The COVID-19 pandemic has disrupted everyone at one level or another. These types of events cause us to pause and take stock of our surroundings and put our thinking caps on to consider what we can do better to prepare for events such as these or even to mitigate the spread of a common cold.
One of the things we can look at from a building perspective is how we can minimize that spread through strategies in our built environment. Over the course of the next few weeks we'll dig into these strategies and hopefully provide you with helpful tips to implement in the future.
Building Health Series - Part 5 of 6: HVAC & Plumbing
Ryan M Anderson, AIA
Contributing Editor: Caleb Bulow, PE, Prairie Engineering, PC
May 21, 2020
We all breathe and nothing compares to fresh air! However, for most people, the vast majority of their time is spent indoors. In order to provide healthy indoor environments we have to condition that air through a combination of heating, cooling, filtering, and air exchanges. Making this point even more real is the threat of a pandemic or just localized spread of pathogens and how movement of air through an air handling system or sharing air with nearby coworkers can create an environment where pathogens could potentially spread. Working from home can certainly alleviate those concerns, but what happens when everyone is back working in their office environment and what can we do to mitigate those risks?
HVAC Filtering and Purification - the first line of defense is looking at how we filter and purify air. The items below can be considered - some are able to be retrofitted easily, others may be more of a challenge, and others may require a new system.
Air Handler Optimization - An air handler is a piece of HVAC equipment that serves two purposes: to move air throughout a building, and to treat the air. An air handler may provide multiple levels of treating the air, including heating, cooling, humidification, and filtering. Air handler optimization is a very general item and is mainly introduced to stress the importance of having the HVAC system fine-tuned to make sure it's operating at the right temperatures, air flow, humidity, and filtered correctly - these all work in concert with each other and play an important role in healthy indoor environments.
Air Handler Filtration - This item has to do with the air filter used in your air handling system. Some systems use reusable filters that can be removed and cleaned while others use disposable filters - important with either of these options is cleaning permanent filters or replacing disposable filters on a regular basis. Disposable filters also come in a couple different depths - 1-inch and 4-inch. 4-inch options offer the benefit of greater filtering surface area and greater longevity. Pay particular attention to the MERV rating and aim for MERV 8 or better, but make sure your HVAC system can handle a higher MERV filter rating as your air handler has to work harder to get the air through it (as a reference, hospital inpatient care recommendations are for MERV 15 and clean rooms is MERV 20).
Ultraviolet (UV) Air Sterilization - A UV lamp system can be added to air handling systems to aid in sterilization and reduction of pathogens. Keep in mind that it is only one component of the filtration system and works best when balanced with air temperature, filtration, and humidity.
Air Changes - Circulation of air through a space is important to make sure air does not become stale or stagnant and become a breeding ground for pathogens. Inducing air changes in spaces with the air handler is how this is accomplished and it forces the air to be circulated, filtered, heated/cooled, and humidity to be removed from the air - all important items to consider in healthy spaces. In general, office settings should have 4 air changes per hour, whereas an operating room should have at least 20 air changes per hour and there's a wide array of uses and air changes in between.
Zone Isolation - Another aspect to consider is creating isolated zones for HVAC systems. This tends to get more complicated and thus more expensive, but it can allow specific areas to not share common air with other areas. We see this commonly in operating rooms or even animal shelters where disease can be spread easily between animals if systems are not separated.
Fresh Air - Not to be forgotten is how important fresh air is - model building codes require introduction of fresh air into the building through the HVAC system, but we can consider other options as well.
As part of introducing fresh air into a building through the HVAC system, an energy recovery ventilator (ERV) unit may be employed. The ERV removes stagnant air from the inside and brings in fresh air from the outside. During the winter, the ERV uses the heated inside air to warm the cold outside air. It does the opposite in the summer, using the cooler inside air to cool the hot outside air. By tempering the outside air, the ERV can save large amounts of energy while providing the benefit of fresh air into the building.
Operable windows are important for many reasons including allowing users to open them at will and introduce fresh air (albeit in an uncontrolled manner) - this strategy has less to do with HVAC systems and more to do with mental health, which will be the next topic in this series.
Again, not related to HVAC systems, outdoor spaces for breaks or semi-remote work areas provide the perfect opportunity to take in fresh air and sunlight, both of which feed into the mental health aspect as well. If you don't have a dedicated outdoor space, I would strongly urge you to consider one!
Building Automation -
As mentioned in a previous post, the less surfaces you have to touch the greater your odds of not spreading pathogens. The plumbing industry caught on to this decades ago with the development of automatic sensors for fixtures. Everything from flush valves on toilets and urinals to faucets, there is an option for not having to touch any part of that equipment. They come in the form of hard wired or batter powered-fixtures - hard wired options can be difficult to get rough-ins located properly, but require very little maintenance whereas battery-powered provide for greater flexibility but require regularly changing the battery.
Mechanical systems (furnaces, boilers, heat exchangers…anything that moves and/or heats/cools air) have developed dramatically in terms of automatic controls. Interactive systems are available that communicate with the various components and provide an interface online or on your phone to give you real-time status and control of those systems. While this article is not about the specifics of those systems, the important point related to this discussion is building automation can alert you when your system is not functioning properly or requires maintenance, which can have a direct impact on the quality of the air being distributed in a building and thereby affect the occupants in the building.
These strategies can be tricky and sometimes difficult to employ and you may need to get a professional involved to address them. Others are a little more clear-cut. In either case considering how much time is spent indoors, it is all the more critical to make sure the air we breathe is as healthy as can be.
Ryan is a Vice President at Ackerman-Estvold and the architecture team lead and has been applying his trade in the region around Minot for the past 17 years. If you have any questions throughout this series or would like more information on a particular topic, by all means contact us and we'd be more than happy to have a conversation.