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Home Lighting and HVAC

Systems 48531 Electromechanical Automation

AQUINO, John 10859799

LOOSLI, Jeremy 10856983

10/28/2011


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Table of Contents

Executive Summary ................................................................................................................................. 3

Introduction ............................................................................................................................................ 4

Purpose ............................................................................................................................................... 4

Scope .................................................................................................................................................. 4

Sources and Methods .......................................................................................................................... 4

Background ......................................................................................................................................... 4

Lighting Control and HVAC Systems ......................................................................................................... 5

Lighting Control Systems ..................................................................................................................... 6

HVAC Systems ..................................................................................................................................... 6

Integration Systems ................................................................................................................................. 7

Occupancy Sensors .............................................................................................................................. 7

Passive Infrared Sensors ...................................................................................................................... 7

Photosensors ....................................................................................................................................... 9

Ultrasonic Sensors ............................................................................................................................. 10

Timers ................................................................................................................................................... 13

Thermostat ........................................................................................................................................... 14

Controllers ............................................................................................................................................ 15

PID Controllers .................................................................................................................................. 15

Direct Digital Controllers .................................................................................................................... 17

Simulations/demonstrations/illustrations ...................................................................................... 18

Conclusion ............................................................................................................................................. 19

References ............................................................................................................................................ 20


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Executive Summary

This report investigates the various autonomous systems that are currently being used in common

households to reduce the consumption of non-renewable energy through the use of sensors, timers,

and controllers in lighting systems along with Heat, Ventilation and Air Conditioning (HVAC) systems.

Lighting and HVAC systems are among the main components that exhibit large amounts of power

consumption within the average household. Through the use of autonomous systems, power efficiency

in these devices can be improved until it is possible for engineers and pioneers to find a more efficient

system or more efficient and environmentally friendly energy sources.

The implementation of optimised, autonomous systems in the household can result in more energy

efficient day to day living and minimising environmental and economic household costs.


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Introduction

Purpose

The purpose of this report is to explore alternative systems that can be utilised to improve the energy

efficiency of common household lighting and HVAC utilities.

Scope

This report considers the application of several automotive techniques that can be considered in the use

of lighting and HVAC systems to improve energy efficiency. The optimised use of sensors, timers,

controllers and integrated systems are aimed to reduce average domestic power usage, although having

limitations that may appear disadvantageous in some environments.

Further research and experimentation may be able to resolve several of these limitations.

Sources and Methods

Information in this report was gathered from professional journal articles, internet websites,

encyclopaedias, professional reports, and material collected from lectures.

Background

Energy conservation has proven to become one of the most important issues in the 21st

century.

Statistics have shown that domestic lighting and HVAC are two major components that are responsible

for household energy consumption.

Through basic applications such as sensors, timers, thermostats and controllers; integrated systems can

be developed to reduce the amount of energy being consumed, and hence enabling the average

household to be more energy efficient.

This report will examine sensors, how they operate and how they can be applied to domestic lighting

and HVAC systems.


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Lighting Control and HVAC SystemsTypical home automation systems are often classified depending on the control of lighting and HVAC

systems. These systems accommodate sub-devices that vary on their functionality depending on design

factors based on the applicable environment.

Comfort and Ease of use are one of the major advantages achieved through the use of autonomous

systems apart from the major decrease in energy consumption. One example is a user-interface that

allows users to control and lighting and/or HVAC systems anywhere in the household from a single or

multiple terminals where the user-interface is located. This implementation can range from one single

system to a group of systems located within different areas of the house. Energy benefits from

implementing a more effective lighting and HVAC control system could result in a 15-30% decrease of

energy usage in lighting systems with a 20% decrease from HVAC.

Figure 1: An example of a central controlled Lighting and HVAC system


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Lighting Control Systems

Lighting Control Systems refer to the innovation of integrated systems in order to use and control

lighting and devices, alone or as part of a system. Advantages from lighting control systems come from

the ability to control a single unit or a network of lights at any given time along with the function to

change the ambience and colour of the light via electronic dimmers and electric illumination levels at

any given time through a governing automation system.

System performance is improved when the use of movement detection, sound, light and temperature

sensors are implemented alongside the traditional manual control of light and temperature output

levels in order to minimise energy consumption whilst maintaining user comfort.

Components of these systems can be categorised into three main areas: the first area involves electronic

integration devices, directly applied to households, governing and controlling a set group and/or sub-

systems. These integration devices include clocks, switches and occupancy detectors through sound and

visual sensors. They can all be applied individually to suit their own purposes or merged together in the

formation of a more intricate system.

The second of these components involves interface devices that provide the necessary control required

in order for the user and system to communicate with one another. Some examples include remote

controls, computers and mobile phones, all of which will transfer user inputs to the control system

whereby the desired action will be carried out and achieved.

The last of the three devices and perhaps the most important of them all, are the controllers, in which

the lighting, electronics and other loads are all processed and connected to one another. These devices

communicate either through a hard line connection, radio and/or infrared frequencies.

HVAC Systems

HVAC (Heating, Ventilating, and Air Conditioning) refer to the automation technology used to adjust or

maintain the desired temperature of the environment for comfort and saving energy purposes. HVAC

systems have been design based on the principles of thermodynamics, fluid mechanics, and heat

transfer and have been widely used during intolerable weather (i.e. Winter and Summer seasons) in

order to regulate temperature and humidity in the dwelling environment.


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Integration Systems

Occupancy Sensors

Occupancy sensors are devices commonly utilised in lighting and HVAC autonomous systems that detect

and measure the physical attributes and quantities of the surrounding environment and converts this

information to be used as feedback to be read by the controller or the user. Examples of common

occupancy sensors include passive infrared (PIR) sensors, photo-sensors, and ultrasonic (ULT) sensors.

The implementation of sensors into lighting and HVAC systems can help improve the energy efficiency

by using feedback controls to achieve the optimal environment for the user.

Passive Infrared Sensors

Passive infrared (PIR) sensors are occupancy sensors which detect infrared (energy that is invisible to the

naked eye) lighting radiation from objects. PIR sensors are a part of an integrated circuit; these circuits

are composed of the following elements: a lens, a pryoelectric sensor, an amplifier and a comparator.

The circuit makes use of a Fresnel lens; the Fresnel lens is responsible for the detection of infrared

energy in the system. The Fresnel lens is a specialised lens which is thinner and flatter than most lenses,

hence allowing it to capture more oblique light from light sources. Furthermore, its special shape

enables it to sufficiently condense light, hence providing infrared detection from a higher range; shown

in the diagram below.

Fig. 2 Fresnel lens


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The infrared captured from the lens is then detected by the pyroelectric sensors. The infrared (IR) filters,

are placed behind these Fresnel lens so that it can filter any mid-infrared wavelengths or noise that the

Fresnel lens may have captured, this is important at it reduces the generation of false alarms that thesystem may experience.

Pyroelectric sensors are composed of pyroelectric and piezoelectric materials which are characterised as

having a stochastic electrical polarisation, which can be modified by temperature changes. As the light

emitted from an object determines the object’s temperature, through the use of pyroelectric sensors,

temperature changes and hence infrared light changes can be detected. After being detected, these

pyroelectric sensors convert these temperature changes into electrical signals.

These electrical signals are then transferred to an amplifier, and then transmitted to a comparator. The

comparator then detects the voltages that are received, if there is an instantaneous change in voltage,

the comparator will cause the light to turn on. Below is a diagram of the PIR sensor system, in this image

it is evident of how the structure of this integrated circuit plays such a significant role in the PIR sensor

system.

Figure 3: Passive Infrared-motion sensor block diagram


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Photosensors

Photosensors are devices capable of controlling and altering a light’s output depending on the amount

of light of the surrounding environment. In areas or periods of high luminance, photosensors will dim

the lighting by altering the control circuit’s current flow to allow more current within the control circuit,

leading to lower voltages which will in turn decrease the amount of light produced. Likewise, when low

luminance is detected, current flow varies and decreases, allowing for higher voltages and thus larger of

amounts of light. The use of a photocell allows the photosensor to alter the amount of current flow in

the circuit.

Photocells have behaviour that is characteristic of a resistor with its resistance being dependant on the

amount of light being transmitted onto the cell. As photocells can be treated as a type of resistor, it is

thus capable of altering the current and voltage within a circuit allowing it to control the amount of light

to be emitted by the light source. The circuit diagram below illustrates how the photocell is responsible

for the circuits varying resistance and its parallels to a voltage divider as when the resistance of the

photocell increases, less voltage is supplied with lower resistance resulting in higher voltages.

Photosensor systems are found and used in open-loop and/or closed-loop feedback systems. In open

loop systems, the photosensors are able to control a large number and grouping of lights due to the

photosensors being situated and located distantly from areas of high light transmission. With open loop

Figure 4: Photocell analogy diagram


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systems, the photosensors adjust the amount of light emitted from the light source in relation to the

amount of its surrounding light.

In the case of closed loop systems however, the photosensors are positioned in areas where the light

source is being controlled, meaning the photosensors will not only measure the ambient environmenttemperature and lighting but also the light being produced and regulated through the electrical lighting

circuit. Ultimately, this means that closed-loop systems can only control a handful amount of lights.

Depending on the surrounding levels of light, photoswitches will turn the lights on or off accordingly and

are more commonly used in outdoor environments to ensure that light is only supplied during night

time when it is needed.

Dimming photosensors are occupancy sensors that adjust the amount of light that a light source may

emit depending on the amount of ambient light detected. There are two main types of dimming

photosensors: manual dimmers and automatic dimmers.

Manual dimmers need to be controlled manually through remote control while automatic dimmers

typically have time-delay and timer settings to the frequency at which the photosensors will re-adjust

itself to the surrounding light levels.

Time delay settings are vital in the operation and use of this system as interfering noise from natural

environment and other devices may cause the photosensors to rapidly and constantly adjust the l ight

levels emitted and must be accounted for when the system is being programmed.

Location is also another essential factor that determines a photosensor’s effectiveness, as indoor

photosensors are best located in a position to receive direct sunlight, whilst outdoor lights are meant to

be placed in areas of minimal sunlight.

Ultrasonic Sensors

Ultrasonic (ULT) sensors are better at detecting occupancy. Ultrasonic sensors operate similarly to radar

and sonar, whereby it emits a high-frequency ultrasound to an area to observe the signals it receives

from the area. Ultrasonic sensors are known to be more expensive than other light sensors but it is able

to give more coverage than most sensors.


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Through the activation of a piezoelectric crystal, ultrasonic sensors are able to release a high-frequency

ultrasonic wave; in return the ultrasonic sensors will receive an echo back from the sensor. Piezoelectric

crystals are small scaled energy sources; they are applied in this system as they are able to generate

small voltages when they are subject to vibration.

Hence if there is a motion from the objects(s) then the frequency of the wave sent from the ultrasonic

sensor will slightly change (the Doppler Effect), causing the piezoelectric crystal to generate a voltage

and sending that message to the ultrasonic sensors. The ultrasonic wave will be able to then determine

the distance of the object through calculating the period of time between the signal it sent and the

signal it received.

The diagram shown below is a basic model to display the elements that are involved in an ultrasonic

sensor circuit. In the ultrasonic sensor circuit shown below there are two transducers (energy converting

device): one transducer emits an ultrasonic wave and the other detects and collects reflections from the

objects surrounding that area.

The reflected waves are then transmitted to the receiver in constant phase if the objects at the area are

stationary. If movement is detected, then the signal detected will experience a phase shift. A phase

comparator detects the shifted phase and transmits a triggering pulse to the alarm.

Figure 5: Ultrasonic sensor diagram


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The advantages of the ultrasonic sensor is that it is very sensitive, hence enabling it to have a fast

response time. Furthermore, as it is so sensitive, it has full coverage on the whole are it is placed in.

However the disadvantage of the ultrasonic sensor is that it is so sensitive so that it tends to fall

susceptible to interference and noise from its surroundings. Below is an example of a ULT Sensor driven

lighting

Figure 6: Ultrasonic light sensor


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TimersTimers are simple, inexpensive control devices used to control lights or other electric appliances for the

duration of short and predictable periods of time. Disadvantages of these devices are that they would

have to be reset for certain events such as daylight savings, holidays and weekends. The resetting

process can be either manual or automated through special devices or a program.

There are two types of timer clocks: the mechanical time clocks and the electronic time clocks. The

timers can work alone if it runs on daily schedules or if it is to be connected with a controller system for

weekly and special event schedules. Mechanical time clocks have a dial with trippers to open and close

switches; this allows users to set their desired time. The mechanical timers are less expensive and are

relatively easier to set up in comparison to electronic timers and are highly suitable for normal

households with settle daily schedules. However, electronic time clocks are more sophisticated and

complex as it can be to be programmed and set up through the use of control systems. Some electronic

timers have time-out warnings to let users know of a shutdown.

The above figure is an example of one type of timer that is available for use in household lighting

systems.

Figure 7: Figure of a household

light timer sensor


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Thermostat

A building in need of temperature control, utilizes HVAC control system technologies in order to switch

between cooling and heating functions to maintain a standard desired temperature. Thermostats offer a

viable method of sensing environment temperature via electronic or mechanical means.

A thermostat is a device which maintains the temperature of a system, adjusting the temperature

relative to a chosen set point. A digital programmable thermostat is designed as a control mechanism to

adjust the temperature according to the user’s settings that take effect at different times of the day.

The advantage of using a programmable thermostat is its increased versatility, allowing for different

options. It allows the user to program various temperature set points throughout the course of the day,

for example: having one setting for the morning and another for the evening.

This programmed timing feature can be used to its full extent, being able to plan various temperature

controls for weekdays and weekends and amount of time for cooling/heating apparatus to operate.

One can also save energy by creating constraints in which the thermostat is allowed to operate. For

example, the user may set the thermostat such that cooling/heating can only be operating for a

maximum of 30 minutes at a time, with 15 minutes in between operation times.

Another constraint that can be used is to prevent operation unless the ambient temperature is within a

threshold of the set point temperature (± 5⁰C). This sort of careful programming allows energy to be

saved as opposed to having a system that is constantly cooling or heating.

An example of a common household thermostat is shown below.

Figure 8: Household Thermostat


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ControllersControllers are devices that have a form of processing system along with a set of inputs and outputs.

The controller’s input collects information on its surroundings such as temperature, air flow, and aur

pressure. The controller’s output controls the other parts of the system in response to its surroundings.

There are 2 essential controllers used in lighting and HVAC automation; these are Proportional- Integral-

Derivative-Controllers (PID) and Direct Digital Controllers (DDC)

PID Controllers

More advanced technologies used in thermostats include the PID controller. It allows the thermostat to

record the ways the system will react to certain changes, allowing for the thermostat to ‘learn’ the most

efficient method of reaching the desired set point. For example, if the thermostat is set to 20⁰C at 1:00

PM, then the PID controller will have to use the information, and calculate how long before 1:00 PM itneeds to operate so that the temperature reaches 20⁰C exactly at 1:00 PM. This sort of process, in which

previous conditions and characteristics of the system are ‘remembered’, creates this ‘optimal start’.

PID controllers are essentially, control feedback loop systems. The basic circuit of a PID controller is

shown in the figure below. The purpose of the control is to ensure that the process variable (in this case

y) follow the desired set point (in this case r).

In the diagram below there is only one disturbance factor represented as e; e is defined as e=r-y. As the

PID controller has to ensure that variable y is equivalent to the set point r, there is a variable u (on the

diagram) which is a variable in the circuit that has a purpose of ensuring that variable y does not stray

from its set point, u is manipulated by the controller.

Figure 9: Basic PID circuit


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The figure below is an extension of the basic circuit above, as it shows how PID controller is involved in

counteracting the change or error that the system may experience. The PID controller counteracts this

change through three steps, proportional control, integral control and derivative control.

Proportional control is involved with the changes to the output; these changes are proportional to the

error value. The Integral control is relative to both the time period and magnitude of the error. Lastly

the derivative control describes the rate of change of the error over time. These three elements are

essential to the feedback system; this is evident through the diagram below and the equation:

Figure 10: PID equation

Figure 11: PID circuit


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Direct Digital Controllers

Aspects of HVAC that are to be considered, such as humidity, ventilation and air circulation are

accounted by digital controls. These parameters are measured by the programmable thermostat and

the most efficient method of reaching the desired temperature is performed. For example, the

thermostat may calculate that it is more time efficient to increase air circulation, or decrease humidity

using installed fan systems or allowing hot air to rise, as opposed to using the less energy efficient air

conditioning unit.

Communication over the internet or via various network connections are available to some digital

thermostats, this in which can alert the user of various issues, such as when the air filters may need to

be changed. This communication system also offers the thermostat to be remotely programmed.

Efficiency of that system is greatly impacted with the function of remote control of HVAC systems in

buildings. This system allows rooms that are currently not in use to be switched off as opposed to

leaving air conditioning appliances constantly running even when not in use. As a result this would

particularly save a lot of energy in workplaces where the usage of the building varies due to time as a

result from only having a day shift (e.g. local libraries).

Through the use of a central computer, the automated control ‘Direct Digital Control’ (DDC) is able to

process and display all information to the user with the use of a computer interface. The centralized

computer system takes analog signal inputs in such as temperature, humidity, pressure etc. and present

the needed output in order to reach the desired conditions.

Similar to the thermostat, the output response of the DDC can be programmed. However the program is

installed onto the main computer which is automated or can be manually operated in real time.

Available functions which the user can manually control include varying the temperature, humidity,

pressure in any part of the building, including turning it off completely. This as a result makes sure that

energy is not being wasted unnecessarily in rooms that are currently unoccupied by people.

Automatic use of the HVAC operations can be used through the use of light and sound sensors which is

used to detect whether or not patrons are occupying those rooms and with the addition to effective use

of DDC technology.


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Simulations/demonstrations/illustrations

1. Temperature over time. The thermostat detects indoor changes corresponding to the red and blue,

which indicate periods of heating and cooling.

2. Screenshot of program used for Direct Digital Control (DDC). Shows the layout of the building, all

parameters within them, and options to control those parameters,

Figure 12: The graph of daily temperature & time from the thermostat

Figure 13: Screenshot of program used for Direct Digital Control (DDC)


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The figure below is an example of how DDC systems can control both light and HVAC systems in a

household.

Conclusion

In conclusion, it is evident that there are available alternative lighting and HVAC systems for household

usage, such as sensors, timers, thermostats and controllers.

Sensors have been proven to be simple yet an effective method to implement in domestic lighting. The

simple structure suggests that it can be easily manipulated into integrated lighting systems to establish a

more energy efficient lighting and HVAC system.

Timers are very simplistic systems which can be easily manipulated and controlled, although through the

integration of this system with other control systems we can create a complex system that is capable of

controlling the lighting systems in households.

Thermostats are also simple systems that control its ambient temperatures through the detection of its

surrounding temperatures and ensuring that the ambient temperatures are kept to the controller’s

desired set point.

Controllers are complex systems that involve feedback loop systems, to counteract changes in its

surrounding environment. They are advantageous because of their sensitivity to ambient changes and

their rapid responses to these changes.

Therefore through the use of these systems, a more energy efficient system can be established.

Figure 14: DDC control system


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PROPOSAL:

An Ambient-Light-Ignoring Infrared Active Motion Detector." from

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Araki, M. "PID CONTROL." CONTROL SYSTEMS, ROBOTICS, AND AUTOMATION I

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HVAC Systems for Energy Saving and Human Comfort. August 21-24

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