building envelope

Consider the Envelope

A building’s energy use can be made more efficient if the envelope—its outermost walls, windows, and doors—is tight enough to prevent air leakage.

F&S worked with The Grainger College of Engineering to test the building envelope tightness of the Transportation Building on May 21.

Paul Francisco is the Senior Coordinator of the Indoor Climate Research and Training (ICRT) group at the Illinois Applied Research Institute. Below, he answers a few questions about the recent test.

Q: So, what were the results, broadly, of those tests?

Paul Francisco: The testing showed that the Transportation Building has substantial air leakage. While there is no standard for airtightness for this type of building, the Transportation Building had about four times the leakage that is commonly targeted.

Q: What’s the importance of indoor air quality and indoor air tightness?

Indoor air quality is important for the health and comfort of occupants. Indoor airtightness can help provide good indoor air quality by making it easier to control the indoor environment with ventilation. Additionally, airtightness is key for energy efficiency. It is not uncommon for discrepancies between expected energy usage and actual energy usage to be explained by air leakage, and so making buildings tight is vital to meet energy and climate goals.

Q: What would you say about the possibility of testing other buildings, or otherwise making changes to so many older buildings on this campus? Is it even possible with this many buildings of this age?

Testing other buildings can absolutely be done. I believe that one of the key things that we demonstrated at the Transportation Building was that, with advance planning, this type of test can be done at scale in a reasonable amount of time for most buildings. As for addressing identified issues, that can also be done but it will obviously take resources. The question is not whether we can do it, but whether we will make the commitment to do what is necessary. One thing to consider is that many buildings were constructed at similar times, and so once we start to address some buildings we will identify common issues that we need to address and it will become easier and faster to do so.

Q: Can you specifically say if/where there were major air leaks, or where there are usually in older buildings?

Many leaks that we identified were around operable windows that had problems, especially at the bottom or in the frame. Window air conditioners were also common sites for leakage, especially around them when they were not sealed well or when they kept windows propped open such that the rails did not meet. There are other common leakage sites in buildings, including around service penetrations (e.g. electrical, plumbing), above dropped ceilings, soffit areas, around doors, and shafts such as for elevators. Many buildings, including new buildings, do not have good seals at wall-ceiling junctions. Lighting is also a common location for air leaks.

Q: What would you like to say about F&S’ involvement?

F&S was fantastic! 

There was really good communication, preparation, and support. I felt as though F&S team members were engaged in the process and did everything that we needed quickly. It was an extremely professional group. This type of engagement and support will be key to efficiently do more of this work on campus.

Story below re-posted from the Applied Research Institute at The Grainger College of Engineering here:

The Indoor Climate Research and Training (ICRT) group at the Illinois Applied Research Institute at the University of Illinois at Urbana-Champaign partnered with F&S to test the building envelope tightness of the Transportation Building (104 South Matthews Ave., Urbana) on May 21.

ICRT provided the blower door test equipment and oversaw the project, including planning, onsite walkthroughs and testing, and analysis of results. In a blower door test, a powerful fan that pulls air out of the building is mounted in an exterior doorway of the building. This lowers the air pressure inside, and the higher air pressure outside forces air inside through unsealed gaps, cracks and other openings, according to the U.S. Department of Energy.

According to William Rose, Senior Research Architect at ICRT, blower door testing is a crucial part of testing airtightness and energy performance in buildings. By identifying sites of air leaking through testing, the results can be used to direct improvements and compare subsequent results. During the test, the Transportation Building was depressurized to -75 Pascals of pressure difference compared to outdoors. Team members moved throughout the building and used smoke pens to find and describe leaks.

“Energy results from building models can go anywhere between being an energy waster to a shining example, depending on the airtightness input,” Rose said. “Real building energy performance shows the same performance result for airtightness.”

As a pilot project for a larger study, the test on May 21 will contribute to developing campus expertise for reducing wasteful heat transfer through building envelopes, which is done in part through improving airtightness of buildings. This project also contributes to the energy efficiency objectives in the Illinois Climate Action Plan, the university’s strategic plan for achieving carbon neutrality no later than 2050.

“Facilities & Services is proud to be an active partner in research that will advance the university’s energy conservation efforts and bring the campus closer to achieving carbon neutrality as soon as possible. With more than 600 buildings at the U of I, this project collaboration has the potential to make a significant impact by helping identify new areas where envelope improvements should be performed to make facilities more energy-efficient and comfortable for occupants,” said Dr. Ehab Kamarah, Interim Executive Director of F&S.

Funding for this project is provided by the Illinois Green Fund, through the Student Sustainability Committee, and the Carbon Credit Sales Fund, through the Institute for Sustainability, Energy and Environment, and Facilities & Services