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TermoDeck and Indoor Health

in the Age of COVID-19 and beyond

Construction is undergoing a forced slowdown worldwide. Limited access to sites, stricter control of workers working on projects, social distancing, uncertain delays in procurement, and a general economic downturn worldwide is holding back projects everywhere. 


This hiatus is the perfect opportunity to rethink old practices and employ new and creative ways to improve how we build so that can live better and healthier. Social distancing is one simple yet effective technique employed to keep us removed from catching viruses that circulate in the air around us. Yet when indoors, we may keep our physical social distance, but the air we breathe has been circulating in far larger spaces and with other people, and can transmit all kinds of particles, including pathogens, negating all our best efforts at minimizing exposure to microbes.


As we have seen with the COVID-19 virus (SARS-CoV-2), opportunistic pathogens (bacteria, viruses, fungi, etc.), are becoming more prevalent and their impact is global. This is exacerbated by our modern buildings and HVAC systems, many of which rely on recirculating cooled or heated air inside the building, and on a significant amount of HVAC equipment installed internally (usually behind false ceilings). These air ducts and fan coil units create an ideal environment for these pathogens to thrive and spread. 


Airborne pathogens (e.g. bacteria, viruses, mold spores, fungus) circulating in homes and buildings can cause discomfort in a healthy person, such as Sick Building Syndrome, and may cause severe health issues for people weakened or compromised immune systems.  


We are susceptible to these pathogens potentially reaching us from other people in the constantly recirculating air flow from the HVAC. Further, these pathogens can also thrive in air supply ducts or HVAC drainage trays, and are released into the airstream when the   HVAC system is turned on. Both these factors add to our health risks.

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Conventional AC in many climates has a few basic health shortcomings:


  1. Air Quality: Air within homes and buildings can often consist of primarily recirculating air and minimal fresh air.

  2. Air Volumes: High volumes of overly cold or warm air can dry out the sinus membranes, causing irritation and inflammation.

  3. Internal HVAC equipment that can create an environment conducive to bacteriological growth.


It is important to understand how this works: The nasal passages’ walls are coated with millions of tiny hair-like structures that form part of the respiratory mucus membranes. Their main function is to trap any incoming dust, bacteria, mold, viruses, etc., in the mucus and transport them to the back of the throat to be swallowed, where the stomach’s highly acidic gastric juices (pH 2-3) can neutralize them.


An overly dry internal environment (whether cold or hot and typical of conventional HVAC) can lead to the drying out of the mucus membranes, rendering ineffective the ability of the body to trap airborne pathogens and send them to the stomach. This allows these pathogens to reach deeper into the respiratory system, possibly leading to upper respiratory infections (sinus and throat infections), and in more serious cases, lower respiratory infections (bronchioles and lungs).


The body is very effective in fighting infections, but chronic exposure to such an environment (e.g., the ones we are exposed to in homes and work spaces using conventional heating and cooling) can overwhelm our defences and can cause many uncomfortable symptoms, including sinus pressure, headaches, sore throats, nosebleeds, dry mouth/nose.


40 years ago, TermoDeck developed a unique HVAC design that circulates air within concrete slabs, utilizing concrete’s thermal mass to reduce the installed cooling and heating capacity by up to 50%, reducing power consumption by 25-35%+, and reducing HVAC-related operations and maintenance by >50%, thereby slashing a TermoDeck building’s carbon footprint while cutting both CapEx and OpEx.


TermoDeck has been applied successfully in over 430 projects worldwide. These include award-winning residential, commercial, educational, retail, health, etc., projects in Europe, Middle East, Africa, N. America and Australia. 

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In addition to these impressive sustainability features, several key features of the TermoDeck HVAC system also provide for a superior indoor environment:


  1. TermoDeck provides a higher fresh air component compared to conventional HVAC; 

  2. It does not rely on recirculating the same air inside each space but rather takes all the internal air out of these spaces to the Air Handling Units, where fresh air is introduced and where all the air volume is properly filtered/treated, and then brought back in to the occupied spaces;

  3. It does not promote any bacteriological growth due to concrete’s high pH levels (12.5-13);

  4. Internal temperatures are maintained within a narrow/comfortable range 24/7 365 days/year;

  5. TermoDeck localizes all HVAC equipment externally (i.e. roof/basement) and so does not require any equipment internally, eliminating a primary source for bacteriological growth;

  6. With external equipment, no HVAC-related maintenance is required within the occupied spaces.  

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Pathogens require an environment they can thrive in, and TermoDeck does not provide such an environment. Highly alkaline and totally inorganic concrete slabs do not allow the growth of bacteria, mold, fungus and yeast. 

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In addition to the ability to reduce the installed cooling/heating capacities by up to ~50% and using 25-35% less power, TermoDeck’s core design principles directly create healthier indoor environments, and are not simply an afterthought. With TermoDeck, the HVAC system runs silently; provides consistently draft-free comfortable temperatures, 24/7 year-round. As a combined radiant and convective HVAC system, it is not only more comfortable (the supply air temperature is only a few degrees higher than the room temperature), but it also reduces the overall air volumes, providing a far higher proportion of fresh air.  TermoDeck further eliminates recirculation of air within each space. All the internal air is removed from the rooms and sent to the Air Handling Unit (AHU), where a significant proportion is exhausted, fresh air brought in, filtered, treated and conditioned before being sent back in to the occupied spaces. 

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It is at the AHU that all the pathogens can be removed by filtration and sterilization. Filtration (including HEPA - High Efficiency Particulate Air - filters), helps purify the incoming air. HEPA filters are designed to capture 99.97% of particles of 0.3 microns or larger. This is enough to capture most pathogens. However, Coronavirus — for example — ranges from 0.06 - 0.14 microns, so some will pass through the HEPA filter. 

As an additional level of protection, UV-C sterilizer (UV Germicidal Irradiation) or ionization modules can be added to the AHU, which will neutralize all viruses in the air-path by destroying its ability to replicate. Such modules can also be placed in the main supply ducts, ensuring almost total sterilization of the entire air volume.

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Whereas in many HVAC systems, 80-90%+ of the air recirculates internally, TermoDeck HVAC’s design compels the entire volume of air to exit the occupied spaces and pass through the AHU allowing the continuous filtration/sterilization of the entire air volume, ensuring near-zero pathogens in the building’s supply air. This is an unprecedented ability for an HVAC system to simultaneously achieve this level of indoor air quality (IAQ) in an environmentally friendly building that uses about half of the cooling/heating capacity of a conventional HVAC building.


These capabilities were recognized by the multiple awards received internationally. For example, in the past 12-18 months, TermoDeck projects received: 

  1. The World Green Building Council’s 2018 MENA Green Building Awards for Indoor Air Quality;

  2. The World Green Building Council’s 2019 MENA Green School of the Year (both audited by KPMG);

  3. Four 2019 MEED Project awards: (i) National Education Project of the Year for the GEMS Dubai American Academy; (ii) National Sustainability Medal (UAE); (iii) National Innovation Award (UAE) and (iv) the Regional Innovation Medal; 

  4. National Energy Globe Award 2019 (one of the most prestigious international environmental prizes, with over 2,000 submissions worldwide, and distinguishes global technologies that conserve resources such as energy, reduce emissions and contribute to the environment). 

  5. Two prestigious 2018 Climate Control Awards for both the building envelope/structure as well as for air movement/ventilation.


It is also worth noting that the World Wildlife Fund (WWF) has designated TermoDeck as a global climate solver. So TermoDeck’s impact goes beyond energy, and into cost, occupant comfort and the environment. 

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In the above school project, TermoDeck redesigned the HVAC to reduce the installed AC capacity by 58%, reducing the connected electrical load by ~33%, while allowing for ~50% fresh air (instead of the usual 15-20%). If we converted the school to 100% fresh air, TermoDeck would require ~29 m2/TR of cooling capacity, compared to ~10 m2/TR if using conventional AC. Put another way, for 100% fresh air, each ton AC would only cool 10 m2 with conventional AC, but would cool 29 m2 with TermoDeck  (3 times as much space).

TermoDeck’s health benefits are evident in all our projects, but one particular project stands out: the Maun District Hospital for Highly Infectious Diseases / Botswana (Southern Africa) — below, where the very nature of the patients being treated (highly compromised/weakened immunities) and illnesses treated (e.g., HIV/AIDS) necessitated a solution that increases the chances of recovery and reduces the chance of cross-infections within the hospital. TermoDeck was able to do just that. 

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TermoDeck’s proven HVAC system has been recognized by the UK government as “mercifully bulletproof”. It is flexible enough to work with almost any commercially available HVAC equipment, and can adapt to greener forms of concrete and 3D printed structures as these become more commonplace. 


The TermoDeck system can also be used in conjunction with solar energy (both PV panels and CSP), i.e., in harmony with other energy saving technologies and natural energy systems. This can help relieve pressure on municipal power supplies and budgets, and also increase liveability by improving IAQ and minimizing the detrimental effects on OAQ.


Social distancing is the most effective way of preventing the spread of COVID-19. Rather than recirculating air internally, TermoDeck sends the entire air volume to the AHU (no internal air recirculation). This enables a “social distancing” solution for internal building air, sending it away from the people who share the same airspace, providing fresh air indoors, reducing the spread of viruses - sustainably. 


As the world prepares for the post-Coronavirus/COVID-19 phase, and as the awareness of the  importance of maintaining a healthy living environment takes the importance it deserves, TermoDeck HVAC is probably the one way for building owners and occupants to be fully confident that they are not only living and working in a place that is free from pathogens in the HVAC system, but also in a building that requires ~50% of the installed heating and cooling capacity and consumes 25-35% less power (compared to conventional AC), and costs less to build, operate and maintain.⬧ 

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