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ArticleTechnical Article

Case Study: Building a Home for the Chemically Sensitive

By HHI Staff

In early 2007 Kevin and Kathy Christopherson set about building a home in Hanover, Wisconsin. This was no ordinary new home construction, though. Since Kathy has an acute chemical sensitivity, special precautions were necessary – precautions that presented particularly challenging construction issues.


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The home was designed as a two-story Cape Cod with a guest home and a loft bedroom, and the dwellings are connected by a breezeway. The Christophersons, who were quite active in the design process, built the guest home so others with acute chemical sensitivity can stay there to alleviate their suffering.

While several construction challenges arose out of the adherence to chemical sensitivity guidelines, the Christophersons and their experienced team were able to produce an excellent end result. Healthy home consultant, Marilee Nelson, president of The House Doctors (Hunt, Texas), directed the chemical sensitivity aspects of the project.

Nelson and the Christophersons required the home be constructed with minimal use of fossil fuel systems in the building and were also concerned about electro magnetic fields or EMF exposure.


Since people suffering from chemical sensitivity can have negative reactions to even minute amounts of certain chemicals, Nelson instructed contractors and subcontractors to empty their work trucks of all non-approved materials and tools prior to entering the jobsite to prevent their accidental introduction to the home. Also, all sheet metal used in the home had to be scrubbed to remove any oils on it.

The homeowners didn’t want to use drywall, and initially considered using a clay-based product for plaster, but it didn’t provide the necessary thickness. They ended up specifying Dragonboard, a magnesium oxide wallboard that’s fireproof, moldproof and waterproof. Also, all equipment had to be stored in the basement of the guest house each evening.

Chemical-free HVAC

With regard to the HVAC system, the challenges were met by a multi-faceted team including: mechanical contractor Don-Martin Heating, Cooling & Geothermal (Janesville, Wisconsin); Radiant Cooling Corporation (Chicago); and engineering firm DS Design Consultants, Inc. (Watertown, Wisconsin). The general contractor was Zimwood Custom Homes, in Janesville.

Don-Martin was contracted to handle the home’s HVAC needs, and from the start of construction in April 2007 through its completion seven months later, the project proved to be most interesting. Initially Don-Martin’s owner, Don Kohlhagen, suggested radiation heating with forced air cooling, but Nelson did not like the idea of forced air cooling. So the mechanical design team selected a dedicated outside air system (DOAS) for fresh air introduction, and a water-to-water unit to heat and cool the home. A WaterFurnace EW042 unit (a geothermal storage tank that maintains consistent water temperature and hot water in connection with a geothermal heat pump or ground source heat pump) with a desuperheater was selected and would be connected to a 50-gallon electric tank for domestic hot water heating.

The pumps selected to run the system had to be bronze to handle condensation issues with the chilled water (they ended up selecting Grundfos pumps for the circulators on the load side).

Additionally, the team sought a chemically-safe and flame-free piping option to connect all the home’s Beka USA (KaRo) radiant cooling and radiant heating by micro capillary tube radiant mats.

These 1/8-inch, inside diameter plastic polypropylene capillary tubes are installed close to the wall, floor, or ceiling surface and provide virtually silent and healthy heating and air conditioning without the dryness associated with forced air systems. The technology is well-established throughout Europe, with over 20 million-square-feet installed.

For the Christopherson home, the mats were installed in the ceiling and then plastered in after leak-checking. Wally Shah, president of Radiant Cooling, had specified the Beka radiant mats and control system. In turn, Beka USA told him about Aquatherm, Inc., and its polypropylene-random (PP-R) piping for HVAC applications, Climatherm. After some research he presented Aquatherm to the rest of the team and everyone – from Kohlhagen to Shah, Nelson, and the Christophersons – was immediately open to using it.

Aquatherm’s polypropylene-random (PP-R) piping alternative has been used in millions of heating, cooling, and industrial installations in 70-plus countries for the last 35 years. Aquatherm’s pipes are joined using heat fusion, a fast and simple process that melts the pipe and fitting together for a homogenous connection.

Aquatherm’s Climatherm product, which is designed specifically for HVAC applications, was a perfect fit for this project since there are no flames, chemicals, or mechanical connections. Once fused, the pipes and fittings have the same physical properties, thus eliminating systematic weaknesses. Climatherm also has a fiberglass impregnated layer that provides exceptional strength, thermal expansion resistance, and a natural R-value of 1. Aquatherm Greenpipe® would have also been ideal for the home’s potable water, but the team learned about that product too late to integrate it.

No Reservations

Kohlhagen was familiar with Aquatherm’s heat fusion welding process from the geothermal work he had done. “I liked it right away because of the R-value and the fact that the pipes won’t sweat as easily as copper,” he said.

Shah purchased the necessary welding irons and equipment to be used by the installing contractor and explained the welding technique in the field. “We found the product easy to install since we are a geothermal company and it is similar to joining pipe for a ground loop,” Kohlhagen said. He added that the natural R-value allowed them to run cooler water through the system without serious sweat or condensation issues that would have occurred with metal piping.

Daniel Schlicher, designer of engineering systems and LEED AP, for DS Design Consultants, drew up the system’s schematics and also handled pipe sizing along with the help of Radiant Cooling. Aquatherm allowed him to simplify the system and size the pipe a bit smaller thanks to PP-R’s excellent flow rates.

“With a product like Aquatherm, you can improve your flow rate, which lowers your material and labor costs and your pump sizes can be reduced,” Schlicher said. “It trickles down and in this case, it made the design easier and helped the job go very smoothly.” Since the technicians were factory-certified, the installed Aquatherm piping has a 10-year warranty on pipe and fittings.

The installation proceeded without any real glitches, Kohlhagen explained, recalling that roughly 1,000 linear feet of ½-inch, ¾-inch, and 1-inch Climatherm pipe sizes and 400 fittings were installed. “The only real challenge was how to connect the pipe to the Caleffi manifolds,” he said. They ended up using a meter socket adapter for the connections and that worked out perfectly.

Dewpoint limiters were installed and wired to the Beka thermostats, and also Caleffi DIRTCAL dirt separators were installed in the lines. The load side of the system was connected to a Boiler Buddy 80-gallon buffer tank, manufactured by Hot Water Products, Inc.

The Rest of the System

In order to meet the other infrastructure demands, two Pure Air Systems purification units with HEPA and charcoal filters, a Lennox PCO system, and Venmar® air-to-air exchangers were used. Thermolec electric duct heaters were installed to temper the air entering the air-to-air exchangers when the outdoor temperature drops below 30°F.

Additionally, the owner directed Don-Martin to install an adjustable control on the exterior of the two Thermolec heaters so he could fine-tune when they would preheat the air. A Thermastor® LLC Santa Fe Classic dehumidifier was also installed in each home to run independently of the other air handler to prevent the humidity level from exceeding 45%. A wall-mounted Honeywell dehumidistat controls the relative humidity (RH).
After the system was up and running it had to be balanced to provide the designed air delivery, which required getting the space under slight positive pressure to prevent infiltration into the space. “This was a challenge since the homeowners wanted to be able to operate the system at different speeds because the home is out in the country and there are occasionally farm chemicals in the air and grass burning in the spring,” Kohlhagen said.

The homeowners wanted to be able to shut off the outside air and just re-circulate the air through the filters, which required the installation of a bypass switch and damper system. “We instructed them that the design was to provide positive pressure, but they insisted that they needed to adjust it at their own discretion; this was understandable considering the circumstances,” Kohlhagen added.

Kohlhagen also said they experienced a challenge in providing a simple change-over from heating to cooling mode since the thermostats need to know how they control temperature. “By using a double-pole-double-throw switch and shunting the connection on each thermostat, we could allow for this,” he said. However, the owner still has to go into the basement and select heating or cooling on the equipment.

Breathing Easy In the End

The job was unique and quite a challenge, according to Kohlhagen. “I liked doing this job, but product selection was tough. It was a time-and-materials-job, and keeping costs down was also a challenge, but in the end, we provided what the home owner wanted.”

Kevin Christopherson said the mechanical system has performed quite well. “It heats in the winter and in the summer it works well too, but when it’s 100°F in the summer, it can be a bit warm, but we can get it to 76° with no humidity and it seems pretty comfortable.

“We’re happy with everything,” he said. In summer 2009, a representative of Thermastor, the dehumidifier company, did some testing on the house and told the Christophersons that the home has the best IAQ and ventilation they’ve ever tested in a residence.

On top of all this, Wally Shah at Radiant Cooling said that Aquatherm and the KaRo Mats provided “a very clean and energy efficient system and a material and labor savings of roughly 15%.”


[Mention of product or service brand names is for informational purposes and does not constitute an endorsement by The Healthy House Institute.]



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Case Study: Building a Home for the Chemically Sensitive:  Created on October 22nd, 2009.  Last Modified on July 22nd, 2010


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