New Green Building Products — May 2014
An ERV that dehumidifies, a tiny ventilation system for single rooms, a rugged ventilation baffle, a cap for recessed can lights, and a tape for XPS seams
It’s time once again to take a look at a few interesting new building products. I recently spotted two potentially useful ventilation products — a new type of ERV(ERV). The part of a balanced ventilation system that captures water vapor and heat from one airstream to condition another. In cold climates, water vapor captured from the outgoing airstream by ERVs can humidify incoming air. In hot-humid climates, ERVs can help maintain (but not reduce) the interior relative humidity as outside air is conditioned by the ERV. and a fan for ventilating small rooms — and two products that are destined for attics — an insulating “hat” for recessed cans and a ventilation baffle that can be installed between rafters. I will also report on JointSealR, a tape distributed by Owens Corning for taping XPSExtruded polystyrene. Highly insulating, water-resistant rigid foam insulation that is widely used above and below grade, such as on exterior walls and underneath concrete floor slabs. In North America, XPS is made with ozone-depleting HCFC-142b. XPS has higher density and R-value and lower vapor permeability than EPS rigid insulation. seams.
An ERV for hot, humid climates
Air Pohoda, a ventilation products manufacturer headquartered in the Czech Republic, has established a new distribution network in the U.S.
Air Pohoda manufactures HRVs as well as ERVs. The manufacturer claims that two of its products — the Ultima240E ERV and an add-on module called the Cool Breeze — are particularly appropriate for hot, humid climates.
The Ultima240E ERV is rated at 240 cfm. It is the first ERV that allows users to set a desired indoor humidity level. According to the manufacturer, the ERV is capable of adjusting the amount of moisture that is transferred between the two air streams (the exhaust air stream and the supply air stream) to meet a desired humidity target.
Air Pohoda USA
13818 Teal Creek Drive
Broomfield, CO 80023
Four Seven Five / Lunos
131 Union Street
Brooklyn, New York 11231
DCI Products / SmartBaffle
415 South Penn Street
Clifton Heights, PA 19018
Owens Corning / JointSealR
One Owens Corning Parkway
Toledo, OH 43659
While other ERV cores have membranes that allow moisture to pass through the membrane and be transferred from one air stream to another, the passageways of the ERV core of the Air Pohoda core are made of a type of plastic that will not allow moisture to pass through the walls of the passageways. Instead, the machine reverses the direction of its exhaust and supply air flows periodically, so that the moisture that has condensed and accumulated on the walls of the plastic tubes can be picked up by the other air stream. When moisture transfer is not desirable, on the other hand, the direction of the air flow doesn’t reverse; instead, the condensed moisture is allowed to drain from the unit.
The manufacturer claims that its ERV core has a high efficiency; however, according to an article in Environmental Building News, “as yet there is no third-party data to verify [the] performance” of the unit.
Purchasers of the Ultima240E ERV have the option of purchasing an add-on module (the Cool Breeze) that contains a small compressor. In hot, humid weather, the compressor’s cold coil is used to lower the temperature and moisture content of the exhaust air stream (before it reaches the ERV core). According to Daryl Jacobson, president of Air Pohoda USA, this counterintuitive approach — cooling the exhaust air stream — results in more efficient moisture removal than the more intuitive approach of cooling the supply air stream. (It’s easier to wring moisture out of 75°F exhaust air than it is to wring moisture out of 90°F supply air. Once the exhaust air has been cooled and dehumidified, it is sent to the ERV core. The ERV core allows heat and moisture in the supply air stream to be transferred to the recently dehumidified outgoing exhaust air stream.)
The Cool Breeze compressor does not have an outdoor unit; it is designed to be installed indoors. In some climates, the compressor's waste heat is exhausted from the building through a dedicated exhaust duct. In other climates, it's possible for the compressor's waste heat to be exhausted via the ERV's exhaust duct.
When the Cool Breeze module is combined with the Ultima240E ERV, the units can provide ventilation and limited cooling for a tight, well insulated home. “We are not making a claim that we can operate like an air conditioner,” Jacobson told me. “What our claim is, is that in a passive home, we are able to maintain a comfortable temperature throughout the year.”
The maximum watt draw of the Cool Breeze is 300 watts. According to Jacobson, the Ultima240E ERV costs $3,650, while the Cool Breeze module costs $1,800. Jacobson told me that all of the materials needed for a ventilation system suitable for a three-bedroom house (including ductwork, grilles, and switches, but not labor) should cost between $5,500 and $6,000.
A ventilation system that moves just 12 cfm
The through-the-wall Lunos e2 fans are usually installed several feet apart or in different rooms. The two fans in each pair are electrically interconnected; while one fan acts as an exhaust fan, its mate acts as a supply fan. Every 70 seconds, the airflow direction of both fans reverses, so that the exhaust fan becomes a supply fan, and vice versa. Each fan includes a ceramic core that provides heat recovery.
Now 475 High Performance Building Supply is providing a new product: the Lunos e-go fan, a small unit designed to provide ventilation for a single room. Unlike the Lunos e2, the Lunos e-go isn’t sold in pairs; all you need is one unit. The Lunos e-go is about the same diameter (about 6 inches) as the Lunos e2; however, the cylindrical duct section is split in half lengthways, creating two parallel ducts. Each Lunos e-go comes with two tiny fans, one for each duct; while one fan is exhausting stale air, the other fan is supplying fresh outdoor air. Every 70 seconds, the airflow direction reverses. Like its larger cousin, the Lunos e-go has a ceramic core that provides some heat recovery. (During the winter, the warm exhaust air flow heats the core; when the airflow reverses, the core gives up some of its heat to the entering supply air.)
Although the Lunos e-go fan is rated at 12 cfm, it also has a 27-cfm "boost" function for bathrooms. According to Ken Levenson from Four Seven Five, 12 cfm is adequate to meet the ventilation needs of a small room. Yes, it's expensive: the Lunos e-go fan sells for $795.
SmartBaffles provide a 2-inch-deep air space
DCI Products has come out with a new ventilation baffle called SmartBaffle. The polypropylene baffle has flanges that are designed to be installed facing upward; since the flanges are 2 inches wide, they automatically create a 2-inch-deep ventilation air space. This is a deeper air space than that provided by many competing products.
According to the manufacturer, SmartBaffles are stiff enough to be used with spray foam insulation. The can be installed from above (before the roof sheathingMaterial, usually plywood or oriented strand board (OSB), but sometimes wooden boards, installed on the exterior of wall studs, rafters, or roof trusses; siding or roofing installed on the sheathing—sometimes over strapping to create a rainscreen. is installed) or from below (after the house is roofed). When installed from below, they are slid into place and are held in position with a toenail in the middle of each baffle (installed directly underneath the baffle) to keep it from dropping away from the roof sheathing. The upward-pointing flanges maintain the proper spacing down from the roof sheathing.
SmartBaffles come in 3-foot lengths and two widths: narrow baffles for installation between 16-inch-on-center rafters and wider baffles for installation between 24-inch-on-center rafters. The suggested retail price is $3.50 each for the 16-inch-wide product and $5.25 each for the 24-inch-wide product.
A recessed can cap for non-IC fixtures
A California company, Ecocycle Solutions, is marketing a new cap for recessed can lights called the CanCoverIt. The caps are made from thin foil-faced fiberglass insulation.
Unlike most other recessed can caps, the CanCoverIt cap can be used above recessed can fixtures without an IC rating. Each CanCoverIt cap includes two removable punch-out vents near the top of each cap. If the cap is being used to seal an IC-rated fixture, the triangular vents should not be opened. However, if the cap is being installed above a non-IC fixture, the vents should be opened by removing the knock-outs. (At least a little bit of airflow is needed to keep non-IC fixtures cool enough for safety. The CanCoverIt caps allow enough airflow to keep the recessed can fixtures from overheating, while still limiting thermal losses through the ceiling.)
When used above a non-IC fixture, the CanCoverIt cap is significantly better than nothing, but still not as good as removing the recessed can fixture and putting it in a Dumpster. After all, you really don’t want any airflow through your ceiling.
A CanCoverIt cap measures about 14” long by 14” wide by 22” high. The caps are suitable for recessed can fixtures that measure up to 7 inches in diameter. A CanCoverIt spokesperson, David Hanacek, says that sealing the bottom of the CanCoverIt cap to the drywall ceiling is optional; however, most energy-conscious builders are going to want to seal the bottom of each cap with high-quality caulk or canned spray foam.
CanCoverIt caps can be ordered online from the manufacturer; the caps cost $20 each, or $16 each when purchased in quantity.
A tape for XPS seams
Only a few years ago, most manufacturers of rigid foam couldn’t provide any advice on which seam tape builders should use. Fortunately, that situation has changed: many foam manufacturers now sell tapes that are compatible with their rigid foam products.
For example, Owens Corning sells a tape called JointSealR that it recommends for sealing the seams of XPS foam (specifically, Owens Corning Foamular). According to Matt Gawryla, a technical lead at Owens Corning, JointSealR is not manufactured by Owens Corning; it is a relabeled product from another manufacturer.
Owens Corning claims that JointSealR tape provides a seal against water penetration as well as air leakage. The tape has an acrylic adhesive. The backer (or face) of the tape is a little bit stretchy, so that if the rigid foam ever moves a little, the tape should remain adhered.
JointSealR is best installed when the temperature is above 0°F and below 120°F. Owens Corning recommends that the tape, once installed, should be firmly rolled with a J-roller or a laminate roller. It can be left exposed to the weather for a maximum of 60 days before it is covered. Once it has been installed and rolled, it is rated for use in temperatures ranging from -40°F to 165°F.
Owens Corning has performed testing to show that its Foamular XPS and JointSealR tape can be used as a water-resistive barrierSometimes also called the weather-resistive barrier, this layer of any wall assembly is the material interior to the wall cladding that forms a secondary drainage plane for liquid water that makes it past the cladding. This layer can be building paper, housewrap, or even a fluid-applied material. (WRB). However, the ESR (evaluation service report) from ICC-ESThis is the International Code Council Evaluation Service. ICC-ES is a non-profit public benefit corporation that evaluates building products, issuing final reports on code compliance of building products and materials. These reports on then made available at no charge to the building community at large. that supports this use of Foamular and JointSealR has not yet been published. (Moreover, builders should remember that depending on any tape to keep the horizontal joints of XPS waterproof for the life of a building requires strong faith in chemistry.)
JointSealR tape is 3.5 inches wide and 9.9 mils thick. It comes in 90-foot rolls that sell online for $35.75 each, which means that the tape costs 40 cents per foot — comparable in cost to 3M All Weather Flashing Tape and Pro Clima Tescon No. 1 tape.
I haven't yet had a chance to test JointSealR at my backyard tape testing facility. As soon as a roll of the tape arrives in the mail, I'll install it and let it weather for a few months. Then I'll report back with the results.
Martin Holladay’s previous blog: “Earthship Hype and Earthship Reality.”
- Air Pohoda
- 475 High Performance Building Supply
- DCI products
- Ecocycle Solutions
- Owens Corning
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