One of the most important components of a building enclosure is the air barrier. Over the past few years the demand for Blower Door testing on large buildings has increased dramatically. Washington State requires that commercial and multifamily residential buildings of greater than five stories have the completed air barrier tested. The United States Army Corps of Engineers (USACE) has an air-tightness requirement and all new buildings must be tested for air leakage. The Army Corps has found that consultants that work with the contractors through the design and construction phases are able to pass the Blower Door test at levels greater than 50% tighter than the standard. As more consultants learn these techniques, this emerging technology will move from the public sector to the private sector.
Documenting the Blower Door tests of these large buildings is certainly more complicated than testing a single family home. The Energy Conservatory has developed free software called TECLOG2 that can be used to control multiple Blower Door fans from a centrally located computer. The software will allow you to do the following:
- Control up to 20 fans from one slider bar
- Monitor the air flow of all of the fans
- Display an average of four outdoor reference pressures
- Display indoor reference pressures on other floors or other isolated areas
- Provide clear, accurate documentation of the test and the test results
One of the major challenges with setting up for this testing is the potential distance between your 3 fan systems and the centrally located computer. In a large building this distance can be hundreds of feet. You then have to decide between running hundreds of feet of multiple hoses or running hundreds of feet of a single cable. Not only is it easier to run a single cable, but there are problems associated with running long lengths of hose. Here are a few of the problems:
- Stepping on hoses can result in pressure spikes.
- Hoses of longer than 100’ will cause measurement errors.
- Hoses of a smaller diameter will cause larger measurement errors.
- Sun shining on long lengths of hose will cause errors
While the DG-700 gauge has both USB and RS232 communication ports, we recommend using the RS232 ports because RS232 communication allows for much longer cable lengths (we have successfully used cables up to 4,000 feet in length). A DB-9 RS232 to CAT5 adapter can be installed on top of the gauge. The DG-700 only uses three of the 9 pins on the connector, so a splitter kit (TEC part # digcablec5sk) can be used to combine the signals of 2 DG-700’s to a single cable. The TECLOG2 software allows you to configure each channel as a pressure or fan flow, so only two DG-700’s are needed for a three fan system (one pressure and three fan flows). An Eight-Port DB-9 RS232 to USB Adapter Hub can be used to combine the signals of eight DG-700’s to a single USB connection to your computer. The TECLOG2 software allows you to control up to 20 Blower Door fans from one computer and using multiple computers allows you to control an unlimited number of fans.
Large building testing is still in its early stages, but the breakthrough of the TECLOG2 software makes it easier to have control over the test from a central location and to have clear, accurate documentation and reporting of the test. The tech support for the software makes it easier for consultants to get up to speed using it. There are obvious advantages to using one CAT5 cable vs multiple hoses and fan control cables to control a three fan system. We expect that this industry will continue to grow for years and expect technologies will continue to make this testing more efficient and accurate.