In hotels, staff accommodation and student housing across Qatar and the GCC, lights left on in empty rooms waste electricity that nobody notices. A shift worker heads to site and the room stays lit all day. The room simply has no way of knowing it is empty.
An energy-saving relay fixes this from the distribution board. It watches the door and a motion sensor, works out whether anyone is still inside, and switches off once the room has been empty for a set time. This article compares the ELKO EP CRM-101 and CRM-102 and shows where each fits.
Why empty rooms keep using power
In most rooms, anything switched on stays on until someone switches it off. Card switches help, but they only know whether a card is in the holder, not whether anyone is in the room, and many staff accommodation blocks have no card system at all. A guest room management system can handle occupancy, but for many accommodation blocks and mid-scale hotels it is more than the project needs.
What these projects need is simple: occupancy-based power cut-off, decided inside each room, with no programming: set on the front panel with rotary switches; no app, software or network needed.
How an occupancy-based energy-saving relay works
Door contact plus motion sensor
Each relay has separate inputs for a magnetic door contact and a motion sensor. The logic follows how people use a room. Here, "on" means CRM-101 closes its output to the room contactor, while CRM-102 re-enables its light buttons.
- When the door opens, the relay switches on.
- After the door closes, the relay looks for movement. If someone moves inside, it stays on.
- If there is no movement after the door closes, it switches off at the end of the delay, adjustable from 1 to 60 minutes.
- If someone was asleep when the relay switched off, their first movement switches it straight back on, with no delay.
Once movement is detected after the door closes, the relay stays on until the door is used again, so a resident sitting still or asleep isn't switched off.
Card switches
CRM-102 has a dedicated card-switch input; CRM-101 can be combined with a regular card switch. Where key cards are used, CRM-102 can run as a card switch relay (MODE 9 or 10); rooms without cards rely on door-and-motion detection.
No programming: set on the front panel with rotary switches
A MODE knob selects how the inputs behave, and rotary switches and potentiometers set the delays. No app, software or network is needed. CRM-101 keeps the room's existing switches; CRM-102 adds a push button or standard switch per circuit plus Master OFF.
CRM-101 or CRM-102: choose one relay per room
The two relays use the same door-and-motion logic but switch different things, so choose one per room.
CRM-101/UNI: room power cut-off via the contactor
The CRM-101/UNI energy-saving time relay is the simpler option. Wired to the room contactor, it switches off the room's supply once the room is empty. ELKO EP describes it as a replacement for the card switch, saving energy when guests are away.
- 1× 16 A changeover output
- Supply voltage AC/DC 12–240 V
- 1 DIN module
- Switch-off delay of 1–60 minutes
Which circuits go through the room contactor is a design decision for the project's electrical engineer.
CRM-102: six lighting circuits with Master OFF
The CRM-102 hotel relay is new in the ELKO EP 2026 range. Instead of switching one contactor, it controls the room's lighting circuits directly:
- Six 10 A outputs, one for each lighting circuit
- A push button or standard switch for each output, in BJC designs, switching a safe 12 V DC supplied by the relay
- A Master OFF button that switches all outputs off at once
- Zero-cross switching: each load switches as the voltage crosses zero, which is gentle on LED luminaires and extends contact life
- A 10-position MODE knob covering door-contact and motion-sensor combinations, plus card-switch operation
- Supply voltage AC 100–240 V or DC 145–335 V, 2 DIN modules
When the room is empty and the delay runs out, every lit circuit switches off and the buttons stay inactive until someone returns.
Quick comparison
- CRM-101: room supply via the contactor, existing switches, 1 module.
- CRM-102: six lighting circuits, button or switch per circuit, Master OFF, card-switch input, 2 modules.
- Common to both: door contact and motion sensor inputs, 1–60 minute delay, no programming.
Use case: staff accommodation, hotel rooms and student housing
The scenarios below are illustrative, not reports from a specific project.
Staff accommodation (best fit)
Staff accommodation energy saving is where these relays fit best. A typical staff accommodation block houses residents on rotating shifts. Rooms stand empty for long stretches, and there is rarely a card system or anyone checking rooms. One CRM-101 per room, wired to the room contactor, switches off the room's supply once the room is empty. If the brief calls for lighting control by circuit, one CRM-102 per room does that instead. Either way, opening the door restores power (CRM-101) or re-enables the light buttons (CRM-102), so residents don't need to change their habits.
Hotel rooms
For hotels that want hotel room energy management without a full GRMS, CRM-102 suits rooms with several lighting circuits, giving guests a push button or standard switch per circuit and a Master OFF. CRM-101 suits simpler rooms where the aim is to switch off the room's supply through the contactor. Key cards can stay (CRM-102 card-switch input, or CRM-101 with a regular card switch), or rooms can rely on door-and-motion detection alone.
Dormitories and student housing
Rooms stand empty during classes. One relay per room, with no software to maintain, fits this pattern.
Where a full GRMS fits instead
CRM-101 and CRM-102 are standalone: each works inside its own room, with no connection to reception. Control from reception, app control and PMS integration are the job of a guest room management system such as iNELS GRMS, where room units connect over a bus to a central unit that can be integrated with the hotel's PMS or BMS.
In short, the relays are a GRMS alternative for local, occupancy-based switching; GRMS suits operators who need central control of every room.
Notes for MEP consultants and contractors
- Both relays mount on a DIN rail (EN 60715) in the distribution board.
- After power-up, the motion input is blocked for 90 seconds.
- A second delay (0.5–120 seconds) blocks the motion input after the door closes, so a brief look inside doesn't keep the room on.
- Specify one relay per room: CRM-101 or CRM-102, not both.
Frequently asked questions
What is the difference between CRM-101 and CRM-102?
CRM-101 has one 16 A changeover output; wired to the room contactor, it switches off the room's supply once the room is empty. CRM-102 has six 10 A zero-cross outputs for lighting circuits, with a push button or standard switch per circuit and Master OFF. Use one or the other per room.
Will the power go off while someone is asleep?
Once the relay has detected movement after the door closes, it stays on until the door is used again. If it does switch off while someone is still inside, their first movement restores power (CRM-101) or re-enables the light buttons (CRM-102) with no delay.
Can we keep using card switches?
Yes. CRM-102 has a dedicated card-switch input; CRM-101 can be combined with a regular card switch. Rooms without key cards use door-and-motion detection.
Do the relays need programming or a network?
No. The logic and delays are set on the front panel with rotary switches; no app, software or network is needed.
Is this a GRMS alternative?
For local, occupancy-based switching in each room, yes. For control from reception, app control or PMS integration, choose a GRMS such as iNELS GRMS.
Can the relays dim lights or control air conditioning?
No. CRM-102 switches its outputs on and off without dimming, and neither relay is a room temperature controller. For occupancy-linked temperature control, look at a GRMS.
Next steps
See the CRM-101/UNI and CRM-102 product pages or browse the ELKO EP Qatar eShop. For help choosing a relay for your project, contact our sales team at sales@elkoep.qa.