The Unintended Consequences of Energy Efficiency...

The building industry is increasingly focused on energy efficiency, with higher energy performance standards being introduced in each new code cycle. There has been a lot of discussion about insulating existing buildings in recent years, however, energy efficiency impacts the design of building envelopes and the types of assemblies we construct. In this video, we discuss the consequences of energy efficiency as it relates to moisture and durability.

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[artiebrown]

"There's nothing more sustainable than building something that lasts a long time". Best quote in the whole piece. A structure must be structurally sound, built with long-lasting materials, and then it should be energy efficient; in that order.

[justincabral]

You just distilled months of watching the build show network into 7 and a half minutes. Bravo.

[tealkerberus]

Insulation, airtightness, mechanical ventilation, and vapour management, have to be done together. Otherwise you will destroy your house.

[clivewilliams]

I am an Architect in UK. Some time ago I did some work with The Cranfield Institute, one of the foremost technical universities in UK, with their energy predictive modelling. I was designing a college library with classrooms and the Govt requirements for classrooms required lightweight, well insulated construction, whereas I was given a free rein on the library due to its specialist nature. For various reasons the library was a heavyweight concrete frame and floors with brick north and west facing walls with the others being single glazed with solar shading. The annual energy consumption showed that the library used less energy than the classrooms and maintained comfort level conditions all the year round with very little input. The A/C, which is vital for book storage was barely used such was the stability of the environment. During the summer the shading prevented overheating but allowed enough solar gain to warm the mass so that it emitted the heat during the night. The process was so slow that there was very limited temperature fluctuation. In the winter solar gain was allowed to heat the building and with its huge thermal capacity there was plenty to keep it warm overnight. The classrooms on the other hand had wild temperature fluctuations that at the height of summer the temperatures were intolerable and require Air Con. As Air Con costs 3x that of basic heating to run, the costs were very high. The principal problem was that the classrooms heated up during the day and couldn't give up the accumulating heat to the point where in the afternoon temperatures were getting to 38/39degC (100+degF). At night all the accumulated heat was lost and the process started over.

What i took away from this was that for energy efficiency it is better to have a heavyweight building than a lightweight, highly insulated building. Our ancestors knew this when they built their cottages of stone with 2ft thick walls that to this day are magnificently cool in summer and cosy warm in winter.

I do accept the points raised by this video but have to say that most builders don't understand the importance of constructing the correct detailing, even when its provided and this is all left to the site worker that simply doesn't give a damn.

[KeijoAmbersson]

I'm not a construction pro, but 100% agree on the point. I'm from Finland, and in the 70's due to oil price induced energy crisis Finland started building in "energy efficient" way. Solid mass timber / brick / concrete building and old-fashioned country-style wood building reduced, in favor of new style with multilayer walls utilizing many different materials, lots of insulation, air tightness etc. For some reason in addition to to this, they also made some buildings with flat roofs! And many with very low foundations!

Well, most of the houses from that time are still on the market, but MANY of them have had to go under significant reconstruction to get rid of mold and air quality problems.

Now being in Finland, we do get harsh winters so it's for sure that buildings need to be at least somewhat effcicient. Those old countryside "rossipohja" wood houses did not rot, because there was constant airflow going under the building and who knows where else. But that will cause significant heat loss. But concrete, brick and massive timber houses from that era are still doing a-ok. I live myself in a 1968 brick house built in older style. My mother lives in an early 60's conrcrete apartment building. In my house the upper insulation has been increased as that's where most heat escapes and windows are updated, but other than that everything structural and insulation is original.

Finnish building code puts too much emphasis on "U-value" when rating energy efficiency, which basically just measures insulation properties of a wall. But basic thermodynamics suggest that massive wall structures capture and release heat energy. It also seems straightforward to me that the more different materials you use in a wall, the more possibilities for moisture to condense in these material change areas. And if any/several of these materials are weak to

So if I was building a new house right now, I would go for massive timber and wouldn't look any further. Overall energy effciency rivals modern multilayer-buildings, but with only one wall material. Timber is faster to build than brick, and it is a beautiful material as is.

Newer style buildings of course can and do last when all is done well. They are just much more vulnerable to circumstances and errors. It's hard to mess up if your wall is just solid, but it's easy to miss a spot or poke a hole on a vapor barrier sheet.

[Nicksonian]

Crappy building is a huge problem. Dominant big companies and smaller builders alike are using unqualified labor to throw up poorly-built, shoddy homes that, despite some attempts at using modern building techniques, are going to be leaky.

[JoelWeyrick]

Thanks for covering this. One other idea I've considered for a more durable house is to extend the eaves much further than is common today. I believe that I've read that wall failures are almost guaranteed within a century if the gutter is on the side of the house, but a house with two foot eaves will rarely have problems.

I've also seen enough termites using foam insulation as highways to wood that I don't intend to use it anywhere near the foundation of the house. Not to mention that it makes houses much more flammable.

I didn't realize that they had exterior rockwool, and I plan to consider using that. It seems that rockwool is a healthy replacement for asbestos.

[rygfhhbb]

Take a look at the picture with the corner of a window and rotted sheeting. Either the picture is upside down or the window was installed upside down. You can see the weep hole cover on the window frame. I use to do service for a window manufacturer and saw plenty of square picture windows installed upside down, even saw sliders installed like double hung. Also the accepted standard leakage for a 3' x 5' is .3 cuft/min that is essentially equivalent to having a 3' x 5' piece of plywood wood with a 7/8" hole drilled in it. Tested at 25 mph at 70F. Not real world, just standardized. They will leak severely when walls are well sealed. The company I worked for lost a large account when a builder used ICF to the roof, but did not use hrv. Even when I explained the well sealed, well ventilated requirements of high efficiency homes, they would not believe it and blamed the windows and cancelled their account. This was before you were around, I could have just directed them to you for an education. Ignorant labor is the weakest link in the high efficiency home market

[larslrs]

Those are great PhD results for building a house but those workers don't have a PhD. The assumption that the work is being executed without errors is flawed. In essence, the concept must not only bee robust against climate and weather but also against tolerances and errors during the build process.

[denys-p]

I probably would dismiss this video, but this summer I replaced oil burner for hot water with hot water tank. And that tank insulated so well that temperature in boiler room dropped significantly and we got a problem with condensation on (cold) water pressure tank and cold water pipes. So we had to remediate it
It is definitely something that is often overlooked, we didn’t even consider such consequences

[foobar]

To summary: if you do it, do it right.

Over here in Germany, air tightness is one of the most important topics in newly built homes. Ventilation is not mandatory, only a concept for ventilation which may contain manual ventilation through the windows. In practice, the necessary air exchange can only be reached by controlled ventilation and in the last years basically all new homes have some type of ERV. For older homes, decentralized ERV can be a good idea

[TakamiWoodshop]

For viewers to avoid confusion: it's not stated but the video is applicable to the UNITED STATES. References to "The Department of Energy" mean "The United States Department of Energy" etc.

[archeanna]

As a person who has had her health destroyed by mold, I am looking forward to changes to building codes that recognise that current codes are not safe. It seems that the insurance industry has become aware of the potential financial impact mold awareness would have on them and they are showing a real interest in - how do we say this? - managing how mold levels are assessed, with an interest in limiting the cost to their industry. So, it will become more difficult to get a useful assessment of and compensation for mold damage.
The protocol for managing mold sickness is complicated and it seems that the best we can hope for is remission, not a total return to pre-infection levels of health.
Please, ASIRI Designs, keep speaking up. If there is such a thing as 'God's work', this probably qualifies.

[Mike_Fortin]

thank you for this video

I am an ICF home builder in IL. I'm all about high performance,

I've even done some research on the SIPs failure in Juneau, in fact I met Joe Lsitburek (who performed 3rd aparty inspections on the failed buildings) at a GBA event earlier this year, very smart man.

As much as I love the high performance community, sometime they deviate from what is practical, common sense, or appealing to consumers.

The biggest issue I see is an unfounded fear of carbon and greenhouse gases, with no consideration for other aspects of a building and its materials such as longevity, safety, disaster resistance, etc. This fear leads builders, designers, and other building professionals to limit what materials they use, and essentially stick to products like wood almost exclusively. products like ICF are frowned upon because of their supposed environmental impact.

However, as you mentioned, more insulation = less drying potential, High performance double wall assemblies have more failure points, and wood homes lack disaster resistance. Furthermore, deforesting the earth and producing milled lumber is not carbon neutral either, requiring gas powered equipment to plant, grow, harvest, plane, dry, treat, transport, and install the lumber. I Couldn't agree with you more when you said "'There’s nothing more sustainable, than building something that is going to last for a long time". ICF building solve the mold issue, the air tightness issue, the insulation / efficiency issue, and also provide disaster resistance and are built to last. While it may initially use more energy to create this building, it will not need to be rebuilt several times unlike its wooden counterparts.

just my 2 cents.

Sincerely, a biased ICF builder :)

[jacobecorder]

Nailed it. I did 2 layers of 1" xps staggered seams cuz rockwool is not possible to get for a non contractor. Wish I did 2 layers of 1.5". I'm in Minnesota zone 6. It was a pain to do but it's a 90 year home and knew I had to be careful as you can rot a house if you do it wrong. Air sealing is super critical from the outside to stop that insane amount of water vapor that can penitrate. I wish I paid more attention to that but it seems good, for now.
Love your videos. Keep em coming.

[bbmoti]

Every builder and diyer need to see and understand what you cover in that video.
And it will save people alot of frustration and disappointment. And money too

[bengorman]

This is a very important warning for remodelers and those using newer constructions techniques and materials. "Build tight, ventilate right" is the saying in weatherization, but too often there is a lack of understanding of what constitutes "right." The tighter you make the envelope, the more attention you have to pay to movement (or lack thereof) of air. Of course, one could eschew the modern building materials---most of which were designed to follow existing building traditions in the most profitable way---and use breathable natural materials, like hemp-lime.

A well-made hemp-lime wall structure avoids the complexity of modern, multi-layer, multi-material walls system while providing moisture management through natural permeability; they provide insulative value and comfort through thermal mass; and they reduce the toxicity and carbon footprints of buildings. A hemp-lime wall can be formed in place (cast) or assembled from pre-made blocks. Exterior and interior finishes of lime-based renders can protect the structure from the elements while maintaining moisture permeability.

Hemp-lime is not load-bearing, so some sort of framed structure is needed. But another benefit of this methodology is that the construction crew needn't be skilled tradespeople: a few hours of hands-on instruction from a single skilled foreperson is all that is required to deputize a hemp-lime building crew. The possible downside of such building methods don't necessarily lend themselves to the economic realities surrounding our housing shortage (in the U.S. and elsewhere). How can we build the volume of housing that we need at the pace that we need it? Perhaps local communities can organize hemp-lime building cohorts that can supply labor to local housing developments. The labor need not be skilled to the same extent that a traditional stick-frame house requires, so perhaps that is an advantage? I'm eager to see how hemp-lime can be integrated into modern construction. It's such a beneficial material, and truly carbon-negative.

[dusdnd]

A good HRV also manages to reduce the humidity difference. The answer here can be to insulate in different ways, but also use better practices to prevent moisture in undesirable locations, which should be done regardless. An AC or heat pump, especially a variable speed system, can be used to properly manage humidity by running it at a very low speed.

[ADobbin]

Leaving aside the cost or reconstruction or repair, rotting buildings are also an incredible health hazard. People will be badly affected by mold and mildew long before anybody realizes its there.

[goyconptyltd]

great explainer for any builder or client who its about to embark on the path of passive house building or energy efficient construction, it can be a real trap if not done properly. thanks for your insight