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ASHRAE Journal Podcast Season 2 Episode 1

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Left, John Constantinide; Hamidreza Najafi

HVAC in Space: Creating Extraterrestrial Indoor Environments

In outer space applications, HVAC is a matter of survival—not comfort or health, according to Hamidreza Najafi, Ph.D., Member ASHRAE. To kick off ASHRAE Journal Podcast’s second season, Najafi and John Constantinide, P.E., Member ASHRAE, discuss how HVAC&R technologies used on Earth can be applied to extraterrestrial indoor environments as well as the opportunities ASHRAE has to help shape the built environment in space.

Have any great ideas for the show? Contact the ASHRAE Journal Podcast team at

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  • Show Notes

    What would ventilation look like in space?

    As private companies race to space (22:00 and 25:15), researchers and engineers are working to create built environments in the final frontier (3:12).

    To kick off ASHRAE Journal Podcast’s second season, John Constantinide, P.E., Member ASHRAE, and Hamidreza Najafi, Ph.D., Member ASHRAE, discuss how HVAC&R technologies used on Earth can be applied to extraterrestrial indoor environments (3:35) as well as opportunities ASHRAE has to help shape the built environment in space (3:50, 21:30, 27:25  and x).

    The pair also talk about how the International Space Station is an example of a living environment in outer space (4:30) and how the station showcases the importance of HVAC&R technologies and indoor air quality (5:45). Then, they discuss the importance of designing HVAC&R systems that help people exist and survive in the harsh environments of space (5:20), among other topics such as design considerations, non-HVAC elements that affect the built environment and sustainability in space.

    Almost two years ago, Constantinide and Najafi co-authored an ASHRAE Journal article about (2:56) environmental controls in space.

    Download that article at

  • Guest Bios

    John Constantinide, P.E., Member ASHRAE, is a Florida-licensed mechanical engineer with more than 10 years of experience with energy management, design and design-build projects for the U.S. Eastern Range supporting the nation's space mission. He also has extensive experience on design and design-build projects of industrial, institutional and commercial facilities for government, aviation and health care entities. John is a Certified Energy Manager, Certified Fire Protection Specialist and LEED Accredited Professional with a Building Design and Construction specialization. In ASHRAE, he serves as chair of TC 5.2, Duct Design, Handbook subcommittee chair for TC 7.6 ,Building Energy Performance, consultant to the Building Energy Quotient and Chapter Technology Transfer Committees and assistant Regional Chair for Region XII.

    Hamidreza Najafi, Ph.D., Member ASHRAE, is an associate professor of mechanical engineering at Florida Institute of Technology. He conducts research and teaches courses in the areas of energy and thermal sciences. He is the Director of the Innovations in Sustainable Energy and Thermal Systems Lab (I.S.E.T.S) where his research is focused on designing and optimization of thermal/energy systems, zero-energy buildings, renewable energy systems, energy efficiency and computational heat transfer. He has authored or co-authored more than 50 published technical papers. Najafi is serving as Florida Tech’s ASHRAE Student Branch Advisor, chair of the ASME Renewable Energy and Energy Conversion Technical Committee, guest editor of ASME Journal of Energy Resources Technology and MDPI Sustainability. Prior to joining Florida Tech, Najafi worked as a lead engineer in Alabama Industrial Assessment Center (funded by U. S. Department of Energy), where he was focused on improving efficiency in industrial energy systems and conducted assessments for more than 50 manufacturing companies in Alabama, Georgia and Mississippi.

  • Transcript

    ASHRAE Journal presents.

    John Constantinide:

    I'll start by noting that ASHRAE again has a unique opportunity to get involved with the built environment and space to not necessarily reinvent itself, but continue its mission and envision a healthy, sustainable built environment for all. It doesn't have to be limited to this planet. It can extend beyond the boundaries of this planet, and ASHRAE has an incredible waypoint to extend its mission and vision, and to really hone in on sustainability on extraterrestrial bodies and elsewhere.

    ASHRAE Journal:

    Welcome to the second season of the ASHRAE Journal Podcast. As billionaires race to space, researchers and engineers are working to create built environments in the final frontier.To kick off ASHRAE Journal Podcast's second season, John Constantinide and Hamid Najafi discuss how HVAC&R technologies used on Earth can be applied to extraterrestrial indoor environments as well as opportunities ASHRAE has to help shape the built environment in space. Almost two years ago, Constantinide and Najafi coauthored an ASHRAE Journal article about environmental controls in space. Download that article at

    John Constantinide:

    Hi, I'm John Constantinide. I'm a Florida licensed mechanical engineer out of Merritt Island, Florida. I have extensive experience with design and design build projects for the United States Eastern range servicing the National Space Mission. And I look forward to talking about the present state and future of environmental control systems in space. It's a very unique topic that we have, and I co-authored it here with Dr. Hamidreza Najafi, from the Florida Institute of Technology.

    Hamid Najafi:

    My name is Hamid Najafi. I'm an as Associate Professor of Mechanical Engineering at Florida Institute of Technology. I do research and teach courses in the areas of energy, building energy and thermal sciences in general. I'm a member of ASHRAE. I'm also serving as the Florida Tech ASHRAE Student Branch Advisor. I'm looking forward to this podcast, very excited to be here with John and all of you and ready to begin.

    John Constantinide:

    So as Dr. Najafi knows, he and I do PowerPoint presentations on the ASHRAE Journal article. So I always start out with the typical space, the final frontier, what is it going to look like? How will space infrastructure look? We have to understand how space and the built environment and the future is going to look because that is the next medium for business opportunities, advancements, and technologies, and exploration for inhabiting planets, moons, and areas outside of our planet. So when we look at deep space, we think of waypoint stations, planetary orbits, transport vessels, and other structures on other planets, but what standards are going to be used in space? What can be adapted from industry today? And what needs to be created?

    So I think all of that is incredibly important to look at when we talk about space regulation and the built environment in space, and ASHRAE has an opportunity to propose standards, guidelines, and codes relating to the indoor environment of extraterrestrial transport vessels, waypoint stations, and facilities. Dr. Najafi has provided a lot of information in the ASHRAE Journal article about the International Space Station. What do you think Dr. Najafi stands out to you in regards to what we reported in the article and what maybe we could carry on in future or what needs to further develop?

    Hamid Najafi:

    Thank you, John. Yes. First of all, let me start with this, that when we talk about International Space Station, this is an excellent example of a living environment in an outer space basically. It's basically located at an altitude of about 248 miles, and it's about 357 feet end to end. Typically, there are up to six crew members working in that environment and it makes it basically a built environment outer space and that's creating this pretty unique situation to see the importance of HVAC systems and IAQ, indoor air quality and in general indoor environmental quality. It comes to outer space applications, it's not really the matter of comfort or just health, it's the matter of survival. And I think that's what makes outer space HVAC systems a pretty unique topic to discuss. So it's not just about designing an HVAC system to keep people or keep the crew members, the astronauts, comfortable. It's to basically survive them from the harsh environment that exists out there. So the topic is very broad and we can delve into it with more details, of course. But I just wanted to talk about the importance and the critical need for IAQ and HVAC systems for outer space applications and the excellent example that will basically ISS would set for us as a pretty unique structure built environment, basically in the orbit.

    John Constantinide:

    So it's a great point you bring up, Dr. Najafi, because when you look at design considerations of the built environment in planetary orbit or deep space, oftentimes you don't have an atmosphere you're encountering, your exterior gas composition around the facility are trace gases dominated by solar winds of radiation and particulate, dust and water. And that particulate dust and water is significant. It actually drives the need for resilient equipment that can endure the elements of space.

    And because there's no atmosphere, the harsh radiation in the solar winds, anything that travels through space travels uninhibited, therefore you need to have equipment that can take on that type of, if you will, wear and tear in space. And it's not the typical wear and tear that you see on Earth with hurricanes or windstorms or tornados, it's of a higher magnitude, I believe. And at the same time, you still need to have that heat transfer, that maximized system energy efficiency, and a lot of closed loop systems, as we will discuss, are present in the International Space Station because parts of the space station that use heat can transfer that heat, or expel heat, can transfer that heat elsewhere, expel it, or even bring in more heat.

    And you also have technology that generates heat such as the instrumentation that's on the space station. So there's several elements in facets to look at that are starkly different from Earth and that needs to be considered.

    Hamid Najafi:

    Absolutely that's an excellent point. When you think about creating a living environment for humans, there are several aspects to be addressed. And specifically in the case of ISS, when you think about it, there's the aspect of having clean air, comfortable temperature and humidity level, having access to clean water, healthy food, handling the wastes, hygienes, etc., etc. So you're looking into an array of aspects that must be addressed properly in order to provide this living environment in the harsh outer space environment. This becomes pretty challenging to address specifically talking about, for example, maintaining a comfortable temperature environment for the astronauts inside of the cabin, thinking about the extreme temperatures that the ISS structure experiences. And we discuss that briefly in the paper, we look into the two sides of the ISS at any time, the sun facing side and the basically shaded side, the shadow side, you're looking at a temperature difference around 500 degree Fahrenheit.

    So about 250 plus, 250 negative, 250 from both sides, which is extraordinary. In order to handle that scenario and provide a proper thermal management for ISS to make it a livable environment for the astronauts, very complex thermal management system has been designed and implemented for ISS. Looking into the passive systems and the active system, passive system, specifically the MLI, the multi-layer insulation system, that is attached to the surface, the entire surface of the ISS with the exception of the windows and that multi-layer structure almost blocks 100% heat flux that is incident on the surface of the ISS. When you think about that you would say okay, maybe that solves the problem. But then as you mentioned, there are heat sources inside of the ISS, like the human body generates some metabolic heat. The electronics on board are generating some heat. So as a matter of fact, sometimes it's not the problem of providing heating, it's providing cooling for the crews who live and work inside ISS.

    And that becomes again a very interesting HVAC problem. And that's a problem that I explained when I teach HVAC here in my class, because students find it very interesting, how different the system is from on Earth HVAC system. The fact that instead of using a condenser that we use on a typical heat pump unit here on Earth that works based on the convection heat transfer, that's one of the three modes of heat transfer, but with the vacuum environment in the outer space, that's not an option. So the only mode of heat transfer that can facilitate this process of heat rejection would be radiation. That's why there are these 14 very large radiator panels attached to the ISS that essentially serve as a condenser to radiate the excess heat to the surrounding from the ammonia to the surrounding and create this nice basically loop of refrigeration cycle.

    So it's fascinating, very detailed designed and lots of challenges to be addressed. Now, thermal comfort in temperature control is only one aspect. Like I said, you can talk about the water recovery system. You can talk about the air flow, the challenges associated with that, the fact that it's Zero-G. So the natural air circulation that we get for earth applications does not exist there. That by itself would be an interesting challenge and so on and so forth. So lots of very interesting aspects that must be addressed and has been addressed related to ISS as again living example of HVAC in space application.

    John Constantinide:

    And furthermore in looking at environmental control, as you mentioned, Dr. Najafi, it's about survival, not necessarily just about comfort. So in a typical HVAC setting, we look at heat and cooling loads. However, there's also the issue of carbon dioxide removal and nitrogen and oxygen control, and also non-HVAC related items that do impact HVAC, such as water processing and waste management, there's even urine recovery.

    There's actually a quote that I believe astronaut, Douglas Wheelock said, "As you inform me, yesterday's coffee is tomorrow's coffee." And that's because literally you have to reuse every resource that's available and it might sound disgusting at first, but as you live through the realities of space, it's like living in the realities of any harsh environment. One has to understand that it's not about availability of resources or the luxury of having resources, but about sustaining and having a net zero cycle all around. And that's why we have the closed loop, because anything you release, whether it's heat or water or waste into space or the environment, that's gone, it is not coming back. You cannot open the door and get it out and get it back in or whatever, forget doors. You're just going to get sucked out and you'll go somewhere far or near or wherever vacuum wants to take you.

    Hamid Najafi:

    Lots of interesting aspects specifically about the water. As you mentioned, the astronaut urine is being recovered. The cabin humidity is being recovered. You mentioned it might be disgusting, but it's necessary disgusting. So it's an absolute need. It's not really optional. The necessity becomes a drive for the researchers and engineers and scientists to develop these new technologies. When you think about, and again this brings me to this idea that when you look into the history of space program in the United States and other countries, many of the technological innovations are rooted in a space program and are spinoff of the space program. I think NASA published more than 2000, the list of more than 2000 technologies products that are considered a spinoff of the space program. And many of the technologies that we do have now are inspired by the space program. And I think HVAC has no exception when you design HVAC systems or in general environmental control and life support system, basically components. These could become drive motivations to develop more, maybe technologies that are also applicable and useful on Earth application.

    John Constantinide:

    And that's a great point you make is that application from space to earth and how you take it from more of an air quality level to more of a chemical level where you're looking at hydrogen, nitrogen and oxygen. And it's about finding appropriate chemical compositions to harvest certain fuels, certain resources. And this actually may inform several discussions that we're having in the built environment about sustainability, decarbonization. One question that may be asked about decarbonization is if you're going to decarbonize, where is that carbon going to go? Can that carbon be used for energy purposes or recaptured? Can there be a closed loop where the carbon doesn't get released into the atmosphere or get released anywhere, but stays in a constant cycle, similar to the refrigeration cycle. And we're not releasing refrigerant into the atmosphere. We reuse the same refrigerant in a closed loop. Why can't we do that with others?

    And may say, well we use CO2 as a natural refrigerant. Okay. And that's a start. Why don't we look at other closed loops or other zero energy, zero water, zero waste processes that are in space and translate them to earth. Is there a higher cost perhaps, but if someone is going to own a building or facility or a site and maintain it and there is no intent on selling it to a different owner or perhaps there's a higher price or there's value associated with a system, then there's payback seen and there's value to that system. I believe that should have some varying on Earth-based conversations that are going on with sustainability in the built environment, especially in regards to waste management and reuse of water.

    Water is such a precious resource that we have. And yet many people would prefer to have water from the aquifer, or bottled water in the supermarket. And those technologies that we've seen on the ISS, you could look at its predecessors to previous space programs and other technologies as well. Space suits, for example, are a microcosm of the ISS. Imagine having a whole indoor environment or a controlled environment, just for one person and blocking that radiation, regulating that 500 degree Fahrenheit temperature delta on the sun side and the shade side, just on one person. I could only imagine my face getting seared by the sun and then the back of my head forming ice. That would be quite an experience, but thankfully the space suit will handle that, not me, but yes, that, and just the resilience of previous astronauts in previous programs and how interestingly enough a lot of what we had from the 1960s is reused again, because there are basic principles of engineering that are carried on and they're just revised further and further, but there has to come a breakthrough point.

    Now, as you mentioned that breakthrough point comes when we're able to sustain on another planet. And I think that's where industry needs to step up. Industry has done quite a bit already in launching and testing, recovering first stages of rockets, trying to make launch more affordable. But now we have to do more than transport. Transport is the first step. The second step is establishment. And then the third step is continuation or sustainability and then growth after that. So having engineers address those third and fourth phases, and even the second phase as well, because transport is important. Having a crew that lives from Earth to moon, and more importantly from Earth to Mars, that's a much longer journey, is important. So how do we store food properly, even dried food? How do we have comfortable and livable environments? How many redundant systems do we have? Do we have a 2N or 3N or 4N redundant system? Because everything is mission critical in space, where most things are mission critical in space. It's not selective and emergency power goes everywhere. It doesn't go to certain items or perhaps it may go to specific items and there are levels of emergency power if you will, based on what is deemed more critical and less critical. And that engineers have to consider because what they're designing is going to affect lives. It's not just public safety and people's lives in buildings as it is here on earth. And we have life safety codes where people can escape out of buildings. Life safety and space is very different. There's nowhere to escape, perhaps maybe an escape pod, but then where does that go? And how long is that going to sustain the people who escape? It becomes a revolving question. How do people move on and survive? Refrigerants and refrigerant cycles are something that I think industries should be addressing in regards to sustainable technologies, machinery resilience, especially with recent anti-satellite demonstrations that have been done in orbits. If they're going to be done here, they'll likely be done elsewhere. There's going to be hostilities happening. And then there will be innocent parties in between and astronauts. And those traveling will be in the midst of that hostility. So how can we be able to move through that and air treatment and revitalization? I think the pandemic has informed us a lot about how to revitalize air, especially to not have HVAC re-entrainment of COVID. So then COVID is taken and then redistributed. What if you have a pandemic on a planet of 5,000 people? I think that's going to be a much bigger deal than the billions and billions we have here on earth, we have a buffer if you will, where you have healthy people and people who are not so healthy. And that creates an epidemiological dynamic that you can't really replicate with a 5,000 population crew or colony. Just looking at those technologies and there are many more, but definitely worth thinking about an ASHRAE has a role in all of those.

    Hamid Najafi:

    Absolutely thinking about again to your point, the role of ASHRAE and steps to be taken and how space and HVAC are related to one another. And that's a question that we often get when you talk about HVAC in a space, people may just raise an eyebrow and ask how do you relevant if they're not familiar with the background of this topic? But we are especially now living in a very exciting era as the space exploration is receiving a lot of attentions, thinking about the growth of the private sector in the space industry over the past 10, 20 years, the space tourism, which is just become a reality. Again, all the NASA plans, very aggressive plans for going back to the moon and going to the Mars, this starts to get more attraction that okay, if we want to send people to the other planets, if we want to think about more manned missions, we need to think more seriously about HVAC systems, indoor environmental quality for outer space conditions.

    And ASHRAE is certainly at the center of HVAC design standards and so on and so forth. So definitely ASHRAE can at least consider to look into this subject matter. Another thing that I want to point out here is if you talk to, I'm a professor, as an educator, when you talk to engineering students nine out of 10 would be very excited about space. Anything about space. When you're talking about a spacecraft, thermal management of a spacecraft, talking about the reentry vehicle, anything space related brings inherently this excitement to a lot of people, including engineering students. I think here's an opportunity to connect between these two topics. It's absolutely a very important need, but it's also, I think an opportunity to get these two topics closer to each other, try to talk both languages between aerospace industry, the needs for the future, again, related to living in a different planet or establishing similar structures to ISS and so on and so forth, and the HVAC needs because if you talk to many students and ask them what do you think an HVAC course is about? They probably think about very, let's say conventional things like, okay, here's, you're probably going to cover refrigeration cycle, probably going to cover basically essential elements of heating, ventilation, air-conditioning system. They don't expect you to talk about international spaces statio, they don't expect you to talk about cooling load calculation on the surface of the Mars or heating load calculation really on the surface of the Mars. They don't expect that when you talk about these topics, when you bring this up, there’s this a-ha moment that captures student's attention, make them to start thinking about this. And I think that's a way to encourage students to develop more interest towards the subject of HVAC or towards the subject of sustainability and a sustainable built environment of the future, which again, benefits the life on Earth. Also certainly benefits the futuristic life on the surface of other planets.

    ASHRAE Journal:

    Thanks for listening to the ASHRAE Journal Podcast. We want your ideas, what topics do you want to hear about and who do you want to hear it from? Email us your ideas at Let's get back to the episode.

    John Constantinide:

    It comes into question many times, when does proprietary or private research become exclusive research. And many times you look at rockets and payloads and such, and that technology is specific to the company, it's proprietary to the company, which makes sense because they use it for launching commercial payloads, government payloads for a profit at the end of the day, that's how the company sustains its operations and rightfully so, it needs to be able to pay employees, pay for space insurance, which also exists interestingly enough. And it asks the question where does regulations fit in? Where does the public domain fit in with space technologies? Where do ASHRAE standards fit in with as part of that regulation? I think space regulation right now is minimal when it comes to companies and corporations, most of that regulation is on nations because at the time the UN space treaty was conceived, nations were spacefaring, not companies, but nowadays companies are more so spacefaring and even nations are giving deference to companies to say, go here, we'll subsidize maybe some of the infrastructure.

    So then you can continue in and go into space and explore. I think maybe because nations know companies have this latitude to be able to go and explore without much, if any, restriction. What is a country going to do to a company that is going to exploit and asteroid or exploit the resources of the moon? Are they going to get fined? What if they set up a company out on the moon and it's not affiliated any longer with the original company or loosely affiliated. And there's a colony on the moon. What are you going to do? Fine the people on the moon and have them ship back the money?

    It comes to a point where we have to ask ourselves where do we draw lines? Where do we draw boundaries? And I think ASHRAE is a very big part of the that, or it's a great venue to start talking about that. Especially when it comes to HVAC technologies, mechanical technologies, having chemicals and refrigerants and equipment, you don't want to have HVAC equipment start becoming part of that space junk besides satellites that are unused floating around in space, because that impacts equipment and waypoint stations. Imagine having a piece of HVAC equipment go on a transport vessel, many people wonder well, how is that like? And I was thinking about this morning and wondering, well maybe if you take a small demolition ball and you just swing it right into your building, right there on Earth, depending on how large you want that floating piece of equipment to be and how fast it's being flung, that could be if you owe the analogy that is used for Earth type buildings. So people obviously don't want swinging wrecking balls at their buildings on Earth. Why would we want to have space junk run into space stations, waypoint stations, even land on planets, where there is no atmosphere? There is no burn up on the moon. They just land and fall and boom, there it goes. So how do you avoid all of that? And I think ASHRAE can provide a lot of precautions. We do have a code of ethics, perhaps, maybe that could be extended to the application of how technology is applied as well. And what engineers need to follow in order to maintain that level of professionalism, and also extend that net of safety. So that we are cognizant of life safety, not in the conventional sense where people escape a situation because that can't be done in space, but situations are prevented. There's more proactive measures taken as opposed to reactive measures.

    Hamid Najafi:

    Absolutely. These are great points that you made, John. I think there's certainly a big demand requirement for developing some regulations and some standards related to HVAC in space. And the first step in establishing these space related HVAC applications, I would say, probably thinking about the problems ahead of us and you made great points. You brought up several very interesting challenges. I think the first step is recognizing and identifying those issues and then try to see if those issues can be categorized. For example, you mentioned the management of the refrigerant or the waste product from HVAC equipment and so on and so forth. Each of these, I think recognizing these issues, understanding them, and then the next step would be trying to come up with solutions. And I think these could be part of series of regulations, standards to address the problem.

    When you look at it, we are still at early stages of the awareness regarding this matter, because when you and I, when we did write that ASHRAE Journal article, we spent a lot of time trying to collect information, if you recall that are published from different basically researchers, different organizations, institutions, and so on and so forth. There are a lot of good resources, but you can see that not many details are shared about many of those basically subject matters, and that makes it hard to even identify those issues.

    So we spent a lot of time discussing some of these. We spent a lot of time collecting information and discussing the topic, but given the emerging nature of this subject matter and given the proprietary nature of this subject matter, it is still challenging to collect enough information about it and create this, let's say, set of data, kind of a database that allows, let’s say, an organization like ASHRAE to start developing, establishing standards around it. So I think it takes us some background research, some let's say ideations, some discussions with experts with different perspectives to understand the issues first, establishing an understanding of, what are the issues that we are trying to address and then maybe categorize those and then maybe through task groups or something basically mechanism like that, try to address each issue in a proper fashion.

    John Constantinide:

    Agreed. And I think having those professionals and engineers consider the scenarios and the possibilities, be creative in what could be out there and anticipate what's out there is important, space tourism for example is creating more possibilities of what people can do, should they have the resources to do it. And then it extends beyond the conversation that I mentioned about companies to individuals. What if individuals go out to space and start building their homes on asteroids and rocks, and they can maneuver their asteroids or maneuver their ships. And they do it in a way where it's their property and they have the right to do what they want with their property, but is it going to be yet the cost of others that may be around them? And we're not talking about just a one acre piece of land on a large planet. We're talking about rocks that can create catastrophe on satellite moons or that can land in planets without atmospheres, or that can crash into stations and such.

    So when one talks about property and some smaller planet or orbiting planet or somewhere there has to definitely be boundaries. And I guess it ultimately boils down to creating an atmosphere, that sense of responsibility, not just among engineers designing, but amongst the operators, amongst the owners, amongst the stakeholders involved. And many times when space systems are created, there's so much complexity it's as if people just throw up their hands and say if it breaks, it breaks, or I don't know how it works. And I think this may be a call to where we have to look at also the systems that we have and make them more user friendly. I know going back to Earth now, we have a lot of those issues with building controls, where more complex building controls become unmanageable. And then building operators just shut down the building controls and create their own parameters for HVAC systems because that's easy. It's simple, as opposed to understanding the building controls and being trained and using the building controls to their advantage to increase the performance of a building. And perhaps that education needs to be provided to those who want to occupy other planets or other extraterrestrial bodies and take the time to know the technologies and use the technologies. Instead of saying, I'm just going to go out and live my life out there, like I live my life here, and that's not possible. So a gravitas, if you will, on the responsibility, not just perhaps the adventure and the luxury of living in space is very important and it's sobering as well, because then it makes people think, is it worth for me to go to Mars and stay out there? How much do I have to learn? I have to reorient everything I learned since I was born and rethink everything.

    And perhaps maybe focus on a niche, allow others to work on other areas. This is perhaps the greatest opportunity for engineers in different disciplines to finally work with each other, instead of stay in their own silos. So many society presidents have talked about breaking down silos. Well, here's a great way to do it. Let's work on space projects. So that is daunting and opportunistic as well. Lots ahead of us. What do you see is going to be happening in the next, I wouldn't say five years, but maybe 10 to 20 years. I know there are many planned voyages to go to Mars and moon as well, but what do you think we can do, Dr. Najafi, from a practicality standpoint, maybe form an ASHRAE Space HVAC task group, or a technical committee, or pursue an energy code on space structures or on lunar structures, or what would ventilation look like in space? Because there's not much ventilation out there in a vacuum.

    Hamid Najafi:

    That's a very exciting idea. Yes. Establishing a task group, or eventually a technical committee, I think it would be very interesting idea to look into the HVAC in space. I think the topic is very broad, John, like I said, understanding the issues ahead of us related to thermal management related to energy consumption, trying to address the creating that full circle with zero energy, basically buildings or built environments and so on and so forth. I think there are lots of issues to be addressed. What I see as an interesting trend now, there are a number of interesting things happening now that I think will bring this topic to a higher priority for many people. It is the fact that on the surface of the Earth, we as humans, we do feel now, we do see the environmental issues.

    It's an era now that everybody are realizing the environmental issues, more or less, and the challenges associated with global warming and the challenges that it has brought and it will continue to bring, it will make earth a less comfortable environment to live on, and it will make us, push us, to become more responsible citizens and engineers, I'd say. It will encourage more engineers to start thinking about sustainability and how it can be addressed in their area of expertise. At the same time, so again, this is on the Earth. So when you look into buildings for example, just look into the huge investments that has been made into making buildings more energy efficient over the past couple decades, and think about all the new technologies that have been developed for zero energy buildings. I think this shows a general awareness with regard to energy, with regard to the environment.

    Now this is happening at the same time that space program is becoming more and more aggressive toward the space tourism, towards landing humans again back on moon and later on Mars, and make these two topics a little bit, I guess, maybe converging, thinking about the more difficult situations for design of HVAC systems for building energy systems. I think this brings these two topics a little bit converging to one another to some extent, of course there are huge gaps between the two environments, but again an opportunity I think. And like I said, I mentioned this before. I'd like to emphasize on it. I think when we think about HVAC design on an space application, let's say on the surface of the Mars or moon, or even just ISS, the situation, the design condition is so challenging that will push the engineers, basically scientists, a lot more innovative. They don't have other choices.

    They have to become innovative to be able to address us the challenges. And I think very much so we can benefit from these innovations on the surface of the Earth and looking into that. If we appreciate that aspect of it, I don't think it is faraway to think about establishing a task group within ASHRAE, let's say to look into this subject matter, again because it's not just about, oh, tomorrow, we want to establish a built environment on Mars. It's about what we can learn, lessons learned from looking into some of these very critical matters. Again, I'm thinking about ISS again, think about how this system was constructed in late 1990s. I think that's when they completed the project and thinking about the providing a cooling thermal management system basically for ISS. More than 20 years ago, it shows where the technology was again in the space program, which was able to address those very challenging problems at the moment.

    So again, right now thinking about maybe 20 years ahead of us now, if we think about maybe establishing a built environment on the surface of the moon or surface of the Mars, what are those needs that has to be addressed? What are the challenges that has to be solved? I think there's definitely an opportunity to look into this subject matter, and I think it will be well received by the engineering community. I think there will be many people who would be willing to start looking into this topic again, because it's just inherently very interesting and challenging

    John Constantinide:

    An ASHRAE 90.5 energy code, I think we're at 90.4 right now, or 62.3, 55.2, so when we're looking at ASHRAE standards, say we're looking at energy, I guess this is a direct application from the standards we have now to the standards we could have. Energy has to be considered in moon, Mars and deep space and asteroids. Let's lump asteroids into deep space, and understand that one, the atmospheres are going to be different. Two, the temperature differentiators are going to be different. So then three, the loads and demands on the facility are going to be different. So those considerations may need to be looked at. The thought of climate zones is going to probably be massively adjusted on moon and Mars, if not thrown out the window, especially for deep space, there's one climate zone in deep space, and that is vacuum. So when you're looking at what we do on Earth, we definitely need to tweak and adjust the energy codes.

    And also renewable energy is going to be the way of collecting energy, unless we have incredible petroleum reserves hidden on moon and Mars, and perhaps there is, but what benefit is it going to be to use that? And is it going to be cost prohibitive? It's not cost prohibitive on Earth because we're here already, but to send all that construction equipment to build plants and such, that's going to have to be after hundreds of years of habitation, but solar and perhaps using solar technologies to capture solar wind, capture solar energy through multiple methods, not just through irradiance and through photovoltaic means, but through other means as well, something to keep in mind with Mars, most of the atmosphere there is made of carbon dioxide, nitrogen, and argon. How can we take atmospheric elements and harvest them to make energy. Or on the moon you have healing for hydrogen, to methane and ammonia, and carbon dioxide that methane, or do you have methane deposits where you could maybe provide some clean sources of energy and then you could reuse for heat and that way you use carbon, if you will, in a closed loop.

    So those are opportunities there, but for 62.1, that's going to be an interesting jump from what we have on Earth, because ventilation can't be done. So if you have like a 62.3, it's not really going to look at minimum ventilation requirements, it's going to look at minimum environmental quality or air quality requirements. So looking at air treatment and revitalization or filtration, that's going to be most of what we have. And if you look at say what we've done in COVID era, the COVID times where we focused on filtration and outdoor air, say you remove the outdoor air component, but you look at the UVC technologies that are there. The filtration technologies, the usage of HEPA filters. That's incredibly important for what's going to be out there in space. And the ability to regenerate that equipment as well, to clean the filters, clean that, because you can't throw away materials out in space. Then that means they have to be replaced, which costs money to send and replace them unless you're going to replace them on site.

    So standards have to create a consideration of reuse of equipment and materials and to minimize waste, which is sustainable in their means. A Standard 55 for thermal comfort, I think is going to be quite similar to what we have a 55.3 out in space, perhaps maybe considering different layers of clothing or different types of clothing. And then going beyond HVAC, the different standards that we have, one comes to mind Standard 211, which is for commercial building energy audits. How do you do an energy audit of the international space station?

    One interesting question someone had when I presented to the ASHRAE Central Florida chapter on the side was what would an ASHRAE building energy quotient performance score look like on the space station? And I'd say, I'd imagine it's zero because you're not pulling any power from a power plane, right? It's all on site regeneration or renewable energy use. But how would energy audits look and what would be your energy consumption survey, the analog to CBECS for different types of facilities out in space. So I think ASHRAE has a lot of opportunities. There's a lot of great groundwork done with the 90.1, 55, 62.1 and other similar standards, but at the same time, revisions need to be done to adapt to space. And perhaps, maybe they may not be useful now, but as Dr. Najafi mentioned, this is forward looking, we need to look ahead.

    We need to prepare because if we don't do it now, then it'll be too late by the time we think about it, because these standards take time to develop. Noting that ASHRAE again has a unique opportunity to get involved with the built environment in space, to not necessarily reinvent itself, but continue its mission and envision a healthy, sustainable built environment for all. It doesn't have to be limited to this planet. It can extend beyond the boundaries of this planet, and ASHRAE has an incredible waypoint to extend its mission and vision.

    And to really hone in on sustainability on extraterrestrial bodies and elsewhere. What is sustainability? Is it a convenience or is it necessary? And then to bring that back to Earth to say, we perhaps need to consider sustainability to be more necessary than convenient, especially if resources are questioned, cost is a question. Right now it may be cheaper to not be sustainable, but is that always going to be the case. And when it doesn't become the case and when we don't have a plentiful amount of resources, everyone, we have to start considering reuse of materials, reuse of equipment, recycling, recapturing, such. What is that going to look like? And our work and space will prepare us for what may also come on earth as well, and ASHRAE should be there and ASHRAE should be ready.

    ASHRAE Journal:

    ASHRAE Journal Podcast team is managing editor, Mary Kate McGowan; producer, and associate editor, Chadd Jones; assistant managing editor, Jeri Alger; and associate editors, Tani Palefski, and Rebecca Matyasovski. Copyright ASHRAE.

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