2012年9月17日 星期一

Indoor Environmental Quality (IEQ) Problems And Opportunities


In reality, the perfect office doesn't exist today. Evidence that it doesn't, if any is needed, comes from a survey of members of the International Facilities Management Association (IFMA). IFMA asked more than 7,000 facility managers at U.S. corporations to rank the complaints they received most often. At the top of the list, according to the 2,400 respondents, were indoor environmental quality concerns. The biggest complaint was being too hot; number two was being too cold.

Employees responding to another survey reported difficulty doing their work because of poor indoor environmental quality. Those employees specified a number of factors as "stressors." Again, being too hot or too cold were among the top complaints. In fact, all of the top five stressors related to indoor environmental quality (IEQ):

1. Lack of air movement

2. Being too hot in summer

3. Stagnant air

4. Cigarette smoke

5. Being too cold in winter

IEQ is a broader term than IAQ - indoor air quality. IAQ deals specifically with the condition of the air within the building's occupied spaces. IEQ addresses the overall condition of the indoor space. Elements of IEQ include indoor temperature, ergonomics, noise and lighting, as well as the quality of the indoor air.

While there's no distinct line between IAQ and IEQ, what is clear is that the HVAC system has a substantial impact on both areas. What's also clear is that evaluating the HVAC system in light of the broader IEQ concerns can bring important benefits, including improved occupant comfort, reduced complaints and enhanced employee performance.

HVAC and IAQ

IAQ, of course, is a familiar topic for facility executives. It's also an area that's easy to overlook until a problem arises. Often, it is an accumulation of factors that cause the problem. Smoke, odors, dust and high occupancy in an area with too little ventilation all can decrease comfort and affect employee productivity. The U.S. Environmental Protection Agency (EPA) ranks indoor air as one of the top five environmental threats to human health. According to the World Health Organization, 30 percent of commercial buildings show signs of Sick Building Syndrome, including headaches, nausea, irritated nasal passages, itchy eyes and skin irritations.

Most code authorities recognize standards for ventilation air qualities established under ASHRAE Standard, which is based on the maximum possible number of occupants in the building. What complicates the matter is that, in the case of outside air, more is not necessarily better. The problem is how to avoid wasting energy by unnecessarily overventilating a building. Among the solutions are the methods used to control the ventilation, such as time-based ventilation, demand-based ventilation, carbon dioxide sensors and mixed gas sensors.

Controlling humidity

Humidity plays an important role in indoor environmental quality. If it gets too low, it causes respiratory problems, particularly for people with allergies, sinus problems or asthma. If it gets too high, more places become breeding grounds for microbial growth.

ASHRAE standards suggest relative humidity levels should be maintained between 30 percent and 60 percent. That means at times humidity needs to be added to the air and at other times it must be removed.

High relative humidity can have an impact on absenteeism and increases the potential for respiratory illnesses among workers. When relative humidity exceeds recommended levels, humans are adversely affected. Our sinuses are affected when humidity is too low and our skin dries out. Too high humidity causes different bacteria to propagate in mechanical systems.

There's another advantage to controlling humidity directly. The building owner can reduce energy bills in the heating season by reducing the temperature that would otherwise have been maintained and increasing the relative humidity within healthy ranges. The opposite can be done in the summer. Raising the temperature above what would otherwise have been maintained and lowering the humidity allows the body to evaporate moisture off the skin to stay cool.

While humidity and airborne contaminants are traditionally considered in IAQ analyses, other important IEQ factors may not be. Consider air movement. So many people look at IAQ from a system level and they tend to overlook what's happening in the occupied space. ASHRAE spells out rules for selecting a diffuser based on an air diffusion performance index (ADPI). An ADPI of 80 or higher assures adequate air movement.

Temperature is another issue that isn't always included in discussions of IAQ. One rationale for excluding temperature is that IAQ should be limited to health and safety issues.

Unfortunately, that distinction doesn't matter to building occupants who are complaining about their space. Rightly or wrongly, complaints about temperature are often attributed to poor indoor air quality. What's more, it can be difficult to separate health issues from ones tied to comfort.

Equally important is that employees who are uncomfortably hot or cold are likely to be less productive than they would otherwise be. That's one more reason facility executives are better off taking the IEQ approach to analyzing interior space.

Gains from good IEQ

A report for the National Energy Management Institute states that even in healthy buildings, a 1.5 percent productivity gain is possible when IEQ measures are instituted. In fact, the 1.5 percent gain is the conservative estimate; the report says that gains may be as high as 10 percent.

Productivity gains are not the only benefits from improving indoor environmental quality. Good IEQ also is good business.

To the building owner, good IEQ is a very clear plus. When you have good thermal comfort and good acoustic comfort, it differentiates your building from your competition. You can market your building as a clean and comfortable environment in which to work.

Analyzing IEQ

There are four basic steps to take. First, listen to your occupants and understand what they are saying about the building's indoor environmental quality. The second is walk through the building checking for those things and take specific measurements for those problems. The third step is to go back to the source - the HVAC system, for example - and take measurements there, making sure the equipment is doing what it is designed to do. The fourth step is to document any revised design or maintenance procedures that are taken to correct the problem. You also want to incorporate an occupant response mechanism for feedback to make sure you have corrected the problem.

Before making HVAC improvements, facilities executives need to conduct an economic analysis. Often, this analysis is based on utilities costs and savings. But, payback periods for HVAC improvements are much shorter when all major cost elements are added to the analysis. Such factors as building operating costs, salary costs and current productivity losses that could be regained shorten the payback period for proposed improvements.

Indoor environmental quality can be improved in nearly every building. And a number of steps can improve quality without costing much. In fact, many steps are just good facilities management.

You need to do proper maintenance of the building. Set up a checklist on a periodic basis and keep a log of all maintenance of your HVAC system. Do carbon monoxide monitoring for ventilation and make sure all controls are operating properly.

Facility managers and their staff need to fully understand how the HVAC and other systems in their buildings were intended to work and keep them operating in that manner. When major remodeling occurs or changes in space occupancy or usage, the ventilation and thermal requirements of the space need to be reviewed. When replacing equipment, the facility's staff needs to be involved in the selection, location and installation of the new equipment. This can help assure that the equipment will meet their needs and that they understand how it is to be operated and maintained. Building managers should also demand that the systems and equipment selected meet the currently established standards-of-care in that industry.

There are many solutions to indoor environmental quality problems, but it's not wise to wait for the crisis. Facility executives are better off looking now, before they have a problem. Chances are they'll find a number of IEQ issues that need to be addressed that can be handled at next to no cost. Half the issues that arise involve simple things your inhouse staff can do, like changing filters, cleaning drain pans, using high efficiency vacuums in housekeeping and so on. When you wait for the complaints, you are in a reactive mode trying to find a Band-Aid when you could have a more serious situation. If you consider IEQ now, you can take a more holistic approach and prevent your building from experiencing many IEQ problems.

Given all things on the facility agenda, it can be tough to find time to tackle a problem that no one is complaining about. But being proactive can pay off. One direct benefit is that, over the long term, a preventive approach will save time, perhaps a significant amount of time. There's another plus: Facility executives who can show senior managers that their actions have increased employee satisfaction or productivity are positioning themselves as problem-solvers and are demonstrating that the buildings they manage are assets, not costs.




Julian Arhire is a Manager with DtiCorp.com - DtiCorp.com carries more than 35,000 HVAC products, including industrial, commercial and residential parts and equipment from Honeywell, Johnson Contols, Robertshaw, Jandy, Grundfos, Armstrong and more.





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