White Paper
LonMark® International and EnOcean Alliance team-up
for optimal network topologies in building automation
When it comes to choosing a facility’s backbone for carrying buildingautomation information, wired LON® bus systems have become thenorm. However, wireless systems have been growing in popularity
since the arrival of energy-autonomous and service free wirelesscomponents based on EnOcean technology. Practical experience
shows that the two technologies, side-by-side, exhibit advantages
that maintain an ideal wired/wireless balance—combining the strong
points of both.

1. Wired and wireless compared
Features
Range
Installation effort and flexibility
Data volume
Availability of information in room
Reliability
Cost

Wired

Wireless++
-++++
+++
-+++++

Table 1: Features of wired and wireless transmission media

This collective assessment of major criteria relevant for the market indicatesthat neither of the two transmission media comes out alone on top in abuilding-automation scenario. For an optimal solution, it takes both; each
implemented where it is better than the other. These criteria are looked atbelow.
Range
If you want to transmit data over long stretches in a building (more than 30meters, for instance) there is no economical alternative to a wired bus. An
obvious example is the transmission of sensor and actuator information
across many floors from a central point. For communication between
buildings, long distances, and for very large amounts of data, fiber optic
networks are a good option.

White Paper – LonMark International & EnOcean Alliance

1/ 9

Fig. 1: UNIQA Tower in Vienna, where the backbone links a large number of floors(© UNIQA Versicherungen AG)

But signal transmission within the same floor, in a radius up to about 30meters, is easily handled by the right wireless technology: EnOcean. The
differentiator that sets EnOcean above other, potential wireless choices is theuse of sub-gigahertz frequencies: 868 MHz in Europe and the Middle East, and315 MHz in the USA and the Far East. These frequencies are in contrast towireless systems like those based upon 802.15.4 RF radios and Bluetooth,nestled in the 2.45 GHz band. The lower, more optimal frequencies exhibit
lower attenuation through walls and achieve about twice the range for thesame transmitting power.

Fig. 2: Transmission loss vs. frequency

White Paper – LonMark International & EnOcean Alliance

2/ 9

Figure 2 illustrates the performance of wireless systems in buildings as afunction of their frequency. Frequencies below 250 MHz are unfavorable
because of the inefficiency of their antennas, if these are to be made compact
enough to match market requirements. On the opposite end, frequencies of
1 GHz and higher suffer increasingly from propagation loss through walls andother obstacles. The ideal range is found between around 300 MHz and 1 GHz,
where you find low attenuation and the range needed to make a systemeconomical; i.e., fewer devices per square meter.
Installation effort and flexibility
When it comes to installation effort, building alterations and subsequent
wishes for expansion, the advantages are clearly on the side of wirelesstechnology. Wireless components can be easily fitted, for little cost, even on
surfaces inaccessible for wired solutions. Speed and flexibility are advantages
not only when expanding and altering at a later date but also during initialplanning and final installation; where components’ placement can be changed
at the last minute—a relatively common occurrence in building operations.
Data volume
Battery-less and service free wireless sensors are ideal for sending measured
data packets and control commands, which in most cases are of small data
volume.
These data packets can then be funneled back to monitoring stations orshared with other devices in different locations via a wired infrastructure,
where higher bandwidths are available, where fully isolating routing can beachieved, and where fewer government restrictions are imposed.
Availability of information
A benefit of using wireless is that the information sent by devices is accessible
anywhere in a room or space, not just along the wires. So components can beoptimally positioned without concern for existing wires or inaccessibility ofplaces for wiring. Combining a wired LON system with EnOcean wirelesscomponents allows an installation to benefit from both technologies.

White Paper – LonMark International & EnOcean Alliance

3/ 9

Fig. 3: Window contact

Fig. 4: Bidirectional wireless room sensor

Reliability
The reliability of wired LON bus systems has been proven for decades in over
100 million devices.
However, when it comes to wireless systems, some people are still skeptical.
But many are feeling increasingly more confident with the advent of EnOceanwireless. After all, there are already tens of thousands of buildings benefitingfrom the advantages of EnOcean wireless technology. Installations include
corporate headquarters (SAP, IBM, Bosch, Siemens, Nestlé), public buildings(schools, hospitals, government facilities), historical buildings, residences,landmarks, and hotels.
First, the technical issues of wireless transmission are addressed by a quality
technology—quite different from the lower quality products marketed byvarious providers. Well-founded planning is the next building block in thereliability of wireless systems. Here, EnOcean offers the support ofinstrumentation tailored to that purpose; plus, planning guidelines proven inpractice.
How wireless components obtain their energy is a further and major aspect ofsecure, reliable installation:
Reduced range, rather than failure of sensing, is the result of batteries runningout of power, which results in having to replace batteries to keep the system
functioning as a whole. In the EnOcean technology, the focus is “no batteries;
White Paper – LonMark International & EnOcean Alliance

4/ 9

so, no servicing.” The use of freely available, ambient energy—generated by
the sun, motion, heat, or vibration, for instance—is a key benefit of the wide
market acceptance of this wireless solution, especially in office buildings. The
concerns of builders, architects, and facility managers regarding batterypowered wireless sensors are quite justified when you think of the thousandsof batteries in a modern building that would need regular replacement. But
these concerns do not apply to EnOcean sensors. Additionally, data published
about the expected, average lifetime of batteries can seldom be taken at facevalue. Although the use of batteries may initially be more cost-attractive, theservice, disposal (toxic waste), and malfunctions can quickly negate the initialsavings.
Cost
Today’s wireless systems already offer cost benefits of as much as 15% upon
first-time installations (depending on complexity) compared to some wired
solutions with the same range of functions. When alterations or expansions
are undertaken (statistics show that the average office building is reconfigured
about every five years), the cost benefit can go up to 80%.
Tying the EnOcean systems into the LON network allows those benefits toincrease by extending the physical reach of the data they share.

2. Examples of EnOcean plus LON
Energy saved through energy efficiency
About 40% of the energy needs of industrial nations are consumed inbuildings—where the potential for savings is quite enormous. How often haveyou driven past an office block late in the evening where all the lights are on,
but only a handful of people can be seen still working? How often have youentered an empty room where the heating or air-conditioning has been goingfull-blast for hours?
The necessity to save energy is not only driven by its high cost, with current
prices of over US$100 per barrel of oil. It is especially due to the predictionthat many nations will simply not have enough energy in the future to satisfy
their needs.
Energy savings, therefore, increasingly becomes a challenge; in answer towhich, a success rate of 100% is a rarity. Costly schemes governed bydemand for those regions highly affected are merely a short-term necessity.
The most effective solution is to construct new buildings, or alter older ones,
to make them energy-efficient. In a typical reconstruction case, it is possible
to save more than 30% of the building’s energy consumption.

White Paper – LonMark International & EnOcean Alliance

5/ 9

Putting LON and EnOcean together
The joint objective of LonMark International and the EnOcean Alliance is:simple but substantial reduction of the energy requirement in buildings. The
two technologies match optimally for the purpose: LON is the leading wiredtechnology (over twisted-pair cable, coaxial cable, optical fiber, and power-linemains) for intelligent building-services management with around 100 million
devices using the technology; while EnOcean represents wireless-based
automation technology, with already tens of thousands of systems
implemented in buildings worldwide.
For example, self-powered sensors and actuators communicate wirelessly as
an intelligent sub-network in a room or area; doing away with conventional
cabling precisely where the configuration of the room is most-frequently
altered. This also obviates the need for those associated costs.
Communication with the control or supervision level can then travel throughLON interfaces, each linking many rooms or intelligent sub-networks to theLON backbone of building automation. In this way, the flexibility of a wirelesssystem is ideally combined with the large bandwidth and range of a wired
backbone.
The rooms in modern office buildings are rearranged, on average, about every
five years; so wireless systems provide just the right flexibility. More andmore, interior architects are discovering the new possibilities of design andinstallation presented by wireless systems, where a switch or sensor is locatedno longer by where electric wires are located. They can be put in the bestplace, in ergonomic terms. Switches to control lighting and blinds can be
attached simply to each workplace of an open-plan office, for example. Lightswitches can be adhered to the headboard of a hotel bed, to a mirror, thetiles, or near the shower partition in the bathroom.
Room temperature sensors no longer need to be installed near doors, avoiding
corruption of the temperature reading by the opening and closing of a door.
Products enabled by EnOcean reduce the laying of cables inside and outsidebuildings, allowing the user to place sensors just about anywhere (e.g., onglass, furniture, windows, and ceilings).
Ideally suited for room automation
EnOcean nodes avoid the 2.45 GHz band of Bluetooth and WLAN. Devices inthat range have to share a limited number of channels. The more popular thisband becomes (the more WLAN-enabled PCs are available), the greater theproblems will become through interference with networks and otherpermanently active systems, such as mobile phones, Bluetooth, and cordlessvideo monitors.
White Paper – LonMark International & EnOcean Alliance

6/ 9

Future, second-generation interfaces will allow entirely bidirectional
communication: Data generated by EnOcean sensors can be retrieved directly
by LON actuators and controllers. LON controllers can in turn communicate
with EnOcean actuators.
Typical applications are those revolving around energy savings, such as
dimming or turning-off the lights when a room is empty; HVAC halting whenwindows are open; or standby mode of heating, ventilating, and airconditioning when a room is not being used.
EnOcean technology has become a standard among architects and system
integrators all over Europe, and is now well set to satisfy big markets in North
America and the Near East. Unlike meshed wireless networks, the wirelessswitches are not active and do not transmit all the time—only when actuated.
Interestingly, the electromagnetic emission of an EnOcean switch is much lessthan that of a comparable, conventional switch for a 100 W bulb. Initial
medical concerns about the high-frequency radiation from wireless sensors
were satisfied by scientific experiments. The use of EnOcean switches canthus be recommended, without concern, in hospitals, schools, kindergartens,
and government and office buildings. Likewise, there are no environmental or
biological concerns regarding attaching such a wireless switch directly to theheadboard of a bed or to a bedside table.
Deployment examples of LON and EnOcean
The combined advantages of LON and EnOcean have been proven in multiple
deployments, such as the office building shown in Fig. 5.
Four Enocean/LON interfaces were installed in the suspended ceilings of thecorridors, each communicating with several offices, all featuring room
temperature sensors, switches for lighting and blinds, window contacts tomonitor the status of balcony doors, and multi-sensors to detect motion andbrightness. Altogether, wireless components were installed in the reception,
the kitchen, the lunch room, the engineering offices, the conference room, andsix offices (the largest more than 1000 square feet).

Fig. 5: Office Building with LON/EnOcean Technology

White Paper – LonMark International & EnOcean Alliance

7/ 9Fig. 6: LON service room

Fig. 7: Layout LON/EnOcean

Installation

Fig. 8: Wireless Sensor on glass

The installation is a good illustration of seamless interaction between wired
LON sensors and EnOcean wireless components. Apart from 230 VAC sockets
and the computer network installed in floor tanks, the offices are cable-less,avoiding any excessive cost if and when the rooms are reconfigured.
The heating and lighting of the single offices are automated. As soon as thewired LON multi-sensors detect a movement in an office, the lights go on—either the entire lighting or just single lamps, depending on ambient light.
The setpoint of the heating system—controlled by the signal of the motion
detector—increases from standby to normal when the balcony door is closed.
The heating valves are controlled by LON I/O modules communicating with thewireless room temperature sensors and window contacts. With the availabilityof the bidirectional LON interface, the outside blinds, lighting, and heating
valves will also be wirelessly controlled by I/O modules. At the moment, theseoutside blinds are still manually controlled. There are also plans to link
automation to a weather station.

White Paper – LonMark International & EnOcean Alliance

8/ 9About LONMARK International
Since its inception in 1994 and new corporate structure in 2003, LonMark
International has become a major driving force in the establishment ofinteroperable guidelines for building, industrial, transportation, residential,and utility automation.
LonMark membership is open to any manufacturer, distributor, engineer,system integrator, or end-user committed to the development, specification,and use of open, interoperable products utilizing ANSI/CEA 709.1 and related
standards.
LonMark International is a non-profit, mutual-benefit trade association withclose to 600 members worldwide, and local affiliates in the Americas, Asia,and Europe. LonMark’s mission is to create, support, and promote thestandards for open, interoperable LON -based products, systems, andprofessionals. For more information about LonMark International, testing, andeducational opportunities please visit www.lonmark.org.
Products, which have been verified to conform to the LonMark interoperability
guidelines, are eligible to carry the LonMark logo.
LonMark and the LonMark Logo are registered trademarks in the US and otherjurisdictions. Other marks belong to their respective holders.
About the EnOcean AllianceThe EnOcean Alliance is a consortium of over 60 companies working to further
develop and promote self-powered wireless monitoring and control systems
for sustainable buildings by formalizing the interoperable wireless standard. It
has the largest installed based of field-proven wireless building automation
networks in the world.
EnOcean®, alliance logo, alliance member logo and ingredient logo areregistered trademarks of EnOcean GmbH and EnOcean Alliance Inc.

White Paper – LonMark International & EnOcean Alliance

9/ 9