Air Quality in Tight Buildings My company, Thoughtful Dwellings, worked with Tim Naugler on the design and energy modelling end of the Naugler House project. Regarding air quality and HRV flow rates: The 70 cfm air flow for the HRV is what is recommended by the Passive House (PHPP) software. The PHPP recommends a minimum 0.3 ACH (based on usable floor area or TFA) to provide healthy air that doesn't overly dry the house. This 0.3 ACH is also used in our Canadian energy modelling software, HOT2000, as a minimum ventilation standard. I would much rather ere on the side of healthy indoor air quality than maximizing energy conservation. With an HRV efficiency of 92% this doesn't amount to much anyway. Issues of air and house dryness can be mediated through humidification, if necessary. In my experience a house without a forced air heating system can be much dryer and still feel comfortable. Much of the dryness that people complain of is from dry dust within the air being recirculated within the house. In the Naugler House the only air being circulated comes directly from outside. The Naugler House residents have so far not commented on the air in the house being too dry. Regarding Heating Load: The PHPP gives a maximum heating load of 1204 watts (4109 Btu) for the Naugler House. The maximum deliverable heat, based on 120 m3/h (70 cfm) average air flow @ 52C (126F), is 1430 watts (4881 Btu). When we had the system apart we set the thermostat at maximum and measured air flow temperatures above 50C near the heater. With conduction losses through the metal ducts we will likely never see anything near this temperature coming out vents. The PHPP says we actually have enough heat to keep the house at 22.2C (72F) under worst case conditions in our weather region. The homeowners keep the thermostat set at 20C (68F) - sometimes lower at night.
Posted: 01:12 pm on February 5th 2013
Re: On-demand electric water heaters The power authority in New Brunswick, it seems, has a different view toward on-demand hot water heaters... In the fall we had representatives from NB Power, our power producer in New Brunswick, visit the Naugler House. As they took the tour of the house they seemed quietly impressed by what they saw. As we went through the mechanical systems nothing changed until they saw the on demand hot water heater. They both seemed quite horrified that we would put an on-demand water heater in an energy efficient project like ours. The power authority is more concerned about peak loads than absolute efficiency or energy use. On-demand water heaters, if many are used simultaneously, are a nightmare from their perspective. Generation for peaks means costly generation that idles most of the time but is always ready for the unknown spike in demand. As we modernize our grid in New Brunswick we may get peak billing at the residential level. If this happens a well insulated tank with the ability to heat at non-peak times becomes a much more efficient and less costly option. This also considers the primary energy picture - as is promoted by the Passive House approach. In the Naugler House we have a solar domestic hot water system so the on-demand is just for top-up needs. This being said, and considering the information from the power authority, we will likely consider a small well insulated conventional tank on future projects.
Posted: 10:27 pm on February 6th 2013
Wanting to hate the Passive House Standard When I read the posts I get the impression that some people just aren't open to believing that the Passive House approach has any value at all. I beg to differ on many of the criticisms. A few facts, largely from a real world project in New Brunswick (www.nauglerhouse.com). 1. We have a similar climate to Vermont here in New Brunswick - maybe colder. 2. The house is 100% heated through the ventilation system and the house is NOT over-ventilated to achieve this. 3. Additional mortgage is less than saved energy costs. This was only made possible with constant collaboration between builder and Passive House designer/consultant as well as sub-trades and building officials. Cost effective solutions can be found with creative thinking outside of the box. 4. Heating cost is $70 per year or <$8 per year. 5. Passive House is (I believe) a better approach than Net-Zero but harder to articulate. See point 6. 6. Passive House aims at greater comfort, greater health and greater durability. I guess this could be three points. This needs to be considered in the cost analysis for those who value these. Comparing a basic house to Passive House is like comparing a 1980's vehicle to a current one. The older one may be more cost effective up front but it doesn't include air bags, anti lock brakes, fuel injection or automated climate control (to name a few) and it will use more fuel and create more pollution. Generally the Passive House (although not something everyone will appreciate) is a superior product. Net-zero may simply be adding renewables and other technology to a basic house. This does not make it a better house but just one that produces as much energy as it consumes. 7. Passive House is an approach that aims to build houses for many generations and not just one. This house locks in energy prices to a degree that no other approach does. The approach provides insurance against rate shock if energy rates skyrocket in the future. There are very low maintenance and equipment replacement costs with fewer moving parts in the Passive House system. 8. Like any technology in it's infancy building a Passive House will be more expensive. As components are developed and built in North America the cost will come down. I thank all the believers and pioneers for investing in building a better house that is built to last. 9. Building to the Passive House standard is also an investment in the local community. More local labour and local materials translates into real and useful local jobs. These jobs likely create less pollution than the energy needed with extra energy production. High quality components create high quality jobs as we develop these components in North America. 10. Well, it is just the right thing to do in the age of climate change - sometimes the best things do cost more. 11. You can really use more space if you use Passive House windows. In the Naugler House the first place kids go is straight to the window sills. I have lived in several houses with bay window seats that never get used in the winter because it is just too cold to be comfortable. A Passive House has these features built in and they actually serve the intended purpose. 12 ... 13 ... 14 ... People will not agree with everything - this is a fact of life - but I get tired with arguments that simply seems dismissive and negative. The Passive House approach is a scientific well proven standard that many, many people are very happy with. Like I said, it is not the solution for everyone - just like not everyone will be happy with a Prius - but I love mine! And thanks for all the great posts!
Posted: 07:12 am on September 26th 2013
Response to Martin Holladay (Comment #37) Martin, I don't think I ever mentioned that I advocate that every house get Passive House certification. I doubt many in the Passive House movement would advocate for this. This is simply a client choice. and a method of third party performance verification. Of all the projects I work on less than 5% will ever get certified. What I believe in, wholeheartedly, is the modelling and performance based process. And I also believe that a consultant, of any type, should save a client in one way or another. This can either be by saving money or by providing a superior product. And I am the first to send a client on their way if I can't offer any service of value. I have worked with many builders. As far as i can see it is only through the energy modelling process that they can fully understand the dynamics of a balanced thermal envelope approach. A prescriptive approach will give good results most of the time. If a client is willing to have a house built by a rule-of-thumb rather than a more targeted approach then that is their choice and they take their chances that the project variables were within that prescriptive norm. If a consultant is not providing useful information to the client, to help make informed decisions, then he/she is not doing his/her job. In every field there will be those who are in it to provide a service and others that just want to make a quick buck. I am always happy to have a frank and open discussion about the pros and cons of any building approach. Some of the comments I have seen on GBA regarding Passive House don't seem to accept some of the facts that real world projects are bringing forward. Many dedicated builders and consultants are working hard to bring efficiencies to a new-to-us Passive House technology. None are saying that Passive House is the only way to build but it is absolutely cost effective for a client that values what it offers and wants a house to last. If all someone wants is granite and square feet at the lowest capital cost and the most corners and roof lines possible then Passive House is likely very poor value. We also need to place a value on future proofing our buildings - or at least provide this option to the client. In this light we should build a house to last a hundred years or more with much higher energy rates coming in the future and from 100% renewable sources. I consider global warming to be a given yet even skeptics should care about air quality and industrial contamination to help move us closer to a clean energy economy that creates more quality jobs in many regions. The Passive House approach to building will increase labour while reducing energy - this is good for local economies. As we make more high quality components in North America this is good for local economies as well. We generally do not look at hidden costs in our economic system but we urgently need to find a way to quantify and value them. I also believe that an HRV, of some type, is a necessary part of a well built house in a northern climate. I would like to see the data to suggest that an HRV is not cost effective in most Canadian climates. I can't speak to warmer climates. There are new machines that do an excellent job of reducing humidity and cooling air. We will see new technologies develop as more leading edge projects are completed. Air bags or anti-lock brakes can be argued as not being cost effective yet it both are now considered an essential part of a new and safe vehicle. And thanks to everyone for this lively discussion! Garth Hood
Posted: 08:24 pm on October 8th 2013
Response to Martin Holladay, GBA Advisor I absolutely stand behind my comment, "... Passive House ... is absolutely cost effective for a client that values what it offers and wants a house to last," for several reasons... First, our first house built to the Passive House standard in Fredericton New Brunswick (actually we almost doubled the standard so the next one should be even better value) has upgrade mortgage costs that are less than the energy saved costs - at current energy prices. If energy prices go up this advantage for Passive house will only increase. The cost of a renewable energy system in our market is far more than the Passive House upgrades to get to the same energy consumption level. Our data analysis was verified by a parallel economic analysis by the Canadian Passive House Institute. Hopefully a third party study will someday verify the data that the Passive House community has gathered so far. Second, this house builds in features that will make it last longer compared to a basic house. This must have some real value for some clients even if the market doesn't recognize it. It is just a matter of when the house is sold - before or after rot is discovered in a wall or before or after windows or a heating system needs to be replaced in a poorly built code house. Not valuing durability is a fault in our current economic system that encourages building poorly. This is not cost effective for future generations. Third, if health and comfort have no value then we may as well save some money and go back to living in a cave. Hardwood floors and granite counter tops are not cost effective yet people want them. It is difficult to quantify the value in building a better house when some of the value added features are subjective. Maybe we need to stop talking about "cost effective" when it comes to housing. Who asks about the cost effectiveness of leather seats or air conditioning or any upgrade package when buying a car (or building a house 10 times bigger than needed)? Do people want them? Absolutely! In the end it doesn't matter much to me whether you believe in the 15 kWh/m2a target or not but I also want to make it clear to folks out there that some designers and builders are proving there are many benefits to aim for this high standard. Passive House is a very challenging standard that has many advantages and some builders are proving it can be cost effective and at the same time they are building a better house. This may not be the the cost effective approach for everyone but it is cost effective for the right client when built by the right builder.
Posted: 11:01 pm on October 9th 2013
Optimism and Political Vision or Why I Beleive we can Dump Coal Excellent article and commentary! This is admittedly mostly anecdotal observation (not to mention philosophical) but... It seems if we as a culture develop a political vision with optimism we can collectively solve most any problem and create a thriving economy along the way. I think this holds true with our making an energy transition to renewables. Two examples are WWII and the space race (any more?). In WWII the US manufacturing economy was transformed from civilian to military in a matter of months. As well previously unimaginable technologies were developed very quickly and creatively. Similar things happened during the space race and both times led to booming economies with good quality jobs and better quality of life in general. The climate crisis might be the first time we can bring this optimism and political vision together truly worldwide and for a non-military purposes. As Einstein said, "We cannot solve our problems with the same thinking we used when we created them." As well I don't think we can, right now, fully imagine all the solutions and technologies that will solve this crisis we are facing. We can be fairly confident that we can collectively solve the problem if we undertake the task with collective vision and optimism. We can also be quite confident that by undertaking this task we will provide a better life for more people in the process. It will likely even be fun and engaging. Solving complex problems is what humans do best! As in both periods of history we will have to make sacrifices and change our outlook on humanity but in the end we will all see this as great progress. My two cents worth...
Posted: 11:13 pm on November 13th 2013
Wow, Passive House, Wow! It is great to read all the comments & controversy developed when Dr. Feist comes to town! In a way the Passive House standard is arbitrary but the target was well chosen through a logical process and backed up by a great deal of data. We can argue for a different set of criteria but this would be even more difficult for us efficiency geeks to understand, let alone the average homeowner who just wants to do the right thing. And nobody is saying that every client needs to hit the Passive House mark. I always model projects to the Passive House standard but I always have alternative options for clients to choose based on personal priorities. In the end about 2/3 choose Passive House while the rest don't. And yes, the target is high, but achievable. The PHPP is a very flexible open source tool that allows energy modelling to any level of performance. I seriously take issue with those who say that the Passive House focus on efficiency is at the expense of overall building quality. At Passive House events I have never been more engaged in the issue of building quality. Most builders/consultants are obsessing about dew-points, vapour open membranes, super-duper tapes and sealants, low-U windows and doors and the list goes on... I have worked in the building world for many years and it is so refreshing that every one on a project is passionate about constructing a comfortable, healthy, long lasting and, oh I almost forgot, energy efficient building. The building science isn't always perfect but we are engaged and learning from our mistakes! Whether you like it or not the Passive House target gives folks something to talk about. This, I think, is one of the greatest benefit as it engages folks in the process of transitioning to a renewable energy economy. It makes the process real and proves that it is achievable with the additional goals of quality, comfort, low maintenance & a longer lasting building. Thanks to everyone for all the great comments, discussion & controversy. Go Passive House Go!
Posted: 04:12 pm on October 1st 2014
Response to Malcolm Taylor Malcolm, Could you provide an example of the compromise you speak of? When building science is considered, there are (to simplify) two extremes that work. The old fashioned house leaks, is well ventilated uncomfortable and consumes large amounts of energy. It does last because moisture never collects in the structure (assuming good roofing, flashing etc). Very good building science that has proved the test of time. The other extreme is a super air sealed structure that breathes to one, or better both, sides of the envelope. And of course continuous mechanical ventilation is necessary. Very good building science that hasn't been proven through with the test of time. The stuff in the middle is where the problems lie and this is how most new homes are built. We already know that many of these homes will develop major issues and it often doesn't take very long. I don't think it is fair to criticize the efforts of Passive House builders in trying to build energy efficient houses before it is proven that it doesn't work. Someone needs to take the good building science theories and apply them. Our current crop of Passive House builders are the innovators and experimenters trying to find better ways to build in an energy conscious world. The Passive House community has already learned a few things from early experiments. Without doing we will never know what works and what doesn't. The other option is to go back to the old leaky house - which in most jurisdictions we aren't even allowed to build. So in my experience the exact opposite is true of what you say about quality. In my work I have opportunities to see almost every example of home building. In almost every project there are compromises made for budgetary reasons. In the Passive House projects the building science is always part of the discussion and rarely sacrificed. As well the Passive House builders tend to be actively researching and networking for best possible solutions. When issues arise the information gets through this community very quickly. Although there is likely one out there, I have yet to meet a Passive House builder where quality doesn't always come first. Only time will tell if the Passive House claims of resiliency are true but I am sure that it will be better than the average code built house I see. Let's hope it is as good as the old ones while using a lot less energy!
Posted: 10:09 pm on October 3rd 2014
Response to Malcolm Taylor I guess my simple question back to you is: How do we achieve both the longevity and durability of older energy hogs and reduce the energy consumption significantly? I think we all know this is a necessity in a world where we must transition away from fossil fuels. Regarding mechanical ventilation this is something we must find a way to make work (at least until something better comes along) if we are going to insulate houses. Both the health of the home and occupants rely on it. We wouldn't ask the human body to function without mechanical ventilation so I don't know why we would think a passive ventilation system will work for buildings? Our first Passive House was so over built that our inspector didn't bat an eye when we did non-conventional things. We had two sheathing layers and three framing layers (two structural). As well we used lots of glue and screws so every layer increases structural integrity. We used almost no spray foam in the project and look forward to the day when we can use none. I guess my point is that anything can be done poorly but we need to be careful about branding a whole movement because of a few shoddy projects. Passive House is not the issue here as any builder can cut corners at the expense of project integrity.
Posted: 01:41 pm on October 8th 2014
Answers to Questions Here are a few answers to questions raised: Plans (for clarification): I always create a full set of construction plans including floor plans, elevations, window/door schedules and a detailed cross section. Construction details are drawn on an, "as needed," basis. Many builders in our region develop their own techniques for building details so comprehensive drawings, that likely will be ignored, are a waste of resources. I always have a conversation with the builder to develop plans suit to his/her needs. Plans are revised to suit these needs. Larsen Truss OSB: The continuous OSB on the Larsen truss is, as Martin pointed out, to facilitate hard pack insulation installation. Continuous OSB is much faster than adding another detail to the Larsen truss construction process. The thermal bridge for 1/2 inch OSB over the wall thickness models as insignificant. There is also a thermal break provided by the offset insulated service cavity. Engineering: There were no engineering details needed for this project. Sometimes building officials will require engineering details for the structural slab. The wooden structure fully complies with the building code so there is no need for engineering. The Larsen truss is considered to be structure beyond the building code. The floor system and roof trusses are engineered, in house, by suppliers. Energy Accounting: I agree that waste heat from, say light bulbs, can provide heat to the house. I hope, however, the successes of this Passive House project will be recognized fairly. Many other things could have been done (such as DHW heat recovery, solar DHW, PV...) and still can be added. I always advocate for investing in the envelope, windows and ventilation first as these things build a better, more comfortable, more resilient and healthier house. It is also a pain to add these things later. Most other things can be added at a later date. To give perspective on where this house stands to the norm I provide a comparison based on estimates (from NB Power, the New Brunswick power utility) for a similar house built to code and with typical occupant behavior in our region. Typical New Brunswick House (2000 sq ft, 5+ occupants, code built, < 5 years old): Heating only: 12,592 kWh All other uses: 14,046 kWh Total: 26,638 kWh Based on these number the Peters family is already using 34% less than the norm for non-heating electrical consumption. For space heating they are using 94% less! Overall the Peters - a family of six - use 63% less electricity than the norm - pretty impressive no matter what column you put the numbers in! In a world challenged by climate change building better houses, using less energy & creating local employment is a great way to start in solving the problem. Thanks for all the interest in this project!
Posted: 04:51 pm on March 24th 2016