The Comfort Zone: Taking the Guesswork Out of Residential Zoning
A new ANSI standard takes the guesswork out of residential zoning.
One bedroom in his house has long posed a problem for Stan Johnson. Located over a garage, the bedroom tends to be noticeably warmer than the rest of the house in the summer and colder in the winter.
As the retired president of, and now consultant to, Stan’s Heating & Air Conditioning, Inc., in Austin, Tex., Johnson knows exactly what to do: Install a zone damper system to regulate airflow and achieve greater consistency of room temperatures. And that task just became easier, he says, thanks to ACCA’s recent publication of Manual Zr: Zoned Comfort Systems for Residential Low-Rise Buildings, approved by the American National Standards Institute (ANSI) as the industry standard.
“Previously, we had some confusion regarding zoning because different manufacturers gave different advice about the same type of equipment,” notes Johnson, a former chairman of the ACCA board. That meant one contractor might install a zone damper system according to one set of specifications that another contractor, following different guidelines, would conclude was installed incorrectly.
“Our specifications and guidance to the contractor don’t necessarily adhere to that of our competitors’,” acknowledges John Brown, chief engineer at EWC Controls, Inc., Englishtown, N.J. “The new manual levels the playing field by establishing industry-specific guidelines that apply, regardless of the equipment used. Having this baseline enhances the legitimacy and credibility of the zoning process.”
A Suggested Approach
Although common in commercial buildings for decades, zoning has gained popularity in the residential market in the past five to 10 years. Interest has grown, believes Johnson, “because people want to keep their houses more consistently comfortable—they’re tired of having some rooms hot and some rooms cold.”
In addition, some states have gotten into the act by considering legislation that requires zoning. North Carolina offers a prime example of a mandated code change, says Ellis Guiles, vice president of TAG Mechanical Systems, Inc., in Syracuse, NY “Now, if you build a new home in North Carolina or renovate an existing one with an HVAC system,” he notes, “you have to demonstrate there is no more than a four-degree temperature differential between the first and second floors.”
That goal might be achieved by installing two separate HVAC systems, one for each floor. Or, instead of relying on one thermostat to regulate temperature for a single floor or the entire house, a home might use two, three, or even four thermostats in various rooms or areas. “All of those thermostats connect to a central control, which opens and closes airflow dampers in the ductwork to direct, or disallow, airflow to particular parts of the house,” says Brown. Those changing air circulation volumes require varying management strategies, to ensure optimal performance of the equipment.
“Although zoning can be complex at times,” Brown adds, “contractors shouldn’t be hesitant to offer the technology, because it can greatly improve a home’s comfort level.” With that in mind, here are five tips for how best to approach the zoning process.
1. Clarify customer expectations. What tops the customer’s priority list: The ability to control temperatures in different rooms? A more consistent comfort level? Given the wide range of zoning systems’ features and price tags, it also helps to get a handle on how much the customer is willing to spend, before discussing possible options.
“Some systems are not elaborate, while others are technologically sophisticated and offer many bells and whistles, such as an iPhone app for monitoring zone temperatures,” says Guiles. “The type of zoning system should really be the homeowner’s choice, which requires a contractor to be familiar with more than one type of equipment or manufacturer.”
2. Thoroughly evaluate the home. What site considerations come into play — for example, does the home have an East-facing wall of glass that will result in solar gain? Does it have spaces conducive to temperature differentials, such as an unfinished basement or a converted attic? What structural limitations—such as accessibility of ductwork in an existing house—are present? In view of the customer’s desires, how many zones are feasible?
Then, says Guiles, “You’ll need to do a load analysis to determine how the load is currently distributed and what airflow is needed to take or bring energy to specific spaces. The results of your analysis will drive the system’s design.”
3. Keep an open mind. “Don’t go in with the preconceived idea that zoning is the solution to any customer concern or complaint regarding comfort,” advises Dave Swett, president of Real World HVAC, Inc., Omaha, Neb. “There may be a simpler or alternate solution that helps the existing system operate better.” For example, the homeowner might enhance comfort by increasing insulation levels, sealing ducts, installing new windows and doors, or simply adding window treatments such as external awnings.
To arrive at the ideal solution, Swett says, “You need to take a whole house, or total system, approach. Zoning isn’t just about the equipment—it involves many interdependencies, including all the home’s peculiarities.”
If you do recommend zoning, Swett adds, revisit the customer’s expectations rather than imposing your own as you consider structural limitations, equipment limitations, potential trade-off s, and overall cost. For instance, he says, “The customer may be willing to tolerate less control of the temperature in one area of the home to improve the temperature level in another area. The customer is a key part of the final decision.”
4. Sell the benefits. Most people readily grasp the concept that zoning improves a home’s overall comfort level. What they may not appreciate is how individualized that comfort can be, says Guiles. “Many cars now have individual comfort controls, for the front, back, and both passenger sides,” he notes. “Yet most consumers don’t realize they can have similar control over room temperatures throughout their homes— unless we, as an industry, tell them.”
Swett notes another advantage: increased equipment longevity. By managing a home’s excess air, zoning protects equipment from straining to operate beyond load temperature limits. Be sure, however, not to overpromise on zoning’s ability to deliver energy savings. In fact, in some cases, energy costs may increase. As Stan Johnson observes, “Zoning can be more energy efficient and save money—but to make that blanket statement 100 percent of the time is just not true.”
5. Follow the rules. “There’s no template, or cookie-cutter approach, to zoning. Every home will be different, because layouts and square footages are different,” says Swett. That said, industry standards regarding design criteria, duct or distribution design, and equipment sizing and selection all come into play. They must be integrated with zoning guidelines to result in a properly designed and installed zoning system.
“When zoning is done correctly, the homeowner only has to change the temperature set point on the thermostat or other control device,” says Guiles. “When zoning is done incorrectly, no one is happy—not the client and not the contractor, because you’ll have to keep trying to fix a problem you created.”
“Remember the old saying: You can do something right, or do it over,” adds Swett. “If you use the ACCA manuals, you’re doing it right.”
Both Guiles and Johnson see a relatively untapped market for installing zoning systems in existing homes. Johnson notes that the biggest potential for zone dampers exists in two-story houses, many of which were built in the United States from the 1950s through the early 1980s.
“We see an enormous retrofit market, especially in starter homes and even in move-up homes that never had zone dampers,” Johnson says. “While the new construction market is driven 100 percent by price, the retrofit market is driven, in part, by consumers willing to pay more for comfort and quality.”
Of course, an existing home doesn’t offer the clean slate that new construction does. You’ll need to work around any restrictions imposed by the home’s structure, current equipment, and existing ductwork, which can increase costs and add complexity to a zoning system’s design and installation.
Even so, don’t shy away from making zoning one of your business offerings. Guiles cautions, “Be careful not to make decisions for customers,” such as assuming only high-end users might want to spend the additional money to install zone dampers and controls. “The average homeowner may be interested in achieving control over temperature or humidity conditions.
“Always present the idea that, through zoning, you can provide a better total solution for the customer—to make their house healthier, more comfortable, safer,” Guiles continues. “Of course, not everyone will say yes. But if you don’t talk about it at all, you’ll never sell or install a single zoning system.”
Look In The Book
Have questions about zoning? You’re likely to find the answers in ACCA’s Manual Zr (Residential Zoning). The 272-page manual is an industry-developed, ANSI-recognized standard designed for use in conjunction with ACCA’s other manuals and standards.
“It’s a first-class guide to deciding whether to zone a residential structure, and it defines—from start to finish—the actual zoning process,” explains Dave Swett of Real World HVAC, Inc., who served on the review committee.
“This manual adds to the industry body of good design practices and is greatly needed by all HVAC practitioners.”
To learn more about Manual Zr visit http://ie3go.ws/manualzr.
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