INsight: The New Wave of Building Engineering
Energy Services: Air Barrier Mandates
By Brian Cleary, P.E., CBST, CxA, BECxP
Air Barriers, “A system of building assemblies within the building enclosure – designed, installed and integrated in such a manner as to stop the uncontrolled flow of air into and out of the building enclosure,” have enormous potential to improve indoor air quality, reduce energy usage, and increase the lifespan and efficiency of buildings. On average, 30% of the energy used to heat or cool a building is lost through the building enclosure. Several energy codes have recognized this and introduced new air barrier requirements. Since 2014, The Department of Energy has made it a requirement that all new construction of government buildings undergo an air barrier test. Randall Lamb addressed the air barrier mandates in a previous Insight article in May of 2013.
CASE STUDY: How Testing Works
Randall Lamb was contracted to perform Whole Building Air Barrier Testing for the CNATT Aviation Training Facility at Camp Pendleton, California. A document created by the US Army Corps of Engineers (USACE) and Air Barrier Associate of America (ABAA), USACE Air Leakage Test Protocol for Building Envelopes, has become the model standard for testing. Specifications for the testing are usually found in Division 07 – Thermal and Moisture Protection.
The Facility consists of 2 main sections; a hangar bay, and 4 stories worth of conditioned space including offices, classrooms, auditoriums, and miscellaneous mechanic shops. Building construction was a poured-in-place concrete slab, with fully grouted CMU block walls, and a poured concrete roof with metal framing. These components make up the air barrier system. During construction, Randall Lamb was often on site to observe and report on the air barrier progress. Quality Control is required in many specifications, and contributes to a more successful final air barrier test. Having a pre-construction meeting with all air barrier associated trades can yield great results as it provides an opportunity to talk about material compatibility, proper phasing, and discuss details.
The USACE Air Leakage Test Protocol requires buildings to have an air leakage rate less than .25 CFM/ sq ft of building enclosure at an induced pressure of 75Pa. The building enclosure square footage is the area of all exterior faces of the building which includes all exterior walls, the roof, and the slab. The Facility had a building enclosure of 233,686 sq ft, which was calculated by the designer of record and used in final calculations of the air leakage rate.
With a building of this size, preparation prior to the air barrier test needed to be thoroughly planned and understood by both the contractor and testing agency. Testing cannot occur until the building enclosure is 100% complete, which includes the installation of all windows and doors. All conduits penetrating the air barrier needed to be caulked, and all plumbing traps filled with water as both of these could be potential pathways for air leakage. All HVAC systems were disabled, and any intentional openings across the air barrier boundary were closed or sealed, including outside air dampers, transfer grilles, and exterior doors/windows. The Facility’s entire mechanical system was fitted with ATFP dampers which were monitored and controlled via the BMS. A single button allowed us to seal the entire building. In the interior spaces, all doors were propped open to allow uniform airflow throughout the building.
After the building was prepared for testing, eight blower door fans were installed in the main lobby doors on the first floor. Locating a proper doorway for the blower door fans was very important to running an accurate test. This location allowed the front staircase to act as a “duct shaft” to supply air to the entire building. Once the building is prepped and fans are installed, we were ready to begin testing.
Initial readings for temperature, humidity, and pressure were taken to establish a baseline for testing. The USACE test protocol requires testing in both directions (pressurization and depressurization) across the building envelope. During pressurization, air is displaced into the building while during depressurization, air is displaced from the building. This is accomplished by simply switching the direction of the blower door fans.
Ten pressure readings were taken each direction, ranging from 40Pa to 80Pa, and flow was calculated for each point. An averaged linear regression and other calculations yielded a final leakage rate of .151 CFM/sqft @ 75 Pa (pascal=unit of pressure). This is well below the maximum air leakage requirement of .25 CFM/sqft @75Pa. Proper specification of materials and air barrier drawings along with careful coordination during construction allowed for a successful test. By meeting these air leakage requirements, CNATT utilizes less energy to heat or cool its facility, along with the benefit of excellent indoor air quality.
Air Barrier Team
As part of our consulting services, Randall Lamb provides technical assistance to the contractors during design and construction including quality control site visits, pre-testing the air barrier system with the contractor prior to the government witnessed test, and assists in locating building leakage using infrared thermography. Final deliverables include an Air Barrier Test and Infrared Thermography Report.
Please contact Brian Cleary at , (619) 713-5709 for further details.
Staff Insight: Engineers Without Borders
By Shweta Maurya, EIT
Engineers Without Borders, a non-profit volunteer organization, was started in 2000 at the University of Colorado (CU) with a mission to partner engineers with communities on a global scale to provide basic human needs. EWB interested me because I was curious about leveraging engineering technology towards a positive impact in developing communities. After three years as a member of the Nepal Water Supply Project at CU’s student chapter, I moved to San Francisco in 2013 and joined the San Francisco Professional Chapter and serve as the Treasurer and Monitoring and Evaluation Lead for the Water Supply project in Arombe, Kenya.
Arombe is a small community of about 500 homesteads located inland of Lake Victoria in Western Kenya. Water sources in Arombe are scarce and remain susceptible to animal and human effluent and surface run-off. Of the seven boreholes in Arombe gifted by foreign entities over the past few decades, three are broken and contaminated, and residents continue to visit the highly contaminated River Munyo for drinking water.
In 2010, the San Francisco Professional Chapter partnered with the Arombe Water Board. Since then, the Kenya team returns each year to assess and implement water source development projects. Last November our team sent six travelers, in groups of two for two weeks each, in order to span our presence over six weeks. The primary objective of our November 2014 trip was to drill two 80m wells and install hand pumps at both sites: the Arombe Clinic and the Abwao Secondary School.
As the Monitoring Lead and a member of the third travel pair, it was my team’s responsibility to ensure project sustainability by finalizing ownership contracts, collecting health survey research on the community, and teaching water sanitation and hygiene workshops to raise awareness about good water treatment practices. Meanwhile, my travel partner and drilling expert, Bill Halbert, would be overseeing the installation of hand pumps at the two completed wells, which should have been ready to go.
But, even the best laid plans of mice and men (and engineers) often go awry. The materials, contractor, and driller had not yet arrived in the village, let alone broken any ground. We were then tasked with the challenge of starting and completing a construction project in a third of the time we had initially planned for, in a wholly resource-starved environment.
As a result of the work of the two travel teams before us, the drillers finally arrived on my team’s second day in Arombe by what we could only call a Thanksgiving Day miracle. Some of our experiences from the trip truly read like comic strips. Did the drill rig really almost fall over? Did our pump installer really get arrested the day before pump installation? Did we actually lose 2 days just getting a drill bit unstuck from a hammer? Yes, yes, and we certainly did.
From one truck breaking down leaving Nairobi to another getting stuck in Tanzania, from only half of the materials arriving initially to only half of the labor force ever showing up, Bill and I were in a constant state of coordination and communication among the stakeholders of the project. We realized that unlike Western projects where we may run different processes simultaneously to save time, our Kenyan counterparts first did A, then B, then C, with a few breaks for monsoon season sprinkled in. We mitigated this linear aproach by dividing and conquering. I surveyed old well sites while Bill observed drilling at the first site, the Arombe Clinic. I then setup the second drill site at the Abwao school and Bill and I switched locations: he observed drilling at the second site while I oversaw pump installation at the first. When our pump installer disappeared for a day and called us from jail for unrelated reasons, we cut our losses and found a local pump installer within the hour who could immediately finish the job.
We learned early on that the drilling company, drilling contractor, and pump installer were not actually communicating with each other. Bill and I held frequent meetings with each party, and would run after the driller with our cell phones, forcing him to speak to his own boss based in Nairobi, or his pump installer arriving from Kitale in order to make sure each moving part was coordinated. Acting as the conduit for their communication allowed us to complete the project on time, and even with some success.
Nowadays, I regularly receive messages on Whatsapp from Dr. Joseph Ada, the doctor at the Arombe Clinic. He informs me that the 55m Arombe Clinic well is working, and that its 3 GPM flowrate has been able to provide safe water for numerous births and procedures at the clinic each month, as well as safe water for surrounding residents.
The well at the second site, the Abwao School, was discovered to be dry, and we capped and closed it after drilling through 80m of granite and some minor wet zones that yielded only 1 GPH of water. A lack of accessible, clean water at the secondary school still persists, and our team plans to assess the potential of rehabilitating existing wells in the area and expanding the rainwater catchment systems at the school to address this issue later this year.
Engineers Without Borders has made a lasting impact, not only on the residents of Arombe, but also on those of us involved in implementing the organization’s mission. As evident by my experience, projects don’t always proceed as planned, but because of this, my team and I were taught patience and communication across cultures. This trip was a humbling reminder of how large the gap is in technology among communities, and just how far the sharing of ideas and skill sets can go in impacting a community. Traveling to Kenya has been an incredible learning opportunity for me and a way to give back to the global community.