Demand Controlled Ventilation (DCV) systems tailor the ventilation rate to building
occupancy by monitoring CO2 levels. This significantly improves the energy efficiency of the
ventilation system as energy is not wasted heating unnecessarily large amounts of fresh
outdoor air, and driving the ventilation system’s fan. Although energy savings vary
dramatically based on occupancy patterns, typically a 25% saving in fan power and
ventilation space heating load is achieved.
CO2 sensing for DCV is currently performed using infra-red technology. These sensors
perform well but are cost prohibitive for domestic installations and their high price has
severely restricted their deployment in non-residential buildings. To date DCV has only been
deployed in a few niche applications that can stand the high sensor cost such as auditoriums,
conference halls, and lecture theatres. Solid electrolyte sensors are capable of providing
accurate low cost measurements (for example the automotive "lambda" sensors). However,
despite being present in the scientific literature for over 20 years, solid electrolyte based CO2
sensors have not yet been commercialised. This is due to poor long term stability (drift), and
large differences between measured and theoretical cell voltages.
The sensors group at the University of Cambridge has recently made a breakthrough which
overcomes these problems (the "ionic separator"), and has fabricated a CO2 concentration cell
with voltages agreeing precisely with thermodynamic calculations, and no signal drift
whatsoever. The aim of the project is to build on this breakthrough and develop an innovative
CO2 sensor prototype suitable for use in DCV systems. The technology is inherently low cost,
making DCV economically possible in all ventilation systems, including domestic systems.
After development is complete, the technology will be adopted by Vent-Axia.