November 1998

TTi will be participating with the Harvard School of Public Health and the Joint Center for Housing Studies in a two day symposium (November 17 and 18, 1998). This meeting will explore "the connections between health, safety, energy and environmental issues in housing design and development." The purpose is to bring together leaders from the fields of public health, housing, finance, design, development and manufacturing to evaluate the "current state of the research and practice in the various disciplines and then work together to suggest ways to integrate best practices and expand their applications in housing design and development."

Tamarack will be working with Building Science Engineering to describe the work the two companies have done as members of the Hickory Consortium (a Building America team) on the award winning Cambridge Co-housing project. This will serve to define the present state of the building design art.

Airetrak™ a Part of the Sound Insulation Program

November 1998

The Airetrak fan speed and timer control is an integral part of the "Sound Insulation Program".  Housing around airports is being tightened to reduce the sound pollution from the take-offs and landings while the runways are being lengthened. Houses in these neighborhoods are being tightened with improved windows and levels of insulation. This tightening then requires a higher level of mechanical ventilation. Homeowners are offered choices between a Tamarack bathroom fan/Airetrak approach or an air-to-air heat exchanger.

The site was crawling with tradespeople all arranged on a tight schedule. Like all projects, the schedule slipped and people and skills overlapped at times. TTi stepped in to install an Airetrak™ control while the Corian installer and helper worked in the bathtub and the electrician installed the fixture over the sink. All work was periodically interrupted for the camera crews and celebrities to step in and discuss what was happening. The project was broadcast live on the CBS "This Morning" show and sections were taped for Bob Vila’s own show.

The site took on circus-like aura’s with the Maxwell House trailer constantly serving up coffee, cranes lifting camera crews high overhead, other cranes lifting wall sections and bathtubs, politicians standing about in suits with their arms folded chatting wisely about the state of the project.

The project was supported by the PATH program and a significant number of state of the art components were included including Photovoltaic roof shingles on the shed, the whole house constructed of stress-skin panels (SIPS), and, of course, the TTi ventilation system.

December 1998

During the "Designing Housing for Health, Safety, Energy and the Environment" Symposium held on November 16 and 17th sponsored by the Harvard School of Public Health and the Joint Center for Housing, an assessment was made of the state of the nation’s construction industry.

Eric Belsky of the Joint Center pointed out that although the construction industry is booming and the remodeling business is exploding, there is still a serious need to address the problems 4.5 million homes with un-vented flues and the 2.7 million homes with rats.

Harriet Burge of the School of Public Health stated that newer houses, especially low income and renovations are moldier than old housing. Houses, she said, should definitely be "ventilated in winter". There was general concensus that ventilation can go a long way in solving these IAQ problems.

"Performance" Ventilation Codes-They’re Coming!

December 1998

In an article from the Canadian magazine "Home BUILDER", they note changes to the National Building Code. Of particular interest is that "essentially, every house must be provided with a mechanical system that complies with CSA Standard F326". This is a performance standard. This means that the system actually has to perform as designed.

At this point the U.S. does not have performance standards - equipment just has to be there. It doesn’t actually have to do anything. Building inspectors simply don’t have the equipment or the knowledge to do performance testing.

It is blatantly foolish for a builder to "comply" with the code by simply mounting a fan in a bathroom ceiling and not duct it to the outside. But if homeowners and builders don’t understand what the fan or ventilation system is for, such abuses will continue, and eventually the regulations will have to be changed. Such new code requirements will be far more burdensome.

Before such prescriptive standards are implemented, it would behoove every builder to gain some basic understanding of the role that the ventilation system plays in building performance and basic installation techniques. Ventilation training is available at conferences and workshops throughout the country. Contact us for a schedule.

March 1999

The Cape Backdraft Damper is the ultimate one way air flow valve, designed to overcome the inefficiencies and limitations of traditional gravity or butterfly dampers. This surprisingly simple design anecdotally first suggested by David Hansen of Memphremagog Heat Exchangers consists of a specially formulated fabric sleeve attached to an outer metal sleeve, the whole assembly slipping inside a duct. One end of the fabric is attached completely around its perimeter. The other end is attached at a single point. Air flow in the desired direction, flattens the fabric against the metal walls, offering virtually no resistance to the flow. In the opposite direction, the fabric collapses upon itself effectively blocking off any leakage.

The remarkable thing is how much resistance standard dampers offer to desired air flow. We set out to test this using a fan that was capable of moving 80 cfm through a short length of 6" ducting. Inserting a good quality butterfly damper into this set up reduced the flow to 17 cfm! A gravity damper worked better, it only dropped the flow to 30 cfm. The Cape Damper had little effect on the flow, reducing it by only 3 cfm to 77 cfm.

For reverse airflow, airflow that should be blocked by the backdraft damper, the Cape Backdraft Damper worked equally well. It provides a positive seal even at very low flows which gets better as the back pressure increases. To test this we compared the leakage of the three dampers at various pressures.

The lighter pressures are the most difficult for the Cape Damper to work in. As the pressure builds up, the fabric is more effectively compressed. But even at the very lightest pressure, the Cape Damper performed as well or better than its competitors. So with very little compromise in back flow blockage, the damper excelled in "going with the flow".

The dampers are ideal for clothes dryer and bath fan applications. The fabric is "slick" so lint won’t clog the operation, and bath fans are notoriously bad at moving air through lengths of flex duct.

October 1999

The Ventilation Deficit

August 2000

It is a beautifully constructed, post and beam home in southeastern New Hampshire. Designed and constructed by Benson Woodworking, the walls are tightly joined Winter Panel structural insulated panels. The owner, sitting in the living room in front of the fire which has been burning for some time, is disturbed by smoke drifting back into the room. Checking with his wife, he discovers that she has turned on the 70cfm Panasonic bath fan upstairs. When the fan is turned off, the smoke returns to its desired path up the chimney.

It is becoming increasingly clear that houses are being built too tightly, and it is critical that the entire ventilation "system" be considered. If the home is going to be under negative pressure through the sum of the exhaust ventilation systems - the bathroom fans + the range hood fan + clothes dryer + central vacuum + water heater + central furnace - there must be adequate inlet air to balance the process. If not, the air isn’t going to go where it is expected to go, and efficiencies of all the systems will be reduced. And worse! It is important to understand that an HRV (Heat Recovery Ventilator) or ERV (Energy Recovery Ventilator) are balanced systems in terms of the air needed for the people only. All of the other components have to be balanced on their own.

Until the manufacturers of clothes dryers, range hoods, and central vacuums understand that their products will work better if the air they are forcing out is balanced by air coming in, there will continue to be a "Ventilation Deficit". Every builder and architect should have a standard practice for considering each of these elements. It should be no different than adding a vent pipe to the plumbing system.

There are only a few inlet products for the "fresh air for people" part of the equation, and Tamarack, with the help of the Department of Energy Building America program, is working on a small, powered, distributed fresh air supply system. Stay tuned.

A Simple Approach to IAQ Control

August 2000

The Pacific Northwest has been on the cutting edge of ventilation for some time. There has been an ongoing effort to improve the energy efficiency of the HUD Code housing stock by tightening up the homes and sealing up the duct work. It then became obvious that much of the fresh air coming into the house was drawn in through the (now missing) holes in the ducting which ran under the "belly". When those holes were sealed, the energy efficiency improved, but the air quality got worse. To solve this, a ventilation system became necessary. This system required a dedicated fan and timer. To satisfy that need, TTi developed the Mainstream™ fan and the Airetrak™ control.

What was needed was a control that could be programmed to operate a fan quietly in the background, that could not be easily defeated by the homeowner, and that could be programmed to operate when the homeowner was . . . home. With the advent of microprocessor electronics, such a control should be small enough to fit inside a standard wall mounted work box, it should be as simple as possible to set up and operate, and it should work with a variety of fans.

The Airetrak™ satisfies all those requirements. The control fits in a standard single or ganged wall box. The actuator fits through a standard toggle switch cover plate. Pushing the actuator causes the fan to turn on at full speed for twenty minutes. This gives the homeowner the ability to control the operation of the fan. But the fan also runs in the background at one of sixteen different speeds, periodically changing the air in the home automatically. The control also contains a battery supported "real time" clock which can be set to operate the fan over a twelve hour period such as when the homeowner is . . . home.

There are now two Airetraks - the Airetrak-1A and the Airetrak-CD. The -CD is an even simpler version of the the original product in that it will cause the fan to run at its preprogrammed slow speed in the background all the time.

The Airetrak’s have become the control of choice for many IAQ projects. There is no other control that does all the jobs that the Airetraks do. If you need assistance with a project design, just give us a call.

Articles related to indoor air quality, ventilation and cooling can be found at  IAQ & Ventilation.