A cold and bitter wind blows outside. Open the door, walk through, and close the door of Desert Rain – immediately you are enveloped in warmth and quiet. Insulating materials in various forms have been applied to the structure this past week. The interior walls have been filled with blown-in cellulose. The cellulose is comprised of ground up, recycled newspaper. The density of cellulose makes it a superior sound barrier. Initially, spray foam insulation was used on the ceilings and all the exterior walls. The north wall of the house has 12 inch framing. Spray foam was applied in layers, the first layer, before any electrical or plumbing obstructions were in place. This created a tight seal. The final coat was applied after the plumbing and electrical inspections. Cellulose was then used for the remaining few inches of space. UltraTouch Cotton batt insulation is being used on some of the interior walls and ceiling spaces as a sound buffer. The denim blue batts are made from 80% recycled jeans and cotton fabrics. No fiberglass, asbestos or formaldehyde is used in the batts. Ecobatt insulation is being used in the garages. It is made primarily from sand and nearly 62% post-consumer recycled content. The binder is not petroleum-based and it has a much lower embodied energy than traditional fiberglass insulation. It does not contain phenol or formaldehyde, elements that are on the Living Building Challenge Red List. It is an earthy brown color, soft to touch, not scratchy, making installation more comfortable than traditional fiberglass batts. With all the insulation in place it was time to put Desert Rain to the test.
Tuesday the house was inspected with a thermal imaging camera. Ryan Davies with Inline Builders, Will Lebeda with Energy Conservation Insulation, and Jim Fagan, builder with Timberline were at the site to view the results. Ryan uses thermal imaging as an energy auditing tool. Thermal imaging is a non-contact, line of sight technology that can measure temperatures of virtually any surface. The thermal image camera takes pictures of heat rather than light, detecting variables in hot and cold surfaces. Ryan said that thermal imaging cameras have become more available, more affordable, and have better technology than the early versions. They are becoming common as the tool of choice to test the performance of a home in both new construction and retrofit projects. Ryan was using the thermal imager at Desert Rain to look for consistency in the insulation throughout the house. He specifically targets vulnerable areas, such as corners where several interconnecting building components meet, and bridging, where framing studs or plates create a connection between the inside and outside envelope. The camera has different color palettes or black, white and gray tones. The cameras are quite sensitive which Ryan demonstrated by pressing his hand on the wall. The camera then picked up that image left from the heat of his hand. Since the insulation in Desert Rain is ‘over the top’ and well above standards and code, the thermal imaging revealed very few areas of concern.
Will said, ‘thermal imaging on the inside only tells part of the story’. He wants to see an outside scan later when the house is completed. An outside scan is done after dark. The thermal image of a well insulated, passive house should only show the windows and doors. If a house is inefficiently built and insulated it may be possible to see every stud. Ryan and Will think the Bend community in general has a great group of people who are motivated to choose more energy-efficient building techniques. Will said that sparks an interest in new products. Ryan sees the insulation industry in general changing. He said, “education is a big part of it – explaining what we are looking for in an energy audit, talking to people about programs that are available to help retrofit a house, and what technologies and materials are available options’.
Desert Rain had another exam on Thursday when a blower door test was conducted. Blower door tests are the industry standard for evaluating how efficiently a home is sealed. The test may be used to assess the quality of the building envelope, locate air leakage pathways, assess energy losses from the air leakage, and assess building performance. Matt Douglas with Earth Advantage Institute conducted the test. The three primary components of the test are a calibrated, variable speed fan that induces airflow to pressurize and depressurize the building, a mounting system that allows the fan to be placed in a window or door opening creating a seal, and a manometer that is used to simultaneously measure the pressure differentials. The test depressurizes the air to measure in cubic feet per minute, how much air is leaking into the home. This is then calculated to air exchange per hour (ACH) – the lower the number the tighter the building envelope. Since the house is not completed there are several areas of obvious air leakage. Jim and Will placed tape over the holes on the doors where the hardware has not yet been installed as that would affect the readings.
Jim was excited about the results of the test and sent an e-mail to the Desert Rain team. He did such a great job summing up the blower door test that I will use his words here:
“A quick update on our blower door test today; we wanted to do this preliminary testing (before walls are closed) so we could address and remedy any problem areas. Our goal for DR is to meet or exceed the Passive House standard of .60 Air Changes per Hour (ACH).
For reference Earth Advantage Certification requires 5.0 ACH, Energy Star and LEED require 4.0 ACH. The three recent Net Zero homes that were built in Northwest Crossing had finished ACH’s of 1.4,1.2, and .96. Sooooo……drum rolll please …….DR main house without drywall and without under-floor foam insulation, tested today at .65 ACH! The Accessory Dwelling Unit tested at 1.0 ACH. If we blend those proportionally it would be .70 ACH. What Matt from Earth advantage explained today is that a smaller volume building like the ADU is more difficult to get a lower number, just as a function of how the math equation works. Long story short we were all very excited to get this good of a test at this stage of construction……yeeha!!”
When you enter Desert Rain, you are embraced by warmth and quiet. The tests that were conducted this week at the site give us an explanation for that inviting feeling. The thermal imaging and the blower door test are tools used to help evaluate the performance of the building envelope, materials, and installation of those materials. Desert Rain not only made the grade, it passed those tests with flying colors!
Desert Rain owner, Tom Elliott, responsed to the test results: “Congratulations to the entire team–this is one of many benchmarks we hope to meet as Desert Rain moves toward completion. Great work! I think about the contribution of each team member from design to contractor to concrete, framing, windows, insulation and so many more! I hope every team member can take a moment to savor this small measure of their contribution.”