“Study group” – resilient design.
I have been thinking about the “pretty good house” (PGH) concept lately and also about “resilient design”.
I find it helpful to think of resilient design in terms of “risk management”.
From a risk management perspective, much of what is already considered in the design process can be called “resilient design”…
For example, bulk water intrusion into an assembly represents an identified risk that many designers mitigate by specifying appropriate flashing details.
From a risk management perspective then, “resilient design” isn’t something new that needs to be considered…
It is something familiar that simply needs to be expanded upon so as to (hopefully) ensure the relevance of an enclosure well into the future.
Given the flexibility of the PGH concept, it seems like this might be a good opportunity to include this expanded form of risk management into all climates.
For the purposes of any further discussion, some clarification:
A risk like potential damage due to the air transport of water vapour is inherent to the house – the risk exists only because of the existance of the house.
Risks like tornadoes, heavy rains, earthquakes or energy scarcity are external to the house.
Within the realm of external risk, I would like to differentiate between:
1. Risk inherent to a specific climate zone (regardless of geographic region) – ie: seasonal potential for extreme heat or cold.
2. Other risk inherent to a specific geographic region – floods, tornadoes, wildfires etc.
At the moment, I am primarily interested in identifying climate specific risks.
Normally, an enclosure shelters its occupants from the surrounding climate through the maintenance of an artificial environment.
However, during periods of prolonged grid failure, maintenance of the artificial environment may be difficult or impossible and risk from the surrounding climate intrudes.
I see this problem as developing a “grid-failure mode” for various climate zones.
Two questions:
What are the risks associated with specific climate zones?
What would be required to keep a house “livable” (not necessarily comfortable) in a “grid-failure mode” for each specific climate – ie: what strategies can be used to mitigate climate specific risk?
I have some ideas for very cold climates, but all climate zones are welcome.
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Replies
Lucas,
Your question is long, but it can easily be reduced: How did people live before the invention of the electrical grid? The answer is all around you...
Maybe it is just seasonal potential for extreme heat or cold that presents the main risk from a specific climate zone...
For very cold climates, I think the SunRise Home is a pretty good model - at the extreme end of the spectrum - for what I am thinking about.
Possibly the basic recipe for a "grid failure mode" in all climates revolves around:
1. Best possible passive solar design.
2. A "pretty good" envelope.
Then for heating climates...
Evaluate a rough minimum amount of additional energy input required to keep things "livable" - ie: interior temperature set point of say 10C/50F...
Determine what the most appropriate means of delivering that energy is and incorporate that into the overall design.
Martin,
Yes, you are right, that is the shorter version.
In Alaska, one can live like the Inuit...
Or purchase a house something like SunRise Home.
Or take your chances that the grid will never suffer a protracted failure during a time of seasonal extremes...
I have my doubts that most people these days would want to (or could even if they wanted to) live like the indigenous people that came before us - or even like our great, great grandparents did.
Lucas,
Your wrote, "In Alaska, one can live like the Inuit. Or purchase a house something like SunRise Home."
Actually, there are other possible ways to live off the grid in Alaska. Many off-grid Alaskans (for at least the last 150 years) have lived in log cabins heated with a wood stove. Such a home will do just fine during the time frames you are worried about: "periods of prolonged grid failure."
If I'm already misunderstanding the scope of this thread, I can retract my question--but I do think Lucas's OP and Martin's abridged version are two separate points. Aren't we now talking about planning for the future, instead, and shouldn't we bear in mind things like population density and its effects on resource usage and availability?
In my urban neighborhood, there's only one house with a pellet/cob/something stove that I've ever found, and I'm sure it's cheap and it keeps that house plenty warm and the owner will be able to afford to heat that house well into retirement--but I can tell six blocks away when I'm biking if it's fired up.
Minneapolis,
Your point is well taken. I didn't bring up Alaska first; Lucas did.
What I meant by my simplified question was to remind those who are worried whether it's possible to live during periods when the grid is down that people lived that way for thousands of years.
If we anticipate that the grid might be down for a month, I think there are many neighborhoods where the use of a wood stove would probably be the best way to get through such a month.
If you anticipate a future in which the grid is down for 20 or 30 years, then wood stoves might be a more noxious method of heating.
Okay, grid failure: I'd think access to potable water would be somewhere at the top of the list. And if a 500-year weather event is looming, isn't much of this irrelevant?
I'm not trying to be a smart ass, but it does seem to me that planning to manage risk can be done only if the extent, severity, and likelihood of the risk is first factored into the equation as a boundary for discussion.
Ok,
To clarify:
I have already narrowed the scope of this discussion in the OP to "climate specific risks" - 500 year weather events are not specific to any climate.
I am not advocating an off-grid existance for everyone.
Nor am I advocating the option of biomass combustion for everyone in a heating climate.
What I am advocating is that an expanded view of risk ought to be factored into PGH design.
I am also suggesting that a PGH in any climate that has the potential to experience seasonal extremes in temperature ought to have at least limited capacity to "survive" an extended power-outage.
It is often the case that where public safety is a concern, mitigation is prescribed by legislation despite the relatively low odds of occurance of a particular risk.
Try to think of the last time you saw an air mask dangling in front of you on an airplane - you may never have, but if you did you may have been happy it was there.
Seasonal temperature extremes are a reality and so are protracted grid failures.
Considering the implications, it does not seem unreasonable to consider what might be done in terms of mitigating against these risks.
Remember, I'm trying to discuss design considerations related to the PGH concept - not for the building code.
Something I've noticed in my area lately is a large number of grid-tied PV installations in people's yards and on their roof-tops (courtesy of the feed-in tarrif program Microfit).
Also, I can't help but notice that the majority of these installations are atop or outside houses that probably would not qualify as "pretty good".
In terms of allocation of resources, I can't help but wonder if it would be better to incentivise efficiency upgrades for those houses including smaller renewable energy systems that could serve to provide at least a portion of the energy required to maintain a "livable" interior environment.
Martin,
Yes, people got by in the past - it's true.
But things are different now...
People who lived in extreme climate zones prior to the electric grid were in a better position do do so in the past.
There were fewer people, more wood, and generally people would have been better prepared (they would have already gotten their wood before winter).
The big ice storm of 1998 may provide a good example of how this type of scenario might play out these days.
In this example, I'm not-so-interested in how the grid was knocked out, but more in what happend after the power went out.
Lucas,
You wrote, "In this example [the Quebec ice storm of 1998], I'm not-so-interested in how the grid was knocked out, but more in what happened after the power went out."
Here's what happened: Houses with wood stoves did better than houses without wood stoves.
This is something that I hear from my clients quite a lot, what if....?
Since we are a rural area in zone 6, these strategies always include some sort of bio-mass heating system, but the key is complete, efficient combustion just as in hydrocarbon based heating systems and some sort of thermal mass to mitigate temperature swings. This system is supplemented with solar heat gain, but often the sun does not shine when it is coldest.
Modern humans need electricity, so we always include a strategy for generating and storing electricity. This can be as simple as a 500 watt inverter that can be fed into the main panel with a spdt switch and supplied by a car battery.
In our beautiful, bucolic mountain valley, food and water are abundant, so these are not complex issues to solve, but in cities where people are disconnected from their food and water supplies, I don't know what would happen.
Martin I think what Lucas is asking for is what you or others think would be design minimums or requirements. Things that make a house livable if the homeowner/buyer doesn't get their wood in time in the case of a freak storm or at all in the case of someone who doesn't feel like hauling wood. Also you could suggest that all houses to be called a PGH should have passive solar design (to use less wood to heat) . You could also suggest that when people think about house orientation on their lot they avoid a pump up type septic system or hopefully their sewer line (in town houses) is gravity to the road. A house would be pretty unlivable with sewage backing up in the house without power even if they had wood for their stove. My point in this answer is we have been through a few ice storms and extended power outages in northeast and Lucas is right to ask about making sure a house is livable without power. My inlaws left their house because no power and it froze up in 2 days. So if no one is their to put wood on the fire, if they have wood and if they have a stove, a house designed correctly should be able to survive on it's own. I love wood stoves Martin but not everybody is going to have one, but everyone needs a safe place to live.
Bill and Michael,
Thanks very much for the constructive replies.
Michael,
You understand what I am saying.
Everybody does need a safe place to live.
And people spend a lot of money buying a new house - not to mention all the material resources that get comitted.
It would be a shame to see a bunch of new "pretty good" houses become a bunch of "pretty good" stranded assets.
Also, that's a good point about ejection pumps - probably a "pretty good" idea to have at least one toilet in the house that gravity feeds into the septic or sewer line.
Michael,
Your suggestion concerning sewage pumps is a good one. I agree -- gravity feed is best.
As long as we are developing a list of the characteristics of the perfect house to survive an ice storm, I would suggest choosing property with a gravity-fed spring uphill from the house.
Superinsulated houses with low levels of air leakage -- a type of construction that GBA has consistently advocated -- are far less likely to have frozen pipes, even when unheated, than conventional homes.
And I would advise anyone worried about power outages to have a cord of firewood handy, because you don't really want to be scrounging for fuel in an emergency.
Martin,
Thanks for contributing.
But to clarify once again, I'm interested in more than just a "list of the characteristics of the perfect house to survive an ice storm".
Lists are necessary but so is perspective.
I'm really interested in seeing the adoption of an expanded view of risk in building design.
A change in perspective can apply across all climate zones.
Complexity breeds risk.
And the world around the houses we build is not getting any less complex over time.
Any new house will hopefully still be in use 50 or more years from now so to me it makes some sense to try to continuously enhance perspective.
I think from the discussion so far, I am able to rephrase my original question to some extent:
How can homes in all climate zones be designed so as to take into account risk associated with grid outages?
Lucas,
I think that many respondents have provided useful answers to your question ("How can homes in all climate zones be designed so as to take into account risk associated with grid outages?")
The provided answers:
1. Include a wood stove.
2. Provide a woodshed to store a cord of firewood.
3. If possible, don't choose a septic system that requires a sewage pump.
4. If possible, choose a water source that allows gravity feed to the house.
5. Build a thermal envelope with a low air leakage rate and high R-values.
Ok Martin.