Effective heating, ventilation and air conditioning systems have always been part of maintaining a healthy building environment, and with the impact of COVID-19 and the unique way the virus is spread, it has never been more imperative that HVAC plays a vital role in keeping occupants of buildings safe, especially as people begin to return to the office and other commercial environments.

COVID-19 has three known contamination routes. First of all, there is person-to-person transmission, which could be indirect too, if the virus travels from someone to a surface they have touched, which is then touched by another person. Then there is airborne transmission. The British Council for Offices (BCO)’s Thoughts on Office Design and Operation After COVID 19 document talks of large droplets, greater than 10 micrometres, “expelled by sneezing and coughing and in still air, typically within about 2 metres of the infected person.” But Dr Linsey Marr, the Charles P. Lunsford Professor of Civil and Environmental Engineering at Virginia Tech, speaking to the New Scientist says that people emit thousands of times more smaller droplets than larger ones. She thinks that it is these ones that infect people with COVID-19. Then there’s the third contamination route: faecal to oral whereby particles from the toilet can enter people’s respiritory systems when using WCs.

Counteracting COVID-19 transmission

There are several methods to counteract these routes of transmission. The risk of the virus spreading from person-to-person can be lessened where there is a focus on smart technology. This begins upon arrival at a building, with the use of touchless entry systems, for instance harnessing facial recognition technology. Once inside, staff could then be directed to an area of the office that isn’t already occupied via digital signage or an app. And instead of manually pressing a button, information from the employee’s ID pass about which floor they work on can be read by a card reader, activating the elevator.

As for transmissions via surfaces, scientists have emphasized copper’s antibacterial properties, with COVID-19 surviving just a few hours on copper, compared with a number of days for steel or plastic. William Keevil, a senior microbiologist at the University of Southampton, has recently suggested that the UK is behind other countries in using this material on communal areas like handrails and doorknobs. Copper-based nickel would perform better than chrome in certain parts of the office too.

The risk of the virus spreading from person-to-person can be lessened where there is a focus on smart technology

To dilute airborne contamination, the Chartered Institute of Building Service Engineers (CIBSE) recommends running ventilation systems at a higher flow rate. “This may require changes to C02 set points for both mechanical ventilation and automated windows,” it states in its COVID-19 Ventilation Guidance.

Airborne Particles and the need for ventilation

Chinese and American academics looking at outbreaks in the Chinese province of Zhejiang found that airborne transmission of the virus may have taken place in 48.3% of people in a badly ventilated office. Essentially to stop the spread of COVID-19, ventilation needs to be increased and more fresh air needs to be brought in. The risk of contamination via recirculated air can be mitigated with a higher level of filtration such as F9. This is a very fine system that will catch nanoparticles of 70nm but does involve greater energy use to overcome the resistance.  The alternative is to keep these systems on for much longer – typically two hours before people arrive and then two hours after they leave. CIBSE’s COVID-19 report also states that, “Recirculation of air within a single room, where this is complemented by an outdoor air supply, is acceptable.”

Getting abundant fresh air in the system is key. This could be as simple as just opening the windows. The BCO’s report goes so far as to say, “Actively use operable windows and openings to boost ventilation to occupied spaces as much as possible, even if this is at the expense of thermal comfort.”

Fan coils and Chilled beams

Getting abundant fresh air in the system is key

The BCO also recommends that fan coils, which recirculate air locally in the occupied space, “should be frequently and thoroughly cleaned and where condensation occurs, drain pans and traps should be maintained frequently to prevent growth of bacteria and mold.” It is also a recommendation that HepVo traps are installed on condensate systems that drain into waste pipework. As far as chilled beams are concerned, CIBSE says that active chilled beams can be operated as normal, while with passive chilled beams there should be a good supply of air.

I would be interested to see some further research on the performance of underfloor and low level air distribution. The lower velocities and laminar air flow associated with these systems causes less air turbulence, particularly in the zone where air is breathed. This would seem to have an obvious advantage in reducing the risk of virus spread in an office environment.

Mixed Mode Ventilation

The ‘mixed mode’ of ventilation will become more commonplace. When it is not high summer, the cooling can be turned off so windows can be opened. This could even eventually replace the familiar sealed building model. This system can happen automatically with sensors, after all, fresh air is good for people: There are several recent examples of this being done successfully, other building such as London Wall Place, have been designed future proofed for ‘mixed mode’ use to be adopted if this is preferred by a tenant.

Meanwhile, to combat faecal-oral transmission, bathroom extraction fans need to be kept on high and again perhaps running the systems for 24 hours a day. Toilets that automatically shut and touchless flushes can also help to stop the spread of the virus. The same goes for anti-bacterial coatings on bathroom doors. Some of clients are considering motorized doors that are effectively ‘touch free’.

Post-COVID Ventilation Strategies

Toilets that automatically shut and touchless flushes can also help to stop the spread of the virus

There is definitely set to be more access to outside air moving forward and there is a strong sustainability argument to be made for this method. However, some of the changes to ventilation strategies being deployed for a post-COVID world will inevitably have some compromises for carbon emissions. If systems are run at a higher rate and for longer, if not continuously, throughout the day then that has implications for a larger carbon footprint, as the buildings become less energy efficient. However, in the middle of a global pandemic, it’s a price worth paying. As energy saving methods (thermal wheels and plate heat exchangers) also present a risk, CIBSE recommends that these are bypassed and not used in the current environment

Of course, some of these solutions are temporary but other, smart office elements like touchless versions of door handles, room/desk booking systems (wayfinding) and reception sign-in procedures look set to be with us for the longer term. These all affect the M&E, as well as the architecture and design of buildings. We will overcome COVID-19 but we need to listen to the lessons that we are learning, and some will most certainly become permanent before the next virus that hits the human race comes along!

Share with LinkedIn Share with Twitter Share with Facebook Share with Facebook
Download PDF version

Author profile

Adrian Gray Executive Board Director, HDR | Hurley Palmer Flatt

Adrian Gray is part of the executive team at HDR | Hurley Palmer Flatt. Based in the Blackfriars office, United Kingdom but with a global role. He is a chartered engineer and has over 25 years’ experience delivering sustainably focused engineering solutions for high quality development projects in London and around the world.

In case you missed it

Could Smart Systems Using Thermal Cameras Replace Thermostats?
Could Smart Systems Using Thermal Cameras Replace Thermostats?

HVAC systems should operate to ensure the comfort of individuals, not based on the temperature in a room. That’s the thinking behind a system devised by researchers that uses thermal cameras to measure the temperatures of faces in a room and adjusts operation of the HVAC system accordingly. Among other things, the scheme shifts the focus away from facilities and toward occupants, who reflect a truer measure of system effectiveness. Researchers at the University of Michigan have developed a plan to use thermal cameras along with three-dimensional video cameras and artificial intelligence in lieu of traditional thermostats to control HVAC systems. Human Embodied Autonomous Thermostat The Human Embodied Autonomous Thermostat, or “H.E.A.T.,” system pairs a thermal camera with a 3-D video camera to measure facial temperature and track whether individuals are hot or cold. The temperature data is then fed into a predictive model that compares it with information about occupants’ thermal preferences. When the H.E.A.T. is newly installed, occupants “teach” the system about their preferences by periodically providing feedback via their smartphones on a three-point scale – “too hot,” “too cold” or “comfortable.” After a few days, the system learns their preferences, relates preferences to corresponding facial temperatures, and then operates independently. The system then determines the temperature that will keep the largest number of occupants comfortable with minimum energy expenditure. The University of Michigan study shows how the system can effectively and efficiently maintain the comfort of 10 occupants in a lab setting. The overarching goal is to keep the largest number of occupants comfortable with the least amount of energy expenditure. Flexible Climate Control In the post-COVID-19 age, the approach enables smarter, more flexible climate control that keeps building occupants comfortable without needing to heat and cool entire empty buildings. The more efficient, personalized approach to comfort could conceivably totally replace the use of wall-mounted thermostats. If building occupants need to wear masks and other protective gear, issues of comfort become even more complex The overarching goal is to keep the largest number of occupants comfortable with the least amount of energy expenditure The research was described in a study published in the July 2020 issue of Building and Environment. A key innovation of the approach is the ability to measure an occupant’s comfort level without requiring them to wear any detection devices, and without the need to use a camera for each occupant.     The University of Michigan research team is working with power utility Southern Company to test H.E.A.T. in their Alabama offices, where test cameras are mounted on tripods in the corners of rooms. (Permanent mounting locations would be less conspicuous.) All camera footage is deleted within seconds, thus eliminating concerns about privacy. Smart Home HVAC Tests A key innovation of the approach is the ability to measure an occupant’s comfort level without requiring them to wear any detection devices Another test will take place in an Alabama community of newly constructed smart homes; a residential system could be on the market in the next five years. Tweaks to the system could make it useful in applications beyond homes and offices, such as in hospitals where care providers struggle to stay comfortable wearing masks and protective equipment. H.E.A.T. is available as a licensable technology through the U-M Office of Technology Transfer. The research was supported by the National Science Foundation, and the research team has filed patent applications related to the technology. It turns out facial temperature is a good reflection of comfort level; facial blood vessels expand to radiate additional heat if we are too hot and constrict to cool the face if we are too cold.

How HVAC Professionals Can Learn, Adapt, and Successfully Lead COVID Reopening Efforts
How HVAC Professionals Can Learn, Adapt, and Successfully Lead COVID Reopening Efforts

The current Coronavirus pandemic and the corresponding socioeconomic crisis has dealt a brutal blow to public and residential facilities alike, as businesses and management bodies worldwide are challenged to constantly ensure that their spaces are safe and healthy for occupants. As the entire world has been forced to adapt to what’s been commonly referred to as “the new normal,” one broad-ranging area has come into critical focus as a priority with a heightened sense of fear and cognizance around virus transmission: indoor air quality (IAQ). Importance of Indoor Air Quality For HVAC professionals, the importance of indoor air quality and ventilation as it relates to building efficiency and occupant comfort is nothing new, but through the introduction of new technologies and research, the topic of occupancy health and wellness as it directly relates to HVAC systems is constantly evolving and providing fresh information. However, while every facility manager, business owner or landlord wants to create a healthy building, HVAC pros are often subject to a constant push-pull dynamic that must be managed when it comes to balancing costs and utility budgets with optimized performance. Recommending improvements that will make a building healthier but may carry an added costThis conflict between competing demands can be incredibly daunting and taxing for HVAC managers looking to justify their decisions to seek out or implement new solutions. Recommending improvements that will make a building healthier but may carry an added cost, which can be a major challenge during times when budgets may be tighter than ever.The topic of reopening businesses, office buildings, schools and public gathering places has stoked prolonged debate over protocol, timing, and appropriate standards for facility management. While every state and industry will have its own set of circumstances, from an indoor air quality perspective, there are three steps that can be taken to ensure your building is offering the healthiest and smartest environment possible: Know Your Air Understanding what is in the air is the most important first step towards optimizing your building. This is critical in determining how to customize the specific needs of your space when preparing to reopen. The most common misconception about building health is that a “healthy building” has to be a newly-created structure. In reality, a healthy building is a structure where the strengths and weaknesses of the indoor air quality have been assessed, and the proper measures have been taken. HVAC professionals should implore property owners to invest in an IAQ monitoring system that monitors multiple pollutantsThis ensures that any areas lacking have been addressed and optimized - age notwithstanding. This can only be achieved through constant intelligent monitoring and familiarization with what’s in your air. HVAC professionals should implore property owners and leadership to invest in an indoor air quality monitoring system that monitors multiple indoor air pollutants. Our Airthings For Business solution, for example, tracks CO2, humidity, temperature, airborne chemicals, radon, air pressure, and light and provides 24/7 access to data that tracks changes, dangerous levels or inefficiencies over time. Once an issue is identified, HVAC professionals can then implement solutions that are curated towards a specific problem. The best part? Taking action by investing in monitoring will actually create perpetual energy savings in the future. On average, spending $40 on improving air quality in a building results in a $6,500 productivity gain. Understanding what is in the air is the most important first step towards optimizing your building Healthy Humidity When developing a reopening strategy, perhaps no indoor air quality component is more important to monitor closely than humidity. The reason humidity is so critical is because studies have proven a direct, established link between the facilitation of seasonal respiratory virus transmission, particularly flu, and the level of humidity in the air. When humidity levels are too low, it means indoor air is dry, which allows airborne drops of water and flakes of skin that contain virions and bacteria to stay airborne longer and travel farther, and tend to be resilient enough to remain infectious. In regions heavily affected by Coronavirus, such as the US Sun Belt, people spend their entire summer days breathing in circulated cooled airThis threat is compounded with the fact that public facilities such as large office buildings that operate with central air conditioning tend to have exceedingly dry air, especially in regions heavily affected by Coronavirus, such as the US Sun Belt, where most people spend their entire summer days breathing in circulated cooled air. While the CDC recommends property managers maintain humidity levels in between 30-50%, other scientific bodies disagree and believe that 40-60% is the optimal target zone. Research from Yale, among many leading institutions, has proven that indoor humidity levels which fall below the range of 40 to 60% can dramatically increase the spread of airborne viruses, including COVID-19. In fact, Dr. Stephanie Taylor, an infection control consultant for Harvard Medical School and a member of the ASHRAE Epidemic Task Force, has been leading a petition called 40 to 60%RH, urging the World Health Organization to establish concrete humidity standards within these parameters for public spaces. The evidence is clear that humidity levels are paramount when establishing a safe indoor environment. Ventilate In addition to focusing on humidity, ensuring the presence of proper ventilation will be a core element of any reopening strategy. When it comes to virus transmission, stale air is the enemy, and poor ventilation can also cause harmful toxins such as CO2, VOCs and radon to accumulate. The best way to manage a ventilation strategy is by monitoring and extracting data-based evidence, and deploying a tailored solution to address your issues. For airborne pollutants (also known as VOCs), monitoring their levels will give you data that indicate if you should increase ventilation, reduce the use of products that emit them or to more regularly replace air filters in your indoor fan systems. In an environment where we are in close proximity, such as the workplace, high concentrations of CO2 can build up if the air is not ventilated properly. While HVAC professionals obviously understand the importance of ventilation, operation costs clearly play a factor in strategy. Most ventilation systems run the entire day, regardless of building occupancy, which can quickly double the cost of energy, maintenance and wear on the ventilation system. It will also lead to spending much more energy on heating as the air is often delivered undercooled. Ways to potentially mitigate this would be to invest in a technology solution that offers smart monitoring of occupancy and overall air quality, or seek out alternative HVAC products such as a standalone heat recovery ventilator (HRV) instead of a one-way fan to save energy and maintain comfort. Conclusion In conclusion, between the pressures of reopening highly frequented buildings and ensuring an indoor environment that is optimized to prevent viral spread, the expertise and assistance of HVAC professionals has never been more valuable. By taking a proactive approach towards indoor air quality, achieving a balance between occupant health and operational bottom lines is well within reach.

What Has Been the Impact of the Coronavirus Pandemic on the HVAC Market?
What Has Been the Impact of the Coronavirus Pandemic on the HVAC Market?

Welcome to our Expert Panel Roundtable, a new feature of HVACInformed.com. We will be asking timely questions about the HVAC market and seeking out experts in the field to provide responses. Our goal is to promote a useful exchange of information on a variety of topics and to create a forum for discussion of important issues facing the industry. Launching this new feature in the middle of a global pandemic made choosing our first question quite easy. We asked our Expert Panel Roundtable: What has been the impact of the coronavirus pandemic on the HVAC market?