Group C - High Rise CIA Facility

The building we are focusing on is a high rise office building in Washington, DC. The building will be a 36 story office facility for the CIA.  Because this is a government building with an assumed large budger, advanced building intelligence and maximum security are both top priorities.
In terms of programming, BIM would be highly useful in allotting spaces for highly classified areas and creating a flow of spaces based on security clearances.  BIM and cost analysis would be the primary technologies in the design process.  BIM would be used to integrate all building systems and to satisfy the client's needs regarding security. Sensors play an important role in security and monitoring systems for energy efficiency. For bidding and approval, the municipality, contractors, and owners would be the key stakeholders. BIM, a building program database, and structural model would all be used in this stage of the building process through cost analyses and permit approvals.
All stakeholders would be involved in the construction process. BIM, surveys, and regional models would all be utilized through construction management.  These technologies would be used to make the building process more efficient. Sensors would be the most important technology during the occupancy of the building.  They would be used to control temperature, humidity, and lighting to control the building conditions. BIM and building analyses would be used during any required renovations as well as the demolition process.

Key conclusions:
high security
low energy
well integrated building automation system
database integration

https://docs.google.com/presentation/d/11zHlbeyAH2uO-qwbqSojYviIMqF4eBdOyr3su7oHtTs/edit?usp=sharing

Movement Sensors

This week was all about sensors and it was extremely interesting to see how many different sensors are available and used in everyday applications. This week I focused on movement sensors and found that the most used type of movement sensor is called a Passive Infrared Sensor, PIR. This sensor uses heat to detect movement within a given area. This sensor is used in automatic lighting schemes, burglar alarm systems, automatic welcome greetings and even motion detecting remote cameras (see video below). These sensors usually have a range of approximately 20 feet but will practically never wear out, are extremely reliable, incredibly cheap and simple to use.
I thought it was incredibly important to note, especially with the talk of data overload in recent classes the number of readings that single sensors are able to take. Both Junwah Ng , and Xiang Li talked about different senosors, humidity and pressure respectively, but both mentioned the number of measurements each of these sensors can take. Even though the PIR sensor is simple I am sure that there are a number of movement sensors that provide an abundance of measurements that can be recorded to help in disciplines such as traffic studies, population tracking, mass transit security and monitoring and many more. 

References:
http://www.gadgetshack.com/motionsensor.html
http://www.ladyada.net/learn/sensors/pir.html
http://www.instructables.com/id/PIR-Motion-Sensor-Tutorial/
<iframe width="420" height="315" src="http://www.youtube.com/embed/dGOgCnlizgU" frameborder="0" allowfullscreen></iframe>

Movement Sensors

Prior to this week’s assigned research, I thought I understood the basic concept of movement sensors and how and why they were commonly used, yet as I continued doing my research I became more aware of the importance and dependability that other systems have over this system.  Movement sensors detect changes in positions of a person or object relative to its environment or the other way around.  There are six types of motion detectors that are commonly used including: infrared, optics, radio frequency energy, sound, vibration, and magnetism.

The types of movement sensor methods are mechanical and electronic methods.  Most people are unaware of the mechanical movement sensors around us, yet unknowingly we use these daily and vastly.  From the moment we wake up we use movement sensors such as the moment we turn our alarm clock off,  when dialing the heating time in our microwaves, typing in our computer keyboards or even the simple motion of flicking the light switch.  Electronic detection sensors are ones that detect optical or acoustical motion.  Examples of when we encounter these sensors include the ones that activate lighting, activate a camera to turn on, or even trigger an alarm. 

Because of the wide range of functions of movement sensors, these are the most used type of sensors.  Other types of sensors are dependent and rely on these sensors in order to activate or deactivate.  For pressure sensors, like my classmate C. Meraz explained, a piezoelectric pressure transducer uses crystal to convert motion into an electrical output since “these sensors are also highly susceptible to shock and vibration”.   With flow sensors, like Brian V says in his blog post, record measurements within a flow meter of flow of fluids or gases.  These measurements are found by observing the movement of such fluids or gases.  Matthew Tedesco also explains that “aside from mechanical flow meters, fluid velocity and flow can be measured using optic sensors”.  As explained before, optic motion sensors fall under the movement sensors category.  In conclusion, we can encounter movement sensors in our everyday life and they also play important roles in other practices.

Sources:

http://en.wikipedia.org/wiki/Motion_detection

http://home.howstuffworks.com/home-improvement/household-safety/security/question238.htm

Humidity Sensors

       A humidity sensor measures three different types of humidity; absolute humidity, relative humidity, and specify humidity. Absolute humidity is the ratio of water to air, the total mass of water vapor that is in the air at a given time. Relative humidity (RH) is where many believe is temperature is actually the saturation level of the air. It’s shown as a percentage of the ratio of the moisture in the air and the total amount of moisture the air can hold. If the RH is at 100% then the air cannot hold any more moisture which can mean a high possibility for rain. The warmer the air is, the more moisture it can hold, the colder the air the less moisture. Meaning that the RH is affected by the change in temperature, which can justify why some believe humidity sensors measures temperature. Specific humidity is the ratio of the mass of water vapor in the air to the total mass of the mixture of air and water vapor. These humidity sensors can be used both indoors and outdoors, as well as being available in both digital and analog forms. The analog sensor uses a system called capacitive measurement. The sensor would be made of either glass or ceramics. The insulator material made from polymers, absorbs and releases that water which changes the level of charge in the capacitor. The measure of the change in the charge is the humidity of the given area. The digital sensor uses an electrode based system consisting of polymers, there are two micro sensors that are calibrated to the humidity of the given area. Which are then converted into digital format using an analog to digital conversion. There are actually another type of system called the hygrometer, where there is a pair of thermometers are used. One is kept wet while the other one is kept dry. The difference of the two moisture levels are measured. I really liked how in Nastasha’s blog, she when more in-depth with the components and circuitry of the sensors. There are many applications that a humidity sensor has. To regulate humidity in buildings like museums, laboratories, and wine cellars. Create a sterilized environment for a hospital and even the defogging or defrosting systems in cars need humidity sensors. Humidity sensors are key into making a green building as in Jeanine’s blog, she mentioned that “The humidity sensors will collect data that will be used to determine the comparative advantages and worth the new technology.”

http://www.tech-faq.com/humidity-sensors.html

http://www.articles-place.com/various-types-of-the-humidity-sensor/

http://www.ehow.com/how-does_5306344_humidity-sensor-work.html

Humidity Sensors

Week 8

2/19/13

Humidity Sensors

                Humidity sensors, or hygrometers, come in multiple forms depending on the desired measurement (absolute vs. relative), cost factor and level of accuracy.  These sensors are used to measure the moisture content in the air.  Measuring the relative humidity is most practical because the reading depends on an associated temperature; where a ratio of current moisture content to the maximum moisture content at that temperature is developed.  This makes the most sense as we are dealing with both moisture and ambient temperature when designing a room to be as comfortable as possible.  In this way, data from a hygrometer will be fed into an HVAC systems computer which will either humidify or dehumidify the air based on the requested conditions.

                Due to their ability to be used in multiple scenarios, low cost and relatively high and stable accuracy, the capacitive humidity resistor is the most commonly used type.  In this style, a film capacitor is sandwiched between a ceramic and a dielectric polymer.  The polymer will absorb or release moisture based on the relative conditions.  The addition or subtraction of water will change the capacitance of the capacitor which can be converted to a digital reading.  These sensors have an average accuracy of about +/- 2%.

                The least accurate humidity sensor is called the metal-paper coil and gives a good visual of the principle that makes the more accurate types work.  In this style, a piece of paper that has been saturated with salt is attached to a metal coil.  When humidity increases, the paper absorbs water and changes the shape of the coil.  These changes are calibrated so a dial can be used to provide relative readings.  Although the accuracy is limited to +/- 10%, these gauges are cheap and require no digital feedback to function.

 Brian did a good job in his post to point out the range of options from the most accurate to least accurate.  He refers to the idea that “primitive” methods of something physically changing such as the length of a hair have been superseded by more technological methods that use electrical properties and digital conversion.  In the end, however, these primitive methods still do the job that they were designed to do.

                Originally, I only thought of hygrometers being used in conjunction with HVAC systems for air condition quality purposes.  Jeanine’s post made me realize that their uses go far beyond just providing comfort.  Having a controlled humidity level in a hospital scenario is very important for controlling the spread of airborne germs and bacteria.  Industries like greenhouses can benefit by controlling the amount of moisture introduced to the plant life.  The uses obviously stretch much further than home comfort in thermostats.   

How flow sensors work?

Flow sensors are used for wide range of fluids in multiple industries for various measurements. There are many types of flow sensors and they all measure “volume or area per unit time”. And depending of the sensor type there are multiple ways this volume per unit time can be measured, but they all use basic concept of fluid flow principles with concept such as the Bernoulli’s principle. Some of the basic flow sensors used today are orifice meter, venture meter, flow nozzle, and pitot tubes which us the principle of difference in pressure from the Bernoulli equation. Then there are sensors which use direct force to measure the flow which include rotameter, turbine meter, propeller flow meter, coriolis mass flow meter. Using pressure differences and direct force are the most common methods used to measure flow rate but there are other complicated methods such as ultrasonic flow meters, magnetic flow meter, calorimetric flow meter, gear flow meter, thermal flow meter, and couple more.

All the flow sensors which use pressure difference use Bernoulli equation which is 

Where the condition on both sides of the sensors are inversely related to each other, therefore the equation can be manipulated into the pressure drop across the flow sensor is equal to velocity of the flow squared. When calculating the flow using the different sensors the area of the opening on both sides of the sensor, density of the liquid, and pressure readings from the sensors are known an can be plugged into the Bernoulli equation to find the velocity because V₁ = V₂ = V. Below are few images portraying how some of this sensors operate and how the pressures differences (dp) can be measured.     

Orifice Plate Flow Sensor

Venturi Tube Flow Sensor

Flow Nozzles Flow Sensor

Sensors using direct force to measure velocity use methods of balancing forces with in systems where the force applied by the fluid flowing through the sensor is measured and manipulated with a proportion factor to get the flow of fluid in the system. Below are some images which portray how the forces applied by the fluid are with few different types of direct force flow sensors.

Rotameter: resistance of gravity force of the bolt is being measured here.

Turbine meter: work is being measured here where work equals force times distance, and the distance id known so the force can be calculated from the work measured by the sensor.

Sources:

http://www.princeton.edu/~asmits/Bicycle_web/Bernoulli.html

https://controls.engin.umich.edu/wiki/index.php/FlowSensors

Infrared Thermometers

Mike does a great job summing up a wide variety of temperature sensors.  Back in high school I learned that the bimetallic strip was used to control thermostats.  The expansion of the metal at a specific temperature would close a circuit, thus turning on/off the HVAC system.  Now we have NEST, which is more accurate and efficient. 

I would like to expand on Infrared (IR) Thermometers.  These thermometers are essentially a laser gun that can read the temperature of an object without any contact.  This type of thermometer is has an increasing popularity in the food industry.  Chefs are using them to read the temperature of food so that they don’t have to puncture the food and because it gives a fast and accurate reading. 

Every object emits an invisible infrared energy.  IR is located on the electromagnetic spectrum between visible light and microwaves.  There are three ways to transfer this invisible heat: reflected, transmitted, and emitted.  The emitted energy is the only type of energy that can be used to get the actual surface temperature.  This is a disadvantage to this type of thermometer.  As I mentioned before this thermometer is becoming popular in the food industry.  If the food is under a heating lamp the temperature measured will also include that of the lamp.  Therefore, when taking the temperature of the food it should be in low light, or the light should be covered with a cloth.

 

Depending on how advanced the IR thermometer the emissivity value can be altered based on the material.  These values can be looked up in charts.  As a comparison, emissivity of aluminum and water are 0.77 and 0.95, respectively. 

Again these thermometers are growing in the food service industry. They are also great for monitoring equipment.  For example, they can be used to find hot or cold spots detecting leaks in HVAC equipment. 

Sources:

http://www.allqa.com/IR.htm

http://www.thermoworks.com/emissivity_table.html

http://www.buzzle.com/articles/laser-thermometer-how-does-it-work.html

Flow Sensors (Fluidic-flow measurement sensors)

            Flow sensors are devices that sense the rate of fluid or gas flow. The sensors installed in different field varied depending on the properties of the fluid or gas being measured. Sensors have different meters and principles therefore, the most appropriate should be chosen for the desire application. The most common sensors in our daily life are the ones used to measure water flow and electrical consumption at our home.

During my research through AccessScience I found two types of Fluidic-Flow measurement sensors known as fluidic-oscillator meter and fluidic flow-sensor. The fluidic-oscillator meter works on the principle of Coanda effect. The Coanda effect of a jet fluid attaching to a nearby surface, and it remains attached even when the surface curves away from the initial fluid direction. In the case of the fluidic-oscillator meter the fluid comes into the device and the fluid attaches to one of the side walls (see attach figure). Part of the flow splits off and goes through the feedback passage forcing the incoming flow to attach to the other side of the sidewall. The frequency of the oscillation back and forth is proportional to the volume flow through the meter. The sensor records the oscillations and transmits the signal to record the flow. These types of meters can be used for fluids and flow meters. The fluidic-flow sensor measures the flow of gas. It consists of air or another gas directed from an outer nozzle onto two small openings. The flow of the gas being measure will bend the air or gas and therefore changes the relative pressure on the two ports. This activates the signal and allows recording the gas velocity.

Rita Pauliushchyk on her blog decided to focus on the common types of flow sensors such as flow of water and energy consumption of a building or household.  These are sensors we use/activate every day for our usage. This sensors are the one in charge of saying how much we have consume at  home shown in our monthly bills. Sensors although they are measuring fluid, gas, air they are also helping to control the usage. Sensors are today recording and serving data to make building more efficient and sustainable. They are a powerfull device that is making buildings sustainable. It is important to know which sensors to install accordingly to the application and characteristics.

Week 7: Movement Sensors

When analyzing movement sensors, they can be broken down into two main types of movement sensors: active motion detectors and passive motion detectors. Active movement sensors utilize sensors that emit a type of signal that is then reflected back and detected. Passive movement sensors do not actually emit a signal like active sensors, but instead detect the signals being emitted by the objects in their field of view and have a predetermined baseline reading for the surrounding area.

Active movement sensors are mainly used in places where a rapid response from a change in detection is needed (ultrasonic or microwave). For example, a motion sensor for a car garage uses an active ultrasonic radar-like sensor that emits sound waves. When the sound waves are emitted, the sensor detects the pattern or the time it takes for those waves to bounce off of its surroundings and return back to the sensor. When an object is approaching the garage door or entering the space under the garage door while it is closing, the sound waves are emitted and bounce off of the object crossing the path of the sensor causing the return time to be faster. This is then computed by the sensing system and tells the garage door mechanism to open so as to allow a car to enter or to prevent the door from closing on something or someone.

Passive movement sensors detect a change in their surroundings by reading the energy of their surroundings. These types of sensors come in various forms, some of the most common being infrared or photo sensors. These sensors detect and measure the energy that is being produced by the objects in their line of sight and are commonly used in home security systems or businesses to warn them of someone entering the facilities. Bodies that generate heat, be they humans or animals, also generate infrared energy (for humans usually ranging between 9 and 10 micrometers). With this range in mind, infrared sensors are programmed to detect emissions within the range of 8 and 12 micrometers with the use of a photo detector. This sensor measures the light being transmitted to it, converts it into an electrical current that is sent to the sensor’s processing core. “The alarm is triggered when the photo detector detects large or fast variations in the distribution of the emitted infrared energy.” (1). This form of detection allows for the movement sensor to ignore slight variations in heat that occur over the length of the day, such as the slow change in temperature of objects in the sensor’s field of view as their temperatures cool down over night.

These sensors are very inexpensive and can offer a very secured environment when combined to cover all entry points of the desired area.

I found it interesting in my classmate Matthew Tedesco's post (http://ae-510-ay12-13.blogspot.com/2013/02/flow-measurement-of-fluids-including.html) how he explained the various applications a specific type of sensor may have. Movement sensors aren't limited to only sensing movement, but as Matthew described, optic sensors (which are a type of movement sensor) can also be used to measure mechanical flow, fluid velocity and flow.


Sources:

(1) http://www.ehow.com/how-does_4596955_motion-sensor-work.html
(2) http://home.howstuffworks.com/home-improvement/household-safety/security/burglar-alarm2.htm
(3) http://home.howstuffworks.com/home-improvement/household-safety/security/question238.htm

Temperature Sensors

    A temperature sensors are devices that measure temperature of a medium. As Mike S. mentions in his blog, there are many types of temperature sensors used from simple home purposes to extremely accurate and precise scientific uses. Thermocouples, resistive temperature detectors, infrared thermometers, bimetallic devices, liquid expansion thermometers, and state-of-change devices are the some of the basic types of temperature sensors used for simple or more complex purposes.

    As Mitchell Butler and John Scanlon mention in their blogs, the most basic liquid expansion thermometers, especially mercury thermometers, are the most common temperature sensors that is very easy to use and accessible to everyone. The main elements of the liquid expansion thermometers are the mercury-in-glass sensor which expands and contracts when there is a temperature change and the means of converting this change into a temperature reading. Although accurate, mercury-in-glass thermometers are delicate and mercury is a hazardous material.

    Resistive temperature detectors (RTDs) are the most common sensors used in laboratory and industrial purposes. RTDs use resistors to record resistance values as the temperature changes. They are very accurate and have a wide temperature range which is why they are used for heavy duty purposes. They are preferred over a thermocouple or a thermistor sensor because of their high accuracy and stability for many years.

    Infrared thermometers are non-contact temperature measurement devices that detect the energy emitted by the medium and convert the energy factor into a temperature reading. Infrared thermometers are very useful for temperature measurements of moving objects, or when non-contact measurements are required due to hazardous material; more conventional thermometers do not seem useful in situations like that.

    As mentioned above, temperature sensors are used for multiple purposes. One use of distributed-temperature sensors is to measure the temperature profile of oil reservoirs, which has been done for many years now. The information provided by temperature sensors are very important for the process control of the oil tanks; they provide visual data to optimize the well performance as well as detect flow and viscosity behind the reservoir casing. Nowadays, there are many temperature sensors used in HVAC systems of  buildings in order to efficiently maintain comfortable indoor conditions.


Sources:
http://www.omega.com/prodinfo/temperaturemeasurement.html

http://www.omega.com/Temperature/pdf/RTD_Gen_Specs_Ref.pdf

http://en.wikipedia.org/wiki/Infrared_thermometer

http://www.accessscience.com.ezproxy2.library.drexel.edu/content.aspx?searchStr=Temperature+sensors&id=YB980600

Temperature Sensors

While initially, sensing temperature may seem like a simple concept (and it's been getting done for a very long time now) the actual details of what we are sensing can become quite confusing. In its most basic sense, temperature is a measure of the movement of molecules within a body of matter. That matter can be solid liquid or gas, and more frequent movements translate to higher temperatures (with absolute zero at the bottom of the scale, meaning no particle movement at all) The reasons we care about temperature are varied, but mainly we want to be comfortable or we want to ensure that a certain process is happening by manipulating the temperature. Of course our perception of comfort is based on our own sensing of temperature by biological processes far more complex than the processes we use to quantify temperature.

Obviously the thermometer is the simplest way to sense and understand temperature. We figured out pretty early on that certain fluids expand when they are heated, so that their volume is a function of temperature. By controlling and marking this expansion of volume we were able to quantify temperature. As John points out, we were later able to recognize the same principle applies to solids, and we began to use this to control the movment of thin metal strips, which would in turn control some basic circuitry, mainly for switching on and off some electrical process. Of course, this is the principle by which most early thermostats operated.

As we progressed in knowledge of electrical properties of materials, it was found that the resistance of certain conductive materials decreases as we increase the temperature, and so we developed thermistors made of ceramics or polymers to effectively convert a change in temperature to a change in resistance that could be easily measured. We also knew that the current changes between to metals at different temperatures, so a slightly more complicated Thermocouple circuit was developed, where this change in current can be measured across dissimilar metals. Furthermore we found that different metals behaved more predictably for certain temperature ranges, so a number of sets of metals were used for varying applications. Finally, the resistance in a coiled wire was found to be more accurately measurable, so RTD's (made of a homogeneous wire wrapped around a ceramic core) became prominent. These could be configured differently to accomodate different temperature ranges and provided high accuracy and repeatability.

Mike does a great job of explaining the usefulness of all of the sensors mentioned above. However, there are still some applications in which even RTD's and Thermocouples cannot be used. For example measuring the surface temperature of an object that is moving or one that cannot be disturbed becomes quite difficult with the sensors mentioned above. Rather than measuring a change in a specific material's response to a temperature, Pyrometers are able to measure a temperature directly as a function of an object's electromagnetic radiation. The methods by which this is acheived can become rather complex, but in their simplest form all pyrometers consist of a lense to concentrate radiation into a point or array of points and an absorber, which chemically translates radiation into terms of flux. It is at this point that the line between sensing and transducing becomes blurred for me. David gives a good explanation of these principles as applied to an array of infrared sensors (thermography).  By some means of transduction the radiation is translated to thermal energy and the thermal energy is translated to an electrical current. The figure below helps explain the process.

References:
http://drexel.summon.serialssolutions.com/search?s.q=thermal+radiation+sensor

http://site.ebrary.com/lib/drexel//docDetail.action?docID=10438390

http://www.electronics-tutorials.ws/io/io_3.html

http://en.wikipedia.org/wiki/Pyrometer

Pressure Sensors

According to the National Instruments website, “because of the great variety of conditions, ranges, and materials for which pressure must be measured, there are many different types of pressure sensor designs” [1].

My fellow classmate, G. Carpenter, first addresses in her post the most common type of pressure sensor (strain gage, see Figure 1 for cross section) and what it measures and how it is translated to indicate pressure.  She then discusses different categories of pressure gauges (force collector and other) and their electrical outputs (millivolt, amplified voltage, and 4-20 mA).

Figure 1: Strain Gauge Pressure Sensor Cross Section [1]

I will now discuss the other two most universal types of force collector pressure transducers (according to National Instruments): variable capacitance and piezoelectric.

A variable capacitance pressure sensor measures “the change in capacitance between a metal diaphragm and a fixed metal plate” and the capacitance changes when the distance between the two plates changes and the degree of this change is converted into an electrical signal [1] (see Figure 2).  (Capacitance is described as the “the ability of a body to store electrical charge” [2].)  These types of sensors are also described as, “very stable and linear, but sensitive to high temperatures and more complicated to setup then most pressure sensors” [1].

Figure 2: Capacitance Pressure Sensor Diagram [1]

A piezoelectric pressure transducer utilizes the electrical properties of naturally occurring crystals such as quartz [1], and uses these stacks of crystal to convert motion into an electrical output as they become strained [3] (see Figure 3).  They require no external excitation and are "rugged" [1], however, are not effective with dc or steady-state conditions [3].  These sensors are also highly susceptible to shock and vibration [1], and also require special signal amplification as their output signal levels are low [3].

Figure 3: Piezoelectric Pressure Sensor Diagram [1]

Sources:

[1] http://www.ni.com/white-paper/3639/en

[2] http://en.wikipedia.org/wiki/Capacitance

[3] http://www.digikey.com/us/en/techzone/sensors/resources/articles/what-you-need-to-know-about-pressure-sensors.html

Humidity Sensors

Of all the sensors used in a typical building, humidity sensors were what I knew the least about before writing this post.  I had a general idea of how the other types of sensors worked, but couldn't even really make assumptions as to how humidity sensors worked.  The first thing I learned with this post is that humidity sensors are called hygrometers.  I did figure that, like other sensors, hygrometers used a combination of temperature and pressure, or change in electrical properties for electronic sensors to determine the moisture in the atmosphere. 

When searching the internet I came across a list of typical types of hygrometers used in the industry; metal-paper coil, hair tension, chilled mirror dewpoint, capacitive humidity, resistive, and thermal conductivity. The metal-paper coil and the hair tension hygrometers seem to be the most "primitive" form of sensor, being that it uses physical properties of materials and calibration to display humidity level on a dial.  The metal-paper coil hygrometer works like a bimetallic thermometer, only instead of two different metals, a salt infused strip of paper is attached to a coil, causing the coil to change shape.  A hair tension hygrometer works by measuring the change in tension in a human or animal hair with the hair shortening as humidity increases.  Both of those types of hygrometers are calibrated to display relative humidity. 

The other types of humidity sensors use the change in a materials electrical properties to determine the relative humidity.  Most of the time a type of salt or electrical polymer is used in these hygrometers. 

Humidity Sensors

Previous to writing this blog post, I could have assumed that humidity sensors calculated their values based upon other factors within the atmosphere such as temperature or pressure. When first searching the internet I found that the term "hygrometer" is the proper name for an object which measures humidity or moisture content. They do in fact utilize other factors such as temperature, pressure, and electrical changes in capacitance or resistance in the atmosphere to calculate the moisture content within a room.

I was actually astounded to find that there were so many types of hygrometers. The primary types being hair tension, metal-paper coil, chilled mirror dewpoint, capacitive, resistive, and thermal conductivity sensors. Each of these types uses a different factor in humidity production in order to determine the level of humidity in a space. For example, the hair tension sensor utilizes the shortening of human or animal hair with an increase in humidity to measure humidity (which explains bad hair days in high humidity!) The amount that the hair shortens directly translates to the amount of moisture in the air on the dial.

A major distinction in the types of sensor utilized is whether or not it is utilizing electrical datum. Chilled mirror dewpoint, capacitive, resistive, and thermal conductivity sensors all fall under this category. Thermal conductivity sensors, measure absolute humidity in the surrounding air rather than relative humidity. This is another distinction in the type that could be measured that had not crossed my mind.

In reading other students blog posts, I found Matthew's to be interesting because flow measurement of fluids is similar to the measurement of humidity in that there are several different factors that can be measured in order to obtain the same result.

Sources:
http://en.wikipedia.org/wiki/Hygrometer

Measuring Flow with Primary Sensors

Flow measurement of fluids, including air and liquids, are measured in a variety of ways. Each type of measurement technique has advantages and disadvantages and therefor implementation varies across the broad field of flow measurement. The applications of different technology vary due to some of the inherent properties of the fluid being measured, resolution of the results, life-span/capability of materials, cost, pipe size, pressure and velocity. Other factors such as cost vary and are sometimes a function of the primary variables, such as reading resolution and operating pressures.

Measurement of flow parameters are often performed by positive displacement methods. An analogy to this method is a bucket and a stopwatch. The bucket is filled with the fluid and the time is recorded that it takes to reach a filled state. The volumetric capacity of the bucket is known and the time duration to fill is known, which constitutes a flow rate. The sensors that can be implemented for this type of monitoring would be a mechanical switch paired with a floating device, which trigger the timer when the cavity is empty and full. The most popular types of positive displacement meters use pistons that operate in a cavity of known volume. Every time the cavity is filled to capacity, the piston is forced to move and subsequently rotate an axle that it is connected to. The signal from the rotating axle can be transmitted to the user by a magnetic drive, needle dial and a counter such as an odometer. A turbine also uses mechanics to produce flow measurements, but instead of positive displacement, the fluid is exerting force on the components and creating work. A turbine is place in the path of the fluid being measured, so that the fluid produces a force on the area of the turbine. The force causes the turbine to rotate, which once established at a steady speed, is proportional to the velocity of the fluid.

A vortex meter uses the phenomenon of Van Karman forces that are created using an object that is located in the flow path of the pipe or channel. The object that is placed in the path is known as a bluff body and results in vortices created in the wake of the body. The Van Karman forces vary between the two sides of the bar at a rate proportional to the fluid velocity. For measurement, a piezoelectric sensor records the number of times the vortices are created by transmitting a voltage pulse.

Similar to the Van Karmen forces, where an object is placed in the path of the pipe, Jalpesh describes in his post the affect that a restriction can cause. The post did an excellent job explaining how the flow was measured using the differential pressures through the restrictions. Each type of restriction was presented and explained correctly. This type of meter was one of the few I saw in the flow sensors postings that relied mostly on heavy theory from fluid dynamics. The other sensors definitely included theory, some of which might have been more complicated than Bernoulli Theorem, but they didn't seem as classic. One thing that wasn't mentioned in the posts I looked was the types of sensors that relied heavily on more calibration and empirical data, such as those that are transcribing through magnetic needles and other sensitive components.

Aside from mechanical flow meters, fluid velocity and flow can be measured using optic sensors. The optic sensors take advantage of lasers of light passing through a tube or pipe containing fluid. Two lasers are contained in a small area of the pipe which track particles suspended in the flow path. The first laser sends a beam of light through the medium and the particles scatter the laser. On the oppisite side of the pipe, a photo detector records the amount of light and sends an electric pulse through a circuit. The same suspended particle then passes another laser beam that completes the same process the first has done with a photo detector sending another pulse. The time between pulses is known as well as the distance between the two lasers, therefor it is possible to calculate the flow rate.

Source:

http://en.wikipedia.org/wiki/Flow_measurement

Term Project

Nowadays, the mission of most contractors is to help people make the most while using less of their energy and simultaneously providing various operational and security services to a building.  This is all achieved by also promoting a “green” environment.  Energy management is aimed in making energy be efficient, reliable, productive, and green, all in order to provide energy usage for appliances, machinery, HVAC systems, security and motors.  Rita Pauliushchyk claimed that the use of sensors improves the efficiency of operations in a building. I could not agree with that statement more considering that one of the biggest technologies that are emerging from intelligent buildings and that rely on energy management is sensors. 

Even though sensors have been around for quite a while now, they are now being used a lot more.  Now sensors come in the smallest sizes and their functionality has increased.  Considering that I have a mechanical concentration, I thought it would be interesting to explore the variety of uses of a sensor in a building, for heating, ventilating and air conditioning, as well as for security measures. I will also explore how the design methods of a contractor vary when placing sensors in a building.  These include the challenges that can be encountered while designing in an existing building, as well as a contractors design preference during the construction phase of a building.  In addition, I will further examine how energy efficient sensors can be, their reliability and how they promote “green”.

My original project idea was to compare two different types of programs, Autodesk Storm and Sanitary Analysis and EPA SWMM.  Because I will be using EPA SWMM for my senior design project in order to plan and design a hydraulic system, I thought it would be interesting to compare it to a similar program by Autodesk.  I was going to first create a design using EPA SWMM and then attempt to exchange this design to the Autodesk software, modify it and send it back.  My initial idea was to investigate the interoperability of both, yet I came to realize that it does not have a big connection to BIM.  Because sensors have such a wide variety of uses and are multifaceted, I decided to explore this topic for my term project.

Sensor Network for Hagerty Library

For my term project I am working in a group with Jeanine Lancellotti and Rita Pauliushchyk. We knew we wanted to further explore the role of sensors in intelligent building design. Clearly that is an incredibly broad topic and needed to be narrowed down significantly if we wanted to write a successful research paper. We met in the basement library to discuss different possibilities and directions we could take the project, when inspiration struck us. We were in a study room in the basement of the library; it was stuffy, hot, and hard to concentrate in those room conditions. We decided we would explore how sensor technology can be applied in the W.W. Hagerty library to create a more suitable and comfortable study environment for Drexel students.

The physical environment is very important in a library because there are specific conditions ideal for academic work.  Conditions such as temperature, humidity control, lighting levels, and heating and cooling requirements for computer rooms must be considered.  Sensors can help building systems efficiently control any condition within a building through monitoring indoor and outdoor climates, occupancy, energy usage patterns, lighting, and water usage.  Implementing a sensor network would greatly improve student comfort levels as well as help increase overall building efficiency.

We will be using a survey consisting of nine simple questions to collect feedback from students on the conditions of the library.  These questions address issues such as temperature, humidity and “stuffiness”, noise and light levels, energy and water consumption, and overcrowding.  After analyzing the survey answers, we will be able to determine what qualities most affect students and explore sensors that can best address those issues.  We will be able to create a network of sensors that could theoretically be utilized throughout the Hagerty library.  Factors we will consider include cost, efficiency, ease of maintenance, and how easily integrated the sensors can be into the existing building systems.  

Term Project - Sensors in Residential Buildings

In the class so far we have talked about a lot of different types of things that go into Intelligent building design. One that keeps being brought up is the use of sensors to do any number of different things. Rita and Dan talk about the applications of sensors in commercial building, Rita more about what sensors would be useful, and Dan about how the information sensors gather can be used in building. However, in class we have not really seen the use of sensors in residential applications. For our project, Nathan Barry, Jalpesh Patel, and myself will be exploring the use of sensors in residential homes, in both new construction and renovation.

What originally got us thinking along this path was This post by Tom, in which he talks about Nest thermostats and how they can be used in a residential home to drastically improve the quality and efficiency of the building. This is the type of sensor that we will do more research on. In David's post, in which he is working with Tom, they seem to be further investigating how to take the Nest thermostat and make it even better. This is similar to what our group will be doing, but while they are choosing to focus on the Nest, we will be taking a much more general look at all different types of sensors and what they could possibly do for a building.

Our primary objective to accomplish in this project is not to simply talk about sensors that could be used in new construction, but find sensors that could also easily be integrated into an existing home.We hope to find sensors that are easy to install and have a payback time of less than 5 years. Using this information we would like to make a theoretical 'intelligent building upgrade' package which would be a series of different sensors that could upgrade your home in many ways, and would also highlight the saving you could potentially get from have a smarter home.

Sources:
http://www.nest.com/

Tem Project

As an HVAC major, I wanted to choose a project that focuses on this aspect of intelligent buildings. Reading about the Nest thermostat in the building of the term intrigued me to research the capabilities of thermostats. It might seem like a primitive control system but it is the first integration of an “intelligent” system into a building.

After my project partner, David Morrison, and I spoke and brainstormed with my friend from Drexel Smart House, Michael Magee, we finalized the scope of the project as the exploration of the capabilities of integrated thermostats. For this project, we will use an Arduino microprocessor to collect temperature and humidity data from different spaces. Sensors will be placed in each of the four corners of the rooms we will use for this study and temperature and humidity differences will be measured. The data will also be compared in the static thermostat controlling each of the spaces measured. This data will be analyzed to draw conclusions about the effectiveness of the thermostat. Location of thermostat, location of diffuser, size of space, and type of air conditioning system in the space will be taken into account.

After the data will be analyzed thoroughly, we will draw conclusions regarding the implications of the study in relation to intelligent buildings. Some implications include actually including multiple thermostats in each space to create an integral system, providing automated diffusers that spread air more evenly, adding automated fans to mix the air better thermally, etc. The project will draw conclusions to help provide a more even thermal comfort throughout spaces and give suggestions as to how to integrate it into intelligent buildings.

Term Project

For my term project I will be working with Natasha Martines and Rita Pauliushchyk to optimize the W.W. Hagerty Library building through the use of sensors. The main concept of this project is that no building is an island, meaning it is important to examine how a building interacts with its surrounding environment. We wish to create a smart building that interacts with the outdoor environment and creates optimum indoor comfort levels. IBM calls these economical, operational and environmental friendly buildings “Smarter Buildings”, and is working towards making all their IBM buildings smart buildings to “lead by example,” as David Bartlett, Vice President of Smarter Buildings IBM says. More about IBM’s smart buildings, as well as an example, can be found in the linked video below.

The project will begin by surveying several students who use the library, asking questions about the quality and comfort level of the library environment. Using the results, and researching case studies on similar buildings, we will design a sensor network able to meet requirements determined to be most important. Our ultimate goal is to minimize resource consumption, optimize comfort levels in the building, predict usage patterns, and integrate the building into the urban environment of Philadelphia.

We will first consider what is most important in a library. For example, the temperature of the environment is key. A room that is too hot can make students tired and groggy, while a room that is too cold can make students unfocused. Lighting is also an important focus when you have occupants reading for several hours. Humidity is also a concern to both comfort levels and preservation of books. Finally, it is important to consider objects that use massive amounts of energy and give off ample heat, such as computers. Based on these factors, we will explore the use of sensors to make the building as energy efficient as possible. Sensors will monitor outdoor and indoor climate, energy usage patterns based on occupancy, HVAC equipment, lighting, and water usage. We will decide which sensors we feel are the most necessary, practical, and affordable and build our network based on this information. 

As mentioned previously, one sensor we plan on considering is a sensor to measure occupancy. I had never thought of using this sensor as David mentions in his post. He says "if the number of occupants in a room is known, it is then possible for a system to try and anticipate the levels of CO2 and start ventilating before the CO2 levels reach a high number." I think this is a very interesting concept and plan on reading about it in further detail. 

http://www.ibm.com/smarterplanet/us/en/green_buildings/examples/index.html