Gareth Evans from PPM Technology discusses the advances in technology that have made it possible for a wireless system to continuously monitor the indoor environment allowing a scientific approach to the systematic monitoring and management of IAQ.
Measurement and monitoring of hazardous gases is a critical issue in industrial and workplace safety, conventionally worker safety has been concerned with acute levels of airborne pollutants but today there is also mounting concern about the affect of long-term exposure to low levels of pollutants.
Indoor Air Quality and conditions such as Sick Building Syndrome (SBS) are a major concern to businesses, building managers, tenants and employees because it can impact the health, comfort, well being and productivity of the building occupants.
There are many factors that can lead to an unhealthy indoor air environment including poor or inadequate ventilation, airborne and chemical pollutants, ozone emissions from printers and photocopiers, high concentrations of Total Volatile Organic Compounds (TVOC’s), Formaldehyde and pollution from external sources (e.g. fumes).
Health effects from indoor air pollutants may be experienced soon after exposure, the immediate effects are usually short-term and treatable, including irritation of the eyes, nose and throat, headaches, dizziness and fatigue. Long term exposure to low levels of pollutants could have an affect on an individuals health in future years, these, according to the U.S. EPA/Office of Air and Radiation, can be severely debilitating or fatal illnesses including some respiratory diseases, heart disease, and cancer.
Measuring air quality
Typical indoor air quality investigation and examination consists of taking single point measurements of pollutant levels. This monitoring method is unreliable, as the pollutant level is subject to hourly, daily and indeed seasonal fluctuations. Building service professionals and designers alike have regarded these IAQ examination methods as being inadequate considering today’s environmental challenges, however advances in technology have made it possible for a wireless system to continuously monitor the indoor environment to be achieved which allows a scientific approach to the systematic monitoring and management of IAQ.
State of the art gas sensors, automatic sampling, data logging, digital technology and IT, has made it possible for IAQ profiling to be a accurate, efficient and therefore a cost effective system and PPM Technology has developed the Wireless IAQ Profile PPMonitor to facilitate simple, effective and flexible management of Indoor Air Quality. It is able to collect a complete and accurate record of IAQ, presenting facilities managers and health and safety officers with the data they need for the effective management of air quality within the building.
Wireless detection
A wireless system enables simple continuous detection and measurement of many of the factors that contribute to a building’s indoor air environment such as temperature, humidity and a number of toxic gases and compounds including Carbon Dioxide, Carbon Monoxide, Nitrogen Dioxide, Sulphur Dioxide, Ozone, Ammonia, Formaldehyde and Total Volatile Organic Compound’s (TVOC’s).
Controlling these IAQ parameters would improve the comfort and work efficiency of the occupants as well as their immediate and long-term health.
These substances are amongst the hundreds under the regulation of Occupational Exposure Limits (OEL) which are limits to control exposure to dangerous substances in the workplace achieved by setting the maximum amount of (air) concentration of a specific substance. Limit values are laid down throughout the EU, but each Member State establishes its own national Occupational Exposure Limits. In the UK the Health and Safety Commission approved Workplace Exposure Limits (WEL) applies to all workplaces.
The limits intend to protect workers from excessive exposure to toxic substances and the exposure limits are averaged over a specified period of time referred to as a time-weighted average (TWA). Two time periods are used, long term (eight hours) and short term (15 minutes). Short-term exposure limits (STELs) are set to help prevent effects such as irritations of the eye, nose and throat, headaches, dizziness and fatigue, these symptoms can occur following exposure for a few minutes.
It is technically an offence to exceed Workplace Exposure Limits. There is also an over-riding duty to reduce exposure to the lowest reasonably practicable level below the WEL – i.e. they are not just target standards.
A wireless IAQ sensor network has the ability for detailed monitoring in inaccessible locations where a wired infrastructure is not viable or possible. Due to wireless technology a building wide network of monitoring units can be achieved which gives a more detailed representation of indoor air quality in general. A network can be extended simply; by adding dedicated repeater nodes or additional wireless units, each unit with unique sensor specifications if necessary.
The system can initiate immediate audible and/or visible warning of the presence of harmful gases in the air thus protecting employees and the public. Buildings can then be evacuated immediately giving minimal exposure to the building occupants.
An alarm can be used to give a warning that gas concentration level has reached a non-critical but concerning level. It can then trigger the air conditioning system in response before the gas concentration reaches a critical level. A further alarm can give a more severe warning when the gas concentration reaches a critical level.
As a result the health of the workers and members of the public are safeguarded thus giving less immediate impact on the emergency services and in the longer period less impact on the health service. The affected areas will not be contaminated for as long, thus minimising product or manufacturing down time and consequently improving productivity.
Integration
The PPMonitor wireless system can integrate with the BMS Software which allows an entire wireless system to be managed and controlled from a single PC, the BMS can set parameters for temperature, humidity and concentrations of hazardous gases which can then activate and control the air conditioning and ventilation systems. It can also turn on/off heating and as a last resort trigger building alarms.
Continuous monitoring of IAQ enables a profile of the indoor air environment to be created and analysis of the recorded data through dedicated software allows for more efficient management of resources and energy. The software can be used as an analytical tool where trends can be identified and problem areas can be rectified which should lead to better indoor air environment and safer, more comfortable working conditions.
If the building service engineer has the correct data relating to the day-to-day operation of the air conditioning system, improvements to the design and management of the ventilation system can be made. A more effective air-conditioning or ventilating system also has a positive impact on the environment and would ensure optimum human comfort, energy conservation, cost effectiveness and health and well-being of those inside the building.
The PPMonitor utilises the low power, high-performance Zigbee mesh wireless network to communicate and the system can show precise changes in concentration of selected IAQ parameters in various locations over time. The data can be received via the PC Zigbee module; the data is then stored and can be used as detailed statistical data using the dedicated software which can also be used to produce reports and configure individual alarms for particular sensors.
Indoor Air Quality is a critical issue in ensuring the health, safety and well-b
eing of employees. A wireless system can effectively manage the indoor environment and through control of third party systems such as HVAC it can prevent unhealthy indoor air from being present and give immediate warning if a dangerous level of toxic gas is detected, ensuring employees are only minimally exposed to the dangerous substance.