legislation to prevent home security and other non HVAC companies from replacing thermostats with products that communicate with security and home control systems. 

HVAC companies claim that HVAC systems use exclusive protocols and special communicating thermostats to control equipment that don't follow standard thermostat configurations, protocols or wiring. 

According to Dominick Guarino, the CEO of the National Comfort Institute, this approach to this issue has little substantiation, as many home security and home automation companies have their employees complete extensive education to be able to install this technology. However,  the issue that should be at the forefront of this battle, is who is responsible if the technology is incorrectly installed.  

Guarino recommends that instead of fighting this issue on a government level,  HVAC companies should fight this battle in the marketplace through education.  Let your customers know that having a third party install an intelligent thermostat could have negative consequences.

To learn more about this issue, visit the original article here.