Using your BMS to manage CO2 – going beyond energy efficiency

A slightly scary statistic is that we now spend around 90% of our time indoors. How can BMS help improve the experience?

Traditionally the focus on the promotion of Building Management Systems has been how they can deliver energy efficient buildings. This is still important as buildings account for 41% of the world’s energy usage. A BMS that is installed to the Class A guidelines of the BS EN15232 standard can deliver up to 30% energy savings compared to one which meets Class C of the standard. But there are so many more benefits that a well-designed, installed and commissioned BMS such as the Desigo system from Siemens Building Products can provide.

There is a growing awareness that the quality of the air we breathe has a significant impact on our health, wellbeing  and productivity. Commercial buildings are becoming clean in order to maintain the health of the people who live, work and play in them. So why is healthy air so important and what can be done about it?

There is science behind this: The result of work by Usha Satish (1) et al. published in 2012 is illustrated in Figure 1. The productivity of students was tested for tasks that required different levels of involvement under various exposures to CO2. It was found that even for simple tasks, such as listening and absorbing information, the performance of the students increased by a significant factor of 1.5 when the air quality was improved. For tasks requiring higher levels of involvements, such as taking initiative, the measured performance increased by a sheer factor of 10. Keep in mind that these high-value tasks are what make people stand out and advance their career and are generally speaking what make a workforce more productive.

A BMS can be used to that brings in exactly the amount of fresh air that is needed to make sure occupants stay productive by measuring CO2 levels and delivering demand-controlled ventilation. Companies who know how to drive productivity get the most out of their people’s talent, produce fewer failures and bring better products and services to the market, which in turn drives revenue and profits. Staff are the most valuable asset of any organisation.

There is an understanding that buildings can give you a headache and/or irritation of eyes and throat in what has been called Sick Building Syndrome (SBS). One major cause of SBS is the out gassing from building materials such as carpets, paints or furniture. These gases are summarised as Volatile Organic Compounds (VOC). Recent laws on energy saving require well insulated and draught-proofed buildings to minimise the need for heating and cooling. The resulting air tightness of buildings, however, also keeps the VOC gasses inside, creating SBS among occupants. Humid air as well can indirectly contribute to SBS by promoting the growth of fungi and mould. Besides devaluing the building value, exposure to mould spores represents a hazardous health risk. Symptoms range from allergic reactions to poisoning by mycotoxins. Today already, every second school child is experiencing sensitisation to one or more allergens.

The number one measure to prevent SBS is proper ventilation. In cases where HVAC is not fully automated, it is all about knowing when to open the window. We are increasingly getting used to what is called “quantified life”: We measure our heart rate, record the number of steps taken during the day and want to know the likelihood that it is going to rain today. Similarly, a BMS can be used for monitoring and quantifying remotely not only the SBS indicators of VOC and humidity, but also temperature and CO2 levels, by using one single wall mounted multi-sensor device.

 Studies suggest that next-generation HVAC control systems will incorporate measuring capabilities for pollution factors such as fine dust, and a room or duct mounting fine dust sensor is now available from Siemens with either DC0-10V or Modbus communication. This enables a trade-off between providing fresh air (thus reducing indoor CO2) and the introduction of pollution from outside. Smart algorithms also anticipate pollution based on weather forecast: A building is ventilated in the middle of the night, when pollution is typically low, or before an inversion weather situation occurs that typically comes with high fine dust concentration.

The air that we breathe has a significant impact on our health and productivity. Since we spend most of our time in buildings it is of great importance to make sure indoor air is clean and healthy and controlled properly. Sufficient ventilation helps to keep people productive and avoid unhealthy conditions. The BMS is key to ensuring you create perfect places for your health and productivity.

[1] Usha Satish et al., Is CO2 an Indoor Pollutant? Direct Effects of Low-to-Moderate CO2 Concentrations on Human Decision-Making Performance. Environ Health Perspect; DOI:10.1289/ehp.1104789, 2012,

Ian Ellis is Marketing Manager at Siemens Building products

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