Does Your Exhaust Fan Suck? Part 2

If you recall from Part 1 of this article written back in September, we discussed why exhaust fans often don’t operate as they are intended. Now, let’s discuss how to rectify these issues. First, we need to understand that all fans are not created equal. To do this, SWA participated in a “blind” study that analyzed a number of today’s common exhaust fans. The study emphasizes the importance of fan selection. With this understanding, we will then discuss solutions and best practices for installing bathroom exhaust ventilation.

The “Blind” Study

To get a comprehensive performance dataset for a number of exhaust fans, the Riverside Energy Efficiency Laboratory (REEL) was engaged for a “blind” study. REEL is the HVI/ESTAR neutral, third-party testing facility. In total, 7 multi-speed fans, 7 single speed fans, and 6 low-profile fans from six manufacturers were sent to REEL without manufacturer markings. In general, ten-point airflow tests were conducted on each fan. Testing adhered to standards used in the industry, namely, ANSI/AMCA Standard 210 and HVI Publications 916 and 920, where applicable. While the dataset is extensive, this paper focuses on the 50, 80, and 110 cfm ventilation rates, as these are the most common specified fan speeds for bathrooms. These fan curves show the relationship of airflow that will be delivered at various static pressures of the duct system.

Figure 1 shows fan curves for single speed fans that were tested. The units are rated for 80 cfm unless noted otherwise in the legend (two are rated for 70 cfm and one for 90 cfm). While all of these fans performed in a similar manner, would it surprise you that two of the fan curves in Figure 1 are for exhaust fans that use DC motors? People often assume that all fans using DC motors are the same and result in constant airflow for a range of static pressures (let’s say up to 0.4” w.g.).

Figure 1

Figure 1. Performance Data for Single Speed Exhaust Fans

It is clear in this data (Figure 1) that flow rates decrease rapidly when static pressure rises over 0.3” w.g., as it often does in real world installations. Oh, are you still wondering which two fans have DC motors? It is actually SS-05 and SS-06. A bit surprising, isn’t it?

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What is the Carbon Footprint of Your Holiday Shopping?

Have you ever wondered about the carbon footprint of your shopping habits? Is online shopping better for the environment than brick and mortar shopping? There are many studies on the subject and there are myriad factors to consider when answering these questions. To try and make this process a little easier, we have pulled together existing research and have developed a guide to reducing your carbon footprint this holiday season.

Image of Santa gifting coal

One 2013 study by MIT looked at the impact of online vs. in-store shopping for a few items (a t-shirt, a Barbie Doll, and a computer) and concluded that a few key factors can tip the scales in either direction. While this study ignored the impact of the embodied carbon of these items (more on this later), let’s look at the biggest factors that could contribute to your holiday shopping carbon footprint and factor into the store vs. online debate.

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Low-Carbon Concrete: Reducing the Embodied Energy of a Notorious Emitter

It is safe to say we are in a climate crisis. Of the last 17 years, 16 have been the hottest on record.[1] Sea level is expected to rise by as much as eight feet by the end of the century.[2] And by 2050, as many as 140 million people will have been displaced by climate change.[3] The time to act is now, and a major area of impact is buildings, which account for 40% of carbon emissions in the United States. Better envelopes, lighting, and mechanical systems are helping buildings become more efficient, which means an increasing proportion of carbon—up to 68% of a building’s lifetime emissions—is locked up in materials.[4] This “embodied” carbon gets released during a material’s extraction, manufacture, transport, maintenance, and, eventually, disposal.

If our industry is to meet the 2030 Challenge of carbon neutrality by the close of the decade, we will need to reevaluate building materials and select low-carbon alternatives.

Embodied carbon life-cycle

Figure 1: Courtesy of Faithful+Gould

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Innovations in Accessible Products

Our accessibility consultants are constantly on the lookout for improvements in product design that will make it easier for our clients to comply with accessibility criteria. As manufacturers become more familiar with accessibility requirements under applicable federal, state, and local regulations and building codes, a number of innovative, accessible products have emerged to make compliance simpler and more stylish.

Here are just a few examples of accessible products that we have been recommending recently…

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Arc – A Performance Approach

“What gets measured, gets managed” – Peter Drucker. This old management adage couldn’t ring more true in the world of sustainability.

The green building industry increasingly relies on the collection and analysis of data to inform a spectrum of building improvements, including monitoring and mitigating the impact of operations and management. The GBCI has embraced this new direction by developing and releasing a new online platform, called Arc, which collects, manages, and benchmarks building performance data as projects move toward LEED certification.

Screen shot of the Arc Platform

Screen shot of the Arc Platform

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