Wireless Lighting Controls:
A Total Cost Analysis

White paper: Wireless Lighting Controls Payback

Table of Contents
Concerns for Building Owners ................................................................ 3
Energy Efficiency .....................................................................................................3
Targeting Lighting ..................................................................................................3
Flexibility & Productivity ..........................................................................................4
Investing in Efficiency .............................................................................................4
Lighting Controls .................................................................................... 5
Existing Buildings ...................................................................................................5
Why Upgrade ..........................................................................................................5
Personal Control ..................................................................................................6
Energy Harvesting .................................................................................. 6
EnOcean Alliance and Interoperability .....................................................................6
Payback Analysis: Open Office Area, Classroom &Warehouse ............................................................................................. 7
Energy Use in Offices ..............................................................................................8
Case Study: Office Area Payback Analysis ............................................................9
Energy Use in Schools .............................................................................................9
Case Study: Classroom Payback Analysis ...........................................................10
Energy Use in Warehouses ....................................................................................10
Case Study: Industrial/Warehouse Payback Analysis...........................................10
Implications of Wired vs. Wireless ....................................................... 11
Wired vs. Wireless: Comparative Costs................................................. 11Open Office Area ..................................................................................................11
Classroom ............................................................................................................12
Warehouse ............................................................................................................13
Energy Harvesting vs. Batteries ........................................................... 13
Conclusion ............................................................................................ 14

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White paper: Wireless Lighting Controls Payback

Concerns for Building Owners
Energy Efficiency
Doing more with less through energy efficiency-focused upgrades to existing buildings
represents the fastest and most economical way to reduce our reliance on foreignsources of fuel and decrease our nation‟s greenhouse gas emissions. Although building
technology investments can provide satisfactory payback periods, the current economic
situation, combined with relatively low electricity rates, can make it difficult for building
owners to make a case for retrofitting. As electricity rates continue to rise and aspressure builds to curb unsustainable energy consumption, the situation will change.
The advent of wireless control systems justify retrofitting even considering low electricity
rates.
Within the next few years regulators and utilities in several states will be revisiting
electricity rates that have been frozen for years. These new rates will be needed to fundnew infrastructure investments, like the smart grid, to help ensure that the electricindustry provides reliable, affordable and clean electricity. The demand for energy is
growing, with electricity consumption expected to increase 45 percent by 2030 according1
to the Energy Information Administration (EIA) .

Targeting Lighting
According to the EIA, lighting consumes 18 percent of the total electricity in the2residential and commercial sectors . The Rocky Mountain Institute (RMI) estimates thatroughly 40 to 50 percent of this energy is wasted as a result of excessive lighting,3
inefficient equipment and careless usage . Lights commonly remain on, well beyond theoccupancy hours for buildings, not to mention that excessive lighting also generates
waste heat, increasing energy costs.
According to RMI, 20 to 40 percent of air conditioning costs can actually be attributed to4excess lighting . This is an important consideration given the average building has
energy costs of about $2.00 per square foot. An effective facility management strategy,
including the utilization of advanced lighting controls, has the potential to save $0.60 to$1.00 per square foot in energy.
Modernizing an existing lighting system can significantly reduce electricity consumption.
Lighting control systems adjust illumination levels to match the requirements of thespace. Occupancy sensors and daylight harvesting photo-sensors can save electricity byautomatically turning off lights when no one is physically in the space and can slightly
and systematically adjust indoor lighting when natural light is available.. Sensors canreplace a standard wall toggle switch and can be mounted on a ceiling, wall or be
integrated into individual fixtures.
1 http://www.eia.gov/cneaf/electricity/epa/epa_sum.html
2 http://www.eia.gov/tools/faqs/faq.cfm?id=99&t=3
3 The Hammersmith Group. “Clicks & Mortar: The Costs and Benefits of Intelligent Buildings. January

2010.
4 The Hammersmith Group. “Clicks & Mortar: The Costs and Benefits of Intelligent Buildings. January

2010.

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White paper: Wireless Lighting Controls Payback

Flexibility & Productivity
In addition to the potential for energy savings using lighting controls, wireless lighting
control devices have the unique ability to control individual luminaries, groups of lights,
entire floors and even entire buildings. Wireless control devices can be placed where
they are needed, without limitations imposed by wiring, including areas that are difficult
to wire. Using wireless technology also shortens electrical planning. Even after
installation, devices can be moved and the system can be expanded to include HVAC,
with relative ease. Studies have shown that proper lighting is beneficial for employees
working in an office environment. The improved comfort and resulting employee
satisfaction brought through day lighting strategies, task oriented lighting and individual
control has resulted in reduced absenteeism and increased productivity.
One research study conducted by the Light Right Consortium of Albany, New York, foundthat occupant comfort increased by 15-20 percent with the use of indirect lighting, wall
washing and personal dimming control. Additionally, occupants with personal control attheir workstation had increased motivation and were able to sustain their persistence5
and vigilance over time, as compared to those without any control over their lighting .

Investing in Efficiency
Even with all of these documented benefits, it is important to recognize that decisions
about upgrading lighting are often based upon “lowest first cost” rather than “true cost”
analysis. Decision makers overlook benefits such as long-term energy savings andmaintenance related cost savings. This whitepaper serves to provide perspective on
lifecycle costs, not just the first costs to building owners, providing stakeholders with theinformation they need to invest in sustainable retrofit strategies.
Energy costs are important in commercial buildings because they are a significant
component of operating costs and overall net operating income. Many organizations areworking to ensure that building owners and developers receive a higher value for energy
6efficient properties upon resale or refinancing . To fully realize the value of highperformance buildings, developers, owners and managers need to engage withappraisers by documenting and demonstrating the financial benefits and risks of theenergy management strategies undertaken.
According to a publication titled “Energy Efficiency and Appraisals”, written by7
BetterBricks , energy should be examined as a separate line item within the operational
budget of a specific building. Data provided on the life-cycle costs of energy
investments, versus “first costs” is something that should be provided to the appraiser.
Life cycle cost assessments, like the information provided in this whitepaper, has nothistorically been applied to the valuation of investment technologies, but will likely
8
become more relevant as innovations and new best practices enter the mainstream.

5 http://www.lightright.org/research/albany_study.htm
6 Institute for Market Transformation. Project on Energy Efficiency and Property Valuation. Feb 1999.
7 http://www.betterbricks.com/
8 http://www.betterbricks.com/graphics/assets/documents/EEAppraisals_Final.pdf

4White paper: Wireless Lighting Controls Payback

Lighting Controls
Innovative and cost effective wireless strategies, when viewed from a life cycle cost
standpoint, present an attractive solution for achieving energy savings, flexibility,
productivity, reduced maintenance costs and personal control. In new construction, theability to run wire to enable hard-wired controls is often considered a more cost effective
solution, particularly when a building owner is only considering these “first” costs.
A wireless solution, in a new construction environment, can make for a difficult sell,unless total costs to the building owner are considered. If the project developer and thebuilding owner are not on the same page, the person in charge of the building‟s
construction is predominantly going to care about first costs. When it comes to building
retrofits, wireless technology provides clear advantages, since no new wires are
required, thereby reducing the labor related costs.

Existing Buildings
Regardless of the argument made, the reality is that the market for green buildings is
exploding and there is an overwhelming interest in retrofits, not new buildings. McGrawHill‟s latest SmartMarket Report finds that new building construction represent only 2.5
percent of the US building market, while retrofitting provides an enormous market
opportunity. According to the report, green building comprises 5 to 9 percent of theretrofit and renovation market activity by value. By 2014, that share is expected toincrease by 20 to 30 percent, creating a $10 to $15 billion market for major retrofit
9
projects .
The economic downturn is encouraging further adoption of energy efficient practices inretrofit projects. Sixty two percent of owners expect that the savings achieved fromenergy efficiency improvements will be recouped within 10 years. The case studies
presented in this whitepaper demonstrate payback periods attained in much less time,
typically within 3 years. The most frequently applied features for building retrofits
10
include energy efficient lighting or natural lighting .

Why Upgrade
With fewer buildings being built and a notable increase in retrofit projects, building
owners and facility managers are beginning to investigate innovative building
automation and control technologies. The opportunities, especially in North America, is
growing, due in part to the fact that there are roughly 5 million commercial buildings in
the United States totaling over 70 billion square feet of floor space.
Small and medium sized facilities account for 98 percent of the total number ofcommercial buildings and 65 percent of this floor space, yet only 5 percent of thesesized buildings are equipped with a building automation system. Small and medium
sized buildings are seldom equipped with building automation because of the relatively
9 http://www.prnewswire.com/news-releases/green-retrofit-market-growing-projected-to-reach-

20-30-of-all-commercial-building-retrofit-and-renovation-in-five-years-says-new-mcgraw-hillconstruction-report-65584762.html
10 http://greeneconomypost.com/huge-growth-in-retrofit-buildings-predicted-10-15-billion-

market-by-2014-5476.htm

5White paper: Wireless Lighting Controls Payback

high up front costs and longer payback periods related to retrofit installation of a BAS.
Variable costs incurred by labor have also limited the adoption rate of building
11
automation system (BAS) .
Energy harvesting wireless technology from EnOcean, including self-powered sensors,
switches and controls, encompass a building automation system that has the ability to
cut the cost and time of installation. Achieving the functionality of a BAS with wireless,battery-free controls is making energy harvesting wireless an excellent choice asbuilding owners consider upgrading their facilities. Self-powered wireless sensor
networks are the key to achieving an intelligent green building.
Personal Control
Within the range of illumination, people have preferences for how much and what kind oflight they want. Given that preferences vary, some aspect of personal control should beafforded to building occupants. Recent laws in Denmark, some of the most stringent inEurope, require that all workplaces have access to daylight. Most experts agree thatbringing some human control into the lighting mix provides an opportunity for further
advancement. To that end, control technologies need to be easy, intuitive, robust andsimple and should be easily integrated with interoperable building level controls.
EnOcean enabled, energy harvesting technology can easily achieve these goals andprovide a comfortable environment for the occupant.

Energy Harvesting
Energy harvesting is the process by which energy is derived from external sources,
namely solar power, thermal power and kinetic energy. This energy is captured andstored for use in small, wireless, autonomous devices like those used in wireless sensor
networks. Energy harvesting devices convert ambient energy into electrical energy.
Energy can be stored using a small capacitor instead of needing batteries, which provide
a constant flow of power. The history of energy harvesting dates back to the windmill
and the future of energy harvesting is motivated by a desire to address climate change
and global warming.
EnOcean GmbH, founded in 2001 as a spin-off from Siemens AG, is the originator ofpatented self-powered wireless technology. EnOcean has long embraced energy
harvesting technology and as a result combined miniaturized energy harvesters andhighly efficient wireless technology to create service-free, sensor solutions for use inbuildings and industrial automation. Instead of batteries, EnOcean enabled technology
uses energy converters to supply power through linear motion converters, solar cells andthermal converters.

EnOcean Alliance and Interoperability
There are now over 750 interoperable, EnOcean enabled, energy harvestingproducts available worldwide. Building automation sensors and controls enabled by

11 http://www.enocean-alliance.org/en/ip-based-wireless-energy-harvesting-sensor-and-control-

technologies/

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White paper: Wireless Lighting Controls Payback

EnOcean include wireless switches, sensors, actuators, controllers, gateways andbuilding management systems. These products are available in both 315 MHz (forNorth America) and 868 MHz (for Europe).
Figure 1 – EnOcean-enabled Product Examples

Leviton 2-Channel
Room Controller

Verve Living Systems Wallmounted Occupancy Sensor

BSC LAN TCP/IP Access Point

After EnOcean technology experienced success, leading companies worldwide collected
in 2008 to establish the EnOcean Alliance. This Alliance, which now boasts over 200
members, aims to standardize and internationalize EnOcean wireless technology and isdedicated to creating interoperability between the products of OEM partners. EnOcean
GmbH remains one of seven promoter members of the EnOcean Alliance.
The Alliance‟s mission is to promote and enable intelligent green buildings through thecreation of a broad range of interoperable, standards-based wireless products. Our
member companies aim to create a better, safer, cost effective, energy efficient andenvironmentally friendlier world through intelligent, self powered wireless systems.
Another function of EnOcean Alliance involves the Energy Equipment Profiles (EEP),
which encompass the technical characteristics of each device by defining profile
elements. It is EnOcean Alliance‟s goal to configure each profile as universally as
possible so as to target an adequate spectrum of devices in the building automation
sector for all participating manufacturers. The Technical Working Group of the Alliancereviews and ratifies the profiles and then the Board of Directors approves or disapprovesof the profile.

Payback Analysis:
Open Office Area, Classroom & Warehouse
An importance part of making a successful argument for the implementation of wirelessenergy controls in commercial, educational and industrial buildings is demonstrating
acceptable payback. A payback period is the time required for the return on an
investment to “repay” the sum of the original investment. Unlike a deeper cost analysis,
payback doesn‟t account for the time value of money, risk, financing or otherconsiderations. This kind of simple analysis is very important when it comes to making
decisions about energy investments.
The wireless technology deployed in the case studies below, included occupancy sensors,
time scheduling and daylighting. Occupancy sensors provide automatic ON/OFF
switching of lighting loads for convenience, security and energy savings. Occupancy

7White paper: Wireless Lighting Controls Payback

sensors can be used for monitoring conference rooms, restrooms, stairwells and parking
garages. Time scheduling works well in open office areas where automatic switching atfixed hours of the day is predictable and can save energy. The last means of control
included daylighting, which uses light sensors to measure the amount of illumination in aspace and can continuously and subtly adjust the desired level of illumination. Theselighting control techniques are some of the most common used in buildings today.
This white paper serves to provide a payback analysis for three different building
environments to show the true payback periods experienced after investing in wireless,building control technology. The wireless payback analysis was performed for an open
office environment, a school classroom (K-12) and a typical warehouse. For eachanalysis we utilized industry accepted assumptions, as described in Table 1.

Table 1 - General Assumptions for Payback Analyses
General Assumptions and Inputs for Payback Analyses
Full Electricity Rate kWh per DOE$0.12

Tubes per fixture

4

Watts per tube

32

Annual Days/Year Office Lights On

50 working weeks/5 days per week

Annual school days

Annual classroom days minimum

Hours per day before controls

DOE Study

Energy saved in open office area

DOE Study

Energy Use in Offices
Owners of commercial office buildings facerising energy costs, creating challenges withrespect to managing a facility‟s budget. Costsof building maintenance products and services
are also rising. Executives of owner occupied
and tenant occupied buildings must take newand creative steps that put energy costs incheck to maintain a healthy, sustainablebusiness environment. The fact is that 70
percent of commercial office buildings are at
12least 20 years old and the average building
uses 20 percent more energy than13
necessary . Energy use in offices has risen inrecent years mainly due to growth in

Figure 2 - Energy Use in

12 Frost & Sullivan, North American BAS Controls Market, 2004

Commercial Buildings (src: US

13 American Council for an Energy Efficient Economy, 2005 Study

Dept. of Energy)
8White paper: Wireless Lighting Controls Payback

information technology, air conditioning, density of use and a competitive market where
tenants see higher value in a comfortable workplace.
At least two-thirds of all energy consumed in an average office building is due toelectricity. Lighting, office equipment and HVAC account for 90 percent of this14
expenditure . Even as energy costs climb, improvements and innovations on the
consumption side are not likely to keep pace. There can be valuable benefits realizedwith energy efficiency improvements, like installing energy management controls.
Energy efficient buildings have greater market value, gain improvements related to
employee productivity and have more predictable energy costs.
Case Study: Office Area Payback Analysis
In our Office case study we investigated the impact wireless control technology would
have in an open office space, similar to a cube farm, containing 25 lighting fixtures. The
technology installed into the office included occupancy sensors and daylight harvesting
technology. The devices installed were 2 wireless switches, 4 wireless occupancy &photo sensors, and 4 dimming controllers, at a total materials cost of $597. Labor to
install the wireless devices was $119, for a materials and labor bill totaling $716.
To conduct the payback analysis, the assumptions in Table 1 above were utilized.
Accordingly we used 250 as the total number of days per year, on average, that lights
are illuminated in office spaces. For our calculations we utilized 9.1 as the average
number of hours per day that office lights are typically left “on”, before the introductionof controls. We also utilized existing data from studies demonstrating that occupancy
sensors alone have the ability to achieve 12 percent energy savings in open office areas.
Furthermore, daylighting has the ability to achieve 26 percent energy savings. When
occupancy sensing and daylighting are combined, energy savings of 35 percent can beachieved.
The payback analysis for an open office space results in energy related cost savings of$307 for the 1250 square foot, open office area via the implementation of occupancy
sensing and daylighting. With a total labor and materials cost of $716 and 41 percent
savings compared to wired solutions, the payback period for wireless controls in an
open office environment was 2.3 years.

Energy Use in Schools
According to the EIA, educational buildings account for 12 percent of all commercial
energy consumption, leaving this sector the third highest consumer of total energy of allcommercial building types. Nearly 41 percent of total energy in educational settings isutilized for space heating, making it the largest category of energy usage in educational
facilities, followed by water heating and lighting, at 22 percent and 20 percent
respectively. Large buildings, like colleges and universities, use energy intensively. On
average, $0.92 per square foot is spent on energy in educational buildings, less than the15
national average for energy usage in commercial buildings, at $1.19 per square foot.

14 http://www.eia.gov/emeu/consumptionbriefs/cbecs/pbawebsite/office/office_howuseenergy.htm
15

http://www.eia.gov/emeu/consumptionbriefs/cbecs/pbawebsite/education/educ_howuseenergy.htm

9White paper: Wireless Lighting Controls Payback

Case Study: Classroom Payback Analysis
In our Classroom case study we investigated the impact wireless control technology
would have in a typical K-12 classroom containing 9 lighting fixtures. The technology
installed into the classroom included occupancy sensors, time scheduling and daylightharvesting technology. The devices installed were 2 wireless switches, 1 wirelessoccupancy & photo sensor, and 3 dimming controllers, at a total materials cost of $321.
Labor to install the wireless devices was $73, for a materials and labor bill totaling $394.
To conduct the payback analysis, the assumptions in Table 1 were utilized. Accordingly,
we used 180 as the total number of days per year, on average, that lights are
illuminated in school classrooms. This is because 180 are the number of instruction daysin a calendar year. For our calculations we used 10 as the average number of hours per
day that classroom lights are typically left “on”, before the introduction of controls. We
also utilized existing data from studies demonstrating that occupancy sensing alone canachieve 45 percent energy in a classroom and that daylighting can achieve 26 percent
energy savings. When combined, energy savings of 63 percent can be achieved.
The payback analysis for the classroom resulted in annual energy related cost savings of$118 for the classroom retrofitted with occupancy sensing and daylighting. With totallabor and materials cost of $394 and 39 percent savings compared to wired solutions,the payback period for wireless controls in a classroom was 3.3 years.

Energy Use in Warehouses
According to E Source, warehouses are becoming increasingly sophisticated. As thisoccurs; energy consumption grows, making energy efficient measures, like theintroduction of building automation, a good way to boost the bottom line. To operate awarehouse in the U.S., it requires spending an average of $0.70 per square foot onenergy. These costs make up more than 10 percent of total revenue. Heating and16
lighting together account for 64 percent of total warehouse energy use.
Wireless building automation and control technology can provide considerable energy
savings in industrial settings. Wireless switches can be used to control lighting andwindow blinds; while room temperature sensors can ensure minimal consumption andstill achieve maximum comfort. Climatic sensors, for humidity and carbon dioxide,
monitor indoor air quality. Central control can occur from a touch panel or PC, with thecapability to remotely monitor and control by using a mobile phone.
Case Study: Industrial/Warehouse Payback Analysis
In our warehouse case study we investigated the impact wireless control technology
would have in a typical industrial space containing 100 lighting fixtures. Unlike thelighting found in office and classroom scenarios, which utilize 32 watts, the high bay
lighting used in a warehouse consume 450 watts. The technology installed into thewarehouse space included only occupancy sensing, since many warehouses don‟t havenatural light sources for daylighting. The devices installed included 20 wireless switches,
20 wireless occupancy sensors and 20 relay controllers, at a total materials cost of

16 U.S. EIA, “CBECS: End-Use Consumption by Principal Building Activity” [1999],

www.eia.doe.gov/emeu/cbecs/enduse_consumption/pba.html

10White paper: Wireless Lighting Controls Payback$4,379. Labor to install the wireless devices was $1775, for a materials and labor bill
totaling $6154.
To conduct the payback analysis, the assumptions in Table 1 were utilized. Accordingly,
we used 250 as the total number of days per year that lights are illuminated inwarehouses. For our calculations we utilized 16 as the average number of hours per day
that warehouse lights are typically left “on”, before the introduction of controls. We alsoutilized data from studies demonstrating that occupancy sensing alone has the ability toachieve 35 percent energy savings in warehouse environments.
The payback analysis for our warehouse resulted in annual energy related cost savingsof $7,560 for the warehouse space with the implementation of occupancy sensing alone.
With a total labor and materials cost of $6,154, a 28 percent savings compared to wired
solutions, the payback period for wireless controls in a warehouse was 0.8
years.

Implications of Wired vs. Wireless
Although wired devices might be less expensive to purchase, the installation of wired
solutions, particularly in retrofit scenarios, entail considerably more labor and materials
than wireless solutions. In a conventional installation of a wired solution, the process
involves pulling wires for sensors, switches and controllers. Wiring in commercial
facilities typically requires metal conduit, secured to a structural member. Obstacles are
frequently encountered when „fishing‟ wires through existing walls. . Furthermore,
wired installations can result in disruption of business operations due to the penetration
walls for wiring. This intrusion can require patching and repainting, increasing theamount of time, and labor costs, required for the install.
When it comes to installation effort, building alterations and the desire for future
expansion in buildings, wireless technology has the clear advantage. Wirelesscomponents, like switches, can be easily mounted on surfaces inaccessible to wired
solutions. With wired solutions, installers can never be sure what they will find when
they begin the installation. With wireless solutions, since no walls need to be disturbed,
there is much less uncertainty.

Wired vs. Wireless: Comparative Costs
Through the detailed payback analyses above, we have demonstrated that theimplementation of wireless controls can achieve more than satisfactory return on
investment for office spaces, classrooms and warehouses with payback periods of 2.2,
3.4 and 0.8 respectively. The question remains, is wireless technology a more costeffective solution than wired control technology in retrofit scenarios?

Open Office Area
The case study presented for an open office area resulted in a payback period of 2.3
years through the installation of wireless occupancy sensing and daylighting controls.
The total material and labor cost was $716. Utilizing a corresponding and comparable
wired solution in the retrofit of the same open office area resulted in total material andlabor cost of $1224 and a payback period of 4.0 years. The cost for wired occupancy

11White paper: Wireless Lighting Controls Payback

sensors, photosensors and switches was less expensive than their wirelesscounterparts. The labor costs of installing the wired devices, however, were many times
more expensive than the labor costs for the wireless solution.

Wired

Wireless

Cost of Installation$1,224$716

Payback (years)

4.0

2.3

Savings vs. Wired

41%

Zones controlled: 4
Total # of Fixtures: 25
Annual Energy Savings: $307

Figure 3 – Wired versus Wireless Cost Comparison: Open Office / Cubical Area

This kind of payback and comparative analysis is important because many building
owners and facility managers make purchasing decisions based solely on the
upfront/first costs and don‟t consider the total costs. The installation of a wired solution
requires dedicated control wiring, switch legs, traveler wires and other raw materials.
Damage to walls, drywall patching and repainting all contributes to the total costs of awired solution. For an open office area, similar to a cube farm, a wireless system
is more cost effective than a wired solution.

Classroom
The case study presented of a classroom resulted in a payback period for the installationof wireless occupancy sensing and daylighting controls of 3.3 years with a total materials
and labor cost of $394. Utilizing a corresponding and comparative wired solution in the
retrofit of the same classroom area resulted in a total material and labor cost of $646
and a payback period of 5.5 years. Although the materials cost of the wired occupancy
sensors, photosensors and switches were less expensive than their wirelesscounterparts, the labor costs of installing the wired devices was nearly twice the laborcosts for the wireless solution. For a school classroom, a wireless solution is morecost effective than a wired solution.

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White paper: Wireless Lighting Controls Payback

Wired

Wireless

Cost of Installation

$646

$395

Payback (years)

5.5

3.3
39%

Savings vs. Wired
Zones controlled: 3
Total # of Fixtures: 9
Annual Energy Savings: $118

Figure 4 – Wired versus Wireless Cost Comparison – School Classroom

Warehouse
The case study presented of a warehouse resulted in a payback period for the
installation of wireless occupancy sensing controls of 0.8 years, at a total material andlabor cost of $6,154. Utilizing a corresponding wired solution in the retrofit of the same
warehouse resulted in a total material and labor cost of $8,520 and a payback period of
1.1 years. Although the cost of the wired occupancy sensing solution were lessexpensive than their wireless counterparts, the labor costs of installing the wired devices
were significantly more expensive than the labor costs for the wireless solution. For awarehouse environment, a wireless solution is more cost effective than a wired
solution.

Figure 5 – Wired versus Wireless Cost Comparison: Warehouse / Factory

Wired

Wireless

Cost of Installation$8,520$6,154

Payback (years)

1.1

0.8

Savings vs. Wired

28%

Zones controlled: 20
Total # of Fixtures: 100
Annual Energy Savings: $7,560

Energy Harvesting vs. Batteries
When it comes to procuring a building automation system, total costs must be
considered by the building owner. Although initial costs remain the prominent

13

White paper: Wireless Lighting Controls Payback

consideration, lower costs over the long-term should influence a better buying decision.
Labor costs for wired control installations as well as battery usage, replacement ofbatteries and disposal of used batteries are additional cost considerations.
Building control sensors powered by batteries must be monitored for battery condition.
Batteries must be stocked, changed out and disposed of properly. This equates to timeand money spent unnecessarily, particularly in locations where reliable operation isessential, like in office buildings and hotels. EnOcean is currently the sole provider ofbattery-free technology - made possible by the extremely low energy requirements of
EnOcean devices.
To ensure performance in wireless, battery powered building technology solutions,batteries must be replaced on a regular schedule, resulting in wasted battery life or
resulting in users accepting the risk of changing batteries only when a low voltage
threshold is indicated. This might be acceptable for tens to a few hundred nodes, but thepotential maintenance cost of replacing batteries for thousands of nodes becomes acontinuous, cost prohibitive undertaking.
Furthermore, commercial businesses are supposed to take their spent primary batteries
directly to a hazardous waste facility. There is fee of around $1.37/lb for the disposal of“flashlight” like batteries. The cost for the disposal of non-rechargeable batteries is
expensive for commercial entities, with the cost for disposing AAA batteries at about
17$0.44 per cell . Although smaller, lighter batteries, like those found in wireless controls
and sensors are the least expensive, it is still a cost that a business has to consider
when using battery operated, wireless solutions. ON World estimates the labor cost forchanging batteries in wireless sensors will be greater than $1 billion over the next
18
several years . These costs for battery replacement are a significant disadvantage tothe growth of wireless, battery powered sensor networks, therefore opening the door to
EnOcean‟s energy harvesting technology.

Conclusion
Although there is little difference between the energy savings capabilities of wired versus
wireless solutions, there are difference associated with the costs of their installation. In
new construction scenarios, wired building control and automation strategies are more
likely to be the cost effective choice. That is primarily due to the ability of installers to
run wire while construction is taking place. Since wired controls are, on average, lessexpensive than wireless technology, especially energy harvesting wireless controls, theytend to be much more cost effective when it comes to new construction.
When it comes to building retrofits, which are by far the more popular energy efficiency
strategies for buildings today, wireless technology has been proven to be more costeffective as compared to wired solutions. The ease of installation and no new wire
requirement of wireless technology makes it a cost effective solution for retrofits ofnearly all types of buildings.

17 http://www.kicknpower.com/disposal.html
18 http://onworld.com/power/

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