Lockdown is upon us again but at some point, we will start returning to our workplaces, hopefully sooner rather than later. People are going to want reassurance that buildings are safe. So, how can we do this? Information is key; what are the conditions in the building?
Traditionally, building management systems (BMS) have used temperature as their key controlling element. This of course makes sense; we want a comfortable environment but also, we want to control in as energy efficient manner as possible by not overheating or cooling, but do we think of other key measurement values when designing a system and the benefits these values can bring to occupants?
Two other elements that can be used are relative humidity (RH) and air quality. There are additional wellbeing benefits by measuring and controlling these elements. If the RH is kept between 40-60% then the spread of cold and flu viruses can be reduced by up to 70%.
Air quality can be maintained by either measuring CO2 levels or VOC’s (volatile organic compound) levels. Maintaining a good level of CO2 brings many advantages.
As an example, 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.
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 summarized as Volatile Organic Compounds (VOC). Recent laws on energy saving require well insulated and draught-proofed buildings to minimize 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 mold. Besides devaluing the building value, exposure to mould spores represents a hazardous health risk.
Air quality will also help ensure adequate ventilation in buildings if managed properly which is another positive.
So, the benefits of measuring and controlling these values can be shown. But how many buildings have these sensors fitted? If I look at our sensor sales in the UK, the vast majority are still temperature sensors. It’s a cliché but if you can’t measure it you can’t manage it. So, in existing buildings there could be options to add additional sensors, although this still will not solve the problem if there is not the plant there to make meaningful changes (e.g. no humidification capability).
But where we can make a difference is on any new builds. These should all have the relevant sensor capabilities (and the relevant plant) specified from the start. Space for the sensors should not be an issue, in many cases multi sensors are available which incorporate temperature, RH and CO2 sensors in a single housing for example. There are added advantages as well. CO2 sensors can be used to drive a demand-based control approach which as well as bringing wellbeing benefits can also lead to more energy efficient control. Remote monitoring of sites with this additional information can help determine decisions on when building can be reoccupied.
But the key to all this is fitting all the available sensors in the first place. So next time you design a control system make sure you have all the measured values available via sensors to help that building work in the smartest manner possible.