Episode 10: Does your home need mechanical ventilation?
Waste management has been a big topic for us lately! Not just because our team member Evangelia has been super passionate about it and introducing a proper system for our office, but also because the building industry is a massive producer of waste.
Around 18 cubic metres of waste come in everyday – from just one building site. The majority of this waste is going to landfill – unless you are working with Rob Holden from Tiger Bin Hire!
Rob has run his business in Bendigo for 10 years now and has dedicated himself to recycling as much waste as possible. He joins us to talk about his motivation behind his business, how he manages his operation and how builders and local government can help with the recycling process.
Sandra Redlich 00:00
I don’t know if you know this, Joel, but you’re actually called the HIV guy in our office. Or a lot of the times that’s what you’re being known as. And it’s great to have you on today to actually get to know you and know more about what you do and talk a little bit about what HRV systems mean, what they do and how they perform. So yeah, maybe you could start off by telling us in your own words, not just by our little unprofessional description, what is it that you do?
Joel Seagren 01:46
Thank you very much, lovely to be here, Sandra and Anthony. I’m going to have to check that domain HRV guy and see whether it’s still available, I like it. So off the back of that, yes, HRV or MVHR, mechanical ventilation with heat recovery as it can be known, ERV. That’s kind of my lifeblood and one or two others at Fantech. It’s a small and growing portion of the Fantech business. But it is not a big chunk of it at this point in time. But in terms of day to day activity, we’re basically helping design high performance heat recovery ventilation systems or ventilation systems in general, to achieve these high performance outcomes. It’s been something that’s been missing in the market in earlier years, and particularly in the sort of class one single dwelling space. So yeah, day to day kind of involvement is helping assemble designs with building designers and consultants to produce these high quality outcomes.
Anthony Jenkin 02:55
When do you think the very first HRV system went into a residence in your career?
Joel Seagren 03:03
Yeah, so I know our New Zealand arm of Fantech actually sold some of the earliest systems in Australia. So I reckon we’ve got to be approaching almost 10 years now as Fantech’s first involvement there. We still speak to those customers, they’re still purchasing filters, and so forth. So we know those units are up and operational. They’re long life systems that we expect are going to be around for kind of life of the building.
Anthony Jenkin 03:35
So what are some of the benefits you think for mechanical ventilation?
Joel Seagren 03:39
Yeah. So it’s been kind of well practiced in that commercial space for a long time that when you’ve got an occupant in a room, there’s really clear design guidelines, around 10 liters per second per person in an office space. But what we’ve had in the resi space is this kind of belief or understanding that as long as you’ve got an operable window, in a residential building, the ventilation is all taken care of. So we don’t need to supply that fresh air any longer. We all obviously know that it’s a little bit of a farce in reality for a number of reasons, but principally one of those is people don’t open their windows and leave them open. And perhaps for a variety of reasons, noise, air quality, security. There is a raft of reasons, comfort, why they’re not doing that. So yeah, mechanical ventilation in the resi context, whilst newer, is just really doing what’s been done in commercial buildings for a long time, in terms of providing that continuous flow rate of fresh air, and on the flip side of that, it’s also the moisture and other contaminant removal in that space. Well behind the Europeans in doing that sort of stuff. They’ve been on to that. But clearly some climatic things have made it much more imperative. But also, I think, and probably everyone agrees, a slightly different approach to building design and construction. It’s not got such a cost driven element in it.
Sandra Redlich 05:16
Yeah, that’s literally what we discuss on this podcast I feel like almost in every episode, how it’s different and how we’re a bit behind. So what I’m interested in, in the commercial space, you’ve mentioned that, you know, there’s rules around this and that you need to have some sort of mechanical ventilation. Why is that? What are the rules and reasonings behind them being mandatory in those spaces?
Joel Seagren 05:44
In commercial versus residential?
Sandra Redlich 05:46
Joel Seagren 05:47
So I guess in commercial, let’s say, an office building, for example, it’s unlikely that you’ve got sufficient operable glazing, in order to even come close to enough fresh air, particularly high rise type stuff. There’s not a lot of, and there may not be anything at all that’s operable. So very quickly, that became a case of elevated CO2 levels and contaminant levels and being a problem in those spaces. Resi on the other hand, as we’ve mentioned, can be operated a little bit differently depending on the people and depending on the climate zone. And so we’ve not really thought about it. The reality is, unfortunately, we’re probably spending more time in our home, way more time in our home than we are in the office space. And particularly post COVID, a lot of remote working now, the real focus on indoor air quality in resi buildings is coming to the fore.
Anthony Jenkin 06:49
Yeah, that’s a great point you make there. I think it’s been emphasized over the last few years, definitely. I remember a study that touched on the fact that we all believe that we open our windows a lot more than what we do. Some people believe that they have this inside outside sort of lifestyle in which they live. And that may be true in some climates in Australia, but for where we are down in the southern states, it’s a bit more cooler. There is something like, you know, into the 90% of the time those windows were closed, and I just tell people, you know, if you’ve got your windows closed, we’ve got you covered. It’s okay. Mechanical ventilation just takes care of that for you.
Joel Seagren 07:27
Definitely. And the other side of that we’ve sort of focused a little bit on fresh air supply in the resi context. But the matching side to that is extract of contaminants and moisture. So contaminants is kind of fairly intuitive that we’re exhaling CO2. If we do any gas related cooking or heating, we’ve got CO2 as a product there. We’ve also got volatile organic compounds coming off sort of synthetic carpets and things like that. So we’ve got stuff to remove out of the building. The other part is, as well as that sort of internal health, it’s actually building health as well. So we obviously in sort of that high performance space go to a lot of effort to manage what we’ll call interstitial condensation. So essentially your wall and roof assemblies getting wet. Now, ultimately, there’s still some moisture transport in there and continuous ventilation inside the buildings helps draw away that moisture also. So not only is there a personal indoor air quality kind of thing, there’s a building durability function to that continuous ventilation. And that’s something that’s perhaps not quite as intuitive. We kind of think of the indoor plaster lining being our sealed box, but it’s not quite like that. We have got some moisture movement through wall and roof assemblies and keeping that assembly healthy also contributes to indoor health but durability,
Anthony Jenkin 09:07
It’s not just the occupants of the home, but the health of the building. Yeah, I love that. That’s great.
Sandra Redlich 09:12
I think another point… I’m not sure if… like that just always comes to my forefront of my head and that tells you a lot about how I operate and what is important to me. Isn’t it true… Like I mean obviously if you have mechanical ventilation, a lot of times the buildings are extremely airtight. So they don’t let a lot of air through, they’re sealed pretty well which has the additional benefit other than being thermally comfortable and you know all the good stuff with condensation and air quality and building longevity, it also means that you don’t have to dust as much. There’s not as many pollutants coming in, which I experienced firsthand when Anthony and I went to a passive house building with an HRV system and I was just Yeah, it was amazing. It doesn’t let any, you know, little creepers and insects and stuff come in because it’s airtight. And that’s another thing that’s important to me. But also, you probably won’t have to dust that much. And you know, especially for people with allergies, I am starting to definitely feel the hay fever coming on to me this season. And yeah, I think that’s another added, probably not the most important one, but it’s definitely another nice little plus that airtightness brings to the table.
Joel Seagren 10:29
That’s it, I can see a whole marketing strategy now around spiders.
Sandra Redlich 10:35
We don’t want them.
Anthony Jenkin 10:37
We’ve seen this on more than one client survey as a request: I don’t want creepy crawlies in my house. We’ve got a solution. For me, like, I know, it’s subjective, but for me, it was the selling point I suppose or that point where I was like, ah. When we realised we could control or manage the relative humidity of your home. And, you know, once you just dive into that a little bit, you can see that humidity levels sitting higher than sort of 80%, for even short periods of time, can bring on mould growth. And those viruses or nasties can exist in that air as well, that can make people sick within that home. So just having that ability, especially when the humidity level outside is high. And if you’re opening your windows, obviously, then that humidity level is going to be the same inside. Whereas if it’s higher than outside, you can have the option to close the doors and windows and let the HRV system or ERV system manage that for you. So that was my moment where I was like, ‘This is amazing’.
Joel Seagren 11:35
That’s it. And it’s interesting, just as a little technical background, ventilation, heat recovery ventilation units, can have different types of cores in them. So in the southern states for Australia, and we kind of probably draw a line from sort of little bit north of Sydney, across to Perth, and sort of say, that’s kind of HRV territory. And in that HRV territory, we’re just getting, it’s called the sensible only heat transfer. But let’s think of that just as temperature transfer. When we go to more humid climates up into Brisbane, we start thinking about the ERV cores. And that’s, as you mentioned, where we can start to apply some different types of control to humidity management.
Anthony Jenkin 12:20
Can I get you to expand on the difference between the two if that’s okay?
Joel Seagren 12:23
I might get you to just explain how, in basic terms, how that system actually works, because I feel like we might actually skipped over this crucial part of the HRV system, how it works in a very basic sense.
Joel Seagren 12:23
Yeah, that gets quickly technical, but I’ll try and keep it light and fluffy as much as possible. So we actually, I guess, 10 years ago, we actually started probably going by gut feel. But about probably 4 years ago, we actually worked with Zendo, one of our suppliers, to set up a monitoring system on a certified passive house. So we knew the airtightness levels were all right, everything else was right. And we actually alternated cores, so one of the beauties of lots of systems is you can pull out an HRV core and put an ERV core in there. And to quickly understand the difference there: HRV core, as we said, think of that as a plastic type film. It’s impervious to moisture movement. So any excess moisture that comes through there when the temperature conditions are right is going to drop out as condensation and disappear, but probably only in small quantities. If we think of ERV, we can now think of that a little bit like a piece of paper. It’s not actually a piece of paper, but it has the ability to transfer heat from one side to the other. But also, let’s assume that paper got wet, we can actually do some moisture transfer as well. Now the real smarts in the technology is that we can allow moisture transfer without any air transfer. So those moisture part droplets, not even droplets, they are vapor particles if you like, are smaller than air molecules, so we can actually allow those through because it’s pretty critical obviously that we’re not allowing air leakage will transfer from an exhaust stream into a supply stream. We don’t want to mix toilet odor with any fresh air. So anyway, we ran this trial for a bit over 12 months and we put in an HRV core for several months at a time and then the ERV core, to really establish a good baseline of what gave better performance. And so for Sydney climate, this was a suburban Sydney build, not on the coasts, so inland a little. We actually found that HRV cores came out the winner. So, again, delving just into a little more technical detail. The HRV core has slightly higher efficiency than the ERV core when we talk about temperatures or the sensible component of that heat transfer.
Joel Seagren 15:20
Yeah, okay, so continuous flow rates, we’re supplying fresh filtered air into all the habitable spaces in a home. So bedrooms, living room, studies, and so forth. And we’re extracting from anywhere that’s wet or odorous, so bathrooms, toilets, mud rooms, anything that meets that definition, always absolutely balanced. We don’t want to pressurize or depressurize for a number of reasons. One, we’re using unnecessarily some extra fan power when we try to pressurize or depressurize. Maximum heat recovery efficiency occurs at balanced flow rates. And if we were to depressurize or overpressurize again, we’re forcing or drawing air through the building fabric, which is really not what we want to do, because that will bring with moisture. And we get into this interstitial moisture condensation kind of problem. So always balanced ventilation. So applying that back into our quick case study that we did, what we found was the HRV core, and it was beneficial with its little bit of extra sensible or temperature related heat recovery. Where the ERV core we’d hoped was going to come into the fore is for Australian climates, higher summer humid conditions, so higher outdoor humidity. And in essence, you can think about moisture transfer in the same way you can think about heat transfer, if we’ve got a really moist air stream and a less moist air stream, we move air from the really moist to the less moist. And so summer in Sydney , it’s quite humid outside, if we get the relative humidity or the absolute humidity down inside the building, and that might come from a dehumidifier or it comes from AC use. So even just your standard split, when it’s cooling, we’ll pull out some moisture. As we bring in that humid outside air in through the heat exchanger, we actually strip away some of that moisture to the outgoing exhaust air stream. And so that way, we can actually reduce the load on internal cooling and also reduce the humidity level in that supply air stream. So that’s the concept. What we found in Sydney was a the period is moderately short of high humidity levels. And by relatively short, we can still be talking a couple of months. But we also found correctly that when there’s purge cooling going on, which is another element of high performance building, and that’s where when your building is overheated in summer, and you’ve got some temperature or diurnal temperature drop at night, open your windows and allow that cooler air into the building to help bring your temps down in preparation for the next day. We found that purge cooling process was actually allowing moisture in anyway. And so our moisture control under those circumstances wasn’t really achieving as much as it might in a much more humid climate where you could use it over longer periods. So the crux of that was unless you’re prepared to buy two cores and do all this changing for Sydney, climate and sort of anywhere that’s less humid than that, HRV cores are a clear winner. The one little footnote I’ll make to that is alpine regions. And we don’t have a lot of that in Australia. But we have done a project at Mount Hotham and another one in another alpine area. And for those projects, the wintertime humidity levels is actually a problem in being too low. And so a bit like reversing the logic for summer, we want to actually retain some of the internal humidity generated from cooking or showering or whatever it is, rather than exhaust all that and bring outside air humidity, which has got really low moisture levels in it. We probably know kind of through good building science, that there’s actually a band we want to keep internal relative humidity in and it’s probably something like 40 to 60. Somewhere in that space. Once we get into 30s and approaching 20, it’s a pretty uncomfortable environment in terms of really dry skin and so forth.
Sandra Redlich 19:53
Yeah, I still remember some winter days back home in Germany, when you would have the heating running really high, because it’s really cold outside, and then you fall asleep and you wake up and you just have the heating on way too high. And everything just like you have a headache, you’re dried out, you’re super thirsty. That’s the worst waking up with that heating headache. That’s what I want to call it. So yeah, definitely shows this importance of keeping that balance. But speaking about balance, we’ve mentioned, you know, passive house before, that’s probably something that doesn’t apply to a lot of people in Australia yet. Does every house need or benefit from mechanical ventilation? Or what’s kind of your target house that you will be working on?
Joel Seagren 20:42
Yeah, good question. So if we start in the really simple form of mechanical ventilation, we can consider bathroom extract fans as mechanical ventilation. They don’t have heat recovery in there, but they do produce mechanical ventilation. And I don’t think you’d find too many people these days that argue you don’t need a bathroom exhaust fan, or a toilet exhaust fan. So with the really simple level, we’re already using mechanical ventilation. What I would probably expand that to be a question we get often is, what’s the threshold for when we can start using HRV systems in a building? Is it 5 air changes per hour at 50 Pascals when you do your blower door test? Or is it more or less? And my engineering answer to that is that it doesn’t make sense to have a cut off number. So being at 5.5 and moving to 4.5, in an airtightness scenario doesn’t suddenly massively change the requirements for ventilation or heat recovery benefits. So we need to kind of think of it in a sliding scale kind of manner. And so if we started out at 10 air changes per hour,at 50 Pascals, which we consider to be relatively leaky, it might be where a really basic build sits, if you’ve paid no attention to any kind of airtightness. Out of that level, you’re definitely going to want to have mechanical extract fans in there, you might start to consider some fresh air ventilation. At that level, you’re not going to get much out of heat recovery in terms of that energy benefit. You will get a little bit of comfort benefit, but you don’t want to be spending much out at 10 air changes per hour, because the benefits you’re going to reap from an expensive system are pretty small. So in that really simple scenario, you might actually have just a fan, a filtered supply air fan that can give you what we’ll call trickle ventilation. And trickle ventilation, we might be sort of talking sort of 10 litres a second or something like that, just really low levels, just to keep a bit of air movement through the house. We obviously don’t want to ramp that up too much. In a non heat recovery scenario, the more outside air we put in there that’s not tempered, the more we’re going to create some discomfort and drive up heating cooling demand. So we need to be pretty careful about how much we deliver there. As you work your way down the spectrum to passive house, which we know requires 0.6 air changes per hour, we start to change the products we use and increase the spend on that sort of system. Let’s say we’re at – and these are arbitrary numbers – we’re at 7 air changes per hour, we might start thinking about a bathroom exhaust fan that’s a high low continuous run type of model. So has a switch to drive it into its high ventilation rate when you’re showering or toilet use. But when you turn that off, or perhaps it’s driven by occupancy, that drops back into a ventilation rate, that’s maybe a third of its maximum. So we might go from 30 liters per second perhaps back down to sort of 8 liters a second as a continuous background ventilation. Now that really helps us with making sure all bathrooms are really well dried out. So that’s the obvious risk with into what we’ll call intermittent mechanical ventilation for a bathroom. You jump in your shower up, you jump out as you head to work, you flick the fan off. No one wants to leave their fan run for the whole day. There’s still a heap of moisture in there in winter, there’s nowhere for that moisture to go. It’s just turning, just being absorbed by your surfaces or ultimately turning into mould growth if you’ve done nothing with it. High low continuous ventilation makes sure it dries out. So that’s kind of a good spend, they’re moderately cheap, those sorts of fans, you might go from 100 bucks to $300 or $400, perhaps a couple of those in your build, it gives you that kind of performance.
Joel Seagren 25:18
We need to be just a fraction mindful where that makeup is coming from. So one of the challenges of having unbalanced ventilation is we don’t know where that air path is. So is the makeup air or air that needs to come into the building to fill that vacuum that’s been created by an exhaust fan? Does it come through our roof space? Does it come through our garage? Is that over mouldy insulation bats with some rat droppings and things like that? So we got to think a little bit about what are the air quality implications. You might actually have a dedicated, like a trickle vent in your build somewhere. So we can kind of define the path that comes in. As we start to move further into tighter buildings, so 5 and lower, we’re definitely in the HRV zone there. But again, you don’t necessarily go for the premium system. At that kind of level, you can start to think about entry level systems and what you want. And as you work your way down, build your spend. The logic is that there’s plenty of data that shows even those 10 air changes per hour, what we consider leaky buildings, can still accumulate large levels of contaminants. So particularly co2, which we use, often as a marker, because it’s the easy one to measure. But there’s plenty of data that we’ve collected locally showing elevated CO2 levels in bedrooms overnight, so a master bedroom, door closed, is going well above sort of that 1000 PPM threshold that we’re keen to stay under. Leaky building doesn’t mean a ventilated building. And we also don’t know the ventilation path as well. So we don’t know anything about the quality of that air.
Anthony Jenkin 27:18
Yeah, that’s a bit of a misconception. I feel there is a definite difference between ventilation and leakiness. You know, it’s, and I think you’ve very much clarified to define what ventilation is, the one thing I just wanted to mention is that you probably would like to have a baseline of air changes for a house to be able to ascertain what the best possible solution is for that home. So the easiest way to do that is a blower door test. And I know, Joel, you’ve referenced a few of the terminologies that we use there, describing what those ACH is, it’s air changes an hour, and we use the benchmark of 50 Pascals so that we can always have… It’s basically an international volume or rate, sorry, that we test at. So we can always have a consistent result from those tests. So yeah, if anyone wants to just know whether they should look at ventilation, or what type of installation will be best for their home, then the first step is probably to get a blower door test and just set your benchmark or your baseline, and then you can speak to someone like Joel and he’ll be able to help you out from there.
Sandra Redlich 28:22
Yeah, that’s a good little segue into the question of: At what point during a project do you get involved? So is this something that should be considered during the design of a new house, the construction of a new house? Or is it even possible to, you know, fit one in after the fact, you know, if people live in an existing home, they do get a blower door test or they want to make some airtightness change, and they’re also then interested in getting some mechanical ventilation. Is that something that’s possible as well?
Joel Seagren 28:52
Yeah, so good question. It’s always easier, like 99% of things, to put it in when it’s been built. And it’ll be lower cost, and you’ll be able to get a more effective system design. So we’d love to be involved at that design development phase. And in practical terms, that really just means as soon as you’ve mapped out your floorplan, that’s the time to kind of chat. Once you’ve locked that away. We know, basically, the duct routing, and we can start talking about spatial walls and whether there’s any structural things that might be impacted. So the later you leave that in the process, the more things we’ve got to deal with in that process. Retrofit projects are certainly possible. They are always going to be more expensive and potentially have some compromises. But for those in the sort of technical space, they’re decentralized units as opposed to ducted units. It’s probably something we’ve not discussed yet. But decentralized in a resi context is something that would also call through wall. And so it’s actually got a wall tube that carries that airflow. Typically, there’s components in that wall tube. So they do have minimum effective wall thicknesses, we’ll call it. And so for the typical Australian build, often, our wall assemblies aren’t quite thick enough, we need to be up around about that 300 millimeter mark, usually, because we’ve got fans in there. And we might even have the heat exchanger itself in that wall tube. Swings and roundabouts with some of those systems. Obviously, in a retrofit scenario, it’s a lot easier to just penetrate a wall, put a unit in. The higher performance units are typically single point, so they will only service one room. There are some other products that we’ll call push pull. So two unit heads simultaneously working together. So we’re not pressurizing or depressurizing. But one is supplying one unit head and the other is extracting and you can park those in different rooms. So you ventilate two rooms and kind of the space between. These are more solutions that are supply air zones. The challenge a little bit with wet areas, and decentralized ventilation is we can’t position them in the best position, which would be at a ceiling line for above a shower in the bathroom, for example. And so our steam and moisture capture’s not great in the kind of the push pull type scenario, when it’s on its supply air stroke, it’s actually driving that moisture into the rest of the house. And so that kind of use is not great. So on a performance basis, a ducted system will always outperform decentralized for a few reasons. As we’ve discussed, it’s kind of the precise location of supply and extract points to make sure there’s no short circuiting and that we’re capturing odors and contaminants at the closest possible point. We also typically find ducted systems have got high heat recovery efficiencies. And obviously, noise can be lower because the unit can be positioned in a less sensitive area.
Sandra Redlich 32:41
We’ve talked about price a little bit here and there. You’ve mentioned it a couple of times. Can you give us a rundown of what people would have to expect to pay if they wanted to get a mechanical ventilation unit, maybe speaking of these two examples you just mentioned of decentralized and centralized?
Joel Seagren 33:01
Yeah, yep. So that kind of entry level point, I guess, is decentralized push pull type units. And they’re probably going to run you in the order of $1,400 to $1,800, something like that, for a pair. They’ll deliver 60 cubic meters per hour, typically around that number, 50-60 on higher speeds. So they’re good to do a couple of rooms. So you get a couple of bedrooms out of there. They must be installed in pairs in that kind of product, so that we maintain that balanced flow rate. And you can apply multiples of those. So if you were ignoring wet area extract in your typical four bedroom house and a living space, maybe you might put three sets in. So let’s say you’re kind of at that $5,000 mark, something like that plus install. When you step up into ducted, you go up a little bit in price, but you’re now also managing your wet area extract better. And I’ll include kitchen in that as well. Kitchen, laundry, toilet, bathroom. And you’re probably going to, for a typical three to four bed home, you probably going to sit in a reasonably wide range, depending on quality of unit and so forth, somewhere between sort of as an installed cost $12,000 out to potentially $20,000 as an install cost, as I said, based on different performance of units, and different size of builds and number of outlets and so on and so on. And it’s probably useful to explain what’s at one end of the spectrum and what’s at the other. It’s a little bit about duct system. So duct systems have a fairly significant impact on actual performance. We want to make sure they’re nice and airtight, they’re not leaky so that our supply is not bleeding away, we want to make sure they’re cleanable. Because ultimately, in five to seven years, we want to be able to come back and effectively clean this ductwork. We’ll do our best to not draw contaminants into that ductwork by putting filters at various locations. But ultimately, there’s probably some bypass on these filters. So duct systems, good quality duct systems, make a part of that. And the other side is the HRV unit. And as your spend goes up, you get higher heat recovery efficiency, you get lower noises. And so both what we’ll call case radiated noise, which is in the room where you’ve installed it, but also in duct noise levels. So what are you hearing in your bedroom or your living room, you’d probably get some better filtration options, and you get probably lower power consumption, when measured as a whole house system.
Anthony Jenkin 33:01
Yeah, I might just get you to just maybe walk through what a typical installation of a ducted system looks like?
Joel Seagren 35:27
So it’s a lot like putting a domestic hot water system or something in. There’s essentially two parts or two phases to the installation: There’s a rough in phase, which is where you’re going to run all your stuff that sits above the plaster line that’s no longer going to be accessible. And then there’s a kind of a fit off phase. So in that rough in phase, you’re going to get all your internal ductwork and your grill housings in place. And later on, you’re going to be able to come back and fit off your grills and then your HRV unit under there. And just kind of recap positioning of those outlets, we’re basically extracting from wetter odorous areas supplying into habitable spaces. Our hallways and passageways and stairwells are known as transition zones. So we don’t actually need to provide dedicated grills, they’re typically because we’ve got movement from a supplier zone into an extract zone. And just to loop back one step on that, typically, we’re only ever going to have one grill in a given room. So we’re not needing a supplier grill and an extract point in that one room. Because we’re ventilating at nice low rates, we can actually pass that air under the door. And we typically only need that sort of eight to 10mm undercut on a standard width door. So at night, you can close the door in your bedroom, you can have darkness and silence, and it just bleeds its way under the door and into the adjoining bathroom or extract zone.
Anthony Jenkin 37:51
Once it’s installed, and plaster has been put up and you’ve come back and fitted the grills, I imagine that you mentioned earlier on that you’ve got to balance the internal air. How do you go about ensuring that that’s the case, that it’s balanced correctly? Is there a testing process or commissioning process as part of that as well?
Joel Seagren 38:09
Yeah, certainly. So there’s a range of sort of technology at the HRV level as well. So some of the more advanced units will assist the commissioning agent by having some flow control. Now, obviously, at the HIV unit, that’s just balancing total supply and total extract, we haven’t yet… there’s nothing around that’s going to give you a balanced flow rate or target flow rates in each individual room. And so there’s still always a requirement for a commissioning agent to go around with a flow hood or a contractor and measure the extract or the supplier rate to each space. Now good suppliers will provide airflow design, and that will provide rates. So for example, when we look at a floor plan, we’ll say look, there’s a bathroom, we’re going to need 40 cubic meters per hour extract from there. So in a passive house type context, on boost, and we’re going to need 20 cube into that bedroom and 20 there. And so we are allocating at the same time rates to different rooms, but we’re having to make sure the totals add up on the supply and the extract side. And so that’s the role of the commissioning agent to make sure all those airflow rates are balanced. And we can say balanced at a what’s known as a standard or a nominal ventilation rate. And then it’s really typical to also then apply a boosted rate for shower use and cooking or if you’ve got a larger number of people than normal in the house, where you apply 30 odd percent increase over that standard ventilation rate.
Anthony Jenkin 40:00
So boosted rate, would that be a personal experience here typically, you’ll see that maybe you know, a bathroom or a toilet where when you put on, you can hit a button like you will typically hit for an exhaust fan and it will go into boost mode for a certain period of time to just increase that air extract, say after you’ve had a shower, that’s what you mean by boost rate in that scenario as well?
Joel Seagren 40:22
Correct. Yeah, so it’s boosted right. Obviously, the system doesn’t have any zoning. So you’re boosting whole house extract and flow rates. To introduce that zoning would just add unnecessarily levels of complexity, and ultimately not much saving. So in a high performance HRV unit good duct design. So let’s call it a 280 square meter three bed house, HRV unit power consumption at the premium end of town is probably about 35 watts. And even at the tier two kind of level, you might be at 40 to maybe 45 watts. So they’re low energy consumption. So by trying to do this zoning that we might be familiar with in heating and cooling, we’re introducing componentary cost, points of failure, complexity, for extremely little energy benefit.
Sandra Redlich 41:16
Speaking about something like boost mode, or just in general, I could imagine people being a little bit concerned about noise. And you’ve mentioned it before, depending on what system you get, there’s low noise that comes with it. How loud are these systems? Is this something that you will hear on an ongoing basis?
Joel Seagren 41:32
Yeah, I always love the ‘how loud are they going to be’? Noise is a pretty challenging topic to quantify for, for the average kind of user or everyone in general. Fortunately, at Fantech, we also sell our HIPAA products around acoustic silences. So everyone’s got a pretty good understanding of noise levels and noise analysis and the things that affect those. Because it ultimately is the thing that the customer is going to pick up on in a finished product. No one’s really going to pick up the difference between let’s say, 90% and 87% effective heat recovery. That doesn’t pop up on your bill. ‘Jeepers, HRV is a little less efficient than I’d planned on it’. If it’s noisy, it’s in your ear 24/7 every day of the week, that’s there. So that is really the pain point for clients. And so it’s important that we start way back at the beginning on system design, appropriate sized, high HRV selection. So we don’t want a unit that’s running right up near its peak capacity for too much of the time, we want to make sure we’ve got some attenuation or silencing in that duct system. And we want to make sure we’ve located the HRV at an appropriate spot too. We don’t want to go putting it into a walk in robe behind a master bedroom. We want it ideally in a wet area like a laundry. That kind of makes sense. So yeah, noise is a fairly critical thing. I think for the layperson, it’s going to be really difficult to do the effective analysis to understand that. I think you’ve really got to pick yourself a good reputable supplier of equipment, who understands the limitations of each piece of equipment. And can provide some explanation, if you’re really interested in that noise level stuff, can sort of break down: Here’s the unit noise output. Here’s what our silencer does, but this is the noise level in the ductwork. And ultimately, the last complicating factor is: The room furnishings and wall coverings impact perceivable noise. So whilst we can give you an exact sound power level at a grill, the way it’s perceived by the occupant is completely different in a tile bathroom versus a soft furnished lounge room.
Sandra Redlich 43:16
Yeah, that’s very true. Maybe just a little anecdote from that visit that I mentioned before where we saw the HIV unit and I was really surprised by the possibilities of filtering out dust and you know, mosquitoes and stuff like that. I was also surprised – we actually did the test. We put the machine or the system into boost mode. It was located in a laundry in a cupboard. So we put it into boost mode, I closed the cupboards. We have a little video of that I’ll make sure to put that up on the page for the podcast as well because you couldn’t hear a thing. Maybe if you close the cupboard and you’re standing there and you’re really listening to it – and this was a house that was, you know, in the final touches of being built so there was nothing on the walls, nothing on the floors, no furniture, nothing, so you won’t really hear it. So you can maybe hear a little humming noise if you’re standing right in front of the cupboard, and you know, you’re really listening for it. But the moment you go out of the laundry, you close that door, you can’t hear it even in boost mode. And I think that was a quite average sized, can’t remember if it was three or four bedrooms, but like an average sized home. So yeah, just speaking of experience, if you’re concerned about noise, I think in, you know, in your normal everyday living conditions, it’s not something that you actually notice from my experience.
Joel Seagren 45:36
That’s it. And particularly bedrooms who want to be quiet. You’re laying there, we know from a variety of different ventilation products, there’s a range of super tolerant sleepers to those who hear a cricket move. And so we need to kind of cater for the really fussy end of town. And the passive house institute do provide some guidelines for noise levels at grills. Utility rooms can obviously be a bit higher, a laundry or a bathroom can tolerate higher levels, but they’ve got quite low thresholds for bedrooms in particular. So my view is they should be virtually imperceptible. When you lay there silently in bed, you might hear the slightest little bit of airflow noise. But it certainly shouldn’t be a hum or a loud noise. It should be very, very quiet and non interactive.
Anthony Jenkin 46:36
Yes, again, in my experience, yeah, there’s no audible noise at all from the flow rate, comparative to say a split air system, which is very evident. One of the other questions we do get a lot is what’s for those who are not familiar with the systems, but maybe looking to introduce one into the build, is one of the ongoing maintenance requirements for a system or even the usability, you know, like, how easy is this for me to understand it, use the, you know, the interface and you know, what are the ongoing upkeeps required from our end once we’ve had the keys of the home handed to us?
Joel Seagren 47:14
Yeah. So usability is a good question. HRV systems are really designed to sit in the background. They’re not designed to be regularly tinkered with or adjusted apart from the use of these boost switches or whatever boosting mechanism is. Some might have an onboard humidity sensor to boost for bathroom use and things like that. So they’re designed to sit in the background. And often we go to great lengths to dissuade people from trying to do an expensive integration into their home automation system. It’s like it’s not worth the money, because you’re barely going to touch this thing down the track. So yeah, that’s the way they should exist. You might put it into a low away mode if you go on holidays. So it’s something we’ve probably not touched on is that there’s benefit in having some baseline ventilation, in order to give yourself or you’re building some condensation protection. Because even in really well designed buildings, sometimes we can still find a little bit of moisture accumulation through condensation. And also gives you that freshness when you return to your home, it doesn’t feel like it’s been locked up and stuffy. And in those kinds of away modes, you might be using 10 watts or 15 watts. So again, power consumption shouldn’t really be a criteria for whether you put that on or off. The other thing is it’s not great to turn your HRV unit off fully for extended periods. There’s always a risk that you’ve made that decision to leave after jumping out of the shower. And it’ll turn your HRV unit off and head off for two weeks and you’ve actually got some moisture in your ductwork still. And as much as that ductwork is really carefully designed in terms of materials and construction to be anti mould growth and bacterial. We don’t want to invite trouble by having high moisture levels in that ductwork. So even that really low ventilation rate that’s costing you 10 Watts is going to keep your HRV system in really good condition there. In terms of maintenance requirements, so principally you’ve got filter changes, and in essence, they’re there to capture all those particles outside your home that you don’t want in and it’s probably worth delving just for a second into some of the detail. The really good standard supply air filtration is what’s known as F7 then. It’s kind of slightly been updated now to an ISO standard. But I don’t think anyone kind of quite speaks that language yet. Certainly not our members. So we’ll pretend we’re in inches instead of centimeters still. So F7 on supply side. And that will get rid of all those particles down in that kind of two micron size, which are particles that have health implications. There’s kind of a particle range there that will get through your respiratory system. That’s the nasties. Bigger stuff than that gets blocked and caught up in various nose hairs and bits and pieces. But there’s a danger range in them. So we want to hit those. You’ll notice there’s two filters. So in HRV unit, one’s catching that outside air we talked about before. It becomes supply air, the other one’s actually catching the extract air or the air that’s coming out of your bathroom to your HRV unit. And its job is basically to protect the heat exchanger. So if you generate some internal dust particles or lint in your laundry, we don’t want that getting up to the HRV. And in fact, typically, extract points, we will also put in some filters, because we don’t even really want that garbage in the extract ductwork. It’s just going to accelerate the cleaning cycle needed. And so the second part of that, obviously, is filter changes, sorry first. And around about six monthly is where you want to budget. At probably five years you probably want to get a contractor back, pull the front off your unit, pull the HRV core out, give it a bit of a wash, they can go into a warm bath and that sort of stuff, just to make sure there’s no buildup of contaminants there. You might wipe out or vacc out the fans, sometimes you can get a little bit of dust accumulation there. You might do an inspection at five years of ductwork just to make sure that visibly it looks okay. But probably somewhere between five and 10 years, you probably want to think about a duct clean. And the beauty of semi rigid duct work, which is for those who aren’t familiar with it, it’s a bit like egg pipe you’ll buy at Bunnings without all the slots in it and with a separate internal lining. The beauty of that is there’s duct cleaning systems that work really well on that. You can access them from the grills, you don’t really need to disassemble anything, you essentially put a duster on a string up there and hook a vacuum to it. And you can quite effectively clean out your duct system to return it to sort of as new condition.
Sandra Redlich 52:43
Well, I’ve kind of saved the more controversial question I feel like for the end bit of our chat. I know everyone’s been talking about the new changes that will be introduced into the building code by next year. So we’re going from six stars to seven stars energy rating. We have talked about this before as well. And one thing that’s been introduced before in the building code as well, is this mandatory, you know, if you’re going below five air changes, it’s mandatory to have mechanical ventilation. But you’ve mentioned before, you know, that there’s not a real cut off number or it’s not, you know, 5.5 is fine, but at 5 you desperately need it. It’s a little bit more gray than that. So there are people out there who say, you know, I don’t really need mechanical ventilation, I’m just going to make sure that the house is not going to be super airtight, you know, have natural ventilation, I can just open a window and I’ll just, you know, achieve the same thing. What is it that you say to these people? I know you’ve kind of mentioned it before, you know, there’s different systems for different houses. And you know, there’s kind of a sliding range. But what if people are just 100% against mechanical ventilation? Is there something you usually say?
Joel Seagren 54:09
To convince them otherwise? Yeah, yeah. So it’s interesting. That 5 air changes per hour threshold that’s kind of in the code. I guess the first point I’ll make is that they’ve presented that as a fresh air supply requirement. It’s got nothing to do with condensation management, or extract there. So we would easily argue that continuous ventilation is probably just or more important on the extract side, for condensation management purposes, at under 5 air changes, but it’s not kind of been structured that way, is my understanding. It’s also I think, from memory, only in one of the volumes of the NCC and so I think it might only apply to class 2 multi res, don’t quote me on it particularly, but I don’t think it’s actually applying to single dwellings. So I don’t think suddenly there’s a requirement for a 3 ACH resi class one building to have some mechanical ventilation in there. It would be nice if it did exist. What we’ve worked hard. And when I say we the Australian Passive House Association, I’m a former director there, we put forward a submission or a proposal for change to the ABCB. Prior to the 2022 update, for some continuous ventilation recognition under the condensation management section there and Anthony obviously, you and I have intimate knowledge of this based on some projects, that the performance solution and work around is a bit of an arduous process to demonstrate that the lower continuous rates meet. So NCC certainly got some work to be done there in order for heat recovery ventilation systems to become easily and simply applied. They are clearly a high performance way to ventilate, and they should be recognized in the building code. So that story kind of aside, how would we go about convincing those who are skeptical of the benefits of ventilation and heat recovery ventilation particularly? The first point, I would probably make and the important one is you’re doing it for indoor air quality and health reasons. So we can also demonstrate some energy savings compared to having your windows open. In terms of say heating and cooling, there’s definitely comfort compared to open windows. But indoor air quality, guaranteed indoor air quality, is principally the thing you’re shooting for. And so when people say, look, it’s not really worth the cost, or it’s too expensive. I’m immediately asking the question, exactly how have you valued health. And I’m not aware of anyone globally who’s yet got a great answer to how we value health. I know in the US at Berkeley, there’s some people who are trying to start to build some models, they’re still needing lots of data to go into there. And they start talking about extended life years and things like that in relation to indoor air quality and trying to price health. But it’s still a pretty abstract kind of model. And so to make a cost judgment, against indoor air quality, to me, doesn’t make a lot of sense.
Joel Seagren 57:56
Agreed, we’ve all got to make some practical decisions about total project build. But if you’re saying, Look, I’m weighing up the flash 2 pack kitchen with marble benchtops versus my HRV. I know which way I’m going. But everyone’s got to make that value judgment for themselves. The other scenario I always like is: build a little bit smaller. If you want those really good functionality things, even want the benchtops still, build a little bit smaller, we’ve still got a pretty bad habit of building oversized buildings. And also make sure you get the important elements that you can’t retrofit easily afterwards. So that’s always going to be building envelope, like get those good quality windows in there, get good levels of insulation, HRV drops into that bucket as well. Get that installed. In the really worst instance, get your ductwork in and apply the HRV unit a year later, when you’ve digested the total construction cost and you’ve recovered, your bank balances recovered a fraction. Fit it off then but to dismiss it on a cost basis doesn’t have a lot of logic to me. And we see comparison also to heating and cooling air conditioning systems like I can get three installed split systems for the price of that, it’s like they’re delivering different kinds of outcomes. So to compare the two doesn’t make any rational sense. And I’d also suggest that measuring the benefits in a short timeframe of indoor air quality is difficult unless you drop into that severely impacted category, so if you’re immunocompromised or really severe asthma sufferer or hay fever sufferer, in those instances, you’ll pick up the tangible benefits super quickly. But for the average person, it’s probably not something you necessarily mark on a daily basis. Yeah, so it’s challenging to even perceive that. But over the longer period, there’s definitely demonstrated benefits to better indoor air quality.
Anthony Jenkin 1:00:30
Yeah, complete agreeance Joel. In all of our research as well, it is indicated, just like the never ending list of benefits for having a good indoor air quality – from the ability to be able to absorb and retain information like in education situations, right through to those who are more sensitive to mould bloom or just dust or smoke. I know there’s people who have experienced some really horrific indoor air quality due to burn offs, or recent bushfires over the last few summers, the HRV system with the appropriate filtration system can even mitigate smoke coming into a home, I’m fairly certain. It just goes on. And when you, as you mentioned, it is subjective to what value you put on health. But if for most people, I imagine that there probably isn’t a number they can define it with. And it’s very, very much worth you know, considering that you can solve that problem.
Sandra Redlich 1:01:26
Yeah, great way to kind of bring this episode to an end. Yeah, there’s no real value you can put on health. So that’s definitely something I think more people need to consider. It’s not just about the looks of the home. It’s also like, it’s more so about how your home can be a safe space for you and your family. And yeah, be a haven for health and for joy and for comfort. And not only for you know, a couple of years, but for a lifetime. So I think that’s really what it is about at the end of the day. Joel, we’ll make sure to put all your contact details where people can reach you if they have more questions or you know, if they want to get some more information on what they can do in their specific home into our show notes on our website. So people can make sure to check that out and reach you there. Yeah, nothing left for me to say other than thank you so much for taking the time and explaining how important ventilation is to homes. And I’m sure if there’s, you know, more questions coming up and new systems being introduced, that we’ll be chatting to you again sometime in the future.
Joel Seagren 1:02:38
Lovely, thank you very much. It’s always a pleasure to chat on ventilation, something I’m passionate about, something I’d suggest everyone at least explores the option of ventilation for their their home and so forth, at least go down that path, get the numbers, get the understanding of benefits and so forth. Don’t be in that ignorant side of the fence, which just goes cost – it’s not worth it. Do the research. There’s lots of smart people out there who can assist you in that space already. It might feel like it’s a needle in a haystack search, because we don’t necessarily all run big ads and banners promoting our wares. But those people do exist and reach out to your networks. You’ll find us.
Sandra Redlich 1:03:24
Awesome. We’ll make sure to link that and yeah, enjoy the rest of your day. And thank you again for your time.
Joel Seagren 1:03:31
Lovely. Thanks. Nice to chat to you Sandra and Anthony.