Open-source bed climate · Design phase
Sleep at your temperature. On your hardware.
Open Bed Climate is an open-source bed climate system. Water runs through a thin mat on your mattress, and Peltier modules cool or warm it, separately for each side of the bed. It runs locally with Home Assistant, is built from standard parts, and has no cloud and no subscription.
Open hardware (CERN-OHL-S-2.0)Open software (Apache-2.0)Not certified, not a medical device
Yours, locally.
No cloud, no account, no subscription. Your temperature schedule runs on the hub next to your bed, and Home Assistant sees every zone natively.
Safety by architecture.
The networked hub can only ask for a temperature. A separate control chip enforces fixed limits, and hardware cutoffs act even if every line of software fails. You never touch mains wiring.
Standard parts, your kit.
PC-watercooling parts, Peltier modules, a Raspberry Pi Pico 2, an ESP32 and certified plug-in power supplies. Every part is listed by the job it does, so you can swap it.
Claims you can check.
Each kit is a small text file. Our test suite checks its temperature claims against an open thermal model. Write your own kit and get the same check.
How it works
Water, a heat pump the size of a coaster, and two small computers.
- Mat. A thin water mat lies on your mattress, one zone per side.
- Thermal module. Peltier modules move heat into or out of the water. A pump circulates it.
- Control board. A Raspberry Pi Pico 2 runs the temperature loop and the safety limits, with a 43 °C ceiling, flow and leak interlocks, and a watchdog.
- Hub. An ESP32 running ESPHome runs your night schedule and connects to Home Assistant. It can only request temperatures.
Pick a kit
Start from a kit. Change anything.
All kits warm to 43 °C, the safety cap. The test suite checks every kit's cooling claim against the thermal model.
Solo Starter
3 Peltiers per side · load cells sensing
- Coldest water
- ~21.7 °C*
- Warms to
- 43 °C
For a first build and a single sleeper.
Kit detailsDuo Standard
4 Peltiers per side · pneumatic sensing
- Coldest water
- ~18.8 °C*
- Warms to
- 43 °C
For couples, with our strongest Tier 0 cooling.
Kit detailsDuo Reference
4 Peltiers per side · piezo grid sensing
- Coldest water
- ~18.5 °C*
- Warms to
- 43 °C
For experienced builders: reference PCBs and the best biometrics.
Kit details* Model estimate for a sleeper in bed in a 25 °C room. Checked in CI against the thermal model, not yet measured.
Safety
Water, several hundred watts and a sleeping person.
We take that seriously: fixed limits in firmware, independent hardware cutoffs, certified plug-in supplies only, and a commissioning checklist before the first night. Nothing here is certified, so you build at your own risk.
- 43 °C maximum setpoint, compiled in, not configurable
- 50 °C bimetal cutoff on every cold plate
- 0.15 L/min flow before any Peltier current
- 10 s without a heartbeat and the bed goes to a safe state
Where we are
Tested in software. Waiting for its first night.
Works in software (tested)
- Thermal model and kit checks
- Control and safety logic (setpoint clamp, flow interlock, heating taper, watchdog)
- OPL protocol (Open Peltier Link), with golden frames shared by Python, Rust and C++
- Pico 2 firmware core matches the reference (compiles, not yet run on hardware)
- ESPHome hub component with Home Assistant entities and night schedules (compiles for ESP32-S3, not yet run on hardware)
- Three kits and a parts catalog listed by role (designed, not yet built)
Next
- Verify the remaining parts against datasheets
- Fan and pump PWM control
- Firmware update path over OPL
- First hardware bring-up of the control board and hub
Needs you
- The first physical build
- Five measurements only a prototype can give us
The most valuable contribution right now
Build one and measure it.
Every number on this site is still a model estimate. One honest build report with photos and measurements is worth more than any line of code.
Get involved
There is a place for you.
You don't need to be an engineer. Each role has tasks that are open today.
Builders
Build the Solo Starter and post a build report
Parts hunters
Verify the {unverified} unverified and {listing} listing-only part examples against datasheets
Electronics & safety
Review the safety concept and the "must not change" limits
Mechanical & textile
Prototype the water mat (welded TPU channels), dry-break couplings and an enclosure with drip tray
Firmware
First bring-up of the Pico 2 control firmware on a real board (wiring in WIRING.md)
Home Assistant & software
Run the ESPHome hub component on real hardware
Researchers
Piezo signal quality per grid position (heart-rate detectability across sleeping positions)
Writers & translators
Clarify the docs; start a translation under docs/i18n/<lang>/