Wireless vs Wired Sensors: The Real Retrofit Cost in 2026

TL;DR: In a retrofit, the wireless vs wired sensors question is almost never about the sensor. It is about the cable run. Thirty wireless monitoring points across three floors of an occupied office cost £5,868.62 ex VAT in hardware and mount in roughly two team-days. The cabled equivalent needs thirty cable pulls, ceiling access, fire-stopping and out-of-hours working. Wired still wins for control and safety interlocks.

Last updated: 29 July 2026. All prices GBP, ex VAT, verified against the Indiott store on the date of publication.

What this guide covers

• The real difference in a retrofit
• Why the cable run is the expensive part
• A worked 30-point cost comparison
• What battery life you actually get
• Where wired genuinely still wins
• A decision table by site type
• How to mix both in one building
• FAQs

What is the real difference between wireless vs wired sensors?

In a wireless vs wired sensors comparison the devices themselves measure comparably. A wired sensor is powered and read over a cable back to a controller. A wireless sensor carries its own power and transmits a small packet to a gateway on site. What differs is everything around them: how power reaches the device, who has to be in the ceiling void, and what has to be made good afterwards.

That is the whole of it. Framed as a technology argument, the wireless vs wired sensors choice becomes a comparison of broadly similar spec sheets that misses the line item actually moving the total. In a new build, where containment is already going in and the ceiling is open, wired is cheap and sensible. A retrofit is a different exercise, because the building is finished, occupied and often old.

That last point matters more than it sounds. The UK Green Building Council notes that around 80% of the buildings that will exist in 2050 are already built, and that non-domestic stock accounts for 23% of the built environment’s operational emissions. Almost every monitoring project you scope is a retrofit. So the retrofit case, not the new-build case, is the one worth costing properly.

Why is the cable run the expensive part of a wired sensor retrofit?

Because in any wireless vs wired sensors costing the sensor is a small fraction of an installed point. Getting a cable from a sensor position back to a panel means containment or trunking, lifting ceiling tiles, coring through fire compartments and fire-stopping them again, cable tray on plant-room walls, testing, then making good the plaster and paint you disturbed.

Then there is when the work happens. You cannot run trunking through a floor of desks at 11am on a Tuesday. Access is evenings and weekends, which carries a premium and stretches the programme.

Older stock adds a step first. The HSE is unambiguous: “If the building was built or refurbished before 2000, assume that there is asbestos in it.” Ceiling voids, risers and switchgear enclosures are exactly where asbestos-containing materials turn up, and exactly where cable wants to go. A survey before you disturb the fabric is real cost and real delay. A sensor screwed to a wall surface never enters that conversation, which is often the single biggest swing in a wireless vs wired sensors budget for older buildings.

The UK industry reference Designing Buildings puts numbers on the shape of the curve. Comparing wireless sensors against wired controllers cabled back to a panel, it reports that four wireless sensors plus a receiver cost about 30% less than the wired equivalent, twelve sensors roughly 50% less, and thirty-two sensors over 60% less. The gap between wireless vs wired sensors grows with point count, because each extra wired point is another cable run while each extra wireless point is another device on the same gateway.

What does a 30-point retrofit cost? Wireless vs wired sensors compared

A concrete scope: three floors of an occupied office, 30 monitoring points. Twenty ambience points covering temperature, humidity, CO2, light and occupancy. That occupancy layer is worked through in the desk occupancy monitoring guide. Six electrical circuits metered in the risers. Four door contacts. Two gateways for floorplate coverage.

The wireless side of this wireless vs wired sensors comparison is exact, because these are live catalogue prices:

Installation is short because there is almost nothing to install. The AM300 series mounts with 3M tape or two wall screws and is configured by holding a phone against it over NFC. The CT clamps are non-invasive and, per the Milesight datasheet, need no de-energising. A two-person team can cover 30 points and commission two gateways in about two days, in normal hours, with no ceiling access and nothing to make good.

Be clear about what is estimated. The £5,868.62 is verified. The cabled column is not, and we will not invent a contractor day rate and present it as fact. What we can say honestly is that the cabled scope replaces two team-days of surface mounting with thirty individual cable runs, containment, out-of-hours access, fire-stopping, making good and, in pre-2000 stock, an asbestos survey first. Price that with your own contractor’s rates.

The point of a wireless vs wired sensors comparison is not the hardware line. Both sides land in a similar place there. It is that one side carries a small labour number and the other carries a labour number that dominates the quote. If your contractor’s cabled quote is mostly labour and containment, that is not overcharging. That is the job.

How long do wireless sensor batteries really last?

Shorter than the marketing, and it depends almost entirely on what the sensor measures. The LoRa Alliance advertises “10+ years of uninterrupted usage without the costs of changing batteries”. That is achievable, but not by every device, and it is the part of the wireless vs wired sensors debate that vendors are least honest about.

Compare two Milesight datasheets. The EM500-UDL ultrasonic level sensor runs a single 19,000 mAh D-cell and is rated at 10 years at a 10-minute interval and 25°C. The AM300 series ambience sensor runs four 2,700 mAh AA cells, and at the same interval the datasheet quotes: AM307 around 3 years, AM307L around 4 years, AM308 over 1 year, AM308L around 1.5 years.

The difference is not radio, it is sensing. The AM308 adds a laser-scattering particulate sensor and a photoacoustic CO2 element to the AM307’s set, and those draw real power every reading cycle. The radio packet is trivial by comparison. Milesight footnotes the figures as tested “under laboratory conditions and for guideline purposes only”, worth repeating to anyone budgeting maintenance.

Three consequences for any wireless vs wired sensors budget. Transmit interval is your main lever: 15 or 30 minutes on an office CO2 sensor is usually plenty and materially extends life. Budget a battery swap as a maintenance line, not a surprise. And where a device can be mains fed, feed it. The AM300 range accepts 5V over USB-C, and the AM319 variant runs mains as a LoRaWAN Class C device.

The neatest case is energy metering. The CT303/CT305/CT310 is described in its datasheet as “self-powered, free from batteries or external wires”, harvesting from the induced current in the conductor it clamps. No cable, no battery, no maintenance interval. If you are scoping IoT energy monitoring, that is as close to free-running as this gets.

Where do wired sensors still win?

Wired wins wherever the constraint is power, speed or consequence. Any honest wireless vs wired sensors guide has to say so, because this is the difference between a system that works and one you rip out. Four cases where you should not go wireless.

Anything safety-critical or interlocked. Emergency stops, gas detection shutdowns, fire and life-safety systems, machine guarding. These are certified as hardwired systems, and a battery-powered device reporting every ten minutes has no business in that loop.

High-frequency data. Vibration analysis, power quality, anything sampled continuously rather than summarised. LoRaWAN devices are duty-cycle limited and send small periodic payloads. Waveform data needs a cable or a mains-powered device.

Control, not monitoring. This is the important distinction in any wireless vs wired sensors decision. Wireless is excellent at telling you what is happening. Actively driving a valve, damper or VSD with tight response requirements belongs on the wired control layer of your BMS.

Anywhere power is already present. If the device sits next to a live panel and a socket, the argument for a battery evaporates. Take the power.

Check radio coverage rather than assume it. Concrete cores, lift shafts and basement risers all attenuate 868 MHz, and an hour with a LoRaWAN field tester before you order saves a return visit. For the underlying radio detail, start with what LoRaWAN is; if you are choosing between low-power radio technologies rather than between wireless vs wired sensors, our LoRaWAN vs NB-IoT comparison covers that separately.

Which should you choose? Wireless vs wired sensors by site type

Site type predicts the wireless vs wired sensors answer better than anything else, because it predicts how hard the cable run is. Use this as a first pass, then check radio coverage and separate control points from monitoring points.

How do you mix wireless and wired in one building?

For most retrofits the wireless vs wired sensors answer is both. Split the job by function, not by floor: monitoring goes wireless, control stays wired. Every point that exists to tell you something (room conditions, energy consumption, tank levels, door status, occupancy) becomes a battery or self-powered LoRaWAN device reporting to a gateway. Every point that exists to make something happen stays on the existing BMS wiring.

The two layers meet in software rather than in conduit. Your gateway pushes to a network server and a dashboard; where the BMS needs a wireless input it takes it over the network, not over new cable. That avoids the mistake at both extremes: cabling points that never needed a cable, or putting a safety function on a battery.

Start small enough to prove coverage. One UG65 gateway and a handful of sensors on the worst floor will settle your wireless vs wired sensors argument faster than any desk study. The LoRaWAN starter kit at £619.49 ex VAT bundles a gateway with three environmental sensors for exactly that. If it works where the concrete is thickest, it works everywhere else.

Wireless vs wired sensors: frequently asked questions

What is the main cost difference between wireless vs wired sensors?
Hardware costs are broadly comparable, so a wireless vs wired sensors comparison turns on installation. A wireless point is surface-mounted and configured by phone in minutes; a wired point needs a cable run, containment, ceiling access and making good. Designing Buildings reports the wired premium growing from about 30% at four sensors to over 60% at thirty-two.

How long do wireless sensor batteries actually last?
From about a year to ten, depending on what the sensor measures. At a 10-minute interval Milesight rates the AM308 at over 1 year and the EM500-UDL at 10 years. CO2 and particulate elements are the drain, not the radio. Longer reporting intervals extend life substantially.

Are wireless vs wired sensors equally secure in a commercial building?
LoRaWAN uses two layers of AES-128 cryptography with separate network and application session keys, and the LoRa Alliance security whitepaper confirms the application key can be hidden from the network operator so it cannot decrypt payloads. Treat the gateway like any networked device: segment it, patch it, control admin access.

Can I mix wireless and wired sensors on the same system?
Yes, and for most retrofits you should. Put monitoring on wireless and keep control and safety interlocks wired. The two layers integrate at network and dashboard level rather than requiring new cable between them.

Do wireless sensors need a gateway?
Yes, and it is the one piece of shared infrastructure a wireless vs wired sensors comparison must include. LoRaWAN sensors transmit to a gateway that backhauls over Ethernet or cellular. One gateway typically covers a floorplate, so its cost is shared across every sensor and falls per point as you add devices.

Are wireless sensors less accurate than wired ones?
No. Accuracy is a property of the sensing element, not the transmission method. The AM300 series is specified at ±0.2°C for temperature and ±2% RH for humidity regardless of how the reading leaves the device. What differs is sampling frequency, where wired has the advantage.

Getting a retrofit priced

If you have a cabling-heavy quote in front of you, price the same scope as a wireless retrofit and settle the wireless vs wired sensors question like for like: hardware, labour days, out-of-hours access, and what has to be made good. Tell us the building, the number of points and what you need to see, and we will scope it with real part numbers and real prices. Get a retrofit quote, or browse the full sensor and gateway range if you would rather price it yourself.