Focus on occupant health
It is now widely accepted that good building control strategies support energy efficiency. Ian Ellis of Siemens Building Technologies in the UK highlights how controls can also support better occupant comfort — and productivity.
It is not startlingly new to say that the indoor environment affects occupants of buildings. Even in the early 2000s, studies from all over the world were showing that issues such as indoor air quality affect humans.
As far back as 2002, a US study by Lawrence Berkley National Laboratory showed in a survey of 100 US office buildings that symptoms of sick-building syndrome resulted in a decrease in occupant productivity of around 2% nationwide, resulting in an annual cost to the country of around US$60 billion.
In 2007, consultants KPMG were saying: ‘Companies ought to be checking CO2 levels in their buildings...otherwise... reduced levels of productivity could cost a company thousands of pounds.’
More recently, research carried out by the World Green Building Council (WGBC) in 2015 highlighted the three main sources of discomfort to occupants.
•Uncomfortable temperature
•Inadequate lighting
•Poor air quality
It found that where these conditions are present, they can cause poor concentration, sickness, absences, poor decision-making and low moods among staff — all contributing factors to a significant drop in productivity for any business.
It has always been a challenge to justify the investment in 'green' or energy-efficient buildings. Since employee costs are always the highest for any business (double those for commercial rent and significantly higher than energy costs) the ability to demonstrate that better buildings mean better business is very important.
The key is to find a balance between energy efficiency and occupant comfort. Finding a sweet spot that optimises energy use, but which also provides a good indoor environment, requires holistic thinking. A good control strategy can balance these two requirements smoothly, and also offer occupants the added benefit of some control over their own environment.
This holistic approach to controlling indoor environments is known as 'total room automation'. It implies an interconnection between elements such as HVAC, lighting and, perhaps, also blinds and windows. Any element of building services that impacts on occupants and energy use is controlled by a central BEMS, with room automation units that allow occupants to make slight adjustments to the temperature, light or fresh air levels.
This is very much a demand-based control strategy. Building services are only used when they are required. This reduces energy use, lowers maintenance costs (because equipment doesn't run continuously) and creates better indoor comfort.
Demand-based control is recommended in the British and European Standard BS EN 15232 (2012). The Standard deals with the impact of building controls and building energy management systems on energy efficiency. It rates controls systems from a D (non-energy efficient) to an A (high energy performance). Demand-based control is a pre-condition for achieving class A. BS EN 15232 shows that a building applying demand-based control will use around 30% less energy than one which uses only very basic control systems.
The WGBC research of 2015 highlighted that the total room automation approach, resulting in a better indoor environment, would give a 3% rise in output from occupants. Even if this only affected 50 staff, such an improvement would result in a payback of just under €80 000 in just one year, with total payback for the installation of a demand-based system completed in two years.
What's more, in terms of energy savings, this equates to a 33% reduction in costs and a drop in CO2 emissions of 120 t per annum.
Another important element of occupant health in buildings is ensuring that occupants feel they have control over their environment. Good-quality room controls will enable occupants to adjust the environment to suit their needs — but also ensure that the building returns to optimum efficiency rather than drifting away from strategic set points.
One example of this is the Siemens Green Leaf symbol which is available on a number of its room controllers. This system automatically detects unnecessary energy consumption in the room and notifies users by changing the colour of the Green Leaf icon on the room control unit: If room operations are energy efficient, this icon is green.
To reset the room control to energy-efficient operation, the user simply presses the display and the icon returns to green. Research indicates this functionality can lower energy consumption by up to 25% without affecting comfort.
For many building owners, improved energy efficiency has often come at a cost to the internal environment. The benefit of a controls strategy that links together each of the determining factors in the quality of that environment is that both objectives can be achieved.
A harmonised approach that allows HVAC to respond to occupants and their behaviour is the way to deliver the optimal working space with the required energy savings — and, crucially, that all-important higher productivity.
Ian Ellis is marketing manager for Siemens Building Technologies in the UK.
