For one who installs heating-cooling systems in about 3,000 new single-family homes a year, finding out what 62.2P, Ventilation for Acceptable Indoor Air Quality in Low-Rise Residential Buildings, recommends in regard to residential ventilation is important. He was heartened that the National Association of Home Builders (NAHB) signed on — at least conceptually — to the idea of an indoor air quality (IAQ) standard for new construction.
“Much as I hate to have things legislated, the homebuilding industry should sign onto the standard,” he said. “We see new homes with three, four, even five furnaces, to say nothing about multiple water heaters. This will starve the house of combustion air if ventilation rates aren’t sufficient.
“We have to come in to fix homes we didn’t do the work on, and we’ve seen many homes that have half the combustion air they should.”
New way of doing businessWhile there are many resources to improve the IAQ of commercial and institutional buildings, little focus has been placed on improving IAQ in residential structures — until now.
Mechanical ventilation for homes took a step forward at the recent ASHRAE Winter Meeting 2000 in Dallas. Here, the final draft of this much-talked-about, much-debated, and sometimes highly controversial standard was opened up for discussion in a question-and-answer session on opening day of the meeting.
Even though the questions covered familiar ground, the answers were apparently satisfactory. There were no food fights or fisticuffs, and the general consensus was that these addenda should at least proceed to the public review period.
To hvac contractors, it will mean a new way of doing business. There will be new requirements, changes in building codes, and perhaps more opportunity to sell up when it comes to selling and installing the basic hvac system. And while the standard does not address existing structures, an expected “pull through” could affect the entire housing industry.
Although no timetable was officially announced, expect Standard 62.2P to be published for public review soon.
At a press breakfast, ASHRAE president Harley Goodman noted that more than half of all problems with indoor air can be attributed to inadequate or improperly operated or poorly maintained hvac systems.
“In the past, residential ventilation was not a concern because it was felt people received enough air through use of windows and envelope leakage,” Goodman said. “But new houses are built much tighter and people are less likely to open windows because of energy costs, security issues, draft, and noise.”
Homebuilders show reluctanceOne of the standard’s proposed addenda would require the establishment of a minimal ventilation level in new homes, a revolutionary concept. Opposition has been stiff from the NAHB, which is cautious when it comes to adding expense to the cost of new homes.
As a result, the new standard will be a mild, “light” version compared to what some IAQ proponents would prefer. One comment was that any necessary equipment modifications or additions would have to add less than $1,000 to the cost of an average new home. Others said an even more reasonable figure would be around $250 or less.
This figure could be translated more simply into a larger size bathroom exhaust fan. The average bathroom fan now sold is used primarily to ventilate just the bathroom area to control excess humidity. A larger fan would draw air from other rooms as well.
Other factors would enter into the equation, and minimal ventilation levels can be met in other ways besides the installation of a larger exhaust fan.
Fans, too, must change, it was noted. As they get larger to move more air, they need to stay quiet or homeowners won’t use them, said a few commentors. It was noted that some fans will operate automatically, according to occupant or humidity sensors, or on timers.
No big added costA requirement for carbon monoxide detectors will also likely be part of the standard.
Joe Lstiburek, Building Science Corp., suggested the cost would include a net increase of about $75 for a larger fan, with an additional $75 for a CO detector.
“The benefit to the builder of this $150 to $250 incremental cost per house is a reduction of callbacks due to condensation and mold problems, and a reduction in liability associated with indoor air quality issues,” he said at the press breakfast.
“It levels the playing field for all builders by establishing a defensible standard of care in addressing indoor air quality contaminants.”
Some of the exhibitors at the International Air-Conditioning, Heating, Refrigerating (IAHR) Exposition, which was held in conjunction with the ASHRAE Winter Meeting, were showing energy recovery ventilators (ERVs) or heat recovery ventilators (HRVs). These exhibitors noted that local or state ordinances, in some cases, are going farther in requiring adequate mechanical residential ventilation — including the state of Minnesota.
Others will watch what Minnesota does and may follow suit, said one, especially in the northern states where energy costs are higher, and in the southeastern states where moisture incursion is a major problem.
But many others agreed that any sort of residential ventilation standard is a welcome starting point. And a stricter standard from ASHRAE probably has no chance of approval, exhibitors agreed.
The need for mechanical ventilation is there, several people said, because of the improved tightness of homes over the past 20 years for energy efficiency. There is less opportunity for natural air infiltration in these homes, leading to a buildup of contaminants and inadequate ventilation.
To keep the standard as simple as possible, it will not address different climate regions. One late change, however, most likely will reduce the ventilation rate for larger homes. There is a national trend towards building and buying larger homes, but unlike commercial structures, larger homes do not necessarily have more occupants than smaller ones, and therefore should not require higher ventilation rates.
Some said that while they are not completely satisfied with the proposed new standard, it is important for ASHRAE as a whole to show consensus and support of the document in order for it to gain acceptance. Other changes can come in the years ahead.