Thermos-Like Passive Homes Aggressively Save Energy | Hacker News Reader

Thermos-Like Passive Homes Aggressively Save Energy

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19 pointsph0rque27 comments

Even "nice" homes in the US seem built out of the cheapest building materials. Just a minimal framing, a couple of girders, and then everything else is medium-density fibreboard prefab junk. It is like living in a very sturdy tent.

They try to make up for how poorly the walls are constructed by shoving tons of insulation (mostly hazardous-during-deconstruction fiberglass) but really it is just nothingness. I'm sure with a wood axe I could literally chop my way into someone's bedroom from outside.

In much of Europe both new and old homes are built using brick(!). These homes have already lasted over one hundred years and will likely last at least another fifty or more with normal maintenance (e.g. roof repair, replacing some plumbing, etc).

Most US homes seem to have a lifetime of around 50 years before they get demolished and replaced by identically terrible homes. Except there are a few places in the Eastern US where older homes were built well (e.g. Maine) but newer ones are built like junk.

I'm not surprised they're bringing in building materials from Ireland. I doubt anyone in the US produces real homes anymore.

There are definitely large swaths of "McMansions" built in the way you describe, but I don't think it's representative of the entire market by any stretch. Many newly built houses (especially in the Northern parts of the US) are using insulating concrete forms that should last hundreds of years going forward (they're moisture, pest, fire, earthquake, resistant). Several close friends and relatives have built new homes with this method.

http://en.wikipedia.org/wiki/Insulating_concrete_form

There are many old wood houses around Boston built in the 1900s. When maintained (The roof and siding are renewed to prevent water damage and termite prevention) their frames seem to hold up well.

Is your 50 years a guesstimate or do you have a source for that?

It is interesting why brick or concrete - preferred materials in other parts of the world, are not so common for residences in the US.

To me wooden houses have a charm that concrete or brick construction does not. Also, I feel that I can fix/update things in a wooden house more easily than in a brick or concrete house because of the drywall construction.

Just want to be clear, a good quality natural wood home can last hundreds of years. But I am talking about "log cabin"-style homes built out of natural cuts of strong woods (typically with few joins or sections).

The stuff that goes into most US homes is not wood in that vein, it is the "leftover" wood chips crushed back into wood-like substance and used as walls.

As to your source, there are some here: https://www.quora.com/What-is-the-average-lifespan-of-a-US-h...

But you won't in general find many homes built like that beyond 50 years. In places around military bases where at one point in home most houses were built in that style, you notice that most of them aren't around now and the few that are are in really bad shape.

Contrast that with much of Europe where in many places your average house is over 100 years old and are still in great shape. But again brick constructed homes last.

But you won't in general find many homes built like that beyond 50 years.

That's not true at all. There are thousands of homes in San Francisco that are over 100 years old (built after the earthquake).

Go to the East Coast and these "crap" homes are even older.

I'm hoping your just on a hyperbole kick because your statements don't really line up with reality.

An axe would be overkill. We built absolute shit in the U.S. because homes are recognized to be consumables. Literally no thought is given to upgradability. Plumbing and electrical is buried anonymously beneath drywall. Stick-built is still the standard, which is a fucking disgrace in the 21st century.

Fortunately there is a sliver of light at the end of this tunnel (article from previous HN post):

http://www.fastcoexist.com/3020237/new-yorks-newest-skyscrap...

> In much of Europe both new and old homes are built using brick(!). These homes have already lasted over one hundred years and will likely last at least another fifty or more with normal maintenance (e.g. roof repair, replacing some plumbing, etc).

AIUI, Brick construction is actually less resistant than wood-frame to many kinds of things including -- particularly relevant to California residents -- earthquakes.

Its less resistant to axes, sure, but then that just means that modifications are less expensive -- but its not exactly like hostile attacks by axe against homes are that common.

The houses I like the most in Germany are the Fachwerkhäuser which have lasted a while and are made of wood.

http://en.wikipedia.org/wiki/Timber_framing#German_tradition...

Unreinforced brick construction is actually illegal in many parts of California, possibly all. It's pretty easy to reinforce, though; if you sink rebar through the brickwork every now & again, it's as resilient as concrete and arguably prettier.

Admittedly this is much easier in new construction...

In the part of the US I'm in (California) they omit the insulation step, but otherwise yeah pretty much.

Folks in the US do produce real homes, but it's in very small numbers as a pseudo-artisanal thing. http://www.vermontframes.com are pretty neat, for example. The trend in timber framing has been to use structural insulating panels (which are actually pretty good and also, funnily enough, insulate) for infill between the timbers. Technically you can make the entire house out of SIPs, although they're not amazing looking.

High quality timber framed houses are built in Europe and the US. Bricks have a much larger carbon footprint, are more expensive, do not insulate as well as a wooden frames with proper insulation. Brick walls also take longer to assemble. Timber framed houses can also be cladded or plastered on the outside.

When I lived in new england for a while someone asked me how it compared to the west coast. "The buildings smell of mud." For someone used to wood covered in drywall and paint, interior bricks smell like the material from which they were made.

I've built an entire house in weeks using concrete blocks (Florida) (https://www.youtube.com/watch?v=ygiPeFoPWO0). Not only is it more sturdy, its termite and hurricane resistant.

> So far, it has been defined by the German standard that limits the heating and cooling load to 4,755 British thermal units per square foot (or 15 kilowatt hours per square meter)—about one-tenth that of homes built to current U.S. codes.

In the comments section, there's a clarification that this is per year. (Kind of a shame to see "unit fail" in a publication that should know better.)

I'm kind of curious to know what sort of new technology (if any) makes high-efficiency targets easier to meet these days. The article talks about triple pane windows and thick walls. Are these stick-frame houses with fiberglass and offset 2x6s in the walls or something like that, or are there new materials? I recently read that aerogel has been coming down in cost to the point where it's plausible that someone with deep pockets might insulate their house with it if they didn't want super thick walls. Insulated concrete forms and autoclaved aerated concrete are also something that some builders use. What else is new?

It's partly materials, but there are lots of factors:

- building codes raising the bar, which has brought down costs for what used to be "fancy" materials

- improvements in building science

- increased energy costs driving demand for improved efficiency

- greater awareness of energy consumption amongst the population

I've renovated a few houses build in the 60's and 70's in Canada. As far as I can tell, they had the materials and knowledge to make far more efficient houses, but much of the time, it was just easier, quicker and cheaper to install a big-ol' heater and drive the cold out. With a few simple and relatively cheap building envelope modifications and a more efficient heat source, it wasn't difficult to bring heating costs down by 50% or more.

There are dangers in sealing home so tightly to control energy use. Blocking the escape of hot/cold air saves on the bills but can lead to condensation problems when the mechanical systems fail or are not designed perfectly.

Even something as simple as replacing an electric range with a gas one (burning gas is a huge source of moisture) can lead to mold in the long term. A clogged vent into a basement can see moisture from a gas water heater creep into wood on the inside the impenetrable vapor barrier.

And don't get anyone started on the dangers of off-gassing from new construction materials in an airtight environment.

There are a number of mitigating technologies which can be used to maintain quality indoor air. Our home has a heat exchanger to bring in air from the outside & venting in the mechanical room which is on a timer to exhaust any buildup of products of combustion from the gas furnace and water heater. The crawl space is also vented to avoid a build-up of radon gas. Interestingly, the homes used as an example in the article are getting mini-splits which don't have venting capabilities. They are awesome and I love the one we have in our home theater, but am afraid that when they are the only solution used for heating and cooling in a well sealed home the important issue of venting the home properly and in an energy efficient manner may not be addressed. With a central air system it's relatively easy and cheap to do an external heat exchanger. With a mini-split solution, a dedicated heat exchanger system would need to be installed separately from the main source of heating and cooling.

There is a horrible trend of sealing homes up tight, and then we start to notice a raft of problems developing - in the fabric of the home, and it's inhabitants. I am lucky to live in a 1930's building in London, with plenty of ventilation built it. It is certainly not the most eco rated property, but, it is healthy. It might cost a couple of pounds more to heat over the year, but, it has proven itself over time, from coal fires, to back boilers, to central heating, air flows throughout, damp does not get a chance to thrive, nor mould nor fungi nor other related issues.

This is interesting. Do you have a reference for this? It seems logical because humans give off moisture a lot and if the air is not exchanged it will accumulate.

Passive Houses use active ventilation for just this reason. Mine draws air from outside, runs it through a heat exchange with the air being pumped back outside, and through dual HEPA filters. I breathe much more easily now than in the 100 year old home I lived in for the previous ten years.

A Passivhaus should be designed to allow for similar ventilation as older houses: http://en.wikipedia.org/wiki/Passive_house#Ventilation

I haven't actually examined one in person, so I don't know how well it's been executed in practice, but thought was given to this issue.

Houses with poor ventilation will have problems, but sealing buildings up is good for energy efficiency. "HRV" (heat recovery ventilators) are common and required by code in many cold climates (Canada, northern Europe) which do whole-house ventilation with a heat exchanger so you're not just blowing all your nice warm air straight outside when it's -40C all week.

The German Passivhaus standard shows what can be done with this approach, and it works very well.

Many of these new energy efficient homes are built for low-income/no-income housing. The middle class who have to pay for their homes themselves can't afford the construction methods, solar panels, etc. Easy to do if you are using someone else's money. Funny thing is these HUD houses won't last long at all because the copper and other precious materials will be torn out and sold for drugs.

"The windows are one of the most expensive features,"

The obvious follow-up is what the 80/20 might be on these features. If going with readily available double-pane windows shaves $10,000 off the cost, it may be a decent trade-off - maybe use that money to buy some solar panels instead, aiming for net-zero?

Even the best available windows are not very good. My not-very-special house has R-17 walls; expensive triple panes windows can go to U-0.15. U values are 1/R values, so that's a whopping R-6.

If your roof is in good condition, points the right direction and is unobstructed by trees, solar power is probably a better economic bet than replacing decent windows with super-windows.

Don't these also have poor indoor air quality since they don't frequently exchange air with the outside?

Yes, with the upshot being that a purposeful entry point for air allows for targeted temperature control and cleaning in the duct.

A sizable living wall/vertical garden would be pretty cool in a home like this.

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