Hearth Labs | Measuring the missing half of thermal comfort
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Scanning Mean Radiant Temperature (SMART) Sensor

The SMART sensor uses thermal radiation measurements and LiDAR technology to scan spaces. Combining these datasets with air temperature and humidity measures allows the SMART sensor to fully measure thermal comfort.

Thermal Comfort

Make people comfortable not buildings

Energy Savings

Halve conventional HVAC energy consumption

Building Controls

Your thermostat isn't broken. It's just measuring the wrong thing

Radiant Systems

The best way to control radiant heating and cooling

A New Kind of Data

The SMART sensor combines surface temperature and geometric measurements to digitally reconstruct spaces with thermal information overlaid.

Our algorithms calculate the radiative heat exchange between the environment and a real or hypothetical person at any location. The sensor also measures the air temperature, speed and relative humidity level.

The SMART sensor can determine the thermal comfort of a person at any location in space from a single scan.

The Missing Half

Convective heat losses account for less than half of thermal comfort in buildings.


In typical indoor environments, less than half of a person’s thermal comfort is determined by the air temperature, relative humidity and air velocity. Air conditions are relatively uniform through space and easy to measure using existing thermostats.

Dataset from Hearth Labs' SMART sensor showing thermal radiation from a person. Thermal radiation is the missing half of thermal comfort.


The other, missing, half of thermal comfort is due to radiative heat flux and there has traditionally been no adequate way to measure it. Unlike the air, radiation is dependent on geometry and varies significantly through space.



Analyze and optimize the performance of existing buildings and systems. Find and fix the causes of thermal complaints and energy leaks.

Occupancy Detection

Detect, count and locate occupants by directly sensing people rather than relying on proxies like motion or CO2. The first sensor accurate enough to control HVAC systems.

Thermal Comfort

Measure all of the environmental and personal factors that influence thermal comfort including calculating a person's metabolic rate from the surface temperature of their skin.


Leverage an entirely new form of data to develop new buildings and systems. Go beyond thermal cameras and black globe thermometers to quantify the radiative environment.

Residential Controls

Drastically reduce HVAC energy consumption while improving thermal comfort by moving from building-centric control to occupant-centric control.

Commercial Controls

Characterize a building's thermal behavior and leverage its thermal mass to reduce energy consumption, smooth and shift demand to off-peak times. Reduce occupant complaints and improve office productivity.