Minor Ventilation Control

Minimise energy costs by measuring CO2

Either too little or too much fresh air in a building can be a problem. Over-ventilation results in higher energy usage and costs than are necessary with appropriate ventilation, but inadequate ventilation leads too poor air quality that can cause occupant discomfort and health problems.

Why measure CO2 in buildings?
The value of carbon dioxide in the air can affect us a lot. The recommended indoor concentration of CO2 is about 800 ppm. If it is lower, like 600 ppm, the room is over-ventilated, which is unnecessary and potentially costly. The hygienic limit is around 5 000 ppm. At higher CO2-concentration, about 15 000 ppm, it causes shortness of breath and raised heart rate. Concentrations of 20 000 to 80 000 ppm may cause convulsions, immediate paralysis and in worst case death.

How does it work?
The CO2-concentration in a room varies depending of the number of people in it. An empty room generally has a concentration about 400 ppm (normal outdoor concentration), then the CO2-concentration in the room increases for each added person. Therefore using a small system of Demand Controlled Ventilation is good. This means that a sensor is measuring the CO2-value, and it sends a signal to a ventilator or a VAV-device (Variable Air Volume) that changes the level of the ventilation to the room. The system has variable dampers that are usually used to regulate the air flow through the sensor. For clarity we can say that a minor ventilation system is an intelligent sensor or analyzer which is adjusting one fan in the same room. This fan is regulating the air flow.

Reduced costs
This application saves a lot of money thanks to the energy savings, when a room is empty or just a few people in it, compared to ventilation with a constant air volume. This reduced use of  energy is also very good for our environment on earth and is an obvious way to conserve the earth´s resources. The indoor air gets healthier because many viruses and bacteria are disappearing. Also the numbers of particles that occur indoors are reduced by ventilating a room. Tests of buildings that are using Demand Controlled ventilation show that the energy costs are reduced by
about 30 %. This can lead to a return on investment in about 1 year. [1]

Benefits?
- Energy saving
- Positive Environmental impact
- Healthy indoor environment
- Minimise energy costs by measuring CO2

[1] PhD Hans Martin, CTO at SenseAir AB, 2013-01-30