Occupancy comfort is it an exact science or fine art?
The comfort of your employees in the workplace is by nature ambiguous. What is ''comfortable'' for one person is not for another and this can extend to light levels, noise, draughts and humidity as well as space temperature.
With the trend towards health and wellbeing in organisations, these factors, individually and combined, play an important part in the occupiers perception of their working environment. They can both promote or reduce productivity and satisfaction depending on what conditions are being achieved and how effectively they are being managed.
In the latest Leesman review (25), three of the top six “physical features” which are important to the responders were:
- Temperature control;
- Natural light; and
- Noise levels.
- The other three just for reference were, desks, chairs and meeting rooms (small).
And most of the responders were "dissatisfied" with:
- Noise; and
- "Quiet rooms for working alone or in pairs".
Facilities Managers are all too aware that year on year occupancy comfort will be amongst, if not, the biggest dissatisfaction for users in their working environment. So what are the issues and what can be done about them? The truth is there is no "one size fits all" solution, managing occupancy comfort is a multifaceted fine art, but do you have the tools to paint the right picture?
We have been measuring the aspects of buildings for over 30 years, providing not only the reassurance that conditions are good, but also the right picture you need to optimise your building's environment.
Below you can see some factors you could consider.
1. Turning up the heat on temperature
The Workplace (Health, Safety and Welfare) Regulations 1992, Regulation 7, Temperature in indoor workplaces, states:
(1) During working hours, the temperature in all workplaces inside buildings shall be reasonable.
(2) A method of heating or cooling shall not be used which results in the escape into a workplace of fumes, gas or vapour of such character and to such extent that they are likely to be injurious or offensive to any person.
(3) A sufficient number of thermometers shall be provided to enable persons at work to determine the temperature in any workplace inside a building.
While there is no absolute law for minimum or maximum working temperatures, "the temperature in workrooms should normally be at least 16 degrees Celsius unless much of the work involves severe physical effort in which case the temperature should be at least 13 degrees Celsius." (ACoP L24).
Depending on the type of environment - dwelling, office, bakery, warehouse, cold store or workshop - the space temperature can vary significantly and strategies for maintaining "reasonable" need to be adopted. Specific working environments also have different ranges of temperature suggested. For example in office environments (general, executive and open plan) CIBSE Guide A recommends a winter circulating air temperature of 21°C to 23°C and in Summer 22°C to 24°C. In further guidance, CIBSE also note "Indoor operative temperatures over 28°C for long periods will result in increased dissatisfaction and reduced productivity."
As well as space temperature, heat derived directly from warm objects/equipment (e.g. the sun, electric fires, ovens/cookers, dryers) can influence occupancy comfort. The HSE highlight that the Radiant temperature resulting from this radiant heat "has a greater influence than air temperature on how we lose or gain heat to the environment" and so needs to be factored in, where occurring in your workplace.
Trade Unions and other groups have lobbied for maximum/upper limits on workplace temperature to be agreed, and other industries, particularly food production/catering, have run initiatives/campaigns on working temperature awareness and control.
With the provision of thermometers, in today's workplaces, digitalisation and wearable technologies have seen a dramatic increase in what can be measured. Accuracy is the key however with BMS sensors as well as any others used needing calibration, if they are to provide meaningful real-time data.
2. Seeing through the fog of humidity
Relative humidity (RH) is the amount of water vapour in air in comparison to the amount needed for saturation of that air (at the same temperature) and expressed as a percentage.
Within the workplace, RH can vary significantly based on external climatic conditions, artificial humidity control, as well as internal processes that may influence the metric (adding or removing water or heat to the local environment). From a health and safety/building services perspective the comfort range is between 40% and 70%.
At levels increasingly and persistently above 70% RH, problems with damp and mould (mold) can be experienced and in recent years the air tightness of particularly dwellings has seen this become more of an issue. As high humidity can also prevent the evaporation of sweat from the skin, some non-breathable types of PPE can also cause issues with prolonged use in warm environments.
As RH drops further below 40%, initially contact lens wearers and other particularly sensitive to the parameter can experience "dry" or "scratchy" eyes and throats. Where it drops to 30% and below these symptoms can increase and issues with for example static electricity on metal surfaces - lift buttons and handrails - can also occur.
One further consequence of longer term low humidity levels can be 'phantom flea syndrome' where occupiers in an area of the building complain of "flea bites" on their lower legs, ankles and sometimes arms. In reality this is again the work of static electricity discharges and surprisingly when an area is sprayed with either a chemical treatment - in response to the concerns - or just water (most treatment chemicals are predominantly water), the symptoms alleviate because the humidity is increased and the static dissipates.
3. Blowing hot and cold with airflow?
Airflow velocity measurements assess the speed of air moving within the environment. They are typically measured in metres per second (m/s).
In naturally ventilated workspaces air flow velocity will depend on the activity occurring in the space and the degree to which external windows, grilles, etc. are opened and the 'breeziness' of the day outside. In mechanically ventilated buildings it will depend on the set up, performance and balance of the system. Some systems incorporating fan coil units for example can have variable speed controls, others such as VAV systems increase or decrease the rate at which air is introduced to the space to optimise temperature.
Typically minimum fresh air requirement in mechanically ventilated buildings would be 8 to 10 l/s per person and this should ideally translate into head height airflow velocity measurements of 0.05m/s - 0.30m/s.
Poorly configured and/or imbalanced systems can lead to both complaints of stuffiness or draughts. Some of the issues that can arise include:
- “Dead areas" where no discernible airflow is occurring being labelled stuffy or stagnant;
- Small air movements in colder environments, or indeed during the Summer when maximum cooling is being called for, can raise complaints of draughts;
- Office moves and/or poorly angled supply grille louvres/deflector plates can put occupants directly in the air supply and again lead to complaints of draughts; and
- Particularly with split or packaged air conditioning units too much user control leads to the "unit on" and "unit off" camps and so a cycle of operation and non-operation. Unsurprisingly leading to complaints of stuffiness and draughts at the same time on occasions!
4. Pardon - Noise in the workplace
Noise in the workplace needs to be considered from two perspective health and safety and nuisance.
Managing noise in the UK is a long established discipline although the current requirements through the Control of Noise at Work Regulations 2005 did see a tightening of the prescribed action levels:
"The level at which employers must provide hearing protection and hearing protection zones is now 85 decibels (daily or weekly average exposure) and the level at which employers must assess the risk to workers' health and provide them with information and training is now 80 decibels. There is also an exposure limit value of 87 decibels, taking account of any reduction in exposure provided by hearing protection, above which workers must not be exposed." (Extract HSE website).
Understanding where noise levels may play a significant part in a person's daily exposure and what cumulatively that exposure is are the elements in determining risk and so how they can be managed.
Nuisance noise is altogether a different matter. Particularly with increasingly open plan offices the ability of our colleagues or pieces of equipment to inadvertently disturb us had increased. Noise levels in typical offices can vary significantly with ranges from 35-40 decibels (dB) to as much as 65-70dB.
Depending on the type of work we are doing, we do have the ability to filter out much of the background noise (music/conversation in shops or coffee shops for example) on other occasions when we need to really concentrate even background noise can distract (how many of us automatically turn the radio down in the car when we are in an unfamiliar town or city?).
Providing a range of spaces and environments for people to work in, segregating "noisy" or intrusive equipment and even acoustic screens provided by furniture, plants or other equipment to absorb some of the noise are possible solutions.
Too little noise can also cause problems with some people describing their environment as "creepy". Because of the very low background levels of noise even a small increases in noise levels are exacerbated. In these environments white noise generators or similar can be installed to help.
5. Shining a light on light
Lighting is another aspect of the work environment that is very personal.
Legally, the Workplace (Health, Safety and Welfare) Regulations 1992 state that "every workplace shall have suitable and sufficient lighting and that, so far as is reasonably practical, this lighting shall be by natural light." The Health and Safety (Display Screen Equipment) Regulations 1992 adds "any room lighting or task lighting provided shall ensure satisfactory light conditions and an appropriate contrast between the screen and background, taking into account the type of work and the vision requirements of the user".
Guidance depending on work activity but primarily recognising that most people will now be using some form of display equipment is 300 - 500 lux. For workers completing detailed they may prefer a brighter illumination.
As well as providing light zoning empathetic to the lay out and usage of an area, consideration must also be given to:
- Natural daylight (with, dependent on building orientation, the need for blinds, screens or similar that you can tilt);
- The provision of task lighting as needed;
- The flexibility to cater for written work, reading and technical design work as well as computer based activities; and
6. Developing your own “work of art”
While we have considered the main elements of occupancy comfort individually so far, in reality they work in combination in providing the overall satisfaction or not as the case may be. Complaints of "dry" or "stuffy" can be as much about airflows and relative humidity as they can about temperature (or indeed the influence of all of them).
As our buildings become more adaptable and flexible places to productively work, so we must also consider the changing nature of these environments in not just in the areas of health, safety and wellbeing but in the levels satisfaction we provide in the comfort of our occupants.
Space planning, sustainability and energy performance initiatives too have potential unintended consequences when it comes to particularly occupancy comfort and air quality.
Fun, creative and dynamic workplaces certainly support this but should never be at the expense of the fundamentals which include not just air quality and equipment (desk, chairs, etc.) but the temperature, humidity, airflow, noise and light levels we are providing.
We have more ability now to measure more aspects of our building's performance than ever before - as do our employees and occupants. Understanding how all these figures and parameters interact is a different matter. Here there is no substitute for in depth, detailed, accredited and independent assessments of your building's environment, covering rationalised inspections, checks and tests, not just arbitrary measurements.
What will you say the next time you have a comment from an occupant on concerns over their comfort, or could you be in a position to proactively promote the environmental conditions within and so well being of your building?
Assurity Consulting are leading experts in workplace health, safety and environmental compliance. For over 30 years we have worked with organisations of all sizes, working with them to measure, track and improve indoor air quality in their buildings. For more information on our services, please contact us on tel. +44 (0)1403 269375 or email us. email@example.com