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My name is Anton Dobrevski and I'm an architect and accredited Passive House Trainer. On this channel, I'll be talking about Building Science and the Passive House Standard, more specifically about Insulation, Airtightness, Vapour Control, Heat recovery ventilation systems, Thermal bridge-free designs, Fresh Air, Healthy Buildings, Comfort, Innovative Building Products, and I will show you around some of the projects I am working on. You'll also find videos revealing the thinking, the process, and the ideas behind the making of Passive House buildings. If you are an Architect, Engineer or Builder hit that subscribe button!
my house has mass timber walls 14 cm thick. wood fiber insulation on the outside also 14 cm and wood siding over that with air vents behind the siding to wick off any moisture buildup. the mass timber, being hygroscopic , controls humidity swings in the house . the walls and insulation are vapor permeable but air tight . the entire interior has no significant off gassing materials making the quality of the air very very good . opening and closing windows and doors is sufficient to introduce fresh air . we have lived in the house for ten years and it is unbelievably comfortable and energy efficient . our blower test was almost at passive house standards .
If you plot insulation R factor versus how many BTUs per sqft/hr loss a wall assembly has, the curve flattens out around a R-12. This represents the beginning of the point of diminishing returns. For high performance homes, this is how much your external insulation should be for the best price/performance ratio. If you are going to commit resources to external insulation, R-12 should be your target. To prevent the interior side of your exterior sheathing from becoming a condensing surface during the heating season, you only want 1/3 of your total wall assembly R value to be external insulation. This lands you at a max combined wall assembly R value of R-36. Most of the time you will be better served upgrading the BTU capacity of your HVAC system than adding additional insulation beyond R-36.
It's a very interesting presentation and I've learned a lot. However, I find the argument in favour of the speaker's preferred active system to be a direct betrayal of the core "passive house" philosophy. Designing a system like that is fundamentally not passive if it required active ventilation/filtering to work! It's just not good enough. You've mandated a more expensive, more technically complicated and breakdown-prone system that many will not be able to afford. I think the dismissal of the 2nd option, extraction ventilation, was not convincing and painted a misleading assessment of its benefits and drawbacks.
I've seen many descriptions of the importance or value of "airtight" homes, but there's still one thing I don't understand. How do you account for cases of sick building syndrome, or other conditions that are exacerbated by airtight spaces? And given that an important lesson from the Covid era has been that free, plentiful ventilation prevents the spread of illness (especially super-spreader events), how can we justify building airtight living spaces? I understand there are expensive filtration and heat recovery ventilation systems that can be added, but that's a lot more money that most people won't spend if budgets are tight.
Also factor in the cost of heating or cooling equipment. If you can buy a smaller unit when you have better insulation, that decreases the costs. And probably maintenance and replacement of heating cooling units later!
Great stuff Anton, a really simple and focused presentation, just what we need to introduce people who are clueless to Passive House principles here in Australia. Would be even better if you could show the actual slides you're speaking to in the vlog, rather than long range shots. Can't really see the details😒
Nice presentation on the basics of insulation optimization. However I think you failed to really address 'future-proofing' adequately. The low probability of high-impact events leads us to undervalue their expected expense. Furthermore there is great uncertainty of how the magnitude of such events is going to change over time. This leads to great difficulty in figuring out a true optimum. However it is really easy to understand that it matters A LOT that you prepare for all reasonable worst case scenarios you could face. For many such scenarios the correct answer is to 'run away' - tornadoes, hurricanes, fires, and floods (and other outlying extremes) are really hard to prepare for. On the other hand we are rapidly learning how to do this stuff, and it tends to be not that hard. Some of these building features may also aid in preparing for less intense disasters - things like extended power outages, other service interruptions, and other more chronic than acute challenges. These challenges can lead to pipes freezing, deferred maintenance, and other expensive impacts that can be mitigated by insulation or other built features. This is a much more complex optimization challenge.
Thank you for your comment, Jim! Indeed you are right, in this video I addressed the best insulation thickness and not The readiness for high-impact events of building. This topic is of course super important and maybe we should cover it in another video. I would be curious to know what do you add to your designs to get them ready for such "worst case scenarios"?
@@AntonDobrevski Hi Anton, I have some thoughts about this, but am under no illusion that my thoughts represent a complete and proper perspective on this question - it will require input from many diverse viewpoints. Since I live in northern Vermont, the insulation-related scenarios of greatest concern to me come from extreme cold combined with service interruptions for basic utilities. One of the key questions in this regard is whether a house has a good, old-fashioned wood stove. If so, the requirement for insulation in emergency situations is reduced. Otherwise my feeling is that the core areas of a house should be able to withstand about 2 days of extreme cold (without electric power) with a very modest drop in temperature (definitions of modest here could vary significantly). Whatever that amount is would probably suffice for avoiding freezing of pipes for at least a week, although this should be checked. This is a very seat-of-the-pants answer, but I have not encountered any scientific- or engineering-based answers to this question. If you do have a wood stove, it would probably still be best to have a house that would not freeze during a week of extreme weather. Maybe that is a starting place? Of course extreme heat is in many ways a much harder question, and I have little to offer there. BTW, thermal mass obviously figures in strongly in this problem area, especially in the case of extreme heat (or - heaven-forbid - wildfire)
I'm a great fan of these principels. However one is missing: heat storage capacity ! passive solar gains lead to rapid overheating of a well insulated home, when the thermal storage capacity is unsufficient - even in winter. I would hate to ventilate these precious gains to the outside !
Thermal mass / heat storage plays a much smaller role in Passive House projects compared to standard buildings, due to the high insulation levels. Basically, the more energy-efficient the building is, the smaller the role of thermal mass is. Therefore, thermal mass is not a leading factor in the decision-making process for Passive House projects for example when choosing between concrete and timber.
I get your point. However: good insulation and ERV only reduce external loads! Internal gains are trapped inside. This is a good thing as long as you need them; otherwise the asset becomes a liability, and heats up the building beyond the comfort threshold. Rather than bypassing the ERV or opening the windows i'd prefer to store the gains in thermal mass for use in the next cold Phase.
These principles are applicable for warm and hot climates as well. ERV still helps in hot climates because it keeps the heat outside and the colder (conditioned) air inside. During the night, when outside it's cooler, we can use night cooling or HRV bypass, which helps cool down the building and make use of the lower outside temperatures. Regarding the thermal mass - in warmer climates it's more effective but still not as effective as the night cooling/HRV bypass.
I'm with you for the summer case. My concern is overheating in winter, if you combine large southfacing windows with low thermal mass as eg SIP- panels provide. Does that show in PHI simulations?
Your video series is very informative and well done. I am confused by the slide at 6:13. Show the wall construction to add context. What is the best location to install a window? I cannot tell from the image or your verbal description. Green Building Forum, in some places, mentions installing windows nearer the inside so that the surrounding building material is insulated and not near the outside where the surrounding building material is at the outside temperature. That appears opposite to your graphics but I might be confused about what you are presenting.
Glad you are enjoying the videos! The shown build-up consists of concrete (grey) and exterior insulation (yellow). So the window should be installed inside the insulation layer to minimise the installation thermal bridge while maximising solar gains, as shown in the video. In case of timber structures, it's recommended to install it in the center of the wall.
I think you did a great job describing the process of achieving an airtight building and you had the control layers in order of importance but I believe the conversation about ventilation should have been at the beginning of the video to also keep the order of importance.
It would be interesting to see the percentage cost increase of incorporating Passivhaus standards into an average new house, and compare that to the cost of upgrading the kitchen and bathrooms from generic to custom. People spend money where they perceive a benefit.
Cute building. I can't agree that taking measures to ameliorate the unwanted heating effect of a black facade is a good choice when you could just not use a black facade, but otherwise this is pretty neat.
That's another point where it all sort of fits together. Sliding windows are preferred for informal ventilation because you can leave them wide open and if the wind picks up the window will be fine - it's well supported by its surround. In a strong wind a casement window can take a lot of damage - either the device holding it open breaks and the window slams against the wall, or the device is strong enough and the full force of the wind is putting perpendicular pressure on the window frame, which is the weakest dimension of its structure so the window frame will eventually break. So if you plan on having your windows open a lot, you want sliding, not casement. If you're moving to mechanical ventilation, you want windows that can be opened for emergency egress but aren't normally left open at all, so it's okay that casement windows aren't good at being left open. And they do seal a lot better when shut than sliding windows. So if you plan to keep your windows shut 99% of the time and want them to seal out the drafts, you want casement, not sliding.
I am not living in a house passively warmed by the sun because in winter when I want my house to be warm, the sun is obscured by heavy clouds and all my big "sun facing" windows just let out whatever warmth we have from other sources. Passive solar sounds great in theory, but in practice in a winter-rain climate it's a very bad design choice.
Towns in temperate climates full of buildings with PV panels all over their roofs should pair very well with a municipal-level pumped hydro storage, if they have a suitable landform available nearby. The excess electricity the buildings put into the grid in summer can be used to pump water up to the top of the hydro system, and in winter they can draw that power back - and rather than losing power in storage like normal battery banks, in winter they should be gaining stored power from precipitation.
Speaking from personal experience, the supply and exhaust need to be balanced for every room. Otherwise as soon as someone closes the door/s to that room, the air movement is going to slow or stop, because the only way for air to get from one room to the next is under the door. If there's a draught under the door, you'll get that much air movement, and if the door is fitted not to have a draught, you'll get no air movement at all. Closing the bathroom door while we're using the shower or toilet, or closing the bedroom door at night, is normal human behaviour. Humans like privacy in these spaces, and the closed bedroom door is a "do not disturb" sign that even cats have to respect. The ventilation needs to be built on the assumption that when ventilation is most needed, the door will be shut.
To avoid oversizing the system, paying too much for ducts and drying out the air inside, supply and extract should be separated in two different zones according to the cross ventilation principle. To allow the air to move freely even at closed doors, are provided transfer openings either at the doors or in the walls. These openings can be designed to avoid the transfer of noise/light. The air volumes are quite low and don't cause any drafts (with the right seizing of the openings).
We don't have any moisture problems in my house in winter because for the past five years we haven't been able to heat it - it's designed to heat from a wood burner but I can't split wood any more - and outside the summer heat I keep my windows wide open all year around because claustrophobia. I would like my next house to keep itself warm without requiring work I'm not able to do, and at the same time I need it to ventilate itself so I can breathe comfortably while being warm.
When you start talking about architects designing net-zero housing for government housing for low-income households, you're talking my language. The people who can least afford energy bills are the people who most need houses that generate at least as much energy as they consume.
Heat lamps kill an awful lot of chicks every year. They catch fire desperately easily in an environment full of wood waste bedding and cereal dusts. Good farmers these days use thermostatically controlled heat panels that won't start a fire even if they're buried in sawdust. The only light they need to produce as a byproduct of keeping chicks warm is a single LED to say the device is powered on and working.
I live in a climate where it's hot (tops of 43 C) in summer, and cool the rest of the year, rarely dropping below freezing but even now in the middle of Autumn it's in single digits every night. What I'm being taught in class is that we shouldn't use vapour-impermeable barriers anywhere in our walls, because whether that barrier is on the inside or the outside of the insulation envelope, at some time in the year it will lead to warm moist air infiltrating through the insulation and hitting the cold vapour barrier, creating condensation. So the recommendation is to have vapour-permeable materials all the way through, and focus on stopping air movement so the only way vapour moves through the wall is by permeating through each layer, not carried wholesale by an air leak. The question I'm grappling with, is how well will this actually work? If the amount of water vapour inside the wall is only what's been able to get there straight through the plasterboard, and then it passes through the insulation to the outside - say a cement sheet cladding - will it pass through that too, or will it get cold enough to condense and drip down inside the wall anyway?
Every building must have an airtight layer. By having the airtight layer, the only way for moisture to move through the wall is via vapour diffusion. In general, it is recommended to use intelligent airtightness systems which are vapour open in one direction ( e.g. allowing the structure to dry out to the inside) and vapour closed to the other side (e.g. not allowing the internal vapour get into the wall). An example is the pro clima intello plus system.
Note that at the current accelerating rate of increase of carbon dioxide in our atmosphere, by the end of this century the air outside will not be useful for ventilating our houses. We need to be designing ventilation systems that will be able to be retrofitted with some form of mechanical or biological decarbonation and recirculation in order to provide healthy indoor air quality.
Of course if you're designing your house off-grid, then the price of electricity is no longer a factor in your calculations. The balance is now between the cost of the extra insulation, or the extra solar panels to be able to heat your house in winter, or cool it in summer, whichever requires more panels. Considering how much less power I get from my fifteen-year-old solar panels now than I did when they were new, I think the assertion that they need to be replaced every 25 years is probably not far wrong. Fortunately, insulation shouldn't have that ongoing expense.
Ehh, don't forget that the amount of new carbon dioxide released into the atmosphere every year is still accelerating. Find the "worst case" forecast for how ambient temperatures are going to change in your region over the next 200 years, double that, and then insulate to make your house habitable in those conditions. The modern building industry likes to assume a 50 year design life, but I don't see a lot of people bulldozing their 50 year old houses to build new. The next buyers might add some insulation, replace the single glazed windows with double glazed, and repaint, but then they go on living in it. A 200 year design life really needs to be our minimum, and for high-quality houses more around 500 years. If you don't think your house will be fit to live in by then, why not, and what can you change to fix that?
I appreciate the eggplant emoji for the size comment. Energy efficiency is a very serious subject, and if we don't insert some humour from time to time it can get quite exhausting. Give us the giggles!
Good explanation. Now, how do we insulate a 40mm timber door without making it so thick it feels like a bank vault, and without using petrochemical foams?
Doors and windows of old existing buildings should be replaced, if possible. You can find high-performance components here - database.passivehouse.com/en/components/
Really informative, thanks! I have a very old stone and lime mortar house, which only adds to the complexity of trying to make it more energy efficient. So I am trying to learn all about that at the moment :)
Tha aim of the video is to shed light on the importance of insulation thickness and the return on the investment. Walls, roofs and floors usually have different thicknesses indeed but this should be determined based on an energy model of the specific project.
The amount of insulation depends on the climate you live in. I wouldn't have R-30 walls in Texas but I would in Minnesota. We can have a delta of 80-100F between inside and outside temps for 3 months up here.
Climate is one of the factors. As mentioned in the video, there are also other factors such as building size, price of insulation and energy, material type etc.
Much easier said than done. So many buildings are poorly insulated and it is uneconomic to significantly improve their insulation. Renewables also have their inherent deficiencies, intermittency and technical which means that they will not replace conventional generation..
@@AntonDobrevski I've been living off-grid with a small array of solar panels and a set of second-hand batteries for fifteen years. The only hard part is getting people who are used to living with unlimited electricity on tap to start thinking about electricity as a limited income which they need to budget just like they budget their money. We would have completed the energy transition already if people were willing to live within their means. Burning fossil fuels for energy is just stealing from our children and grandchildren, because they're the ones who are going to have to deal with the consequence of our self-indulgence and waste.
Thank you! I'm happy to see you are enjoying the videos 🙂 SIP panels can also be used for Passive House projects and we are working on a few projects using SIPs.
I’m just completing my third project using SIPs (6 1/2” R37). Thermapan SIPs has never supplied a wall panel thicker than 8 1/4” (R47) even in the far north in Canada. There must be a “Rule of diminishing returns” relating to SIP panel thickness. Passive house standards are R75 which would be a 12 1/4” inch panel
@@qualitybydesign5119 If the tinsulation thickness in the prefabricated panels is not enough, then additional external insulation can be added to achieve the desired U-value.
Thank you! I'm happy to see you are enjoying the videos. You can reach out to me at support@passivehouseschool.com about your project and I would be happy to help out.
Thank you! 🙂 If the roof space is heated, it is recommended to have ventilation and connect it to a Mechanical Ventilation with Heat Recovery (MVHR) system. This ensures a continuous exchange of air while recovering heat, contributing to both indoor air quality and energy efficiency. If it's unheated, it is still recommended to ventilate it but in that case, it shouldn't be connected to the heat recovery system. On the other side, whether there should be a ventilated cavity in the roof buildup depends on the buildup itself.
Very interesting video! Can you recommend a counterflow HE? The majority seem to be crossflow. What about ERV, is there any model/series you can recommend which is available in Bulgaria?
Thank you! You should check out Zehnder. They are one of the best performing units on the market, all their units are PHI certified (i.e. have guaranteed efficiency within a working range) and that's why we use them for all our projects. Furthermore, they have ERV versions and are available in Bulgaria.
Thank you, Philip! When using the cross ventilation principle you will either need door vents, gaps under the door or dedicated transfer air grilles in the walls.
@@vitoshabg To achieve air speeds below 1 m/s, we multiply the volume that has to pass through the door by 2.78 and this gives the area of the gap under the door in square centimeters
In a warm/hot climate like Texas, switching from double to triple glazing would barely have any effect and sometimes even no effect on the cooling bills. That's because the problem in these climates are the solar radiation loads. The g-value of triple glazing might be slightly lower compared to double glazing but this is compensated by the lower Ug value which keeps more of the heat inside. In these type of climates, strategies such as shading and airtightness would be more important for improving the energy efficiency of the building.
@@pathfinder509 I had them done in 2014 for $6200, brand was Simonton “Pro Solar Low-E”. They were the lowest of 3 grades of vinyl windows the contractor sold. They did help a bit with sound, but energy savings were negligible over the original “builder” windows from when the house was built. House was 1800 sq ft and had 9 windows.
@@pathfinder509 I paid $6k to have 9 windows replaced in 2014. They were Simonton Pro Solar Low E windows. They were the lowest of 3 grades of windows the contractor sold. They were non-insulated, but vinyl with hollow core frames. Sound from outdoors to indoors was reduced a bit...
After watching the video I went to the channel to see general content and was surprised that it is only 681 subscribers !! like there should be a "K" at the end !! . nice video that explained much, thanks for that 🌱
Some aspects of passive house make sense others not so much . Airtightness and HRV must be part of every new house , when savings from expensive windows will never recoup the investment Another issue is the price to build a passive house, sip house very close by most features but cheaper and faster to build
The Passive House standard offers a cost-effective approach to constructing energy-efficient buildings. Despite potentially higher initial investments, the average return on investment occurs within 5 to 10 years. In some cases, building a Passive House can be even more economical than a standard structure. It's important to note that the Passive House standard is versatile and not limited to specific construction methods; for instance, some of our students are using SIPs and ICF systems for their Passive House projects.
Super high insulation renovations indeed work to lower energy needs to stay warm, comfortable and safe in the winter. We completely gutted our old two story 1912 house. In all the stud bays we installed vertical lathe for an air space for the house to breathe and stay dry. We then installed 2" foam and then 1" foam boards in all the perimeter walls. We will install our vapor barrier and then another 1.5" of foam. We now heat our home with electricity not natural gas. I support our global transition to renewably powered electricity.
Anton, just went through a bunch of you videos. Thanks for all the information. I have a question. The ridge vent and the vent where the top of wall meets the trusses. 1. Is this good enough? Two doesn’t it defeat the purpose if I was to run 4-6” foam board insulation between the trusses. Pushing the heat out of ridge vent and the other vent. I know the moisture is the enemy. Can you elaborate?
Happy to see you are enjoying the videos. It depends on whether you want to have a heated (insulation along the pitched roof) or unheated attic (insulation on the ceiling). For unheated attics that’s not a problem as the attic will be vented with the outdoor air that will be getting in/out through the soffit and ridge vents. When you have a heated attic (where the insulation is between the trusses), then the attic space should be connected to the ventilation system of the building and the soffit and ridge vents will be used to only to ventilate the space between the insulation system and the roof tiles (sort of how a ventilated wall façade works).
@@centerbuilder7677 If the attic is unheated and you are not planning to have any living spaces in it, then it's better to insulate the attic floor. The insulation thickness very much depends on the building location, size, design etc. and it is determined by making a complete energy model of the building in the PHPP software.
If you're planning on installing 18 inches of insulation on the attic floor, that should provide substantial insulation for your unheated attic (You can also check out my video "What's the BEST Insulation Thickness?"). This is generally the preferred method for unheated attics, as it keeps the heat in your living space below, not in the attic. Insulating between the trusses is typically done when the attic is a heated, livable space. However, if your furnace is in the attic, you might want to consider some localized insulation around it to protect it from extreme cold, which could improve its efficiency and lifespan. But broadly speaking, for an unheated attic, focusing on the attic floor insulation is usually sufficient and more cost-effective.
