Product category:
Building management systems
News Release from: Seeley International (Europe) | Subject: Breezair
Edited by the Processingtalk Editorial
Team on 06 August 2007
Producing comfortable thermal
environments at work
Working in high thermal environments, in buildings with inadequate ventilation, reduces staff morale and productivity, and leads to accidents and absenteeism: Breezair offer a cost effective answer
The aim of HVAC is to provide good air quality and a comfortable thermal environment that will ensure occupant satisfaction, health and high productivity The challenge for engineers is to achieve this aim while keeping energy costs at a low level
This article was originally published on Processingtalk on 3 Jul 2008 at 8.00am (UK)
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Working in high thermal environments affects those functioning in both commercial and industrial surroundings.
As outside temperatures increase, buildings with inadequate ventilation become unbearably hot and stuffy.
This problem is compounded in premises into which direct sunlight can penetrate causing the building to behave like a greenhouse.
Further reading
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Not only does this affect staff morale, but it can lead to absenteeism, reduced productivity and accidents.
According to studies carried out by the National Aeronautics and Space Administration (NASA) as long ago as 1968, productivity falls 3.6% for every degree above 22C and 4.7% per degree over 30C.
In addition, with moderate heat stress, cognitive performance is also adversely affected with mental performance showing a reduction of 2% per degree.
* How the Human Body Handles Heat.
As environmental temperatures approach normal skin temperature, cooling of the body becomes more difficult.
If air temperature is as warm as, or warmer than, the skin, blood brought to the body surface cannot lose its heat.
Under these conditions, the heart continues to pump blood to the body surface, the sweat glands release liquids containing electrolytes onto the surface of the skin and the evaporation of the sweat becomes the principal effective means of maintaining a constant body temperature.
Sweating does not cool the body unless the moisture is removed from the skin by evaporation.
Under conditions of high humidity, often experienced in the UK, the evaporation of sweat from the skin is decreased and the body's efforts to maintain an acceptable body temperature may be significantly impaired.
With so much blood going to the external surface of the body, relatively less goes to the active muscles, the brain and other internal organs.
Strength declines, fatigue occurs and alertness and mental capacity may be affected.
Workers who must perform delicate or detailed work may find their accuracy suffering, and others may find their comprehension and retention of information lowered.
Studies carried out by Langkilde in 1978 found that the optimum industrial work temperature to be 17 - 24C whilst the optimum temperature for arm movements is 21C.
Other studies carried out by the British Industrial Fatigue Board found that there was a lower output in hot / heavy industries in summer than winter and an increase in accidents when air temperature deviated from 20C.
* Office Environments.
Poor air quality within the office workplace can have an enormous economic impact on costs due to lost productivity.
Improvements to the workplace environment are a highly cost-effective way of enhancing employee satisfaction, productivity and the company bottom line.
It has been shown that office task performance becomes slower as temperatures rise above 21C.
In a study carried out by Niemela et al (2001) it was found that call centre worker productivity decreased by 1.8% per degree C when the temperature was above 25C.
Whilst heat has a debilitating affect on a workforce, refrigerative air conditioning necessitates sealing a building, resulting in reduced ventilation and poor indoor air quality.
The requirement to provide a healthy workplace environment under Health and Safety Legislation is an on-going problem for many employers.
It is now known that all sorts of airborne contaminants are present in the workplace.
Gases, vapours, dusts, fibres, pollens, insect fragments, bacteria and fungi and their spores, plus viruses all contribute to indoor pollution.
Certainly many of the pollutants can adversely affect the health of the building occupants.
It is now thought that natural ventilation is the safest, most economic and healthiest way of introducing cooling into the office environment.
Whilst opening windows on days when temperatures are below 20C can produce a cooling effect, once outside temperatures exceed 23C, only warm air is being introduced.
The Workplace (Health, Safety and Welfare) Regulations 1992 states that workplaces should be adequately ventilated.
In order for a workplace to be adequately ventilated clean air should be drawn from an outside source and circulated around the building.
The ventilation system should remove and dilute warm humid air and provide air movement; this should create a sense of freshness without causing a draught.
Humidity and ventilation should be maintained at levels which prevent discomfort or problems of sore eyes, especially if display screen equipment is used.
* Evaporative cooling accomplishes these requirements.
First, it cools the air, producing a more comfortable thermal environment.
Second, it adds water vapour to the air, increasing the relative humidity and relieving symptoms such as dry skin, nasal and throat membranes.
Third, it reduces the vapour pressure deficit (VPD), which is the force that evaporates water from the environment.
Evaporative cooling reduces the temperature of the air by natural evaporation as it passes through a water saturated cooling pad.
As water is evaporated, heat energy is lost from the air, reducing its temperature.
The major components of this system are: water saturated cooling pads, a water supply and pump, a water distribution system, water reservoir, and air supply fan.
Evaporative cooling systems such as Breezair systems offer an automatic drain valve that keeps the system clean: this is pre-programmed to automatically drain stale water from the reservoir and replace it with fresh.
When the Breezair machine is switched off the drain valve will automatically empty the water from the reservoir after a fixed predetermined time, leaving it clean, dry and healthy.
At the same time a "weather-seal" will close off the air conditioning ducts to impede dust from entering the building, and to minimise heat loss from cold draughts.
* Industrial Environments.
Providing cooling for workers in industrial environments to improve productivity and reduce absenteeism from heat stress has previously been perceived as financially prohibitive.
Instead, companies have chosen to reduce heat and humidity by opening widows, using fans or creating airflow through exhaust ventilation or air blowers.
Whilst in some cases this has gone some way to improve conditions, most workers report that such measures have made no marked improvement on their working environment.
Now, however, many companies are turning to evaporative air conditioning systems such as Breezair to provide a cost effective solution to providing environmental cooling.
Costing a fraction of the cost of air-conditioning to install and run, evaporative cooling can be utilised to spot cool a specific area / areas, or cool a complete building.
Providing decreases in temperature of around 8C, evaporative cooling can have a marked effect on a company's bottom line by increasing productivity, reduced operating temperatures, decreasing absenteeism and accidents.
It is not just during the summer that evaporative cooling is needed.
High internal temperatures in factories, warehouses and office complexes effect workers and productivity throughout the year.
Evaporative cooling provides all businesses with a cost effective solution that helps increase production, decrease downtime and improve workers' morale.
For Case Studies describing industrial environments where Breezair evaporative cooling has achieved improved working conditions in factories, mezzanines and processing areas, please consult the Processingtalk story listing from Seeley International.
This article was contributed by Steve Kirkwood BSc (Hons) ATI, who is currently Sales Manager for Breezair Seeley International (Europe) Ltd.
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