Over the last few months, Cx Associates has helped a number of schools throughout Vermont test their ventilation rates. As we’ve discussed in previous blog posts, providing adequate ventilation rates is an important part of providing good indoor air quality (IAQ), both during the pandemic and normal times. While most buildings were designed to meet a ventilation standard, there are numerous reasons why rooms may not meet the current ventilation recommendations. In most buildings, measuring airflow is really the only way to know that you meet the recommendation.
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Throughout the COVID-19 crisis, HVAC system recommendations have been a primary focus because of the impact they can have on mitigating the spread of the virus inside buildings. Since we saw a period of time when many buildings were completely vacant and unused, it’s important to ensure your water systems are also safe for occupants before reopening. The concern here is not the spread of the COVID-19 virus, but harmful pathogens such as Legionella (bacteria that can cause Legionnaire’s disease) that can grow in stagnant water.
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We’ve learned a lot about COVID-19, the spread of a virus, and the mitigation of the spread over the past several months. The recommendation of the first line of defense - masking and social distancing – hasn’t changed since this pandemic started in January 2020, but it seems like every other recommendation has evolved throughout these long months. In our business of HVAC, we have kept up with the industry and CDC recommendations on ventilation and filtration and have been active in assessing commercial and institutional buildings.
Topics: HVAC COVID-19 ventilation
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Basics of steam coil and face and bypass operation
Many air handling units in colder climates are equipped with steam heating coils. These coils use control valves to modulate the flow of steam to the coil. Due to the low mass of water in a steam coil, it has a higher propensity to freezing when conditions are right. One of the neat ways we’ve design around this is to use a Face and Bypass (F&B) damper arrangement to allow the coil to have maximum steam flow to prevent freezing. The F&B dampers direct a portion of the airflow through the steam coil and another portion bypasses the coil in order to achieve the necessary discharge air temperature and prevent a freezing airstream from damaging the steam coil. Pretty neat, huh?
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In my previous post How to do BAS Graphics Right: Part I, I wrote about the 5 basic rules to BAS graphics I learned during my years as a controls system master integrator. If you’ve not read that post yet, I’d encourage you to go back and give a glance as it’ll put the rules below into perspective, and feel free to ask a question if you got one using the comment section at the bottom of the post. Here’s a quick recap of the rules:
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In my first blog on Common VRF (Variable Refrigerant Flow) Installation Issues I focused on issues during mechanical and hardware installation that typically lead problems during startup and pre-functional checkout commissioning. This blog will focus on controls issues identified during commissioning design review which usually lead to issues during start up if not addressed up front during design. As mentioned in the previous article, VRF systems can allow for better comfort and overall satisfaction, but if not properly programmed for the owner’s specific application, can lead to numerous complaints during the first year of occupancy.
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COVID-19 has turned our world upside down. From what we’ve learned about the transmission of COVID, spending time in an enclosed space with others is ill advised, and social distancing means working from home and homeschooling. I’ve been doing the former since March, even though Cx Associates’ offices reopened in June. Reopening the office was not an easy choice to make, as was my decision to remain at home, and I thought I’d write a bit about it.
Topics: COVID-19 coronavirus remote
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I started this post before the COVID-19 pandemic. While a lot of our attention has shifted to slowing and fighting the pandemic, I hope you find some refreshment in a lighthearted but still important sustainability story.
Topics: Sustainability Heat Pumps
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The prospect of reopening schools under the new CDC guidelines in response to COVID-19 can be overwhelming for facilities and administrative personnel. In addition to increased surface cleaning, hand washing, maintaining six feet between classroom desks, and wearing face masks, the schools are faced with making decisions on how to best operate their HVAC equipment. As much as the world is trying to help them with these decisions, the HVAC guidelines from the CDC and ASHRAE are all encompassing; it is difficult to identify which measures are applicable and even more difficult to prioritize the measures under a school’s constrained budget. This may overburden an already burdened school facilitator.
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As we are all learning to adjust to life with COVID-19, many areas are considering re-opening schools for the coming school year. Although many teachers are finally starting to unwind into a stranger-than-usual summer break, now is the ideal time to get a jump on adjustments to school operations to make in-person education as safe as possible for students, faculty and staff alike.