Code Minimum is Affordable, Green Building Isn’t
(In zone 3a at least.)
When we set out to build a custom passive solar home, energy efficiency was a big goal. I wanted to have a near passivhaus , superinsulated ,very airtight house.
Then the reality started setting in and I started seeing the Data.
For example I saw right here on gba that doubling my insulation would save about $20 a year. If I added that insulation to the exterior my taxes would increase by about $100. Net money loser.
Then I priced green building components, like European windows? Holy cow they were expensive and would save maybe $30 a year.
Then when you introduce the time value of money and opportunity cost? Omg! The cost get over 30 years is huge. Only solar pv comes close making sense.
So anyhow, green building was DOA from the get go for me.
We did incorporate several common sense , and free, green strategies though, like building with a low heat loss form factor, (a rectangle box with a living gable roof), using a white roof to reject heat in the summer, and general orientation to reject heat in summer and gain heat in winter.
I’m still going back and forth on solar pv but in the current environment even solar pv doesn’t seem to make financial sense.
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A lot of the GBA readership is in colder climates, and so you might get the impression that R40 walls and triple pane windows are the only way to go based on discussions here. That, plus the fact that PV has come down in price, minisplits offer amazing performance, and it's increasingly possible to get clean electricity from the grid mean that a high quality very green build needn't be extreme at all in the envelope. Modest insulation and inexpensive windows (with low-e argon and an appropriate SHGC) can result in a very green, easy to build, and low cost house. But attention to details such as air barriers and water management can get you better comfort and durability--not everything is about saving money on energy bills.
I remember when I wanted to go r40 walls and Dana dorsett (on another forum) basically said it would be stupid to go more than r21 in my climate..
I'm glad I listened.
Green building might be more then saving money on energy bills but that's definitely how it's positioned in the mainstream
Interesting that that is your impression of what is in the mainstream (note everyone doesn't share the same mainstream).
I would argue that the ROI approach might make better environmental sense if we internalize externalities in the market.
Instead we take a market as religion approach.
Can you expound on this part. I want to make sure I understand.
"I would argue that the ROI approach might make better environmental sense if we internalize externalities in the market.
Instead we take a market as religion approach."
>"if we internalize externalities in the market."
That roughly translates to "the realities of the market don't fit my view of how I wish things were, so I want regulators to make arbitrary decisions to bend the world to what I want". This is how things get crazy, overboard, and far too expensive for little or no actual gain.
The BIG BIG emphasis here is on ARBITRARY. There is also a lot of "one size fits all", which makes things cost too much for people who don't need something. A lot of the "externalities" you here talked about are either flat out made up, arbitrarily "defined", or impossible to quantify. Nothing technical in nature should be defined by feelings or emotion, it needs to be justified with actual data to back anything up. This means REAL things that can be MEASURED.
All that fun stuff said, green building CAN be economical, and there ARE some intangible benefits. It's well known that tight houses and things like triple pane windows can improve comfort, not just save money, for example. It's also well known that energy costs generally increase over time, so any extra insulation put in today -- for what is essentially a one-time, fixed cost at build time -- will likely save you more money in the future than it will today. How much is hard to say, but everyone can probably agree that there will be SOME increase in energy costs in the future.
It doesn't make sense to do R40 double stud walls in a mild climate though. The extra cost to build those walls could be better spent somewhere else where you'd get more benefit. This is a market reality, and it's the market telling you that in your set of conditions, you waste money building too much R value into your walls, you'd probably be better off spending that money on something like a higher SEER A/C unit instead. The market helps you to allocate your money to where you get the most benefit from the money you spend, and that means best efficiency. In a green sense, in my example, the more efficient A/C unit is likely to result in lower energy consumption over time than the excessively high R value walls would.
I'm big on efficiency improvements. A lot of the basic air sealing stuff is cheap to do at build time, and has real energy efficiency improvements for the entire life of the home. You can step up from there to more R value, maybe exterior rigid foam or something similar, etc., with the pinnacle of energy efficiency something along the lines of the Passivhaus stuff. What you actually build is probably somewhere between code minimum and a full passive house, and you allocate your money to get the best mix of parameters for your specific project.
Bill
Utter garbage bill. You may be expert engineer, but not economist. Do some homework.
Too bad.
Max I'll elaborate tomorrow if the need is still there.
Thank you zephyr7.
You are right on the arbitrariness (not a real word) of it all .passivhaus for example. Arbitrary. To add insult to injury it becomes about bragging rights. I even heard you have to pay thousands of dollars to get the plaque that says the house is passivhaus?
I actually wouldn't lump the passivhaus standards in with the same kind of arbitrary I was talking about. The passivhaus people had to DEFINE some target to reach, and they did. But they have ways to measure to see if they hit their design target, which is proper engineering. I don't have a problem with that, and some of their ideas trickle down into more "regular" buildings which can be a good thing, similar to how the space program developed some new technologies that benefitted other industries. Essentially all units of measurement start out with someone picking something to be a standard, because everything started from nothing, basically.
Tyler, what I was talking about really isn't garbage. I work with this stuff professionally all the time, and see how asinine regulations can drive up costs, or completely price things out of the market, without providing any tangible benefit at all. Many are even self defeating and make things worse. It is an unfortunate reality that many who push for green regulations are well meaning, but not very knowledgeable about what they're pushing for. There are a LOT of very poorly thought out regulations out there. This doesn't mean I think there should be no regulation at all, but things have to be quantifiable, and measureable. Technical issues can not be worked on with emotion and feelings.
Bill
Bill,
I apologize for my harshness. Was past my bedtime.
I do feel the need to suggest that perhaps you reap what you sow, however.
This:
"That roughly translates to 'the realities of the market don't fit my view'..."
Is not only rude or disingenuous, but ignorant.
I respect what you offer here Bill, but on this issue you have entered politics and frankly appear to be out of your wheelhouse.
If you disagree and think this is your wheel house, then I suggest you take a different approach that shows willingness to discuss the nuance of the issue rather than denigrating those attempting to have said discussion.
All the best Bill,
Tyler
Tyler, sorry if you took that line about "don't fit my view" personally, it was meant more as a rhetorical/general statement. It was certainly not meant to be personal in any way.
My basic point was just that there are a lot of well meaning people out there that often don't understand the realities of things they are vocal about. I had not meant to target any particular person, it was just a generality. As I like to say, physics doesn't care about any of us, it just is. We have to deal with it as it is.
Bill
Max,
As Charlie said, a lot depends on climate. I'd add: a lot depends on what code minimum is where you are. Here in BC code minimum now yields a pretty well performing house. It didn't used to. To me that incremental improvement has been much more useful than having a few extraordinarily well performing houses amidst a mediocre housing stock. There are certainly limits on how much sense it makes to improve building performance of the building envelope - especially if it c0mes at the expense of putting the effort into other things, like perhaps increasing PV, or further reducing the affordability of housing.
The standards seen to be getting higher and higher. I wonder how that has impacted the affordability in your area.
It's definitely had an effect. You can't add requirements for seismic resistance, full-time mechanical ventilation, and increased R-values without some cost. However, here anyway, the increase in house prices have been driven much more sharply by land, material and labour costs - and the largely irrational market bubble that has formed locally.
I can confirm this to be the same issue here in Southern Ontario where I live. Building code really hasn't changed that much over the last ten years when my current house was built (minimum code) but it is now worth twice what I paid for it. Most of that increase has happened in the last 2-3 years.
Arnold
America was founded on cheap land. Immigrants came here from all over the world because we had land, and lots of it. Bob Hope made a fortune in California real estate, and he quipped that the secret was just to drive out to where the houses stopped, and build some more. When land is cheap the cost of housing is very closely linked to the cost of building housing.
We're going through a shift now, because many American cities have effectively become built out. What that means is there isn't any cheap land left. This creates a big gap between the cost of housing and the cost of building housing. Adding to the cost of building housing doesn't really add to the cost of housing, it just depresses the value of land. Where I am -- Washington, DC -- the government has piled a lot of mandates on -- stormwater, sprinkler, tree preservation -- and housing is expensive, but even without the mandates there's no reason to believe the housing would be any cheaper, the price is driven by scarcity and not cost.
Where you see resistance to expensive mandates is in places where the land is still cheap and it effects the affordability.
Dc, do you think builders would be able to build more homes, and faster without all the mandates?
Max, of course we could build more homes, faster if there were not regulations to follow. But is it necessary to build more homes, faster? I don't think so.
Max --
I honestly don't. In a built-out city the supply of land is finite, the market sets prices, not costs.
To give some perspective, the new houses going up in my part of the city are selling in the $2.5 million to $3 million range. Recent government mandates might cost $100,000 to $200,000 per house. But even without those mandates, those houses would still cost that much, because that's what people are willing to pay. It just means less profit for the landowner. The zoning dictates that there be one house per lot, and what its size is. So really until you get to the point where mandates cause a house not to be built there at all, or a house that nobody wants, the effect on supply is minimal.
What would really affect supply would be revising zoning to allow more multi-family housing and smaller lots -- ie, more units of housing on the same land.
2.5 - 3 million starting costs for a house seems like a really extreme example of a housing market and I don't think that is representative. According to the NAHB, the average percentage of the cost of land for new construction was 18.5%. So for the vast majority of Americans, doubling the cost of construction would profoundly affect their housing and mortgage costs.
I'll point out that the code was drafted with an eye toward practicality. How did they settle on R38 instead of R35 or R40? Well, if you take a 2x10 ceiling joist, which is 9-1/4" thick, and fill it with fluffy insulation, which is R4 per inch, you get R38. So that's the value that gives the most insulation with the least incremental cost. Every time you read R13, just know that they're expecting a 2x4, and every time you read R19, it's a 2x6. Those numbers aren't arbitrary.
The code was drafted with the goal of optimizing efficiency and cost-effectiveness, using common building techniques and materials. So it should come as no surprise that code-minimum construction is the most cost-effective -- that's what they set out to do.
I have deep respect for the new codes. Houses being built today are so much better than even a few years ago. With durable goods like houses and cars that consume energy there is a real problem that the first purchaser gets to make decisions that effect the lifetime energy use for all subsequent purchasers, but often that first purchaser doesn't care about efficiency.
Dccontrarian
I can't say I agree that houses today are built better then they were. My 1980s house, used full studs instead of finger jointed. It has actual plywood and not osb. The brick work is better than what you find today. They may be better insulated but it doesn't mean they are better built
Right, I should have said better-insulated.
"...using a white roof to reject heat in the summer"
If you're insulating to code minimum or better, using a white roof will yield meager additional energy savings, and could increase moisture risk if your interior air barrier is lacking. This is more risky in colder climates than 3A, but worth mention.
"and general orientation to reject heat in summer and gain heat in winter."
I assume you're referring to glazing orientation. This is an okay general strategy but hitting the fabled 'sweet spot' with fixed shading elements is dubious, and will always involve compromise in the shoulder seasons where limited heating could be needed as often as ample heat rejection. In 3A I would always err on the side of too much shading and lower SHGC in absence of a good energy model. You don't want additional heat gains you can't carefully control.
Jason s, when I switched my current roof from dark shingles to white metal, my summer electricity bill dropped by more than a third. Its probably the most important energy saving truck one can employ here.
I always wonder why we say compromise in regards to orientation and shading. To me it's so simple. With no overhangs you get the max amount of heat when you want it, and with external shades you get zero heat when you don't want it. It's this too simplistic?
We're talking vented attic with no ductwork in it, right? Code levels of insulation and airtightness in the ceiling? I would appreciate seeing comparable energy data given the above, and I would walk back my "meager" statement, but not the moisture statement. I would also love to see affordable and operable exterior shading elements.
The initial assertion was about cost effectiveness. What is the real target you are comparing to code minimum? Is there an energy model guiding the insulation targets or are the goalposts moving here?
Passivhaus levels are set with the possibility of delivering all of the peak heating and cooling demand via low-volume ventilation ducting already meant for the HRV/ERV. This *potentially* allows the eliminatation of conventional heating and cooling system distribution networks and vastly reduced system size. Only through that lens can it be seen as a potential 'cost-effective' measure. In temperate Europe expensive hydronic systems are the norm, so there's often more savings to be had.
*This potential is seldom realized in US climates.
I have painted 20,000 square foot flat building roofs on datacenter facilities white and have seen measureable (we have to measure everything because we have to show our customer what we accomplished) improvements in building cooling load. I saw two things after painting the roof:
1- The peak temperature in the facility was lower than it was prior to the white roof (it was originally a black roof in the specific facility I'm thinking of)
2- The time of day the peak occured shifted several hours later into the day after the roof was painted. We attribute this to lower overall solar gain due to reflection from white paint, resulting in less energy warming the facility and a lag in temperature rise as a result.
We normalized things to previous days since we had several years worth of hourly logging data to work with. If you're in a hot/sunny climate, a light color roof most certainly CAN result in lower energy use for air conditioning. I've seen it happen in controlled enviornments where we monitored, and made measurements, usually every 5 minutes for days or even a month or more. I don't remember what the payback was in my first project where we tried the white paint, but I think it was only a month or two. All we did was send a crew up on the roof with a sprayer and a bunch of cheap white paint.
Bill
Bill,
That's great and I don't doubt your measurements. See my response above; it's unclear if existing compact roofs of unknown insulation levels are comparable to what Max has in mind.
>"I have painted 20,000 square foot flat building roofs on datacenter facilities white and have seen measureable (we have to measure everything because we have to show our customer what we accomplished) improvements in building cooling load. "
A PITCHED roof on a RESIDENTIAL sized structure experiences a lot more convection cooling of the roof than a large flat-roofed data center.
That said, high solar reflective index roofing isn't usually much of a (often zero) cost adder, and thus pays for itself even with meager energy use savings.
Back to the original post, in most IECC zone 3A locations it's possible to hit net zero energy far more cheaply and cost effectively with ~R2o-R25 (whole wall), heat pumps, and rooftop PV than to go all Passivhaus on it. That could be a 2x6 wall with air tight sheathing, R20 cellulose in the wall cavities with 1-1.5" of exterior foil faced polyisocyanurate sheathing.
Even though it wasn't analyzing what it takes for net zero, Table 2 on p.10 of this document is a pretty good guide. Pay attention to the zone 3 row:
https://www.buildingscience.com/sites/default/files/migrate/pdf/BA-1005_High%20R-Value_Walls_Case_Study.pdf
That analysis was more about lifecycle ROI, and the table was the approximate sweet spot in terms of price/performance at that time. Heat pumps have become more efficient since then, and solar has become dramatically cheaper (and more efficient) so it's possible to cheat that by a full climate zone and still do OK, but it's still a pretty good guide. Just about any Energy Star window would meet the <U-0.30, SHGC <0.3 spec for zone 3 in that table. Most builders in 3A would skip the sub-slab R5, but any performance home builder/designer would pay attention to that.
Dana, what you're saying makes me thing there could be a few levels of guidelines:
1- code minimum, the cheapest you're allowed to get away with. I doubt any of us on this forum are likely to build this way though.
2- a starting point of "optimized optimization", the "sweet spot" you're talking about. I often advocate for the same thing, spending money in a way that gets the most bang for the buck. That doesn't always mean doing what first seems obvious, since you're looking to achieve the best OVERALL system efficiency. This would be a sort of minimum "green" standard, a step or two up from code minimum
3- A mostly-optimized, higher priced version. This would be higher than #2 in terms of energy efficiency, but not all the way to passivhaus. Essentially a "I have some extra money to spend, and want to maximize energy efficiency without going overboard" level.
4- Expensive and unusual stuff, closer to full-on passivhaus building.
2 would be something of an affordable green building level, 3 would be like a higher finish level, more optimized, and more expensive, but still reasonable for a higher end "regular" building. 4 would be the "cost is no object" type of build.
It would be interesting to see if some basic guidelines could be published for these levels. Right now we have the code book as a minimum, and then a whole lot of various ideas and details to choose from to add stuff, but not necassarily a semi-formal outline.
Bill
Bill, your #2 and #3 items are at the core of the Pretty Good House approach. Many people seem to focus on the prescriptive R-value recommendations we started with, borrowed from the BSC document Dana linked to above. But that's only for climate zone 6, and we also recommend energy modeling to fine-tune details like insulation levels. I often find that R-40 walls are hard to justify in zone 6 but R-30 walls have a good ROI, for example. The PGH approach says to keep making improvements until they stop making financial sense.
Dana, I have measure the underside of my roof, ie inside the attic at 128° when it was a dark shingle roof.
with the white roof, the underside of the roof barely rises above ambient.
thanks for posting that pdf. good info in it.
Hi Max,
Re externalities:
First, are you familiar with the general concept of externalities? A google search will yield more than you'd ever want to read about that, but here's one link: https://en.wikipedia.org/wiki/Externality
The concept of externalities are not some fringe theory but a widely accepted reality of markets. And (Bill) pricing externalities DOES NOT need to mean imposing arbitrary regulations, of which certainly many do exist.
If we can't move past this point of admitting that externalities in-fact exist and at significant magnitude, then there's no discussion to be had. If the issue becomes, rather, how we should price externalities or somehow compensate for them, the discussion gets far more nuanced, difficult, and productive.
Arbitrary: "based on random choice or personal whim, rather than any reason or system."
One COULD assign a price to an externality arbitrarily, but that does NOT mean that the existence of the externality is arbitrary.
Difficult: "needing much effort or skill to accomplish, deal with, or understand."
^ This is more accurately what it would be to accurately assign a price to an externality. There are loads of nuance and discussion to be had in this regard. But to have that discussion, we must move past the zealotry and illusion of a 'perfect free market' and discuss logically the connections that exist between economics, the environment, and human well-being.
So what did I mean in my original statement? Quite simply I meant that there are externalities associated with energy use and unless those externalities are somehow accounted for, a simple ROI approach does not accurately reflect environmental and/or human health costs.
Note this has NOTHING to do with standards like Passive House. In-fact, accurately pricing externalities should in theory make such standards largely moot (save for innovations brought about by such standards). If we can carefully and judiciously improve the market to reflect true costs, then an ROI approach will in-fact be a very sound way to assess efficiency implementation measures.
Tyler, I agree but not 100% . a code minimum house in my zone has the lowest cost of ownership over 30 years, imo if you dont factor in externalities, like embodied energy. it may still have the lowest cost if you do code minimum plus solar pv.
Max,
Embodied energy isn't really the same as externalities, though embodied energy may certainly contain external costs.
For clarity, I'm not suggesting any specific 'level' of achievement in relation to code. It was simply a suggestion that in regards to environmental impact, using $ROI is not the best metric given current market structures and unpriced externalities.
I'm also not suggesting which specific externalities we should price, nor how we should price them (that would be too far gone from the topic of this thread). I only suggest that they exist and so if the goal is environmental impact assessment, then a monetary ROI analysis will be lacking in accuracy.
We make many decisions as consumers on a daily basis devoid of ROI analyses because the point in many purchases is not for $ returns.
As an example, the ROI for putting in a hot tub is less than $0 in returns, but the point is not to make money unless your running a soakery*. We can of course buy a more efficient hot tub and calculate how long it would take to recoup the increase in upfront cost, and in that way perform an ROI on efficiency measures.
Houses are like proverbial hot tubs in this way. It seems far too common for people to start with a specific end-product design, and then impose an ROI analysis on it.
But few seem to ask what the ROI is of turning down the heat, or making the house smaller, or living closer to where you work (thing of past with pandemic?). Some of these ROI are arguably infinite given 0 upfront cost.
It sounds like you did think about these things by considering the "common sense , and free, green strategies... like building with a low heat loss form factor"
That is wise and something I think more people should do before performing an efficiency ROI for a preconceived monstrosity.
If we, as a society, were able to apply a sort of macro-ROI analysis to our collective well-being, I imagine the areas determined to have the highest ROI would be quite different than that which a micro-level analysis would determine. In regards to housing, I imagine getting existing structures up to code min (for example) would be far and away a higher priority than refining the Passive House standard.
The concept that monetary ROI is different from environmentally friendly should be self evident, and not controversial. There are countless examples that prove this; basically our entire throwaway society can be cited. We keep buying junk that won't last because it's dirt cheap. One of reasons it's dirt cheap is that there's minimal financial cost to discarding them, and virtually none of that is borne by the supply chain. The environmental damage of a product or service is an externality; the parties making and selling the product/service don't pay for that damage, so it's not built into the price. So unless you can say you don't care about our environment, I don't know how you can claim that externalities are a thing and that they matter. In which case, what are you doing on this site?
Passive house standards are well and above what would be reasonable for the majority of the United States. Seems silly at aspire to PH standards in CZ3a in any case "Green building" is a range. Some buildings are more green than others. PH standards are on the extreme. There's no reason to shoot that high in most of the lower 48.
John,
The Passive House Institute US (PHIUS) has optimized the goals and metrics for each US climate zone as of 2015, updated 2018. They have their eye on more cost-effective ways to net zero, as I would say do many folks on this site. Net zero or zero-ready is a very real goal for many people, not easy, but also not one I would assert to be unreasonable.
It would be wise to draw the distinction between that standard and the german Passivhaus Institute PHI.
Jason S , i am of the opinion that the most cost effective way to get to net zero is code minimum house + enough solar pv + some common sense practices.
john clark, agreed.
Max,
If your opinion is correct why aren't we seeing net zero homes with current code minimums?
Answer: you can hardly build enough south facing roof for the necessary PV system at code minimum levels.
It is entirely possible that certain code minimum assemblies can get you to net zero though. We arrive at which ones by developing a comprehensive energy model, an airtightness target, rough assembly pricing, a kWh target to size the PV system, so on and so forth. You still haven't stated your real target except to save money.
Best of luck.
>you can hardly build enough south facing roof for the necessary PV system at code minimum levels.
Could you elaborate on that? I'm trying to think what about code limits the amount of roof.
Was that really equivocal? No, nothing about code limits the amount of roof. The size of the roof is the practical (not absolute) limit of a residential PV system. If code minimum insulation is the horse he bets on to hit net zero, then ride it and find out if the roof sees enough kW to meet demand. I bet not, certainly not cost-effectively. If you have to make the roof bigger you're going the wrong way.
No house "needs" to be net zero. Net zero is just an arbitrary goal. In any case there are thousands of older code minimum homes in California, SW US and Florida which had solar installed and for at least a few months out of the year end up selling/generating more power than they use. This isn't news and has been going on for about a decade now. The PPA (Power Purchase Agreement) is what allowed solar to get a foothold in those states.
The only state I can think of which adopted something of NZ in their codes is California. Their dry climate allows them to hit that goal comparatively easy.
Jason s said
"If your opinion is correct why aren't we seeing net zero homes with current code minimums?
Answer: you can hardly build enough south facing roof for the necessary PV system at code minimum levels"
I'll propose a different answer- the opportunity cost of net zero even with solar panels is still too great.
Since I'm building a passive solar house, I have 1300 sf of roof facing south.i can fit enough panels to never have an energy bill.
But,I feel that I can make more money overall by keeping the money I would spend on pv invested.
Ya I'm aware of the difference and imo it doesn't change what I'm saying. PHIUS is still overkill for CZ 3 and below. Getting close to Net Zero is incredibly easy in CZ3b by what amounts to essentially throwing a solar array on the roof and that's exactly what's happening in California with regards to current code for new residential construction.
The other thing is that "code minimum" is different in all states so everyone has a different starting point.
https://www.energycodes.gov/sites/default/files/Residential_State_Code_Map_12_14_2020.png
CZ3a adds the challenge of humidity but triple-pane windows aren't needed.
"code minimum" is different in all states."
Precisely, John. And which do you suppose those codes correspond better to: the math of cost-effective paths to net zero energy across a given climate zone, as Max has asserted, or to a given state's political leanings, energy goals and taste for regulation?
In absence of design specifics, you can't assert to know the PHIUS targets for CZ 3 and below. You would need to run hypotheticals on approximate envelope area and conditioned floor area per occupant to even have a target to consider "overkill".
https://www.phius.org/phius-certification-for-buildings-products/project-certification/phius-2018-getting-to-zero
Overkill is subjective and depends upon project goals. If it's cheap to throw up PV then by all means keep feeding the insatiable energy machine in absence of a more targeted approach and if your climate is easy like California (for now).
Admittedly it has been a while since I was last on the PHIUS website. In any case PHIUS is not synonymous with NetZero. There is zero reason to force people to spend the capital to design/build to PHIUS standards when it's not needed. Especially in solar friendly temperate/warm climates.
John,
Actually that's exactly what PHIUS+ is positioning itself to be--the most cost-effective path to net zero. Cost-effectiveness is murky water and their requirements are quite new, so it's debatable but also measurable and I wouldn't dismiss it blindly. Nor would I suggest an unwilling client needs to pursue that goal if it doesn't fit their values or budget.
I had the same concern and largely the same conclusion from a ROI perspective. At the very least, after reading so much GBA and FHB, I feel better about the house I'm building. On the green building front it gets murky as you can instead invest in increasingly cheap PV as you suggest, or if your city is committed to going all renewables in the next decade it's arguably more of a moot point how much energy your home uses anyway. For me, I was able to roll PV into my loan payment and the costs actually made financial sense comparing the increase in my mortgage to my utility bills. If PV doesn't make financial sense I'm not sure there's any other reason to get it, it's cheaper for utilities to build and maintain at scale anyway. I went with slightly above code insulation and air sealing details more for comfort concerns, though I can't say I've gone into a recent code built house and felt uncomfortable, so it's more that I have the luxury of having a little bit of financial leeway to go above and beyond and hope it's worth it over buying a fancy fridge/etc. I can't help but suspect that a lot of people reporting the joys of super insulated or solar heated houses have a bit of emperor's new clothes about it given their immense financial and emotional investment into their homes. I think it would be really useful, or maybe it already exists, for someone to do a rigorous blind test of occupant comfort in a code built vs above code built house in various climate zones. Even then, would the money have been better spent on in floor radiant than triple pane windows and double stud walls for occupant comfort given that comfort seems to be related to either radiant heat loss from lower insulation or increased convection from air leaks? I have seen such a study on health effects of air quality, so at least there is a pretty good argument for paying for mechanical ventilation of some kind.
Carsonb, interesting commentary. The part about emperor's new clothes is interesting. I think I read somewhere about the principal of phius suffering through a hot summer or two because they didn't want to use the ac.
And it's not the only instance either. So, I would say I'm some extreme cases green building can even increase the level of discomfort
Regarding mechanical ventilation, in my climate, natural ach of leaky house can be as low as 0.1-0.2 ach.
Houses are just not that leaky when there is not a blower door running.
yes, ph are a whole other level... I'm doubtful they even make sense carbon wise; especially if you factor in the article on GBA that found that workers driving their trucks to the site every day made up 60% of the carbon footprint of the build while ph details seem really fussy and labor intensive. My statement on mechanical ventilation was not about air leakage but about the study on co2 levels and brain function. That seems like a fairly new area of study, however, but I do often find houses a bit "stuffy". For air leakage, I do plan on running around my site with a caulk gun and using zip based on comments on GBA, though I have no empirical way of determining if it's worth it in terms of comfort, nor have I run the calcs on energy loss with 5ach50 vs 1ach50 in my area.
Cars0n,
It's funny how comfort has come full circle in green building. One of the big knocks on early energy efficient houses in the 70's was that they were so uncomfortable to live in. The occupants had to put up with large temperature swings, and often high humidity from attached greenhouses. In many ways you had to reconcile yourself to living in a machine designed primarily not for your needs, but for its own goals. It's a real switch to see comfort being lauded as an aim, or even byproduct of high-performance houses.
I like to point out that the whole point of HVAC is comfort. The easy way to use less energy? Turn the thermostat down. In the winter, if your home is warmer than the minimum needed to keep the pipes from freezing, you're wasting energy. If you use cooling in the summer, you're wasting energy.
It's not a matter of trading comfort for efficiency, it's a matter of how much comfort you're willing to pay for.
This point has been made many times before on GBA, so I won't belabour the point, but it's worth considering that net zero energy is not the same as net zero power.
And this may become a greater issue as utilities themselves turn to more renewables, having peak supply at the same time as your roof.
Also (sorry to say it again) but the externalities of chinese solar panels are arguably greater than added insulation in many cases. (Depends)
What are the negative externalities of chinese solar panels?
John, are you asking because you are actually curious and want me to answer?
I would challenge you to try to think of a few and if you really cannot come up with even one, I will oblige.
If it helps to quell a defense posture you might be taking, note that I am in a cold climate where heating loads are proportionately larger than both cooling and plug loads compared with Zone 3.
In other words, I could see how in certain environments, solar would make sense sooner vs envelope improvements. In colder climates where heating is a large load and winter solar does not match it terribly well (reliably), the story is probably a bit different. These are vague assertions and one should crunch some numbers (even if they are simple ROI numbers devoid of externalities) if one wants to be precise about it.
I won't claim to know how to make better environmental cost comparison calculations (compared to simple ROI) because it's true that bringing externalities into the mix is difficult to do quantitatively. But that difficulty does not preclude knowing they exist at some non-zero number. The easy and imprecise way out is to make relative externality comparisons when there are choices and use some personal judgment after gathering as much information as tenable. This is what everyone is doing here on GBA when they recommend against using XPS—assuming that it has a non-zero externality based on GWP, and additionally a higher externality than the alternatives. It's an easy choice in that case.
This is what I am asserting with solar. When comparing ballpark costs of installing solar vs certain envelope improvements, one might make some judgments as to the relative externalities between those choices. I believe solar has relatively higher externalities (perhaps more so into the future, but this is a grey area) than something like increasing insulation (low carbon insulation). The question is 'how much' and therefore how much more would I spend on insulation vs solar in the name of the environment. I think the goal posts will be in constant flux on that question. I'm waiting for AI to come and help us with these questions. (Too dystopian?)
When speaking about externalities there are either positive or negative so it helps to indicate which. I still don't know what externalities you're talking about which is why I asked. I assumed you meant a negative externality because usually whenever someone mentions a product made in China is has a negative connotation.
AI will never supplant the price discovery mechanism. It just can't because humans are too complex and they alone determine which behavior is/is not rational.
John,
I'm far from an economics expert, so forgive this wiki link:
https://en.wikipedia.org/wiki/Price_discovery
In it it says:
"The futures and options market serve important functions of price discovery.[citation needed] The individuals with better information and judgement participate in these markets to take advantage of such information."
It already involves human speculation based on information. My mention of AI is to say that compiling and processing all the relevant information for true cost pricing may be above the capacity most humans have. Just because the word 'mechanism' appears in the phrase "price discovery mechanism" does not mean it produces perfect results in regards to proper pricing of human activity on this planet. I know some people push back against this on virtue (hence why I mentioned the zealotry) but I'm sorry, we need to move past this.
I have no general beef with China and don't use it as a generic slight.
I'll have to come back to address the solar externalities because I don't have time to properly address it. Frankly, I think there is some disingenuousness on this front (0ne could easily google such things and come up with loads of information without asking me to type it all here), but such assumptions have made an ass of me before, so...
The production of solar panels requires a lot of energy and can produce a lot of pollution.
They're also highly subsidized.
The adage of "no such thing as a free lunch" applies.
I have heard from multiple sources that PV panels pay their carbon debt in about 2 years of operation. I don't have the source data so I don't know how broad the LCA was. But what other energy-generating devices pay their carbon debt at all? Most just keep accumulating it.
I have also heard numbers close to that (a bit longer I have heard, but it depends of course, ).
I think that is overall great news, but somewhat of an over simplification regarding whether one should simply 'add more solar' as a solution to offsetting environmental impacts.
The issues I wonder about:
The first are those externalities I refused to list in thinking they were self evident. Think mining. Think waste stream. These are not insignificant when we start talking about generating all of our energy via renewables.
There is also the 'Energy Invested' in solar (the EI in EROEI) that has externalities; so once again $ROI is lacking, but carbon payback does account for that.
There is also a land use issue, but if anything that's an argument in favor of putting the panels on the roof.
The other question is one of future costs. As far as I can tell, we don't really know how we're going to operate a grid entirely on renewables. We likely will need breakthroughs in energy storage. Putting solar on the roof inherently doesn't help with this, and means 'some' cost of storage/batteries should perhaps be included on the balance when making investment decisions at build time.
Increasing building thermal resilience arguably does help this future resilience, especially if/when heating becomes predominantly electric.
None of this is to say I think solar on roofs is bad. At all. And frankly, I couldn't run the analysis I'm claiming one 'should' run. It's just food for thought. There's enough bouncing around in my brain along these lines that I feel comfortable leaning a bit heavier into insulation and other resiliency/reduction measures rather than simply adding more generation when it becomes monetarily advantageous.
But obviously at some point, it makes sense to stop insulating and invest elsewhere.
Tyler, all good points. I'd argue that increasing building thermal performance to increase future resilience is not an arguable point, but I know someone will say it is. Otherwise I agree with you. And I'll keep recommended PV panels until someone convinces me that there's a better option.
This thread has been fascinating to read through. The entire time I've been insulating my basement with rigid I haven't been able to stop wondering if what I'm putting into it is actually any better for the environment than the energy loss it would experience if I left it alone. All the plastic, foam, foam cans, various containers, straws, vinyl tubing, trips to Home Depot, rubber, tape, and whatever else I've used probably consume way more fossil fuel in their manufacture than my little 1500 sf basement will lose it its lifetime.
Yes, this is a perfectly valid question(s). I've kind of brought this up (in other arenas) regarding POV emissions; increased emission controls result in gummed up components (I've been hands-on here, so it's more than just a "concept") requiring cleaning and or replacement. What exactly are these costs? We tend to externalize a lot of stuff, either by way of marketing hype or by ignorance (we can't know everything!). I'm neutral on everything, wanting to see as much data as possible before making a choice. I never really switched to CFLs (only ever having a few of them- I tend to have lights on only when they're needed- reduce consumption first!) and after it became clear that they were horrible for the environment I was glad I avoided them. I'm a bit more warmed up to LEDs, but I don't figure they're going to "save" the planet. AND, will we one day learn of some undisclosed disaster lurking under their cover?
And regards to saving the planet... As long as our social model is that of promoting continual growth it is a certainty that we will fail no matter what levels of recyclables and efficiency we achieve. Jevons Paradox tells us that efficiency means we become more efficient with consuming a resource: ultimately it comes down to energy; as long as we perpetuate growth we will come to the point of maxing out on available "renewable" energy; at some point growth WILL have to cease. Any engineer that doesn't understand the exponential function should hang up their degree.
In another thread someone was talking about spending $40k on windows. My budget could only manage to buy and store them. For sure, though, folks buying such are helping producers design more affordable products for a larger percentage of the population (this will run into the growth wall, the only debatable point is WHEN). I can't help but think about all the people who are being dumped out into the streets (in the US). There's a disconnect that I'm struggling with.
Well said Mark.
You are expressing points/concerns I was also trying (struggling perhaps) to make.