By Bob Baker

At the annual meeting of ASHRAE, the board of directors decided to develop a ventilation standard for homes. This is an outgrowth of the activities of the committee that has been considering revisions to the society Standard 62-1989, which addresses ventilation in commercial buildings. The committee had considered adding a chapter dealing with the needs of residences in the revision. Comments received in the public review of the document indicated that there are vast differences between residential and commercial needs.

This development is important to contractors with a customer base largely made up of residential business because ASHRAE standards serve as the basis or are incorporated into local building codes. Whatever requirements end up in the new standard will most likely be part of our designs of the future.

What will a Residential Standard 62 Include?

We can only guess at what provisions a residential ventilation standard may include. ASHRAE is just now taking applications from those interested in becoming a part of the committee that will draft the standard. The final form that such a standard will take will depend on their ideas and input received from the public at large.

We have some indications, however, of current thinking in the industry. The committee working on the revision of the 1989 version of the commercial standard proposed inclusion of a chapter that they felt incorporated residential needs. We can look at the thinking of at least some of the "experts" by reviewing this chapter (Chapter 9 of 62-R).

Much of the attention given to this chapter has focused on Table 9.2. This, like the famous table 2 in 62-1989 provides minimum levels of outside air that must be supplied to living areas. We have long included an outdoor air supply in the design of commercial HVAC systems. Separate outside air inlets in home systems has been the exception. Does this new requirement mean that every home will now have an inlet for outside air? The impact could be large. The cost of a system will increase due to the outside grill and added ducts. There will also be a corresponding increase in instillation labor. When calculating the system capacity, the outside air will have to be taken into account. Operating costs will increase both in warm climates where the outside air will have to be cooled and dehumidified and cold climates where it will have to be heated and humidified.

Cost Concerns

Many who viewed the draft document expressed concern about all of these new costs. The requirement for a supply of outside air has been included because most authorities in the field agree that outside air is needed to dilute the built up contaminates that lead to indoor air quality problems. In many commercial buildings that have air quality problems one of the causes has been found to be outside air dampers closed. At the same time, many are already concerned about the present construction and operating cost of home HVAC systems. It seems wrong to spend more when we have worked for years to sell high efficiency furnaces and air conditioning units with improved SEER numbers.

The draft standard called for 5 CFM of outside air per 100 square foot of occupiable floor space or 15 CFM per person. Even a modest home could require 50-100 CFM of outside air. In extreme climites, that could both call for a larger system and increase operating costs. In addition, the language following the table suggests that even higher rates of outside air may be required if sensitive individuals occupy the dwelling or there are strong sources in the home. (It is not clear what the authors mean by strong sources.)

Not A Radical Change

On closer reading, the suggested requirements may not be all that different from current practice. The notes on Table 2 mention that outside air requirements may be satisfied by any of three methods: a) Mechanical ventilation, b) Demonstrated Ventilation, or c) Natural Ventilation. Only the mechanical ventilation option would require an outside inlet and special ducting. More than adequate natural ventilation to meet the standard could be made available in the vast majority of homes just by opening the windows. Section 9.6 of the draft states clearly that operable windows satisfy the requirements and the occupants are responsible for opening the windows when needed. Even a home with fixed windows might meet the standard if not sealed too tightly. Section 9.6 also makes allowance for "demonstrated ventilation". Thus, a home with enough unsealed cracks and air leaks to satisfy the requirements through air infiltration would appear adequate. A contractor could complete the home, bring in a blower door and document the envelope leakage. If it were high enough, the requirement would be satisfied. If not, an air inlet could be added for the remaining amount of outside air. Since even well sealed buildings have considerable infiltration, that alone may meet the outside air needs. All in all, it looks like an outside air requirement for homes may be a "non-issue"…or is it?

What is Your Opinion?

If this is not an issue, then why all the concern that has been expressed and why was a requirement even included in the draft standard? The second part of the question is simple. There are homes (usually upscale) that do not have operable windows and are tightly sealed. Thus, a minimum standard is needed. The reason for so much concern is any new standard, even one that is minimal, holds the potential for added costs. It also further limits the freedom and flexibility of the designer. Many oppose a new standard for that reason.

There are also many that oppose introduction of outside air in any quantity on the basis of energy savings. They point out that increasing outside air in commercial buildings has not solved all IAQ problems. Until there is greater proof of the value of increased outside air, they will continue to oppose requirements for homes. What is your opinion? Please write or call and share your feelings with me. We will summarize the answers and provide them to the new committee. I will also share the responses in a future column.

Outside air is not the only design factor addressed. Next month, we will review the other components of the Chapter 9 draft and speculate on additional directions a residential standard might take.

Mr. Baker's field of expertise is the control of contamination in air-conditioning and ventilating systems by mold, mildew and bacteria. He writes and speaks frequently about the efficacy, legal risks, and regulatory issues involved in various control strategies. He serves on ASHRAE Technical Committee TC 2.3, TC 2.4, TC 9.8, and Sampling of Airborne Particulate Concentration in Commercial and Residential Buildings GPC 17P. He also serves as a member of ASTM D22.06 (Indoor Air Quality) and is on the Board of Directors of the Indoor Air Quality Association and the Florida Public Health Foundation. Because HVAC applications encompass new uses from an U.S. EPA regulatory standpoint, Mr. Baker works closely with the EPA and industry groups, including serving as the chair of the IAQ committee of the Consumer Specialty Products Association, to help formulate policy in this area.

Bob Baker is Chairman and CEO of BBJ Environmental Solutions, Inc., a company specializing in providing clean air through environmentally responsible products, such as BBJ MicroBiocide , BBJ Micro Coil Clean , "FreshDuct Odor Eliminator ", and BBJ Mold and Mildew Remover™ as well as the revolutionary new Power Coil Clean™. For additional information, Mr. Baker can be reached at (800) 889-2251 or through the company web site at http://www.bbjenviro.com.