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

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.   

Pressure Sensors

    Pressure is defined as force per unit area that a fluid exerts on its surroundings. A pressure measurement can further be described by the type of measurement being performed. There are three types of pressure measurements: absolute, gauge, and differential. Absolute pressure measurement is measured relative to a vacuum. Gauge pressure is measured relative to ambient atmospheric pressure. Differential pressure is similar to gauge pressure, but instead of measuring relative to ambient atmospheric pressure, differential measurements are taken with respect to a specific reference pressure.

    A pressure sensor, sometimes called a pressure transmitter, is a transducer that converts pressure into an analog electrical signal. 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. Often pressure can be converted to some intermediate form, such as displacement. The sensor then converts this displacement into an electrical output such as voltage or current. As C. Meraz introduced in her post, the three most universal types of pressure transducers of this form are the strain gage, variable capacitance, and piezoelectric. Chunyi Wang adds other two types of sensor named resonant wire pressure sensor and Pirani gauge sensor. Besides, according to G.Carpenter’s blog, there are three types of electrical outputs available for pressure sensors: millivolt, amplified voltage, and 4-20 mA. 

    Figure above provides an overall orientation to the scientist or engineer who might be faced with the task of selecting a pressure detector from among the many designs available. This table shows the ranges of pressures and vacuums that various sensor types are capable of detecting and the types of internal references (vacuum or atmospheric pressure) used, if any. 

    Common causes of pressure sensor failure include dynamic impact that results in sensor overload, spikes that cause a hole or tear in the diaphragm, moisture ingress whereby liquid seeps in through an interface and between a cable and the sensor, extreme temperature, stress when being calibrated, and wear and tear that produces drift and failure. Advances in pressure sensors should be focus on miniaturization with integration of electronics and control capabilities into the same chip as the sensor resulting from the new, smaller form factors.  By reducing the size of the sensor, pressure sensors can be used in more area.

source:

http://www.omega.com/prodinfo/pressuretransducers.html

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

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

http://www.omega.com/literature/transactions/volume3/pressure.html

Humidity Sensors

Developments in semiconductor technology have made possible humidity sensors that are incredibly accurate, durable, and inexpensive.  The three most commons types of humidity sensors are capacitive, resistive, and thermal conductivity.

Resistive humidity sensors measure the change in impedance of a medium which has an inverse exponential relationship to relative humidity.  Mediums used include conductive polymers, salt, or treated substrate.  These sensors typically use ceramic as a coating for protection from condensation.  The voltage output provided from the sensor become directly proportional to the relative humidity when signal conditioning is applied.

Thermal conductivity humidity sensors calculate the difference between thermal conductivities of dry air and air containing water vapor to measure absolute humidity.  Because of their ability to measure absolute humidity, these sensors are also referred to as absolute humidity sensors.  This sensor consists of two negative temperature coefficient thermistor elements within a DC bridge circuit.  One element gets sealed in dry nitrogen and the other remains exposed to the environment.  Absolute humidity is directly proportional to the difference between the resistances of each element.

Capacitive sensors are the only type of full-range sensor that can accurately measure to 0% relative humidity.  This type of relative humidity sensor is most commonly used in industrial, commercial, and weather applications and is used over wide ranges of temperature due to their low temperature effect.  Capacitive sensors measure the change in dielectric constant which is proportional to the environment’s relative humidity.  A 0.2-0.5 pF change in capacitance is related to a 1% change in relative humidity. This type of sensor would most likely be used in HVAC applications.

Regardless of the type of relative humidity sensor, all outputs are affected by both temperature and perfect of relative humidity.  When higher accuracy or wide operating temperature ranges are considered, temperature compensation is included in the application. Relative humidity integrated circuits, or RHIC, have linear voltage outputs that are a function of the supply voltage, percent of relative humidity, and temperature.  This allows for the sensor to translate supply and output voltages to determine the true relative humidity of an area.

Temperature Sensors - Thermocouple

As the other groups mentioned, resistive temperature detectors (RTD), simple mercury thermometers, and more technologically advanced infrared sensors are all used to sense temperature. I would like to discuss a different type of temperature measurement – thermocouples. As Elda mentioned, thermocouples tend to be less accurate than RTDs, but they are still widely used in industry. They are simple and easy to understand. They have some advantages too which include a wide temperature range, robustness, rapid responsiveness, and lack of self heating.

Like most scientific inventions, the thermocouple was invented by accident. An Estonian physician accidentally discovered the ability to sense temperature by the effect of joining two different metals together. When two different metal wires are joined together and a temperature difference exists along them, they generate voltage, which is indicative of the temperature difference. Figure 1 presents a simple thermocouple diagram: the junction where the metals meet is called the measurement junction, or the hot junction. That point should be exposed to the temperature we would like to measure. The wires should then be placed in what’s referred to as the reference junction, or the cold junction. At that point the wires are generally inserted in a bath of ice water to maintain a constant 0 degrees Celsius. Thermocouples measure the relative temperature between the two junctions, and therefore the reference junction must be known, and is usually kept at 0 degree Celsius.

Figure 1: Thermocouple Diagram

The metals used are indicative of the sensitivity, temperature range, and voltage range measured by the thermocouple. Table 1 has this information about the common types of thermocouple. The types also indicate the error in measurements. As mentioned before, the error in measurement can be significant when using thermocouples. Figure 2 shows the possible error for four different thermocouples for the temperature range of 0 to 400 degree Celsius.

Table 1: Types of Thermocouples

Figure 2: Error in Thermocouple Measurements

What is actually measured when using a thermocouple is the voltage created by the difference in temperature. In order to interpret this date, one needs to know how to convert the voltage data to meaningful temperature data, which is, again, dependent on the type of thermocouple. The seedback coefficient is the voltage change per degree Celsius in μV per degree Celsius, and it is represented in Table 2 for the different thermocouple types at 25 degree Celsius. The seedback coefficient is not constant, though, which makes the fitted graphs used to interpret the temperature nonlinear. Software needs to collect the voltage data and have a function imbedded within it used to convert these measurements to useful temperature data.

Table 2: Seedback Coefficient at 25 Degree Celsius

References:

http://cds.linear.com/docs/Application%20Note/an28f.pdf

http://www.analog.com/library/analogDialogue/archives/44-10/thermocouple.pdf

Thermography

I think that Mike did an excellent job of going over the history of temperature sensors and how they work. When I was assigned this post, I immediately though of a thermistor, however it is important to think about the history of temperature sensor, and that the analog approach has worked very well for a long time. I personally got very interested while reading Elda's post when she talked about the use of infrared thermometers. Elda talks about how infrared thermometers are used to detect temperatures without the need for surface contact. This brought me to the idea to discuss thermography as a type of "temperature sensor."

A paper written by Maldague shows there are two main types of  thermography, passive and active. These two types of thermography are discussed as a means of Non-Destructive Evaluation Techniques (NDT). The idea behind active thermography is to send a wave of energy (in the form of heat), and see how the heat moves in the observed medium. Passive thermography on the other hand uses energy already found in the observed medium such as the difference in temperature of a pipe or electric box that generates or takes heat to show how the materials around it act. Thermography can easily be used to determine if an electrical box is overheating and needs attention. It can also be used for firefighters to determine what is going on in a household in the event of a fire, and where people are located inside the burning structure.

The most basic description of thermography, is the use of an infrared camera to detect the radiation from a given material, that then is translated to a surface temperature. It is important (according to NDT sources) to know the emissivity of the material observed to get an accurate reading of what temperature is being observed. If the wrong emissivity is chosen, than the entire process of thermography can become a fruitless exercise.

One can see each different way of measuring temperature has its pros and cons, and there is no one solution fits all approach for measuring temperature.

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

Temperature Sensors

There are many different types of temperature sensors, and many of them operate in completely different ways. The most basic type of temperature sensor is the classic mercury thermometer. This sensor works purely based on the expansion and contraction of mercury in a glass tube. The next step up technologically is the bimetallic strip temperature sensor. This sensor makes use of the different coefficients of expansion that different materials have. These sensors are usually composed of steel and copper, which expand and contract at different rates. This sensor takes the temperature change, and turns it into a mechanical displacement. This technique can be used in many different types of sensors.

There are also much newer sensors that instead of turning heat into mechanical energy, they read the heat change in a difference of electrical energy. The two most common sensors are a thermistor and a resistance thermal detector (RTD). These two objects work on very similar principles, they both measure the change in resistance and correlate it with the change in temperature. The main difference between the two is the materials used to make them. Thermistors use primarily ceramic, whereas RTDs use pure metals. This difference in materials usually results in thermistors having a more accurate reading in a smaller range of temperatures whereas RTD stay accurate even at extreme temperatures.

Most of the previous sensors all require contact, or to be within convection range of the heat source to get a viable reading, however there are also non-contact thermal sensors that use radiation. These sensors use Plank's Law to correlate the radiation given off by an object and its overall temperature. These sensors are really useful as you can measure the temperature of something while being far away from it, whether it be the temperature in an oven, or the temperature of the sun.

Of all these sensors, the most useful for our applications is the RTD. The sensors themselves are really just metal, so they have no moving parts, and never need to be calibrated. Because of the simplicity and cheapness of these sensors they can easily be applied almost anywhere in a building. Couple the readings of these sensors along with the HVAC system or even window/blinds control and, without any human interaction, a room could always be at an optimal temperature. This is just one example that these sensors could be used in, the fact that they are so small and cheap and easy means they could be used almost anywhere, in ovens, in fridges, in water heaters, anywhere that temperature levels are of interest, these types of sensors could be applied.

Because I was the first to post, I discussed the history of sensors and their many different types. It seems the other posters used mine as a base and talked about what the different sensors are used for now or what they could be used for in the future. David talks about thermography which, in simple terms, is seeing heat which I think is a really cool concept and, like David said, has many uses including assisting fire fighters to save lives. Nathan goes on to discuss how IR sensors are used a lot in cooking to ensure the quality of food. Not only is it being used to ensure the food is done cooking, but I just saw on the news the other day, police are pulling over food delivery trucks and using these IR sensors to ensure the truck is at correct temperature for food shipment.

Sources:
http://www.ehow.com/how-does_4928076_temperature-sensor-work.html
http://www.instructables.com/id/Temperature-Sensor-Tutorial/
http://en.wikipedia.org/wiki/Bimetallic_strip
http://en.wikipedia.org/wiki/Thermistor
http://en.wikipedia.org/wiki/Resistance_thermometer

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

Before understanding humidity sensors, one must first understand what humidity is. “Humidity refers to the water vapor content in air or other gases.” A humidity sensor measures and regularly reports the relative humidity in the air. As Kayleigh's post says, "hygrometer is the proper name for an object which measures humidity or moisture content.” The most commonly used type of humidity sensor relies on the ability of two nearby electrical conductors to create an electrical field between them. A source describes the process; “A polymer film on the conductors collects moisture from the air, and the moisture causes minute changes in the voltage between the two plates. The changes in voltage are converted into digital readings showing the amount of moisture in the air.” Humidity sensors then use the information collected to help regulate the space.

Humidity sensors are helpful in everyday residential uses. For example, people who suffer from conditions that are affected by high humidity, such as allergies or asthma, can have humidity sensors installed in their homes to control humidity. Humidity sensors are also very useful for medical purposes. Hospitals generally use humidity sensors to carefully maintain humidity in spaces containing sick patients. These sensors can also be very useful in spaces that store objects damaged by exposure to moisture. Examples include wine cellars, humidors, greenhouses, or antique storage areas. 

Humidity sensors are also an important part of building design, especially as we move towards green and energy efficient buildings. In an article entitled “Putting Building Science Into Practice,” a retrofit project of Fraunhofer’s new Boston headquarters is discussed. The rehab project aims to test emerging build technologies. One of these technologies relies on the use of humidity sensors to measure its efficiency. “The Showcase building will try many types of insulation on the walls, including vacuum panels that use gas, rather than cellulose or fiberglass, as the actual insulator.” The humidity sensors will collect data that will be used to determine the comparative advantages and worth of the new technology.

When reading over other student’s posts, I found Matthew's post about flow sensors to be very interesting. The comparison he made between the displacement method and the bucket and the stopwatch helped to simplify the method and make it easy to understand.

http://www.technologyreview.com/view/510131/putting-building-science-into-practice/

http://EzineArticles.com/4695977

http://www.wisegeek.com/what-is-a-humidity-sensor.htm

http://www.sensorsmag.com/sensors/humidity-moisture/choosing-a-humidity-sensor-a-review-three-technologies-840

Pressure Sensors

Pressure sensors, as the name indicates, measure pressure.  The pressure that it is being measured is typically that of a gas or liquid although pressure applied by a human or animal is also available.  According to Omega.com, pressure transducers “converts pressure into an analog electrical signal”¹.  A strain gage is the most familiar, and common, engineering pressure sensors.  For a strain gage, an electrical signal is generated when “the physical deformation of strain gages which are bonded into the diaphragm of the pressure transducer” ¹.  The strain that is formed from deformation of the diaphragm produces “an electrical resistance change proportional to the pressure” ¹.  Other types of pressure sensors include sensors that measure fluid/gas flow, speed, water level, and altitude².  Some common examples of these are piezometers, manometers, and tire pressure gages.

There are two different categories of pressure gages: force collector types and other types².  Force collector types (e.g. pizoresistive strain gage, capacitive, electromagnetic, piezoelectric, optical, potentiometric) use an item of known area – typically a piston or diaphragm – to measure strain/deflection of the applied force over the applied area².  The other types of pressure gages use different properties (e.g. density) to determine the pressure of the medium.  Some examples of these pressure sensors include resonant, thermal, and ionization².  Wang Chunyi's post describes how resonant and thermal pressure sensors work.  According to his post, resonant pressure sensors have a wire that vibrates at its natural frequency.  As the pressure changes, the resonant frequency of the wire changes in response.  The magnets around the wire create electricity through the wire's vibration which is then transmitted to the readout.  Thermal pressure sensors determine pressure through measuring the heat of a wire.  Under high pressure and constant volume, temperature within the gas, and subsequently the wire, will increase.  This increase in temperature must be calibrated based on the type of gas that surrounds the wire.

There are three types of electrical outputs available for pressure sensors: millivolt, amplified voltage, and 4-20 mA.  Millivolt transducers are typically the most economical sensor and their output is directly proportional to the input power or excitation¹.  However, their output is typically low and so they are not recommended for noisy environments, and distance between the sensor and the readout equipment should be short.  Amplified voltage sensors include “integral signal conditioning which provides a much higher output than the millivolt sensor” ¹.  Because of the higher output level, they are able to be used in noisier environments, like industrial.  The 4-20 mA sensors are the “least affected by electrical noise and resistance in the signal wires” ¹.  This benefit allows the signal to be transmitted long distances (1000+ ft.)¹.

¹ “Pressure Transducers.” Omega.com.

http://www.omega.com/prodinfo/ pressuretransducers.html.

² “Pressure Sensor.” Wikipedia.com. http://en.wikipedia.org/wiki/Pressure_sensor

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 - Sensor Database in BMS

For my AE-510 term project I am researching how a collection of data, provided by sensors throughout a building, is compiled into a database and how this database interacts with the Building Management System (BMS) to specifically influence HVAC system control. Like Rita Pauliushchyk stated in her blog post, sensors improve the overall efficiency of building operation. By themselves, sensors provide very little information; it is not until the sensor data is compiled and processed that the information can be used to report data or perform a task. My project will explore the interaction of the sensors in a database with the BMS to operate the various components of the HVAC system efficiently in order to optimize the building and lower the operating cost and environmental impact.

In order to do this I will define the aspects of a building management system which involves a network of controllers, sensors and output devices that can control metering, air systems and water systems within the building. I will then explore the various kinds of sensors and how their data is collected and formed into a database of all the sensors within the building. This data is processed and recorded and displayed to the user through the database so the information can be used. I will look at the specific ways that data is used in order to automate the building systems. I will also look at the future of sensors and their interaction with the BMS.

Many of the students in the class are researching intelligent vs. green building. I believe that the interaction between sensors and the BMS are a link between these two as it is using the intelligence of sensors and automation in order to improve system efficiency, lowering the amount of energy used and minimizing the buildings impact on the environment.

Project: Physical Temperature Measurements

I am working with Tom Ben-David on creating a network on sensors in a room that will hopefully provide a better reading of the temperature in the room, and provide for a greater analysis of how a room acts. This type of strategy has not been widely implemented as there is not too much data on this subject. However, this has not been that practical of a solution for that long. A research paper by Lin details life in 2002, where one sensor per room was not that common, and they were exploring the use of a temperature sensor in each room as an alternative to one temperature sensor per zone. This is still how most homes operate, but as sensor prices drop, can we can more efficient use out of our HVAC systems. Can we also provide better comfort to ALL of the occupants, not just the occupants who live in the spaces with temperature sensors in them. If by adding more sensors to a room, can we then even adjust an HVAC system to make sure all occupants in one room are happy. Think of the many times you sat right under a vent and were too cold, while your companions were too hot just a couple feet away. With more sensors, hopefully an HVAC system will know how to respond to such an event happening.

Our idea is to create the physical sensors will be Arduino hardware. The Arduino hardware will report a humidity and temperature back to a central database where this information will be able to be complied over a time range. Knowing where these sensors are placed in the room, and what is near each sensor (ie: a window or diffuser that would account for a change in temperature). Hopefully with knowing the location of the 4 sensors, and the different types of data they provide, we will be able to make a general consensus as to wether a multi-temperature-sensor room is a viable option and would provide for a more intelligent building.

I found Jeanine's topic very interesting, and applicable to the same type of model we are looking to design. In her post, she talks about how they are going to be selecting sensors to improve the students comfort in the library. We are also interesting in achieving a similar goal, however not with such a specifica building. I am excited to see how well their findings coincide with the findings in our report about ventilation rates.