Air Quality: Indoor Environment and Energy Efficiency


In the days following the oil embargo of 1973, it became common practice to cover outside air intakes. This was just one of many actions taken by the uninformed in the hope of reducing energy consumption. Many of these measures, unfortunately, had a negative impact on the quality of the indoor air. Out of such ignorance came an assumption that energy efficiency (EE) and indoor air quality (IAQ) could not both be served in the same facility.

Over the years, the owner’s dilemma regarding IAQ and EE has persisted. Many professional facility managers and real estate managers perceive only two options. There is the constant demand to run facilities as cost effectively as possible, which means that EE should be given a high priority. Unfortunately, many believe that this will result in poor IAQ, which can hurt productivity and/or lose tenants. They fear that a focus on IAQ will drive up their energy costs.

Today, we know that the IAQ risks associated with EE are more perceived than real. Yet fears remain that EE measures may have a negative impact on IAQ. These fears have increased the perception of IAQ risks, created EE sales resistance, and changed the financial dynamics of many projects. Recognizing that these fears exist and need to be treated is a critical first step in serving EE needs. This article addresses those fears and the real relationship between EE and IAQ.


To examine the concerns related to energy efficiency (EE) and indoor air quality (IAQ), and to establish ways to achieve both in a given facility, it is important to:

1. Identify the sources that have linked EE and IAQ and determine whether any causal relationship between the two exists

2. Assess the advantages and disadvantages of ventilation as an IAQ mitigator

3. Consider ways that EE and IAQ might be compatible in a given facility

For years, the second or third paragraph of nearly every IAQ article has mentioned the energy crisis of the 1970s, the resulting tight buildings, and the growing IAQ problems. Readers have been left with the impression that as energy prices soared in the 1970s, owners and facility managers tightened buildings to save money and left occupants sealed in these tight boxes with pollution all about. These fears seem to be substantiated by a report by the National Institute of Safety and Health (NIOSH).

In its early report of investigations to date, NIOSH stated that 52% of the IAQ problems found were due to “inadequate ventilation.” Somehow, that got translated to “inadequate outside air.” A more careful look at that

NIOSH’s 52% figure reveals that such a translation misrepresented the findings. The “inadequate ventilation” problems encountered by NIOSH included

• Ventilation effectiveness (inadequate distribution)

• Poor HVAC maintenance

• Temperature and humidity complaints

• Filtration concerns

• Inappropriate energy conservation measures

Inadequate outside air was only one of a long list of problems

National Institute of Safety and Health also pointed out that the 52% figure was based on soft data. To the extent, however, that they represented primary problems in the investigated buildings, the NIOSH findings imparted another critical piece of information that typically is overlooked: of the problems NIOSH found, 48% were not solved by ventilation. National Institute of Safety and Health determined that nearly half of the problems it had investigated were not related to ventilation. If the NIOSH data and problems identified by other investigation teams are considered collectively, it seems safe to surmise that a great many of our indoor air problems cannot be satisfied solely by increasing outdoor air intake.

Somehow, indoor environment thought processes have been permeated by the idea that a tight building is not good and that it uses only recirculated air. Too often, ventilation has been perceived as being the preferred answer—which, of course, has increased energy consumption.


If the air outside contains more contaminants than the inside air does, an outside-air solution may not be the answer. Fresh, natural air sounds wholesome, and it seems to be an attractive option. However, that natural air can be heavily polluted. When stepping outside the United Airlines terminal at O’Hare International Airport, for example, even a casual observer can tell that the air outside is much worse than the air inside. There is no “fresh air” for the O’Hare facility people to bring into the terminal. Natural ventilation could be a disaster. Opening the windows is not a viable option.

Hay-fever sufferers also tell us that opening the windows and letting in natural fresh air won’t work. Between sniffles, they argue strongly against it.

From another perspective, we should analyze what happens inside when we open the window. What seemed like a good idea can cause a stack effect, in which warm air rises and pressure increases near the ceiling or roof. If we are concerned about a classroom, we could create negative pressure in the basement. Should that school have radon problems, cross-ventilation could cause even more radon to be drawn into the classrooms.

An alternative may be to induce outside air mechanically; that air then can be filtered and diffused through the facility. This method may be helpful, but it is not without problems.


Ventilation is not always the answer. If we are to clear the air about the relationship between IAQ and EE, we need to make that statement even stronger. Ventilation is seldom the best answer. Certainly, it is an expensive answer.

The ASHRAE 62 standard is titled “Ventilation for Acceptable Indoor Air Quality.” To the uninitiated, that sounds as though ventilation will deliver “acceptable” air. It may not. At the very least, the title implies that an organization as prestigious as the American Society of Heating, Refrigerating, and Air-Conditioning Engineers, Inc. has given its blessing to ventilation as the mitigating strategy.

As the various versions of ASHRAE 62 have been formulated over the years, the idea that most of our IAQ problems can be cured by ventilation has prevailed. ASHRAE 62 has, of course, brought relief to many, many people, who otherwise would have suffered from sick-building syndrome. The ASHRAE 62 standard met a key need during the years when it was very difficult to determine what some of the pollutants were, what their levels of concentration were (or should be), and what their sources were. Investigation and measurement protocols have come a long way since the first ASHRAE 62 standard was written, but we are not there yet. Increased ventilation can continue to give relief to occupants when we aren’t quite sure what else to do.

Ventilation, however, is not the preferred treatment for IAQ problems—and it never has been. The U.S. Environmental Protection Agency has been telling us for years that the best mitigating strategy is control at the source.

In the 1970s and 1980s, outside air was reduced so that we wouldn’t have to pay the higher energy costs of conditioning air and moving it around. With less outside air, we suddenly became aware of the contaminants that had been there all along. Less outside air meant greater concentrations. Because reduced ventilation was a fairly standard remedy in the 1970s, it is not surprising that the knee-jerk response to the air-quality dilemmas has been to increase ventilation.

Drawing more air into the building and blowing it around, however, has not necessarily solved IAQ problems. Sometimes, in fact, it has made things worse.


Ventilation has created some IAQ problems where they did not previously exist. Two cases in point will help document the problems that the more-ventilation “remedy” fosters.

Relative Humidity

Historically, when construction costs exceeded the budget, one of the first ways to cut costs was to remove the humidifier/dehumidifier equipment from the specs. Today, without those humidifiers or dehumidifiers, it is very hard to correct the negative impact of increased ventilation on relative humidity. To reduce potential indoor pollutants where IAQ problems may not exist, increased ventilation has invited in all the IAQ problems associated with air that is too dry or too humid. With more than 50 years of data on respiratory irritation—even illness—due to dry air, creating drier air in colder climates suggests that we may be exacerbating the problem.

With all that is known about microbiological problems and their relationship to humid air, creating more-humid air in subtropical climates through increased ventilation is a questionable “remedy.”

The Dilution Delusion

Increased ventilation thinking has prompted heavy reliance on dilution as the answer. Visualize, for a moment, all those airborne contaminants as a bright neon-orange liquid flowing out of a pipe in an occupied area. Would hosing it down each morning be considered to be a satisfactory solution? We have gained false confidence in dilution because the air pollutants cannot be seen—that does not mean they are less of a problem or that dilution is necessarily the solution.

The problem may not have been eliminated by reducing levels of concentration. There is still a lot that we do not know about chronic low-level exposure to some contaminants. A very real possibility exists that in a couple of decades, science may reveal that solution by dilution was nothing but delusion—a very serious delusion.


Using increased outdoor air as an IAQ mitigating strategy tends to make several other assumptions.

First, it assumes that increased outside air is going to reach the occupants in the building. As recently as the mid-1980s, a study of office ventilation effectiveness by Milt Mechler found that 50% of offices in the United States had ventilation designs that “short-circuited” the air flow. When considering possible treatment for IAQ problems, owners, EE consultants, and energy service companies should look at the facilities’ air distribution system. Where are the diffusers? Increasing the outside air may cause a nice breeze across the ceiling, but it may do little for the occupants.

Second, the outdoor-air focus may prompt increased outside air when recirculated cleaned air may be better. Filtration and air cleaning were virtually ignored in ASHRAE’s 62-89 standards and have not been treated sufficiently in subsequent work. Bringing in more outside air, which may be better than inside air, can still cost millions and millions of dollars. The fresh-air focus has too often overruled economics when specified filtration of recirculated air could provide the needed IAQ.

When unnecessary fossil fuels are burned to condition and circulate additional outside air, concern is raised about the impact on the quality of the outside air. A study conducted by the author that was reported at the Indoor Air 1991 conference in Helsinki determined that compliance with ASHRAE 62-1989 increased U.S. public schools’ energy costs by approximately 20%. This measure not only expended a lot of precious tax revenue, but also offered an indication of the tons of additional pollutants that were put into the air each year.


Historically, the amount of outside air needed in a facility has been gauged by the CO2 concentration in the air. This has been done because CO2 is easier to measure than many contaminants are, so it serves as a good surrogate. Because people give off CO2, it logically followed that the air changes per hour should be based on the number of people in an area. People-pollution thinking partially has its roots in the Dark Ages, when baths were not common and associated body odor was a major concern. Through the years, smoking problems have also led to using the number of people in an area as an air intake barometer. In fact, earlier ASHRAE ventilation standards were often referred to as odor standards.

Total reliance on people pollution has led us away from all the other pollution sources. We have subsequently had the Renaissance, the Industrial Age, the Technological Age, and the Information Age, each contributing new pollution concerns.

New volatile organic compounds (VOCs) are added to the list each year. As we “progress,” people pollutants become less of a factor and building materials, furnishings, and “new and improved” equipment take on greater importance. Recent European studies have shown that the building pollutant load is much larger than we expected. When we measure our air intake per occupant, the pollutants created and dispersed to the outdoors by other sources are often overlooked.

Ventilation per occupant does not meet IAQ needs if pollutant sources other than people dominate an area. Laser printers and copiers, as they operate, give off just as many pollutants whether there are two people or 20 people in an office. Bioaerosols released from previously flooded carpet may pose as great a threat if there are 30 people in a room as they will with 300 people in the room. In fact, increased air circulation may draw air up from floor level and increase contaminants at nose level.

The problem has been aggravated by NIOSH’s describing energy-efficient buildings as tight buildings. “Sick-building syndrome” and “tight-building syndrome” became synonymous. The idea became so pervasive that it prompted some very energy-inefficient operations. Too often, operable windows have been removed from building designs. Citing such concerns, one Midwest architect designed a ten-story municipal building with all the windows sealed shut. Recognizing the problem, the energy/environmental manager for the city went through and manually changed all those windows to be operable.

Blaming tight buildings gave us charts like the one in Fig. 1, where we were encouraged to compare those minuscule energy savings with the huge personnel losses. The implications were clear: we were trying to save pennies in EE while losing many dollars to lost productivity due to poorer working conditions.

The conclusion seemed to be obvious: there is a direct correlation between EE and IAQ problems.

To prove this hypothesis, however, it is necessary to show that EE buildings have poorer air quality and lower productivity. Or, to state it another way, there is a direct correlation between a tight building and occupant health.

Cost of energy and salaries in a typical office building.

Fig. 1 Cost of energy and salaries in a typical office building.

With a little regression analysis, we ought to be able to build a straight-line relationship: the more energy efficient a building becomes the greater absenteeism and lost productivity become.

As the virtues of tight buildings are weighed, it is easy to forget that those creaky, decrepit old leaky buildings were full of unconditioned, unfiltered, uncontrolled breezes. Drafty buildings were just as apt to cause discomfort as fresh air was.

More than a decade ago, Joseph J. Romm’s excellent article “Lean and Clean Management”1-4-1 cited several instances in which EE improved productivity. One example he offered was West Bend Mutual Insurance Company’s 40% reduction in energy consumption while it documented a 16% increase in productivity.


Ventilation definitely has its place in an IAQ program. Ventilation can be a good mitigating strategy when the contaminant or its source cannot be determined. Ventilation can also serve as an intermediate step until action can be taken. Further, ventilation may be the best option when source mitigation strategies are simply too costly. Specific applications of ventilation (e.g., localized source control or subslab ventilation to control radon) are valuable control measures. In such instances, more energy may need to be consumed to satisfy IAQ needs.


In considering IAQ needs, the distinction between energy conservation and EE becomes critical. By definition, conservation means using less. Further, conservation is still associated with the Emergency Building Temperature

Restriction regulations of the 1970s, which led us to equate conservation with deprivation. On the other hand, EE means using the required amount of energy for a healthy, productive workplace or for a process as efficiently as possible.

If we are true to such a definition, it is always possible to have both EE and IAQ.


There is a surprising relationship between IAQ and EE. First, survey after survey tells us that when utility bills started climbing in the 1970s, the first place where many owners and facility managers found the money to pay those bills was the maintenance budget. This was especially true of institutions on rigid budgets, such as public schools and hospitals. As the utility bills have gone up through the years, those institutions have progressively cut deeper and deeper into maintenance until their deferred maintenance bills have become staggering.

The second relationship between IAQ and EE can also be traced back to energy prices and maintenance. As energy prices climbed, owners bought more sophisticated energy-efficient equipment. Unfortunately, the training of operations and maintenance (O&M) personnel to operate and maintain that equipment did not keep up. Sometimes, the training wasn’t offered when the equipment was installed. More often, there was turnover in the O&M personnel, and the new staff did not receive the necessary training.

Keeping these relationships in mind, it’s sad to learn that for a long time, we have known that a majority of the IAQ problems found are due to inadequate operations and maintenance. Table 1 offers a review of IAQ problems found by NIOSH, Honeywell’s IAQ Diagnostics Group, and the Healthy Buildings Institute (HBI) in the early 1990s. The labels are different, but the commonality of O&M-related problems is very apparent.


A careful look at our true goal is needed. Every facility management professional and design professional professes that it is his or her desire to provide owners a facility that has an attractive, healthy, safe, productive environment as cost-effectively as possible. If indeed that is the goal, IAQ and EE are very compatible. They go hand in hand.

Assessing some guidelines of the “1980s” will help bring these two aspects in line. First, let’s look at what we call the 80-10-10 rule. Eighty percent of IAQ problems can usually be spotted with an educated eye and a walk-through of a facility. This walk-through may include some very basic measurements (temperature, humidity, CO2, etc.), but it is not a sophisticated, in-depth investigation. The other 20% of problem facilities require more specialized testing—often exhaustive, expensive testing, which typically finds only one-half of the remaining problems. To summarize, 80% of IAQ problems are detected through a relatively simple walkthrough; 10% are resolved through sophisticated, expensive testing; and nearly 10% remain unresolved.

When considered from the EE perspective, a U.S. Department of Energy study conducted by The Synetics Group (TSG)[5] reported that up to 80% of the savings in an EE program comes from the energy-efficient practices of the O&M staff. What bitter irony! To save money to pay the utility bill, owners cut operations and maintenance. Then they end up with maintenance-related IAQ problems and higher energy bills. So the vicious cycle starts all over again, with more cuts in the maintenance budget.

Fortunately, a positive side to such a vicious cycle can help reverse the situation.

If an IAQ walk-through investigation is paired with a walk-through energy audit, (For more information on audits and auditing, see Hansen and Brown.[2]) it is quite conceivable that the identified future energy savings can pay for the needed IAQ work. One walk-through can identify the IAQ problems and determine ways to finance the mitigation. This approach proves once more how compatible IAQ and EE can be.


In pondering this relationship, it is well to consider what will happen as energy prices continue their upward trend (and they will), if for no other reason than that we need to start calculating the real cost of energy. Whether the increases are due to unrest in the Middle East or increasing demands from China, or whether we start doing a better job of figuring the costs of externalities, prices will trend upward. We are dealing with a finite source and increasing demands. It is a serious miscalculation to assume that fossil fuel prices will have a downward trend.

Table 1 Sources of indoor air quality (IAQ) problems

Bldgs. 529 50 223
Yr. 1987 1989 1989
Inside contamination (17%) Maintenance Changed loads Distribution (46%)
Outside contamination (11%) Design

Ventilation/distribution (75%)

Poor filtration Low filter efficiency (57%)
Microbiological contamination (5%) Filtration (65%) Accessibility/drainage (60%) Poor design (44%) Poor installation (13%)
Building fabric contamination (3%) Contaminants (60%) Chemical Contaminated systems Excessively dirty
Thermal duct work (38%)
Biological Condensate trays (63%)
Humidifiers (16%)

As the cost of energy goes up, IAQ and EE are apt to be at loggerheads. This does not have to be the case. If IAQ leaders persist in attributing IAQ problems to energy-efficient buildings, as well as relying on more and more outside air for the answer, we lose. For cost-conscious owners, climbing energy costs typically outweigh most IAQ concerns. Only expensive—and often unnecessary— regulations setting outside air requirements can compete against escalating energy prices. The regulated solution may not solve the IAQ problem, but it will definitely increase energy costs—and increase pollution emissions. Sadly, it could all be paid for with money that typically is wasted on energy inefficient operations.1-3-1

Environmental concerns, higher energy prices, national security issues, and the unnecessary waste of our limited energy resources make increased ventilation a costly answer at the very least. Sustainable development means that we all put our heads together and work for a quality indoor environment, EE, and a quality outdoor environment.

Research has shown that the use of outside air is not always our best option, and that there is nothing wrong with a tight building—provided that a tight building is well designed and well maintained. Tight buildings more readily reveal professional errors. Tight buildings are less forgiving of poor maintenance. A well-designed, well-maintained tight building, however, can provide EE and quality indoor air.

If our ultimate goal is to produce a comfortable, productive indoor environment as cost effectively as possible, EE and IAQ are on the same side. Good managers and effective EE consultants need to have command of both if they are to do their jobs effectively.

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