David Clarke Thesis

Dublin Institute of Technology

BSc in Electrical Services Engineering & Energy management

Final Year Thesis

A Study into the Energy Saving Potential of Lighting Controls

In an Office Building

David Clarke

C03653692

Project Supervisor Dr. Kevin Kelly

A Study into the Energy Saving Potential of Lighting Controls In an Office Building

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Abstract

This paper examines three different lighting controls on a single floor of a typical

office building for a period of six months during 2009. The energy savings and

effectiveness of the three different lighting controls in operation were evaluated. The

lighting controls examined are occupancy sensors, daylight controls and central off.

The energy saved from these lighting controls in over a six month period in 2009 was

compared against figures from 2008 when manual switching was the dominant

control.

It was found that after six months of data in 2009, results indicated a significant

savings from 2008 figures. In the single floor of the office building, where the three

controls were installed, savings of 19% were obtained. Automatic dimming of the

lights through daylight sensors, automatic switching of the lights through occupancy

sensors and the central off timing function turning off forgotten all helped towards

this 19% savings.

Since the six months of data saved 19% of energy from the previous year, the typical

pay-back period for this type of investment would be between 3-4 years. This research

indicates a pay-back period of just over 3 years.


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Declaration

I hereby certify that the material, which is submitted in this assignment, other than

what is appropriately referenced, is entirely my own work and has not been submitted

for any academic assessment other than as part fulfilment of the assessment

procedures for the programme Bachelor of Electrical Services and Energy

Management (DT/018).

I authorise Dublin Institute of Technology to lend out single copies as requested.

David Clarke

Signed: ____________________

Date: ______________________


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Acknowledgements

I would like to sincerely thank the following;

Dr. Kevin Kelly in his role as supervisor throughout the thesis. Without his guidance

and knowledge, I would not have completed it.

Mr. Paul Byrne (Director of Rockbrook Engineering) for providing me with

information and assistance throughout the thesis.

Mr. Martin Barrett in his role as Lecturer, for his assistance, guidance and enthusiasm

throughout this thesis.

All other lecturers in the School of Electrical Services Engineering who have

provided support and guidance over the years.

To my fellow colleagues who have aided me over the course of this thesis.

I would also like to thank my fellow classmates as well for any guidance that I would

have received from them.

Finally, I would like to thank my family and friends for their support, patience and

understanding throughout my college tenure.


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Table of Contents Page

Abstract..................................................................................................................... 2

Declaration................................................................................................................ 3

Acknowledgements ................................................................................................... 4

Table of Contents…. ................................................................................................. 5

Glossary .................................................................................................................... 7

List of Abbreviations................................................................................................. 9

List of Tables and Figures….................................................................................... 10

1.0 Chapter One: Introduction ................................................................................. 12

1.1 Introduction ................................................................................................... 13

1.2 Why Install Lighting Controls?...................................................................... 16

1.3 Siemens Head Office Building....................................................................... 17

1.4 Lighting System prior to Energy Efficient Saving Measures .......................... 18

1.5 Lighting System after the Installation of Energy Efficient Saving Measures... 19

1.6 Power Monitoring System ............................................................................. 20

2.0 Chapter Two: The External Environment........................................................... 21

2.1 Introduction ................................................................................................... 22

2.2 Kyoto ............................................................................................................ 22

2.3 Kyoto and Ireland .......................................................................................... 22

2.4 Irish Government Commitment...................................................................... 23

2.5 Copenhagen................................................................................................... 24

2.6 Carbon Tax.................................................................................................... 24

2.7 Obtaining Tax Incentives ............................................................................... 25

2.8 The National Energy Efficiency Action Plan 2009 – 2020 ............................. 25

3.0 Chapter Three: Literature Review...................................................................... 27

3.1 Introduction ................................................................................................... 28

3.2 Current Legislation ........................................................................................ 29

3.3 Latest Research.............................................................................................. 30

3.3.1 Daylighting Controls............................................................................... 30

3.3.2 Occupancy Sensors ................................................................................. 34

3.3.3 Discussion .............................................................................................. 36


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4.0 Chapter Four: Methodology............................................................................... 37

4.1 Introduction ................................................................................................... 38

4.2 Research Questions........................................................................................ 38

4.3 Methods for Collecting Data .......................................................................... 38

4.4 Adequacy ...................................................................................................... 39

4.4.1 Reliability ............................................................................................... 40

4.4.2 Validity................................................................................................... 40

4.4.3 Limitations.............................................................................................. 41

5.0 Chapter Five: Data and Analysis........................................................................ 42

5.1 Data and Analysis.......................................................................................... 43

5.2 Calculations – C02 Consumption.................................................................... 47

5.2.1 Analysis of C02 Consumption ................................................................. 48

5.3 How lighting controls can be used to moderate peak demand in buildings?.... 49

5.4 Simple Payback Method ................................................................................ 50

5.4.1 Calculations ............................................................................................ 53

5.5 Net Present Value Payback ............................................................................ 54

6.0 Chapter Six: Discussion and Conclusion............................................................ 55

6.1 Introduction ................................................................................................... 56

6.2 Future Research Questions............................................................................. 58

References............................................................................................................... 59


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Glossary

Ballast A device connected between the supply and one or more discharge lamps which serve mainly to limit the current of the lamp(s) to the required value. Note: Ballasts may also include means of transforming the supply voltage, correcting the power factor and, either alone or in combination with a starting device, provides the necessary conditions for starting the lamp(s). Daylight Is the visible part of global solar radiation Note: When dealing with actinic effects of optical radiations, this term is commonly used for radiations extending beyond the visible region of the spectrum. Daylight factor (D) Ratio of the illuminance at a point on a given plane due to the light received directly or indirectly from a sky of assumed or known luminance distribution, to the illuminance on a horizontal plane due to an unobstructed hemisphere of this sky. The contribution of direct sunlight to both illuminances is excluded. Note 1: Glazing, dirt effects etc are included. Note 2: When calculating the lighting of interiors, the contribution of direct sunlight must be considered separately. Direct lighting Lighting by means of luminaires having a distribution of luminous intensity such that the fraction of the emitted luminous flux directly reaching the working plane, assumed to be unbounded, is 90% to 100 Directional lighting Lighting in which the light on the working plane or on an object is incident predominantly from a particular direction. Disability glare Glare that impairs the vision of objects without necessarily causing discomfort. Note: Disability glare may be produced directly or by reflection. Discomfort glare Glare that causes discomfort without necessarily impairing the vision of objects. General lighting

Substantially uniform lighting of an area without provision for special local requirements.


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Glare Condition of vision in which there is discomfort or a reduction in the ability to see details or objects, caused by an unsuitable distribution or range of luminance, or to extreme contrasts. See also: Disability glare and Discomfort glare Indirect lighting Lighting by means of luminaires having a distribution of luminous intensity such that the fraction of the emitted luminous flux directly reaching the working plane, assumed to be unbounded, is 0 to 10%.

Lamp Source made in order to produce an optical radiation, usually visible. Note: This term is also sometimes used for certain types of luminaires.

Localised lighting Lighting designed to illuminate an area with a higher illuminance at certain specified positions, for instance those at which work is carried out.

Local lighting Lighting for a specific visual task, additional to and controlled separately from the general lighting.

Luminaire Apparatus which distributes, filters or transforms the light transmitted from one 66 Lighting Guide 7: Office Lighting or more lamps and which includes, except the lamps themselves, all the parts necessary for fixing and protecting the lamps and, where necessary, circuit auxiliaries together with the means for connecting them to the electric supply. Note: The term lighting fitting is deprecated. Luminous environment Lighting considered in relation to its physiological and psychological effects.

Reflectance (r) Ratio of luminous flux reflected from a surface to the luminous flux incident on it. Sunlight

Visible part of direct solar radiation Note: When dealing with actinic effects of optical radiations, this term is commonly used for radiations extending beyond the visible region of the spectrum.


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List of Abbreviations

C02 Carbon Dioxide

EPA Environmental Protection Agency

ESB Electricity Supply Board

ETS 3 Engineering Tool Software

GHG Greenhouse Gas

kW Kilowatt

kWh Kilowatt Hour

LED Light Emitting Diode

Mt CO2eq Million Tonnes Carbon Dioxide Equivalent

NEEAP National Energy Efficiency Action Plan

NPV Net Present Value

PIR Passive Infra Red

RQ’s Research Questions

SEI Sustainable Energy Ireland

SPB Simple Payback

T5 Lamp 5/8" in Diameter

T8 Lamp 8/8" in Diameter

T12 Lamp 1½" in Diameter

UNFCCC United Nations Framework Convention on Climate Change


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List of Tables and Figures Page

Figure 1 - Total UK Energy Consumption by Buildings in 2000 13

Figure 2 - Photograph of a PIR in the Siemens Building 15

Figure 3 - Photograph taken of a Daylight Sensor in the Siemens Building 15

Figure 4 - Photograph taken of the Siemens Building 17

Figure 5 - Operation Daylight Controls in an Office 19

Figure 6 - Greenhouse Gas Emissions by sector 2007 23

Figure 7 - C02 Emissions in various sectors 26

Table 1 - Total kWh used over the last six months in 2008 and 2009 43

Graph 1 - Total Electricity Consumption for July to December 08/09 43

Figure 8 - Average monthly day-lit hours in Dublin 45

Table 2 - Total C02 emissions used over the last six months in 2008 and 2009 47

Graph 2 - Total C02 for the months July to December 2008 and 2009 48

Figure 9 - Max Demand Example A 49

Figure 10 - Max Demand Example B 50

Table 3 - ESB Tariffs for 2008 and 2009 51

Figure 11 - kWh changed to Units (2008) 52

Figure 12 - kWh changed to Units (2009) 52

Table 4 - NPV over five years 54


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‘Energy efficiency is a prime consideration for all

lighting professionals’

Loe (2009)


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1.0 Chapter One: Introduction


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1.1 Introduction

The use of energy in buildings has increased in recent years due to the growing

demand of energy used for heating and cooling in buildings. According to Loe (2009),

“energy efficiency is a prime consideration for all lighting professionals with the

reasons being a threat from climate change, sustainability of energy supplies, burning

of fossil fuels as well as rapidly increasingly costs”. Lighting is a major contributor to

the energy costs in commercial buildings as illustrated in Figure 1 below. These

figures were taken from CIBSE Guide M (2008) and they are the UK energy

consumption by buildings in 2000.

Figure 1 – Total UK Energy Consumption by Buildings in 2000

(Source - CIBSE Guide M 2008)

Hedge (2004) states that “substantial savings and cost savings can be made if lighting

is controlled correctly to make use of available daylight and to eliminate lighting use

when the rooms are unoccupied”. According to the SEI Lighting Guide (2008)

approximately 40-60% of the installed load can be saved when lighting controls are

used properly. However, even the most efficient lighting controls system is wasteful if

lighting is in use when it’s not required and this is where intelligent lighting systems

play a major role in making cost savings.


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The environment in which we live and work has two basic elements: the external with

which we have little or no control over and the internal, which can be controlled to

our specified needs. There are many reasons for installing lighting controls such as

reducing your buildings energy consumption, providing a healthy environment for

your employees and reducing greenhouse gas emissions (GHG). Lighting controls

merit study because Ireland, like other countries world wide, is aiming to deliver a

sustainable energy efficient future. A report by Energy Efficiency in Ireland (2009),

state that 18% of the world’s electricity demands will be used for lighting. According

to the Sustainable Urban Infrastructure (No Date), more efficient lighting in

buildings could lead to an annual reduction of 0.19 Mt CO2 and save investors

approximately €78m annually in energy and maintenance costs.

Lighting controls provide an array of functions such as dimming controls to adjust

output ‘up’ or ‘down’, and can integrate daylighting with artificial lighting to provide

flexibility, energy and cost savings and also provide the functions of turning lights

‘on/off’. It is possible to find many commercial buildings where one measure or

another has been undertaken by management to decrease electricity consumption.

This thesis will focus on the energy saving potential of three lighting controls in a

building (the Siemens Head Office, Dublin), which may also offer significant benefits

for both large and small office type buildings.

This thesis will focus on a retro fit project where three different lighting controls have

been installed on the fourth floor of the six storey Siemens Office building as a test

bed to examine what energy and cost savings can be made. If significant energy and

cost savings are made, the Siemens group will continue to install these lighting

controls throughout the other four floors. The three lighting controls examined in this

dissertation are presence detection, central off and constant daylight (dims lighting in

response to daylighting levels).

Presence Detection - Presence detection sensor as shown in Figure 2 on the following

page, works by detecting the presence of people using Passive-Infra Red (PIR). PIR’s

are used to detect people in an area, sitting at a desk and working quietly, rather than

requiring them to actually get up and move around the detection field in order to


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trigger lights. This makes them ideal for open plan offices, corridors and reception

areas etc.

Figure 2 (Photo taken of a PIR in the Siemens Building by David Clarke, 21/12/09)

Constant Daylight - This function shown in Figure 3 below, causes photocell to sense

daylight and to maintain a constant light level in that given space. It can be combined

with presence detection to provide a constant lighting load which is switched off

when occupancy has ceased. In some cases, on bright sunny days, constant light

control can eliminate the need for artificial lighting completely. One major

disadvantage with this is that it will not work at night. Figure 3 below is a photograph

taken in one of the cellular offices in the Siemens building (it is showing a daylight

sensor in operation). The sensor is detecting daylight and has turned off the two lights

nearest the window.

Figure 3 (Photo taken by David Clarke on the 21/10/09 of a Daylight Sensor in

operation in a cellular office in the Siemens Building)


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Central Off – Central off is a timing function that switches off forgotten lights. Some

advantages of a centralized lighting system are;

• Remote dimming of lighting within each zone

• Automatic sequencing control of individual groups of lights

• Remote status monitoring within the building

Energy usage is also a major factor in lighting design. Energy usage is the product of

the energy consumption of individual luminaires and the time that they are used. The

type of lamp, ballast, and lighting control used are all very important. The reason for

this is that they are all linked with energy consumption. Efficient lamps, ballasts and

luminaires can lead to a reduction of kW installed, whilst using lighting controls

properly can lead to a reduction of hour’s usage. Although the subject of reducing the

kW installed by using energy efficient lamps, luminaires and ballasts is an important

note to consider when lighting controls are mentioned, they are not part of this

research and will only be mentioned briefly.

As stated in Section 1.6.7, the NEEAP Action Plan (2009-2020) argues that existing

technical improvements in lighting could lead to saving of 40% of the total energy for

lighting, such as switching from incandescent light bulbs to compact fluorescent light

bulbs (CFLs) or light emitting diodes (LEDs). They also mention that the Government

has committed to the use of fluorescent lighting wherever practical. As part of the

Carbon Budget 2008, the Government announced its intention to bring forward

legislation to remove inefficient lighting products such as incandescent bulbs from the

Irish market.

1.2 Why Install Lighting Controls?

With growing concerns over global warming and climate change, more building

owners/managers have decided to “GO GREEN”. They have taken it upon themselves

to reduce the buildings energy consumption and help fight the war on climate change.

“The reasons for this may be the threat from climate change from burning fossil fuels

or the sustainability of energy supplies or the increasing costs” as mentioned by Loe

(2009). There are many ways to reduce overall energy consumption in buildings and

lighting controls is one of them. Lighting controls were introduced to buildings


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initially to save energy. Di Louie (2006), states that “lighting controls overall purpose

is to eliminate waste whiles supporting a productive visual environment”. This

involves providing the correct amount of light, where it’s required and when it’s

required. The correct amount of light would depend on the type of task it is required

for. When and where lighting controls are required will depend on the time of day

light levels and the task at hand.

1.3 Siemens Head Office Building

The Siemens Head Office, as shown in Figure 4 below, is located on the Southside of

Dublin City Centre and is a six story office building. It has gone under major

renovation as part of a large effort to modernise the building. Siemens have taken on

the task of reducing the buildings energy consumption through the use of lighting

controls. They decided to try a test bed on the fourth floor of the six storey building.

The fourth floor is approximately 1900 sq. feet. The idea of the test bed is to examine

the energy savings and cost effectiveness of the three different lighting control

systems in private offices, open day lit areas and interior open plan office spaces. By

installing lighting controls on that particular floor and monitoring the electricity

consumption from the lighting controls, it was possible to compare the figures when

lighting controls were installed to previous years when no lighting controls were

installed. If savings in electricity consumption are adequate, Siemens will continue to

install the same lighting controls on the remaining five floors.

Figure 4 (Photo taken of the Siemens Building by David Clarke, 19/12/09)


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Since the building has been in use for many years now, this was a retro-fit project.

They sub-contracted a company to design the lighting controls on the fourth floor.

The sub-contractor installed a power monitoring system in late June 2008. The power

monitoring system measured the energy consumption for the building from June 2008

to present. The lightings controls were commissioned in late June 2009 with the

system fully operational from July onwards. The data that was used in this study was

gathered from a power monitoring system. The power monitoring system is integrated

with the lighting installation and it collects energy consumption from each electrical

device such as light switch, light fitting, occupancy sensors etc. The data is illustrated

via tables and graphs in later chapters.

1.4 Lighting System prior to Energy Efficient Saving Measures

The lights on the fourth floor, prior to the installation of lighting controls were

activated by manual rocker switches placed at the entrance of each illuminated space.

The manual rocker switch used was very basic in terms of what is available now.

Along the hallways and inside the offices and meeting rooms, the luminaires used

were recessed modular fittings (600mm x 600mm). There was no window lighting

and no special down lighters for projectors in the meeting rooms. In the cupboards

and janitor closets, a simple 20W 2D surface fitting was installed which was

controlled by a switch inside the door. Toilets were also fitted with down-lighters and

controlled by a switch on the exterior.

The lighting I the meeting rooms was switched on and off according to usage. The

lights were never left on all day as this room was generally only used occasionally.

Office lighting was left on throughout the day, sometimes up to ten hours during the

day. The building was not in use at the weekends. Most of the floor space is taken up

by open plan offices which have windows on one side allowing a great amount of

daylight in. There are also a number of small cellular offices for the managers. They

also have windows allowing daylight into them.


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1.5 Lighting System after the Installation of Energy Efficient

Saving Measures

The lighting system now installed in the Siemens building is controlled via a KNX

network. KNX is the successor to, and convergence of three previous standards:

• EIBA (European Installation Bus Association)

• EHSA (European Home Systems Association)

• BCI (BatiBUS Club International)

KNX is a standardised communications protocol for intelligent buildings. KNX is

used throughout buildings to make control a lot easier. This allows every light fitting

to be monitored regularly to check for faults. All lights are controlled by KNX

through time channels or presence detectors. The lights in the offices are combined

with daylight sensors in appropriate areas that will switch off lights when there is

sufficient natural light as shown in Figure 5 below. The corridors and toilet lighting

are controlled by PIR’s. The fourth floor is also controlled via a Central Off timing

function which turns off forgotten lights after a pre-set time when everyone has left

the building after close of business hours.

Figure 5 – Operation Daylight Controls in an Office

(Source – Siemens AG 7/11/2008)


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All lighting is monitored by a power monitoring system allowing each individual light

fitting (not just circuit or zone) to be regularly checked for faults. This is very helpful

in detecting whether any light fittings needed to be replaced. Meeting rooms were

fitted with different types of down-lighters, some task orientated and others for affect.

All lighting is now dimmable and can be switched on/off automatically. Emergency

lighting is also wired and monitored with KNX.

One special feature of KNX mentioned by Mr. Joost Demarest (System and

Administration Director of KNX) during a recent CPD event in October 2009 is that

you can program your KNX system by pressing a single push button; the entire house

can be illuminated. KNX can also be used with heating. Examples of this are using

motion detectors to adjust heating levels. Motion detectors can also act as an alarm at

night. Therefore KNX can be used as a protocol to link devices controlling lighting,

heating and security services.

1.6 Power Monitoring System

A power monitoring system has been installed on all floors. Power monitoring

systems collect and analyse data. The data collected will be analysed in order to

investigate whether lighting controls work or not in this particular building. You can

also compare energy consumption from one floor to the next.

The power monitoring system was installed late June 2008 and it operates on a 24/7

basis. The power monitoring system enables you to monitor individual devices of the

installation (such as each light fitting, ballast, switch, PIR, dimmer and photocell is

logged) and record their energy consumption (kWh).


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2.0 Chapter Two: The External Environment


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2.1 Introduction

The main drivers towards a sustainable future have been the Kyoto protocol in 1997

(where Ireland is committed to reducing greenhouse gas emissions to 13% of 1990

levels) and Copenhagen in 2009. Other main drivers for Ireland include the carbon

tax, tax incentives for using energy efficient equipment and the National Energy

Efficiency Action Plan (NEEAO) 2009-2020.

2.2 Kyoto

As of February 2009, 183 states have signed and ratified the Kyoto Protocol to the

United Nations Framework Convention on Climate Change (UNFCC), aimed at

combating global warming. The major feature of the Kyoto Protocol is that it sets

binding targets for 37 industrialized countries and the European community for

reducing greenhouse gas emissions (GHG). As stated by the UNFCC (1997) these

amount to an average of 5% against 1990 levels over the five-year period 2008-2012.

2.3 Kyoto and Ireland

According to McGee (2009) of the Irish Times, he states that “In recent years,

Ireland’s emissions have come close to 70 million tonnes of CO2 per annum, eight

million tonnes above the Kyoto target”. Last year, the Environmental Protection

Agency (EPA) projected that “Ireland would have to purchase 3.6 million tonnes per

annum under the terms of the Kyoto protocol”. Figure 6 on the following page

displays a breakdown of GHG emissions for 2007. According to the EPA (2009), the

Industrial and Commercial sector (17.9%) is the fourth biggest producer of GHG

emissions in Ireland.


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Figure 6 – Greenhouse Gas Emissions by Sector 2007

(Source EPA 2007)

Due to Ireland’s current economic climate, the EPA has confirmed that this has led to

a dramatic reduction in greenhouse gas emissions in Ireland. McGee (2009) states that

the new projections show that Ireland will be closer to the 2012 targets set out in the

Kyoto Protocol, due to the downturn in economic activity and Ireland will need to

purchase less CO2 per annum than previously expected. Ireland’s strategy to meet its

commitments will be via the purchasing of allowances through the Kyoto Protocol’s

flexible measures.

2.4 Irish Government Commitment

Ireland will reach its Kyoto commitment but this is largely due to the economic

downturn and buying credits from other countries who have reached their targets. The

Kyoto protocol provides several flexible mechanisms which enable Annex I countries

(Industrialised countries) to meet their GHG emission targets. This can be done by

acquiring GHG emission reductions credits. Credits are acquired by an Annex I

country financing projects that reduce emissions in non-Annex I countries or other

Annex I countries who have excess credits. The flexible mechanisms are emissions

trading, the clean development mechanism and joint implementation.


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Legge and Scott (2009) published a report “Policy Options to Reduce Irelands

Greenhouse Gas Emissions” mentioning that a side effect of our economic recession

since 2008, is that Ireland may meet its required Kyoto commitment for 2008-2012 to

reduce its GHG emissions, but that the long term targets for 2020 and beyond remain

stringent. This is good news in one sense that not everything regarding the recession

is bad news. This can help Ireland in a big way by;

• Saving the economy money by not having to buy credits from other countries

to meet our targets

• A reduction in GHG emissions throughout this recession will help meet our

targets

2.5 Copenhagen

The Copenhagen climate change summit (COP15) is the successor to the 1997 Kyoto

Protocol. This is the 15th Conference of the Parties (COP) under the United Nations

Framework Convention on Climate Change (UNFCCC). Officials will try to achieve a

new climate treaty to the successor of the Kyoto Protocol. The main issue behind this

treaty is of burden sharing. Scientists believe that by 2050, the world must cut

emissions by 80% compared with 1990 levels to limit global warming to a 2ºC

average rise.

2.6 Carbon Tax

A carbon tax may be the best way to make countries more aware about what fuels

they use and burn. A carbon tax could work as the central mechanism to reduce

carbon emissions. A carbon tax cannot combat climate change by itself; it may require

other synergistic actions as well. Baumol and Oates (1971) say that “the cheapest way

to meet any emission target is to set the marginal cost of emission equal for every

source”. They are implying that the cost of emissions reduction is equal throughout

the economy (i.e. emissions for transport are equal to emissions for electricity

generation). This argument is also backed up by Baumol and Pearce (1972 and 1991)

who states that “the easiest way to establish a uniform price for emissions is to impose

the same emission tax on all sources”. According to Tol et al (2008), Ireland’s carbon


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tax will not stop climate change and is unlikely to impact on global warming as

Irelands emissions are a tiny fraction of global emissions. It does however show our

commitment to international climate policy and as part of a global strategy through

Kyoto and Copenhagen can make a difference.

2.7 Obtaining Tax Incentives

Tax incentives for buildings are available but the specified requirements must be met.

The Accelerated Capital Allowance (ACA) is one such scheme which was introduced

in the Finance Act 2008 and will run for an initial three year period from 9th October

2008. According to SEI (2009), the ACA scheme enables businesses to write off the

entire cost of a specified set of energy efficient motors, lighting and building energy

management systems in the first year of purchase.

For a building to be granted a tax incentive from the Government, it must use energy

efficient equipment. Lighting and lighting controls fall into this category with a

minimum required expenditure of €3,000. There is one Siemens product that falls

under this scheme and that is the Siemens Gamma Lighting Control which is used in

the Siemens building and these costs are shown in Section 6.1.

2.8 The National Energy Efficiency Action Plan 2009 – 2020

The National Energy Efficiency Action Plan (NEEAP) 2009-2020, has set out an

energy policy framework to combat problems such as Ireland’s over-reliance on fossil

fuels, which accounted for 96% of all energy usage in 2007 and our problem of

security of supply of reliable and affordable energy.

The NEEAP represents the next step in addressing the imperative for energy

efficiency. As Ireland move further into the future, price hikes in gas and oil are

expected. This is where Ireland needs to react to our current economic situation and

build on becoming an efficient, low-carbon-energy system. Energy efficiency offers

the most cost effective means of reducing GHG emissions (electricity in buildings use

61% and lighting uses 23% of this). See Figure 7 on the following page where the

figures are taken from CIBSE Guide M (2008) and incorporated into two pie charts.


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Figure 7 – C02 Emissions in various sectors

(Source – CIBSE Guide M 2008)

Ireland has agreed to meet the set target of delivering 20% energy efficiency savings

in 2020 and 33% target for the public sector. NEEAP is Ireland’s first national energy

efficiency policy. This policy details the range of actions currently committed to by

the Government across all sectors of the economy. Between now and 2020 there will

be additional initiates to this. It is believed by The National Energy Efficiency Action

Plan (2009-2020) that the future Action Plan in 2011 and 2014, will demonstrate

Irelands progress towards achieving our targets.


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3.0 Chapter Three: Literature Review


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3.1 Introduction

The information obtained for this literature review will be from the most relevant

books, journals, articles, website, conferences as well as past and peer reviewed

papers regarding lighting controls. The use of these information sources will help set

the research questions for this study. Lighting controls have been used worldwide,

allowing buildings to save energy. Lighting controls such as daylight controls

(photocells) or occupancy sensors (PIR’s) are amongst the most common type of

controls used today, although various types and combinations exist and will be

different depending on each individual building.

According to the European Commission Directorate-General for Energy (1995),

recent developments in lighting technologies combined with planned lighting control

strategies can result in very significant cost savings. The main aim of this thesis is to

examine how much energy can be saved in this building by installing lighting

controls. Di Louie (2006) states that lighting controls can reduce lighting energy

consumption by 50% in existing buildings (retrofit) and by at least 35% in new

constructions. The percentages mentioned above by Di Louie (2006), do not

specifically refer to office buildings. The existing buildings Di Louie (2006) mentions

may be a school or a warehouse.

Recently there has been an increasing interest in saving energy by incorporating

daylighting and lighting controls such as PIR’s into building design. According to

Energy Efficiency Lighting in Offices (1995), lighting accounts for 50% of total

electricity used in offices. Through the use of daylighting controls (photocells) and

PIR’s, buildings can now reduce energy consumption thus saving costs. There has

been a lot of research by engineering professionals towards these two lighting controls

and this is reviewed in this chapter but prior to these controls being examined, current

legislation and its effect on lighting controls is analysed.


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3.2 Current Legislation

Part L requires that energy efficient lighting be used in both domestic (Part L1) and

non-domestic (Part L2) buildings. The regulations currently apply to all new buildings

and refurbishments of over 100m2. The document provides design information in the

following areas for non-domestic buildings:

• Effective use of daylight

• Selection of lamp types

• Associated control gear and power factor correction

• Luminaire efficiency

• Use of lighting controls

The requirements can be met by selecting an efficient lamp, control gear and

luminaire performance combination, along with lighting controls that make maximum

use of daylight and avoid unnecessary lighting during times when spaces are

unoccupied.

Lighting controls can be simply an increased use of switches, time switches and

photocells to turn luminaires on and off. More advanced solutions include using high

frequency dimmable control gear linked to photocells to provide constant illumination

and daylight linking. According to the Building Regulations - Approved Document L

(2006), intelligent luminaires, such as Intellect, provide a straight forward solution to

providing lighting control with user selectable functionality.

The Building Regulations (2006) require as a minimum;

• Use of daylight as much as possible,

• A efficacy target of greater than 40 lumens/circuit watts remains,

• Control of electric lighting.


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3.3 Latest Research

There are a number of research papers available regarding lighting controls and

especially PIR’s and photocells as these two are leading the way for lighting controls

in modern office buildings. The purpose of the literature review for this thesis is to

investigate what past and present research has been published, those in support of a

particular position, those against and those offering alternative theory entirely.

Lighting controls have become a popular topic with regards to academic literature and

the government’s agenda and must be investigated further.

3.3.1 Daylighting Controls

There is much evidence to suggest that people find daylight more appealing than

artificial lighting and there has been a lot of research carried out to discover if

daylight is linked to increases in productivity performances. Past research supports the

notion that daylight is important, with studies finding a direct relationship between

higher satisfaction about daylight in an office and increased work. For example; in his

book titled “Reactions of computer users to three different lighting systems in

windowed and windowless offices”, Hedge (1994) argues that windows provide more

light than artificial lighting alone. Hedge (1994) also suggests that “increased daylight

relates to psychological well being”. There has also been links made between higher

productivity of work and daylight. Hedge (1994) measured the performance of a

clerical task on a computer in a room lit by different electric lighting systems, with

and without windows. He found a small but statistically significant improvement in

task performance when windows were present. The windows provided more light than

artificial light alone and the performance in productivity was increased as a result of

the window.

Boyce et al (2003) argues that some events in life such as uncomfortable

environmental conditions can give rise to increased stress levels, a simple view, real

or simulated of a window, has been shown to be a means of relieving stress. Stress

can be linked to glare, noise or overcrowding to name a few. Prolonged experience of

stress can be related to high blood pressure, poor job performance or absenteeism. A

technical report by The National Renewable Energy Laboratory (No Date) has


David Clarke 31

published results indicating that “properly designed daylighting decreases the

incidence of headaches, seasonal affective disorder and eyestrain”.

Companies must begin to realise that efficient use of energy can reduce operating

costs and have environmental benefits. Daylight is the preferred method for people to

work in. Studies by Markus (1965) and Heerwagen and Heerwagen (1985) have

shown that working in daylight results in less stress and discomfort than working in

artificial light. General and visual health becomes more apparent when working under

daylight. Increased productivity and well being are linked directly to users having a

direct visual connection to the outdoors. A case study on an office block by

Daylighting Dividends (2004) produced an article, where 70% of their staff would

like to be seated near the window even though the employees realized that there could

be problems with glare on their computer screens as mentioned by Akashi & Morante

(2004, p.6).This argument of working beside windows is backed up by (Markus 1965)

and (Heerwagen and Heerwagen 1985) who identified that people prefer to work

beside windows rather than further back into a room, especially when those windows

have direct access to sunlight. They claim that employees, if asked where they would

prefer to work, would respond “beside a window” (i.e. beside daylight).

According to Di Louie (2004), good personal control can be linked to human comfort

leading to higher productivity. Di Louie (2004) also states that “people costs outweigh

building costs on a ratio of 3:1”. Therefore it makes sense for management to take a

more serious interest in relation to productivity and the workplace design. Di Louie’s

fact regarding people costs outweighing buildings costs may be true, but will lighting

controls have such a positive effect on workers performance that you will see an

increase in profits? Maybe good control is the key to positive attitudes in work and

increased productivity. But the ideal lighting scenario is different for every user.

Offices that want to be seen as having good personnel control will require T5 or T8

lamps, dimmable electronic ballasts, task lighting if required in some areas and some

sort of occupancy sensor. It could well be the occupant’s preference over the energy

efficiency side of lighting control that will create the ideal system, and energy

managers must be aware of this.


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According to D. H. Li & J. C. Lam (2001), energy savings resulting from daylighting

mean not only low electric lighting expenditure and reduced peak electrical demands,

but also decreased cooling loads. Although utilizing daylight is an effective way to

reduce energy in your building, daylight may not however, always be desirable and

may often be undesirable. For example, working beside day-lit spaces can be

associated with thermal and visual liabilities such as solar heat gains during summer

months and heat loss during winter months. The best solution would be a combination

of daylight without unwanted heat gain.

There are disadvantages associated with daylighting systems such as glare. Glare can

cause problems such as visual disability and discomfort. Glare can have adverse

affects on people and productivity alike. Artificial lighting can also cause direct glare.

Glare from daylight can be controlled with properly selected blinds and careful

location of visual display terminals. One way to combat direct glare from artificial

lighting is to install an array of ceiling mounted luminaires with the luminaires having

a luminous intensity distribution that avoids glare reflected from display screens. This

has consequences for wall and ceiling luminance values but these problems can be

overcome with good design.

Daylight is an important factor in buildings and “it is difficult to overestimate the

significance of daylight in a particular building and the people who use it” according

to a report by Daylighting in Buildings (No Date). Some buildings require more light

than others. For example, an office block requires more daylight than a cinema or

nightclub and the reasons for this are obvious. Daylight is the light to which we are

naturally adapted to. But daylighting will not save energy without control of the

electric lighting system.

Di Louie (2006) states a number of reasons why daylighting fails. He mentions;

• Under-dimming, which results in less than expected energy savings.

• Over-dimming, which results in user irritation.

• Frequent cycling of dimming or switching, resulting in user irritation.

• Lights left on at night, which results in less than expected energy savings.


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The reasons mentioned by Di Louie (2006) above, such as over and under dimming

and frequent cycling are very important and Di Louie (2006) offers arguments as to

why the use of daylight to reduce artificial lighting energy sometimes fails. These

reasons are not monumental and they are more like kinks in the system rather than

major problems of the system and can be overcome with the right programming and

training. If the proper training and commissioning of a well designed and installed

system is achieved, then there is no reason why energy savings cannot be achieved.

Indeed that is the central premise of this dissertation.

Daylighting controls also fail in some buildings because of improper location of

controls and inadequate specification of the control systems. Daylighting in Buildings

(No Date) state that “the potential for energy savings through daylighting is affected

by the location, climate, building use and form”. In Ireland there is an outside

illuminance of 10,000 lux or greater for 70% of the working day throughout the year.

Boyce (2006 p.27) argues that “lighting installations did not have the simple effect on

performance or well being that many researchers have sought”. His argument is

correct to some degree as not all lighting installations would help increase

productivity as they were simply not designed to do this. They were designed to

perform a task of illuminating an area. Lighting designers are now taking many more

factors into account when designing a system. They will look at different designs and

combinations of previous lighting systems that worked effectively and were beneficial

to the environment. This creates a healthier environment which past research

indicates, helps increase productivity. Good lighting contributes to an improved visual

environment and this can aid visual stimulation and general well being. There are

many papers on using daylight controls in buildings and they primarily tend to

indicate that the daylight controls have more pros than cons. A substantial amount of

money has been invested in research to find out if daylighting controls in buildings

could improve productivity and well being and most results come back positive

showing increases in productivity. An example of this would be Di Louie (2005)

where he suggests that “access to daylight versus no daylight in classrooms has been

correlated into large increases in students test scores”.


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3.3.2 Occupancy Sensors

Occupancy sensors or presence detection is another example of how energy savings

can be made. Occupancy sensors are automatic switching devices that sense human

occupancy and control the light accordingly. Although designed to monitor small

areas, they can be linked together to control the lights in large areas but will require

much more flexible control. Occupancy sensors are used in spaces where occupancy

varies such as open plan offices, corridors, toilets and storage closets. Lights can be

frequently left on in these areas and are not regularly switched off. Di Louie (2007)

states that “occupancy sensors are ideal for areas that require greater control than can

be achieved using scheduling such as office buildings with perimeter offices that must

be controlled individually”. The use of an occupancy sensor positioned correctly is a

practical automatic control that will turn the lights off. Di Louie (2007) in his study

found “energy savings from using occupancy sensors can range from 13% to 50% in

private offices, 30% to 90% in toilet areas, 30 to 80% in corridors and 45% to 80% in

storage areas”.

There are a few different methods of occupancy detection such as PIR, ultrasonic and

microwave. Ultrasonic sensors are more sensitive at greater distances than PIR. Both

ultrasonic and microwave sensors detect in a sonic manner and they don not require a

direct line of sight of a motion source. They will however detect a slight movement

which can lead to false and nuisance tripping, such as a draught moving a piece of

paper or movement beyond a glass partition or window. The Lighting Research

Centre (2002), mention an example of false triggering from ultrasonic sensors such as

when the sensor detects movement in any part of the space near the sensor. They also

mention what ultrasonic sensors are best at detecting movement in any part of the

space, even around corners and movement towards the sensor rather than movement

across the space. PIR which is the most common method of occupancy detection

reacts to changes in heat patterns and they works better in open spaces than offices

separated by partitions, as the partition can block the beams. Frequent switching of

lights can be a nuisance for employees and will also decrease the lamp life.

There are two main control options. Full occupancy sensing involves both presence

detection and absence detection. This works by switching lights on when the sensor


David Clarke 35

detects movement, and switches back off when the sensor detects no movement for a

pre-set period. Full occupancy sensors with presence detection is particularly useful in

spaces where people do not expect to control the lighting themselves like corridors,

storage cupboards or toilets. When retro fitting a building, time switches are usually

impracticable due to the extensive re-wiring and/or local over-ride switches.

According to Morante (2006), “occupancy sensors are a viable option to reducing

wasted light energy use”.

There are a number of problems linked with occupancy sensors as identified by

Glennie et al (1992, p.8), who stated that “lighting controls are often disabled because

they create problems for the occupants”. Glennie et al (1992) also mention that

“motion sensors do not really respond to occupancy” so tasks associated with

relatively stationary positions (typing, reading, etc.) are periodically interrupted

because they occupant must stop to make overt movements such as having to wave

their hands to turn the lights on again.

According to the Lighting Research Centre (2002), examples of false triggering (for

PIR’s only) is when sunlight falls on a shiny surface such as a desk or when

machinery near by to the sensor heats up and causes false triggering. Other significant

problems include improper location of the sensor (regarding to PIR and ultrasonic

sensors) resulting in nuisance triggering, which can occur when someone walks past

the door of a controlled room and is picked up by the sensor.

Occupancy sensors can be unwelcome in working offices. People tend to resent the

lighting system coming on automatically when they feel they should have control,

especially in situations when they believe that lighting need not have been switched

on anyway. Also nuisance triggering can become a real problem if passers by are

detected. This in turn wastes energy.

Some benefits of continuous dimming with daylighting controls as mentioned by Di

Louie (2006) include the highest level of flexibility and user satisfaction, and also

often the greatest energy savings. Some disadvantages include the extra costs of

dimmable ballasts and the potential wiring in addition to the initial cost and

commissioning.


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3.3.3 Discussion

There are a number of problems identified in this literature review with daylighting

controls and PIR’s. Some of the problems associated with daylighting controls were

glare, improper locations of controls, lights being left on and under-dimming,

resulting in less than expected energy savings and over-dimming resulting in occupant

irritation. The challenges associated with PIR’s was that occupants disabled the

controls because of the sensor not interacting with the occupants while they worked at

their desk leaving them to wave their hands to turn the lights back on, false triggering

due to improper location of the sensor leading to lights being turned on and false

triggering from machinery near by heating up.

There are some on going challenges with lighting controls and some barriers to

realizing cost-effective energy savings. According to the Inter Academy Council

(2007), new technologies or methods improving the efficiency of energy use are often

not adopted as quickly as might be expected because of these challenges and this

research is aimed at addressing these challenges for this building.


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4.0 Chapter Four: Methodology


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4.1 Introduction

The methods used in this research set out to determine if energy and C02 savings are

possible using lighting controls in an office building. They also set out to determine

how to moderate peak demand when using lighting controls in the office building.

4.2 Research Questions

The research questions of this thesis are to determine;

• How much energy and C02 emissions can be saved by integrating lighting

controls into an office building.

• How lighting controls can be used to moderate peak demand in buildings?

4.3 Methods for Collecting Data

The methodology for this thesis includes various methods of collecting data for

lighting controls for the Siemens building described in Section 4.0 to answer the

research questions (RQ’s) above. The data was gathered during various site visits to

the Siemens building between July and December 2009. The data was logged on a

power monitoring system described in Section 1.5. Excels spreadsheets were used to

create tables and graphs to present the data in a clear manner and also to facilitate

methods for payback periods and net present value (NPV) examination.

To answer the RQ’s the electricity consumption was examined. The electricity

consumption was logged daily on the power monitoring system in kWh. These figures

displayed in tables and graphs represent the electricity consumption for the fourth

floor of the Siemens building where lighting controls are used during the period of

July to December 2008 and July to December 2009.

The power monitoring system was installed in June 2008 allowing the energy

consumption be collected and analysed from June 2008 onwards. Each month, the

energy consumption for the fourth floor would be analysed. When the lighting

controls were installed in June 2009, a comparison could be completed between 2008

figures (when no lighting controls were installed) and 2009 figure (when lighting

controls were installed). These sets of results would indicate if energy savings were


David Clarke 39

made or not using these lighting controls for the same six month period over two

years (2008 and 2009).

This data was then analysed and provided an opportunity to examine possible ways to

reduce energy consumption through the use of lighting controls. Gathering the kWh

data over the six months also enabled carbon dioxide (C02) reductions to be

calculated. The C02 emissions for that same six month period were calculated. If the

kWh used over 2009 was less than 2008, then there would also a corresponding

reduction in C02 emissions for that same period.

The KNX EIB Bus described in Section 1.4 monitors each device and records data.

Each device sends and receives information back to the power monitoring system on

their current status (such as faults). The Engineering Tool Software (ETS 3) is used to

design and configure the intelligent building control installations made with the KNX

system.

To evaluate the benefits of controls, a cost benefit analysis was performed. This cost

benefit analysis will examine the pay back period for the system installed in the

Siemens building. It will take into account the capital cost of the system, annual

maintenance, electricity bills and tariffs etc. The payback period does have certain

limitations and qualifications for its use. It will not take into account the time value of

money, the risk involved or opportunity cost. The cost benefit analysis was completed

using an excel spreadsheet and is shown in Section 5.4. A Net Present Value (NPV)

was also performed in Section 5.5 to find out the time value of money for long terms

projects like this. Although the payback period for projects like this are usually

considered in around 3-4 years, the Siemens indicate a payback period of 3.3 years on

their investment. Anything over that period would be considered a bad investment.

4.4 Adequacy

Adequacy can be evaluated by examining the reliability and validity of the research

and critically evaluating any deficiencies. The first obvious deficiency in this research

is that there is only data for six months after the controls had been installed by

Siemens. Other difficulties are examined below in Section 4.4.3.


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4.4.1 Reliability

The first test of reliability is, how does the examination in this research, compare with

Siemens own data analysis and conclusion. Siemens projected 44% savings but this

research does not concur with that figure and there are a number of possibilities for

that. One reason may be that only six months of data was available for analysis whilst

Siemens projected their savings for a full year.

This research analyzes actual evidential savings where as Siemens are making

projections based on staff patterns and better building usage which have not yet been

substantiated by evidence as yet. This analysis is based on analysis available from

June 2008 to 2009. The claims by Siemens of 44% savings are worth further

investigation.

4.4.2 Validity

Earlier in this thesis, it was shown that possible savings could be made using lighting

controls. As mentioned in the literature review earlier, Di Louie (2006) stated that

lighting controls can reduce lighting energy consumption by 50% in existing

buildings (retrofit) and by at least 35% in new constructions. The data analysed in this

thesis did not project a savings of up to 50% for a retro-fit building as stated by Di

Louie (2006) above, but he does not however mention if this 50% would account for

office buildings. Di Louie (2006) may be referring to a school. One factor that both

sets of data agree on is that savings are possible in retro-fit buildings with regards to

lighting control.

In relation to daylight controls, this research does not bring up the subject of increased

productivity that is mentioned in the literature review. This is one area where this data

differs from the literature review. This research focused on the possibility of using all

three lighting controls to save energy. An example of where this research differs from

the literature review is a report by The National Renewable Energy Laboratory (No

Date) who mentions that “properly designed daylighting decreases the incidence of

headaches, seasonal affective disorder and eyestrain”. This argument is backed up

again by Di Louie (2004) who mentions that “good personal control can be linked to

human comfort leading to higher productivity”.


David Clarke 41

Regarding the occupancy sensors in the Siemens building, this research found that

initially, the occupants had problems with the sensors and often disabled them. The

reason for this was that the occupants were working at their desk for long periods of

time and when the PIR did not sense any movement (after the pre-set period 5-10

minutes), the lights went off. This led to the occupants overriding the system and

manually dimming lights or switching lights on in offices. This data agrees with

Glennie et al (1992) from the literature review who says that “lighting controls are

often disabled because they create problems for the occupants. They mention that

“motion sensors do not really respond to occupancy, so tasks associated with



their hands to turn the lights on again”.

4.4.3 Limitations

The lighting controls had only been installed by Siemens six months prior to this

research being conducted. On the basis of this evidence, it was not possible to

complete a yearly analysis. Also the first month the lighting controls were installed,

the energy consumption increased from 2008. The reason being was that the system

was just installed and some fine tuning was still being completed. The five month

period after the installation, indicated a savings of 19% compared to Siemens

projection of 44%, however this is only half of the year compared to Siemens whole

year projection. The availability of only six months of data also meant limitations

were incurred when determining the amount of C02 emissions that were saved in

comparison to the previous year. To analyze the data for twelve months would have

been more effective.

Also noted was that the climate and corresponding daylight levels during which the

lighting controls were installed (late summer, autumn and winter) as displayed in

Figure 8, in Section 5.1. Daylight levels are beginning to fall as the winter months

move in. This means less daylight available, indicating lights being turned on earlier

during the day. Also, the daylight sensors may only have 70-80% of daylight

available (between 9am – 5pm) compared to summer months when 100% daylight

was available during the time frame (9am – 5pm).


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5.0 Chapter Five: Data and Analysis


David Clarke 43

5.1 Data and Analysis

Below in Table 1 and Graph 1, are figures indicating how much energy was saved in

2009 compared to 2008 figures. The months outlined in yellow below represent the

months where there was savings in electricity consumption from 2008 figures due to

the lighting controls being installed. This led to an overall saving in electricity

consumption of 19% from the 2008 figures.

Table 1 – Total kWh used over the last six months in 2008 and 2009

(Source – Data from Siemens Building)

Electricity Consumption

0

2000

4000

6000

8000

10000

12000

14000

16000

1 2 3 4 5 6 7 8 9 10 11 12

Months

kW

h

2008

2009 (Lighting Controls Installed)

Graph 1 – Total Electricity Consumption for the months July to December


David Clarke 44

The graph and table on the previous page represent the months of the year. The

lighting design company installed the power monitoring system in June 2008 allowing

energy consumption to be monitored. In 2008 there were no lighting controls were

installed in the office.

During July 2009 (month 7), the lighting consumption went up by just over 19%

compared with 2008 figures. The reason for this was that it was the first month the

lighting controls had been fully operational with some commissioning still being

completed. Sometimes, the power monitoring system logged zero kWh for some of

the devices. This led to some devices not showing any energy savings when actually

they did. For the graph and table above, July’s monthly savings/loss of savings was

left out of the total six months savings. The reason being was that it was the first

month in operation and as mentioned above, some modifications were still being

completed with the devices and power monitoring system. Every month after that

showed a savings in energy compared to 2008 figures and is discussed in greater

detail below.

On a site visit to meet the manager of the Siemens building, he mentioned that the

occupants had problems at first adjusting to the controls in the office and that

complaints were made to the manager who then forwarded on the complaints to the

lighting designers regarding the pre-set time period for lights to turn off if no motion

was detected. The lighting designers set the pre-set time (5-10 minutes) to turn lights

off if the PIR’s did not sense motion. Most of the time, the occupants could be

working away and not move for over 10 minutes at a time, when suddenly the lights

turned off. This led to the occupants overriding the system and manually dimming

lights or switching lights on in offices. This in turn, led to the designers increasing the

pre-set time from 5-10 minutes to 15-20 minutes. The outcome of this change was

that the energy consumption being saved on the system would be less. There is a

positive side to this design change in that the occupants requested the pre-set period to

be changed, they would be happier in that environment and this in turn may increase

user satisfaction and worker productivity.

The following months, August to September show a significant savings in electricity

consumption with a combined total of 53.13% from the previous year (2008). This


David Clarke 45

would suggest that the lighting controls were working better. This indicates that the

PIR’s were switching off lights according to detection leading to increased electrical

savings. Usually the lights were left on in the corridor and toilets with the old system

but the new system was saving electricity by switching lights off when the area was

unoccupied.

Figure 8 – Average monthly day-lit hours in Dublin (Source - http://www.climate-charts.com/Locations/i/IE03969.php)

As August and September are summer/start of autumn, the day light hours would still

be high as shown in Figure 8 above, so the occupancy sensors would offer more

potential savings in electricity consumption. This would suggest that the photocells

were detecting daylight in a given room or space and either adjusting the light level

accordingly or turning off the lights completely when the room is unoccupied to save

electricity.

October (9.48%) and November (11.56%) 2009 saw a decrease in electricity savings

compared to August (31.45%) and September (21.68%) 2009. Reasons for this are

that the days are getting shorter. This suggests that lights are being turned on earlier

during the day unlike some days during summer when less light may have been

necessary. Another reason why the savings decreased from the previous months is

that lights would be on more often in the morning during the months with less

daylight available. Lights will be left on 100% in morning and then again late during

the day.

December (24.4%) 2009 indicates the second highest savings in Table 1. The reason

being is that the Siemens building is left idle over the Christmas holidays. That’s


David Clarke 46

approximately nine days of the month and no lights were left on unnecessarily in the

building. If a space was unoccupied, the lights were off, unlike 2008 when corridor

and toilet lighting would have been left on all day until the security guard walked the

building after everyone is gone home.

The data gathered from the Siemens building indicates that savings were made using

the lighting controls as described in Section 1.0. The main findings from this data

were that a 19% savings in electricity consumption was made in five months of the

year (July being excluded as per reasons already discussed). If July was to be included

and six months of data was shown, this figure would drop from 19% to 12.4%.

Siemens projected a 44% savings from these three lighting controls installed for the

whole year. This research showed savings of 19% (if July was excluded) for five

months and 12.4% (if July is included) for six months. If we were to speculate and

divide the 44% savings in half, giving us six months data instead of 12 months data.

Therefore 22% is equal to six months of the year. This research’s savings (12.4%) are

not too similar to the projected saving made by Siemens (22%) for half of the year.

The reason being again, that July was the first month the lighting controls were in

operation and the system was still being modified.

The months where there was a recorded savings of energy (August to December –

19%) are the months that should be focused on. If the 44% was divided by 12

(number of months in the year) and then multiplied by five (number of months where

a savings was recorded), then this data would be closer to the initial projected data by

Siemens. Actually it would be higher than the projected data by Siemens by 0.7%

(July excluded = 44/12 * 5 = 18.3% compared with actual savings of 19%). You

could then speculate that this data (savings of 19% over five months) is equal to the

five months projected by Siemens (18.3%) using these lighting controls.


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5.2 Calculations – C02 Consumption

Carbon dioxide or C02 has become a hot topic with regard to climate change.

According to Rohrer (2007), C02 can be released into the air from a number of ways

such as burning fuels like oil, natural gas, diesel, organic diesel, petrol and ethanol to

name a few. According to the EPA (2009) Ireland’s total GHG emissions were 67.43

million tonnes carbon dioxide equivalent (Mt CO2eq) which is 0.21 Mt CO2eq (0.3%)

lower than the level of emissions in 2007.

Since we have evaluated how much energy the Siemens building was using in 2008

and 2009, we can find out how much C02 emissions that relates to by using Table 2

below. This is done by first finding out how much C02 equals to 1 kWh. According to

the CarbonIndependent.org (2009), the C02 emission factor for electricity is taken to

be 0.527 kg / kWh. The total kWh for each year is then multiplied by 0.527 kg to see

how much C02 emissions are being used. Figures are displayed in Table 2 below and

Graph 2 on the following page. The kWh (A) multiplied by C02/kg (C) equals C02

emissions 2008 (D). The same applies for C02 emissions 2009 (B*C=E).

Table 2 – Total C02 emissions used over the last six months in 2008 and 2009


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C02 Consumption

0

1000

2000

3000

4000

5000

6000

7000

8000

1 2 3 4 5 6 7 8 9 10 11 12

Months

C0

2

20082009 (Lighting Controls Installed)

Graph 2 – Total C02 for the months July to December

5.2.1 Analysis of C02 Consumption

As shown in Table 1 (Total kWh used over the last six months in 2008 and 2009),

there was a decrease in electricity consumption. This in turn will lead to a reduction in

C02 emissions as both are interlinked. As only six months of data was available to

examine, a whole year study of C02 emissions could not be completed.

July 2009 C02 figures were higher than July 2008 C02 figures, so there were no

savings made in this month, but a loss. August 2009 was the first month where C02

savings were made (1637.2 C02/kg) and as explained earlier, the reason for this being

that the system was fully operational and all kinks were worked out of the system.

September to December 2009 also saw savings in C02 emissions from the previous

year with a total of 3707 C02/kg being saved. The reasons for this were that the

lighting controls were working efficiently and effectively. Each month from August to

October saw a decrease from the previous month.

August 1637.2 C02/kg

September 1268.1 C02/kg (-369.1 C02/kg from August 2009)

October 584 C02/kg (-684.1 C02/kg from September 2009)

The reason being, again, the days are getting shorter, meaning less available daylight

for the daylight sensors to detect and turn or dim lights accordingly.


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5.3 How lighting controls can be used to moderate peak

demand in buildings?

According to a report called Managing Energy Costs in Office Buildings (No Date)

the consumption component of a bill is the amount of electricity in kWh that the

building consumes monthly or annually. The demand component is the peak demand

in kW occurring within the month.

Max demand (Figure 9 below) metering is one way to reduce lighting load. Max

demand metering records the highest kW value consumed in one 15 minute period

over a monthly billing cycle. The reason to control demand is not to exceed the

contracted demand limit and to avoid penalties set up for exceeding the max demand.

One way to do this is to shed the critical loads on non essential equipment like

lighting.

There are many ways to reduce peak demand in a building such as using LED’s for

exit signs, daylight controls, occupancy sensors or timers and install compact

fluorescent lamps (CFL’s) and ballasts to name a few. All of these controls can help

reduce peak demand and occupancy sensors can help reduce the number of hours per

day that the lights are on. Also by allowing the occupants to controls the light levels is

another way to reduce peak demand in a building.

Figure 9 – Max Demand Example A

(Source – Colin Conway – DIT Lecture 01/04/09)


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Figure 10 – Max Demand Example B

(Source – Drawing by David Clarke 29/12/09)

As shown in Figure 9 on the previous page, any attempt to reducing energy in a

building includes reducing one parameter in this graph (i.e. power or time). Reducing

energy in this building could involve using the most efficient lamps consistent with

the qualitative requirement. In this research the reduction in power is achieved by

dimming the lights during time of daylight, whilst time can be reduced by occupancy

sensors. Both a reduction in power and time were tested in this research. Dimmers

were used in the open plan offices and cellular offices to dim lights accordingly with

the available daylight whilst the occupancy sensors in corridors, toilets and offices

reduced the time that the lights were on. Both these methods are great ways to reduce

energy in a building.

5.4 Simple Payback Method

The Simple Payback (SPB) is the amount of time it will take to recover installation

costs based on annual energy cost savings. The equation for simple payback is annual

energy cost savings per year divided by the initial installation cost. The annual cost of

energy savings proposal is the cost of electricity for operating the energy saving

equipment and the annual cost of maintenance on the energy saving proposal.


David Clarke 51

The Siemens building used all their own equipment such as power and energy meters,

motion detectors, push buttons and photocells etc so the only real cost was for the

contract for the lighting designer and commissioning. The total cost for this was

€10,525. To find the payback period, first we had to find out how much money was

saved over the six months by changing our kWh into (ESB) units and multiplying the

units accordingly with the ESB tariffs for each particular year. We then subtracted

2009 figures from 2008 figures. The only problem with this is that is does not account

for the full year savings that could be made from these lighting controls. To find out

how each column in Figures 11 and 12 (A through I) are worked out, (e.g. to find out

how column C is worked out, see in the tan segment {Column B is divided by column

H}). The tariffs in Figures 11 and 12 are based on latest ESB prices. They are as

follows;

Unit Charges – As indicated on the ESB (2009) website, the first 47815 kWh of

electricity you use annually is charged at the Block 1 rate. This works out as 131 units

per day. Everything in excess of this is charged at the Block 2 rate.

2008 2009

Block 1 €0.1504/kWh €0.1444/kWh

Block 2 €0.1670/kWh €0.1527/kWh

Table 3 – ESB Tariffs for 2008 and 2009

(Source – www.esb.ie)


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Figure 11 – kWh changed to Units (2008)

(Source - Table by David Clarke 09/01/10)

Figure 12 – kWh changed to Units (2009)

(Source - Table by David Clarke 09/01/10)


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5.4.1 Calculations

Total Costs for July to December 2008 = €10164.3 (Taken from Figure 11 on the

previous page)

If this figure is multiplied by two to give 12 months of electricity costs, that figure is

€10164.3 * 2 = €20328.6

Total Costs for July to December 2009 = €8415.7 (Taken from Figure 12 on the

previous page)

If this figure is multiplied by two to give 12 months of electricity costs, that figure is

€8415.7 * 2 = €16831.4

Then subtract 2009 costs from 2008 costs and that equals annual electricity saved.

€20328.6 - €16831.4 = €3497.2 saved annually from the lighting controls.

The Simple Payback Method is as follows;

yearsSavingsAnnual

CostCapitalSPB 3

2.3497

10525

_

_===

Capital €10525

Annual Savings €3497.2

Payback 3 years

Siemens projected a pay back of 3.3 years against the actual pay back of just 3 years.

This examine was only made possible by allowing us to double the money saved in

last six months (so that 12 months of savings could be accounted for). This figure in

not 100% accurate as we had actually six months of data to examine but from looking

at Figure 8, we could assume that the last twelve months would be similar to the first

twelve months of the year (Figure 8 displays day-lit hours of the year in Dublin and

the first six months of the year are a mirror image of the last six months of the year)

Conclusions could be drawn up indicating that the savings made for the last six

months would be similar to that of the first six months of the year.


David Clarke 54

5.5 Net Present Value Payback

The Net Present Value (NPV) has an advantage over the SPB method in that it

accounts for the time value of money (i.e. a Euro today is not worth the same as a

Euro tomorrow). The NPV method determines the value of a project over time. It also

accounts for the savings that occur after the payback period. The greater the NPV

value of a project, the more profitable it is.

nIR

SNPV −

+×=

1001

- PV = Present Value of S in ‘n’ years time (€)

- S = Value of cash flow in ‘n’ years time (€)

- IR = Interest Rate

- N = Number of years

The NPV method calculates the present value of all the estimates future cash flows

(i.e. capital costs and net savings) incurred throughout the life of the project (Note: the

higher the NPV, the more attractive the project). Table 4 on the following page

indicates that these lighting controls would be a viable option because after five years,

the NPV is positive.

Table 4 – NPV over five years


David Clarke 55

6.0 Chapter Six: Discussion and Conclusion


David Clarke 56

6.1 Introduction

In this thesis, the following controls were examined:

1. Occupancy sensors (PIR’s),

2. Constant Daylight or Daylight Sensors

3. Central off.

1. Occupancy Sensors

It was found that with the use of PIR’s, energy savings were made. The PIR’s work

effectively in the building now but during the initial stages, there were some problems

with them such as switching off lights in occupied areas. The reason being, that the

occupants often worked at their desk (typing, reading etc.) for long periods of time

without moving around. The PIR would then turn lights off as they were designed to

(after sensing no motion). This pre-set period was then increased (from 5-10 minutes

to 15-20 minutes) because of complaints made by the occupants to the manager who

reiterated this problem back to the lighting consultants, who increased the pre-set

period. This had some side effects as, the energy savings would decrease if the pre-set

period was increased but the occupants would be happier and have more control over

their environment. This data ties in with the literature review in that the same

problems occurred with Glennie et al (1992) who says that “lighting controls are often

disabled because they create problems for the occupants. Glennie et al (1992) mention

that “motion sensors do not really respond to occupancy, so tasks associated with



their hands to turn the lights on again”. This thesis agrees with past papers in this

regard and found that there can be problems relating to PIR detectors. But in this case,

increasing the pre-ser period appears to have solved this problem.

2. Constant Daylight

With regard to the daylight controls, there were no issues involving them and the

occupants. They worked well in the building dimming or turning lights off

accordingly and as indicated by the data in section 5.0, they helped toward energy

savings of 19% over five months. This data may be higher if a yearly analysis was to

be conducted.


David Clarke 57

3. Central Off

The central off lighting control worked efficiently in the Siemens building. It turns off

forgotten lights on the fourth floor that would have been previously left on before in

areas such as toilets, stairwells or offices for example.

It was found out that with the three particular controls examined in this study that

energy savings could be made for the office building. One floor was examined as a

test bed and the data indicates energy savings as a result of these lighting controls.

Although this data and results indicate a savings in energy, the Siemens group is

waiting on data for the whole year before committing to the redesign of the remaining

five floors with the same lighting controls. As mentioned before, this single floor was

examined as a test bed. If results indicated savings, then the Siemens group would

retro-fit the remaining five floors of the Siemens building with the same lighting

controls. If the results were poor, then they would not go ahead with the installation.

While performing the research, the following difficulties were encountered:

• Only six months data was available for analysis. And of that, only 5 months

were considered reliable. The first month that the lighting controls were

installed, showed an increase in energy consumption. Reasons for this was that

it was the first month the controls had been installed and commissioning and

some fine tuning was still being completed.

• Other problems encountered were in relation to the user’s patterns. The

occupants had problems with the occupancy sensors. They found that when

working at their desk for long periods of time without getting up, the lights

would turn off. The PIR’s had trouble detecting occupancy whilst occupants

were stationary. To counter-act this problem, the pre-set time for the PIR to

automatically turn lights off was increased from 5-10 minutes to 15-20

minutes. This led to smaller energy savings but led to increased user

satisfaction and as stated by many authors in the literature review, occupant

satisfaction can be linked to higher productivity. To conclude, the Siemens

group put occupant satisfaction ahead of energy savings.


David Clarke 58

Lighting controls when designed properly can add value to your building. Not only

are the controls important but the design is very important. The reason for this is that

if the building was to be sold in the future and the new client wished to change the

layout, no extra wiring would be required, only re-programming of the system would

be necessary. This is one benefit that lighting controls have because the building

energy rating may be improved and this is an increasingly important factor in modern

building usage.

This research has concluded that the three lighting controls discussed in this study

were successful in this case study

6.2 Future Research Questions

This research has highlighted the necessity for further research in some areas. One

such are would be to find out if higher productivity is linked to daylight? For this

study to be completed on the Siemens building, a year analysis would be required and

also that the occupants to be interacting with the controls for the whole year. This

would give the occupants time to find any discrepancies with the system. Following

this, the year’s results of productivity with lighting controls installed would need to be

compared against the productivity of the occupants when no lighting controls were

installed. One limitation of this would be the current economic status. As Ireland is

still in recession, the Siemens group may have had to reduce staff numbers, so

naturally productivity would decrease against last year’s figures.

If this thesis were to be carried out in the future, there is one main area that would

warrant further investigation; to have a whole year’s data to analyze. This twelve

months data could then be measured against the Siemens projected data. This would

tell you if these lighting controls, when integrated together actually save the 44%

energy claimed by Siemens. The carbon dioxide emissions could also be looked at

further to see how much could be saved on a yearly basis.


David Clarke 59

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